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Sample records for complement virus opsonization

  1. Complement Opsonization Promotes Herpes Simplex Virus 2 Infection of Human Dendritic Cells

    PubMed Central

    Ellegård, Rada; Nyström, Sofia; Rondahl, Elin; Serrander, Lena; Bergström, Tomas; Sjöwall, Christopher; Eriksson, Kristina

    2016-01-01

    ABSTRACT Herpes simplex virus 2 (HSV-2) is one of the most common sexually transmitted infections globally, with a very high prevalence in many countries. During HSV-2 infection, viral particles become coated with complement proteins and antibodies, both present in genital fluids, which could influence the activation of immune responses. In genital mucosa, the primary target cells for HSV-2 infection are epithelial cells, but resident immune cells, such as dendritic cells (DCs), are also infected. DCs are the activators of the ensuing immune responses directed against HSV-2, and the aim of this study was to examine the effects opsonization of HSV-2, either with complement alone or with complement and antibodies, had on the infection of immature DCs and their ability to mount inflammatory and antiviral responses. Complement opsonization of HSV-2 enhanced both the direct infection of immature DCs and their production of new infectious viral particles. The enhanced infection required activation of the complement cascade and functional complement receptor 3. Furthermore, HSV-2 infection of DCs required endocytosis of viral particles and their delivery into an acid endosomal compartment. The presence of complement in combination with HSV-1- or HSV-2-specific antibodies more or less abolished HSV-2 infection of DCs. Our results clearly demonstrate the importance of studying HSV-2 infection under conditions that ensue in vivo, i.e., conditions under which the virions are covered in complement fragments and complement fragments and antibodies, as these shape the infection and the subsequent immune response and need to be further elucidated. IMPORTANCE During HSV-2 infection, viral particles should become coated with complement proteins and antibodies, both present in genital fluids, which could influence the activation of the immune responses. The dendritic cells are activators of the immune responses directed against HSV-2, and the aim of this study was to examine the

  2. Differential activity of candidate microbicides against early steps of HIV-1 infection upon complement virus opsonization

    PubMed Central

    2010-01-01

    Background HIV-1 in genital secretions may be opsonized by several molecules including complement components. Opsonized HIV-1 by complement enhances the infection of various mucosal target cells, such as dendritic cells (DC) and epithelial cells. Results We herein evaluated the effect of HIV-1 complement opsonization on microbicide candidates' activity, by using three in vitro mucosal models: CCR5-tropic HIV-1JR-CSF transcytosis through epithelial cells, HIV-1JR-CSF attachment on immature monocyte-derived dendritic cells (iMDDC), and infectivity of iMDDC by CCR5-tropic HIV-1BaL and CXCR4-tropic HIV-1NDK. A panel of 10 microbicide candidates [T20, CADA, lectines HHA & GNA, PVAS, human lactoferrin, and monoclonal antibodies IgG1B12, 12G5, 2G12 and 2F5], were investigated using cell-free unopsonized or opsonized HIV-1 by complements. Only HHA and PVAS were able to inhibit HIV trancytosis. Upon opsonization, transcytosis was affected only by HHA, HIV-1 adsorption on iMDDC by four molecules (lactoferrin, IgG1B12, IgG2G5, IgG2G12), and replication in iMDDC of HIV-1BaL by five molecules (lactoferrin, CADA, T20, IgG1B12, IgG2F5) and of HIV-1NDK by two molecules (lactoferrin, IgG12G5). Conclusion These observations demonstrate that HIV-1 opsonization by complements may modulate in vitro the efficiency of candidate microbicides to inhibit HIV-1 infection of mucosal target cells, as well as its crossing through mucosa. PMID:20546571

  3. Opsonization of HIV with complement enhances infection of dendritic cells and viral transfer to CD4 T cells in a CR3 and DC-SIGN-dependent manner.

    PubMed

    Bouhlal, Hicham; Chomont, Nicolas; Réquena, Mary; Nasreddine, Nadine; Saidi, Héla; Legoff, Jérôme; Kazatchkine, Michel D; Bélec, Laurent; Hocini, Hakim

    2007-01-15

    In the present study, we demonstrated that opsonization of primary HIV-1 with human complement enhances infection of immature monocyte-derived dendritic cells (iDC) and transmission in trans of HIV to autologous CD4(+) T lymphocytes. Infection of iDC by opsonized primary R5- and X4-tropic HIV was increased 3- to 5-fold as compared with infection by the corresponding unopsonized HIV. Enhancement of infection was dependent on CR3 as demonstrated by inhibition induced by blocking Abs. The interaction of HIV with CCR5 and CXCR4 on iDC was affected by opsonization. Indeed, stromal-derived factor-1 was more efficient in inhibiting infection of iDC with opsonized R5-tropic HIV-1(BaL) (45%) than with heat-inactivated complement opsonized virus and similarly RANTES inhibited more efficiently infection of iDC with opsonized X4-tropic HIV-1(NDK) (42%) than with heat-inactivated complement opsonized virus. We also showed that attachment of complement-opsonized virus to DC-specific ICAM-grabbing nonintegrin (DC-SIGN) molecule on iDC and HeLa DC-SIGN(+) CR3(-) cells was 46% and 50% higher compared with heat-inactivated complement opsonized virus, respectively. Hence, Abs to DC-SIGN suppressed up to 80% and 60% the binding of opsonized virus to HeLa cells and iDC, respectively. Furthermore, Abs to DC-SIGN inhibited up to 70% of the infection of iDC and up to 65% of infection in trans of autologous lymphocytes with opsonized virus. These results further demonstrated the role of DC-SIGN in complement opsonized virus uptake and infection. Thus, the virus uses complement to its advantage to facilitate early steps leading to infection following mucosal transmission of HIV.

  4. Impaired NK Cell Activation and Chemotaxis toward Dendritic Cells Exposed to Complement-Opsonized HIV-1.

    PubMed

    Ellegård, Rada; Crisci, Elisa; Andersson, Jonas; Shankar, Esaki M; Nyström, Sofia; Hinkula, Jorma; Larsson, Marie

    2015-08-15

    Mucosa resident dendritic cells (DCs) may represent one of the first immune cells that HIV-1 encounters during sexual transmission. The virions in body fluids can be opsonized with complement factors because of HIV-mediated triggering of the complement cascade, and this appears to influence numerous aspects of the immune defense targeting the virus. One key attribute of host defense is the ability to attract immune cells to the site of infection. In this study, we investigated whether the opsonization of HIV with complement (C-HIV) or a mixture of complement and Abs (CI-HIV) affected the cytokine and chemokine responses generated by DCs, as well as their ability to attract other immune cells. We found that the expression levels of CXCL8, CXCL10, CCL3, and CCL17 were lowered after exposure to either C-HIV or CI-HIV relative to free HIV (F-HIV). DCs exposed to F-HIV induced higher cell migration, consisting mainly of NK cells, compared with opsonized virus, and the chemotaxis of NK cells was dependent on CCL3 and CXCL10. NK cell exposure to supernatants derived from HIV-exposed DCs showed that F-HIV induced phenotypic activation (e.g., increased levels of TIM3, CD69, and CD25) and effector function (e.g., production of IFNγ and killing of target cells) in NK cells, whereas C-HIV and CI-HIV did not. The impairment of NK cell recruitment by DCs exposed to complement-opsonized HIV and the lack of NK activation may contribute to the failure of innate immune responses to control HIV at the site of initial mucosa infection.

  5. Complement-Opsonized HIV-1 Overcomes Restriction in Dendritic Cells

    PubMed Central

    Posch, Wilfried; Steger, Marion; Knackmuss, Ulla; Blatzer, Michael; Baldauf, Hanna-Mari; Doppler, Wolfgang; White, Tommy E.; Hörtnagl, Paul; Diaz-Griffero, Felipe; Lass-Flörl, Cornelia; Hackl, Hubert; Moris, Arnaud; Keppler, Oliver T.; Wilflingseder, Doris

    2015-01-01

    DCs express intrinsic cellular defense mechanisms to specifically inhibit HIV-1 replication. Thus, DCs are productively infected only at very low levels with HIV-1, and this non-permissiveness of DCs is suggested to go along with viral evasion. We now illustrate that complement-opsonized HIV-1 (HIV-C) efficiently bypasses SAMHD1 restriction and productively infects DCs including BDCA-1 DCs. Efficient DC infection by HIV-C was also observed using single-cycle HIV-C, and correlated with a remarkable elevated SAMHD1 T592 phosphorylation but not SAMHD1 degradation. If SAMHD1 phosphorylation was blocked using a CDK2-inhibitor HIV-C-induced DC infection was also significantly abrogated. Additionally, we found a higher maturation and co-stimulatory potential, aberrant type I interferon expression and signaling as well as a stronger induction of cellular immune responses in HIV-C-treated DCs. Collectively, our data highlight a novel protective mechanism mediated by complement opsonization of HIV to effectively promote DC immune functions, which might be in the future exploited to tackle HIV infection. PMID:26121641

  6. Staphylococcal protein Ecb impairs complement receptor-1 mediated recognition of opsonized bacteria

    PubMed Central

    Amdahl, Hanne; Tan, Lydia; Meri, Taru; Kuusela, Pentti I.; van Strijp, Jos A.

    2017-01-01

    Staphyloccus aureus is a major human pathogen leading frequently to sepsis and soft tissue infections with abscesses. Multiple virulence factors including several immune modulating molecules contribute to its survival in the host. When S. aureus invades the human body, one of the first line defenses is the complement system, which opsonizes the bacteria with C3b and attract neutrophils by release of chemotactic peptides. Neutrophils express Complement receptor-1 [CR1, CD35) that interacts with the C3b-opsonized particles and thereby plays an important role in pathogen recognition by phagocytic cells. In this study we observed that a fraction of S. aureus culture supernatant prevented binding of C3b to neutrophils. This fraction consisted of S. aureus leukocidins and Efb. The C-terminus of Efb is known to bind C3b and shares significant sequence homology to the extracellular complement binding protein [Ecb). Here we show that S. aureus Ecb displays various mechanisms to block bacterial recognition by neutrophils. The presence of Ecb blocked direct interaction between soluble CR1 and C3b and reduced the cofactor activity of CR1 in proteolytic inactivation of C3b. Furthermore, Ecb could dose-dependently prevent recognition of C3b by cell-bound CR1 that lead to impaired phagocytosis of NHS-opsonized S. aureus. Phagocytosis was furthermore reduced in the presence of soluble CR1 [sCR1). These data indicate that the staphylococcal protein Ecb prevents recognition of C3b opsonized bacteria by neutrophil CR1 leading to impaired killing by phagocytosis and thereby contribute to immune evasion of S. aureus. PMID:28273167

  7. Myeloperoxidase reduces the opsonizing activity of immunoglobulin G and complement component C3b.

    PubMed

    Coble, B I; Dahlgren, C; Hed, J; Stendahl, O

    1984-12-20

    The effect of myeloperoxidase, hydrogen peroxide (H2O2) and a halide (Cl) on the opsonizing molecules in immunoglobulin G (IgG) and complement factor C3b was assayed. At concentrations of the enzyme (1 microgram/ml) that can be found in the extracellular fluid during inflammation, the myeloperoxidase-H2O2-Cl system inhibited the opsonizing effect of IgG and C3b measured as phagocytic uptake and superoxide generation. The effect was related to the enzymatic peroxidative activity of the protein. The presence of albumin (10 mg/ml) reduced the effect of myeloperoxidase with 10-20%. Taurine, which in the presence of myeloperoxidase-H2O2-Cl forms hydrophilic chloramines, and D-penicillamine, which scavenges HOCl, neutralize the inhibitory effect of myeloperoxidase. This suggests that either hypochlorous acid or lipophilic chloramines may exert its effect by oxidizing free sulphydryl groups exposed on the opsonizing ligands. Since the myeloperoxidase-H2O2-halide system also affects chemotactic factors, leukotrienes, proteinases and membrane receptors, the system may in several ways affect the development of the inflammatory response.

  8. In Vitro and In Vivo Differences in Murine Third Complement Component (C3) Opsonization and Macrophage/Leukocyte Responses to Antibody-Functionalized Iron Oxide Nanoworms

    PubMed Central

    Wang, Guankui; Griffin, James I.; Inturi, Swetha; Brenneman, Barbara; Banda, Nirmal K.; Holers, V. Michael; Moghimi, Seyed Moein; Simberg, Dmitri

    2017-01-01

    Balancing surface functionalization and low immune recognition of nanomedicines is a major challenge. Opsonization with the third component of the complement protein (C3) plays a major role in immune cell recognition of nanomedicines. We used dextran-coated superparamagnetic iron oxide nanoworms (SPIO NWs) to study the effect of surface functionalization on C3 opsonization in mouse serum and subsequent macrophage/leukocyte recognition in vitro as well as on intravenous injection into mice. Previously, we found that in mouse serum, SPIO NWs became opsonized with C3 via complement lectin pathway. Crosslinking the dextran shell with epichlorohydrin significantly decreased C3 opsonization and uptake by mouse peritoneal macrophages. Crosslinked nanoworms (NWs) further functionalized with polyethylene glycol (PEG) or with PEG-antibody (Ab) (~160 IgG molecules/particle) did not show an increase in C3 opsonization and peritoneal macrophage uptake in vitro. Following tail vein injection into mice, plain crosslinked NWs and PEGylated crosslinked NWs showed very low C3 opsonization and mouse leukocyte uptake. However, Ab-decorated crosslinked NWs showed significant C3 opsonization and high level of complement-dependent uptake by leukocytes in mice. Decreasing the number of conjugated Abs to 46 IgG molecules/particle significantly reduced C3 opsonization and leukocyte uptake. Using fresh mouse lepirudin plasma rather than serum showed better correlation with C3 opsonization in vivo. The reason for this difference could be related to the known instability of complement classical pathway in mouse sera. Our data illustrate that fine-tuning in nanoparticle surface functionalization with Abs is required to avoid excessive complement activation and complement-mediated immune uptake in mice, and raise issues with in vitro immunological assays of nanomedicines intended to mimic in vivo conditions. PMID:28239384

  9. Preliminary characterization of complement in a colonial tunicate: C3, Bf and inhibition of C3 opsonic activity by compstatin.

    PubMed

    Franchi, Nicola; Ballarin, Loriano

    2014-10-01

    The complement system is a fundamental effector mechanism of the innate immunity in both vertebrates and invertebrates. The comprehension of its roots in the evolution is a useful step to understand how the main complement-related proteins had changed in order to adapt to new environmental conditions and life-cycles or, in the case of vertebrates, to interact with the adaptive immunity. Data on organisms evolutionary close to vertebrates, such as tunicates, are of primary importance for a better understanding of the changes in immune responses associated with the invertebrate-vertebrate transition. Here we report on the characterization of C3 and Bf transcripts from the colonial ascidian Botryllus schlosseri (BsC3 and BsBf, respectively), a reliable model organism for immunobiological research, and present a comparative analysis of amino acid sequences of C3s and Bfs suggesting that, in deuterostomes, the structure of these proteins remained largely unchanged. We also present new data on the cells responsible of the expression of BsC3 and BsBf showing that cytotoxic immunocytes are the sole cells where the relative transcripts can be found. Finally, using the C3 specific inhibitor compstatin, we demonstrate the opsonic role of BsC3 in accordance with the idea that promotion of phagocytosis is one of the main function of C3 in metazoans.

  10. Ectromelia virus inhibitor of complement enzymes protects intracellular mature virus and infected cells from mouse complement.

    PubMed

    Moulton, Elizabeth A; Bertram, Paula; Chen, Nanhai; Buller, R Mark L; Atkinson, John P

    2010-09-01

    Poxviruses produce complement regulatory proteins to subvert the host's immune response. Similar to the human pathogen variola virus, ectromelia virus has a limited host range and provides a mouse model where the virus and the host's immune response have coevolved. We previously demonstrated that multiple components (C3, C4, and factor B) of the classical and alternative pathways are required to survive ectromelia virus infection. Complement's role in the innate and adaptive immune responses likely drove the evolution of a virus-encoded virulence factor that regulates complement activation. In this study, we characterized the ectromelia virus inhibitor of complement enzymes (EMICE). Recombinant EMICE regulated complement activation on the surface of CHO cells, and it protected complement-sensitive intracellular mature virions (IMV) from neutralization in vitro. It accomplished this by serving as a cofactor for the inactivation of C3b and C4b and by dissociating the catalytic domain of the classical pathway C3 convertase. Infected murine cells initiated synthesis of EMICE within 4 to 6 h postinoculation. The levels were sufficient in the supernatant to protect the IMV, upon release, from complement-mediated neutralization. EMICE on the surface of infected murine cells also reduced complement activation by the alternative pathway. In contrast, classical pathway activation by high-titer antibody overwhelmed EMICE's regulatory capacity. These results suggest that EMICE's role is early during infection when it counteracts the innate immune response. In summary, ectromelia virus produced EMICE within a few hours of an infection, and EMICE in turn decreased complement activation on IMV and infected cells.

  11. TRIM21 Promotes cGAS and RIG-I Sensing of Viral Genomes during Infection by Antibody-Opsonized Virus

    PubMed Central

    Watkinson, Ruth E.; McEwan, William A.; Tam, Jerry C. H.; Vaysburd, Marina; James, Leo C.

    2015-01-01

    Encapsidation is a strategy almost universally employed by viruses to protect their genomes from degradation and from innate immune sensors. We show that TRIM21, which targets antibody-opsonized virions for proteasomal destruction, circumvents this protection, enabling the rapid detection and degradation of viral genomes before their replication. TRIM21 triggers an initial wave of cytokine transcription that is antibody, rather than pathogen, driven. This early response is augmented by a second transcriptional program, determined by the nature of the infecting virus. In this second response, TRIM21-induced exposure of the viral genome promotes sensing of DNA and RNA viruses by cGAS and RIG-I. This mechanism allows early detection of an infection event and drives an inflammatory response in mice within hours of viral challenge. PMID:26506431

  12. Incorporation of Host Complement Regulatory Proteins into Newcastle Disease Virus Enhances Complement Evasion

    PubMed Central

    Biswas, Moanaro; Johnson, John B.; Kumar, Sandeep R. P.; Parks, Griffith D.

    2012-01-01

    Newcastle disease virus (NDV), an avian paramyxovirus, is inherently tumor selective and is currently being considered as a clinical oncolytic virus and vaccine vector. In this study, we analyzed the effect of complement on the neutralization of NDV purified from embryonated chicken eggs, a common source for virus production. Fresh normal human serum (NHS) neutralized NDV by multiple pathways of complement activation, independent of neutralizing antibodies. Neutralization was associated with C3 deposition and the activation of C2, C3, C4, and C5 components. Interestingly, NDV grown in mammalian cell lines was resistant to complement neutralization by NHS. To confirm whether the incorporation of regulators of complement activity (RCA) into the viral envelope afforded complement resistance, we grew NDV in CHO cells stably transfected with CD46 or HeLa cells, which strongly express CD46 and CD55. NDV grown in RCA-expressing cells was resistant to complement by incorporating CD46 and CD55 on virions. Mammalian CD46 and CD55 molecules on virions exhibited homologous restriction, since chicken sera devoid of neutralizing antibodies to NDV were able to effectively neutralize these virions. The incorporation of chicken RCA into NDV produced in embryonated eggs similarly provided species specificity toward chicken sera. PMID:22973037

  13. Complement Component 3 Regulates IFN-α Production by Plasmacytoid Dendritic Cells following TLR7 Activation by a Plant Virus-like Nanoparticle.

    PubMed

    Lebel, Marie-Ève; Langlois, Marie-Pierre; Daudelin, Jean-François; Tarrab, Esther; Savard, Pierre; Leclerc, Denis; Lamarre, Alain

    2017-01-01

    The increasing use of plant viruses for the development of new vaccines and immunotherapy approaches poses questions regarding the mechanism by which the mammalian immune system recognizes these viruses. For example, although natural Abs (NA) and complement are key components of the innate immune system involved in the opsonization, phagocytosis, and destruction of microorganisms infecting mammals, their implication in plant virus recognition and immunogenicity is not well defined. In this study, we address the involvement of NA and the complement system in the activation of innate immunity through engagement of TLR7 with papaya mosaic virus (PapMV)-like nanoparticles. We demonstrate that NA, although binding to PapMV, are not involved in its recognition by the immune system. On the other hand, C3 strongly binds to PapMV nanoparticles and its depletion significantly reduces PapMV's interaction with immune cells. Unexpectedly, however, we observed increased immune cell activation following administration of PapMV to complement-depleted mice. TLR7 activation by PapMV in the absence of C3 induced higher IFN-α production, resulting in superior immune cell activation and increased immunotherapeutic properties. In conclusion, in this study we established the involvement of the complement system in the recognition and the phagocytosis of PapMV nanoparticles and identified an unsuspected role for C3 in regulating the production of IFN-α following TLR7 activation.

  14. Identification of hot spots in the variola virus complement inhibitor (SPICE) for human complement regulation.

    PubMed

    Yadav, Viveka Nand; Pyaram, Kalyani; Mullick, Jayati; Sahu, Arvind

    2008-04-01

    Variola virus, the causative agent of smallpox, encodes a soluble complement regulator named SPICE. Previously, SPICE has been shown to be much more potent in inactivating human complement than the vaccinia virus complement control protein (VCP), although they differ only in 11 amino acid residues. In the present study, we have expressed SPICE, VCP, and mutants of VCP by substituting each or more of the 11 non-variant VCP residues with the corresponding residue of SPICE to identify hot spots that impart functional advantage to SPICE over VCP. Our data indicate that (i) SPICE is approximately 90-fold more potent than VCP in inactivating human C3b, and the residues Y98, Y103, K108 and K120 are predominantly responsible for its enhanced activity; (ii) SPICE is 5.4-fold more potent in inactivating human C4b, and residues Y98, Y103, K108, K120 and L193 mainly dictate this increase; (iii) the classical pathway decay-accelerating activity of activity is only twofold higher than that of VCP, and the 11 mutations in SPICE do not significantly affect this activity; (iv) SPICE possesses significantly greater binding ability to human C3b compared to VCP, although its binding to human C4b is lower than that of VCP; (v) residue N144 is largely responsible for the increased binding of SPICE to human C3b; and (vi) the human specificity of SPICE is dictated primarily by residues Y98, Y103, K108, and K120 since these are enough to formulate VCP as potent as SPICE. Together, these results suggest that principally 4 of the 11 residues that differ between SPICE and VCP partake in its enhanced function against human complement.

  15. Complement

    MedlinePlus

    ... fungal infections and some parasitic infections such as malaria . Normal Results Total blood complement level: 41 to ... Glomerulonephritis Hepatitis Hereditary angioedema Kidney transplant Lupus nephritis Malaria Protein in diet Rheumatoid arthritis Septicemia Shock Systemic ...

  16. Opsonic activity of blister fluid from burn patients.

    PubMed Central

    Deitch, E A

    1983-01-01

    The combination of skin loss and immune depression after thermal injury predisposes burn patients to an increased risk of infection. Since the commonest site of infection in the burn patient is the burn wound itself, we elected to study the opsonic activity of locally produced blister fluid, from 18 thermally injured patients, for the two most common organisms colonizing the burn wound (Pseudomonas aeruginosa and Staphylococcus aureus). Blister fluid was as good an opsonin source for staphylococcus as normal serum. In contrast, the blister fluid did not support either the phagocytosis of the intracellular killing of P. aeruginosa. The poor opsonic activity of blister fluid for P. aeruginosa did not appear to be due to the presence of an inhibitory factor(s) since the addition of normal serum restored the opsonic activity of the blister fluid to normal. The concentrations of immunoglobulins and the complement components C3 and C4 in the blister fluid samples were less than half the level of those in normal serum. The opsonic activity of the blister fluid could not be restored to normal by the addition of either immunoglobulin or heat-inactivated serum (56 degrees C for 30 min). Thus, the opsonic factor(s) missing from the blister fluid was heat labile and thus probably represents complement components. That blister fluid had impaired opsonic activity for P. aeruginosa but not for S. aureus indicated that a local humoral defect may be responsible, at least in part, for the high incidence of gram-negative organisms, especially pseudomonads, colonizing the burn wound after thermal injury. PMID:6411619

  17. Complement requirement for virus neutralization by antibody and reduced serum complement levels associated with experimental equine herpesvirus 1 infection.

    PubMed Central

    Snyder, D B; Myrup, A C; Dutta, S K

    1981-01-01

    Pony foals, negative for detectable serum-neutralizing antibody to equine herpesvirus 1 by the standard tube-culture virus neutralization test, were experimentally infected with equine herpesvirus 1. Complement-requiring (CR) and non-complement-requiring (NCR) serum-neutralizing antibodies were evaluated in preinfection and postinfection sera by means of a complement-enhanced plaque reduction assay. Low levels of CR antibodies were found in the preinfection sera of only group II ponies. Upon infection, CR antibodies were detected by day 2 postinfection and reached peak titers between 7 and 14 days postinfection in the antisera of all ponies. NCR antibodies were detected later than CR antibodies and at levels approximately 40 to 150 times lower than the latter. CR/NCR ratios indicated that complement requirement was greatest early in the acute stages of disease and that this requirement decreased during the convalescent phase. Fractionation of 1-week and 2-week postinfection antisera of group I ponies indicated the CR antibody activity resided in both the 7S and 19S fractions. Total serum complement levels of the ponies were quantified throughout the infection with an equine anti-goat erythrocyte hemolytic system. In vivo, complement levels were depressed for all ponies during the first 2 weeks of infection. A decline in complement levels was seen as early as day 2, and they decreased to an average of 35% of preinfection levels on day 10 postinfection for all ponies. PMID:6260672

  18. Septin: a factor in plasma that opsonizes lipopolysaccharide-bearing particles for recognition by CD14 on phagocytes

    PubMed Central

    1992-01-01

    We have previously reported that lipopolysaccharide (LPS) binding protein (LBP) opsonizes endotoxin (LPS) for recognition by CD14 on phagocytes. Here we show that normal human plasma contains high titers of an activity that also binds LPS (Re, 595) and mediates recognition by CD14. Opsonization of LPS-coated particles with plasma enables the particles to be bound by phagocytes. Further, opsonization with plasma also enables subnanogram-per-milliliter concentrations of LPS to induce dramatic alterations in the function of leukocyte integrins on polymorphonuclear leukocytes and to induce secretion of tumor necrosis factor by monocytes, suggesting that opsonization by factors in plasma may be important in responses of cells to endotoxin. The opsonic activity in plasma appears distinct from LBP since it is not blocked by neutralizing antibodies against LBP. Surprisingly, the opsonic activity of plasma is not present in a single protein species, but at least two species must be combined to observe activity. Further, the opsonic activity of plasma for LPS is blocked by addition of protease inhibitors, suggesting that proteolytic activity or activities are required for opsonization. These properties are suggestive of the action of a protease cascade, but opsonic activity of plasma is not affected by blockade or depletion of either the complement or clotting cascades. We propose the name "septin" to describe this novel LPS- opsonizing activity in plasma. PMID:1380975

  19. Complement inhibition enables tumor delivery of LCMV glycoprotein pseudotyped viruses in the presence of antiviral antibodies

    PubMed Central

    Evgin, Laura; Ilkow, Carolina S; Bourgeois-Daigneault, Marie-Claude; de Souza, Christiano Tanese; Stubbert, Lawton; Huh, Michael S; Jennings, Victoria A; Marguerie, Monique; Acuna, Sergio A; Keller, Brian A; Lefebvre, Charles; Falls, Theresa; Le Boeuf, Fabrice; Auer, Rebecca A; Lambris, John D; McCart, J Andrea; Stojdl, David F; Bell, John C

    2016-01-01

    The systemic delivery of therapeutic viruses, such as oncolytic viruses or vaccines, is limited by the generation of neutralizing antibodies. While pseudotyping of rhabdoviruses with the lymphocytic choriomeningitis virus glycoprotein has previously allowed for multiple rounds of delivery in mice, this strategy has not translated to other animal models. For the first time, we provide experimental evidence that antibodies generated against the lymphocytic choriomeningitis virus glycoprotein mediate robust complement-dependent viral neutralization via activation of the classical pathway. We show that this phenotype can be capitalized upon to deliver maraba virus pseudotyped with the lymphocytic choriomeningitis virus glycoprotein in a Fischer rat model in the face of neutralizing antibody through the use of complement modulators. This finding changes the understanding of the humoral immune response to arenaviruses, and also describes methodology to deliver viral vectors to their therapeutic sites of action without the interference of neutralizing antibody. PMID:27909702

  20. Differential mechanisms of complement-mediated neutralization of the closely related paramyxoviruses simian virus 5 and mumps virus

    SciTech Connect

    Johnson, John B.; Capraro, Gerald A.; Parks, Griffith D.

    2008-06-20

    The complement system is an important component of the innate immune response to virus infection. The role of human complement pathways in the in vitro neutralization of three closely related paramyxoviruses, Simian Virus 5 (SV5), Mumps virus (MuV) and Human Parainfluenza virus type 2 (HPIV2) was investigated. Sera from ten donors showed high levels of neutralization against HPIV2 that was largely complement-independent, whereas nine of ten donor sera were found to neutralize SV5 and MuV only in the presence of active complement pathways. SV5 and MuV neutralization proceeded through the alternative pathway of the complement cascade. Electron microscopy studies and biochemical analyses showed that treatment of purified SV5 with human serum resulted in C3 deposition on virions and the formation of massive aggregates, but there was relatively little evidence of virion lysis. Treatment of MuV with human serum also resulted in C3 deposition on virions, however in contrast to SV5, MuV particles were lysed by serum complement and there was relatively little aggregation. Assays using serum depleted of complement factors showed that SV5 and MuV neutralization in vitro was absolutely dependent on complement factor C3, but was not dependent on downstream complement factors C5 or C8. Our results indicate that even though antibodies exist that recognize both SV5 and MuV, they are mostly non-neutralizing and viral inactivation in vitro occurs through the alternative pathway of complement. The implications of our work for development of paramyxovirus vectors and vaccines are discussed.

  1. Monoclonal Antibodies against Epidermal Growth Factor Receptor Acquire an Ability To Kill Tumor Cells through Complement Activation by Mutations That Selectively Facilitate the Hexamerization of IgG on Opsonized Cells.

    PubMed

    Tammen, Annalina; Derer, Stefanie; Schwanbeck, Ralf; Rösner, Thies; Kretschmer, Anna; Beurskens, Frank J; Schuurman, Janine; Parren, Paul W H I; Valerius, Thomas

    2017-02-15

    Triggering of the complement cascade induces tumor cell lysis via complement-dependent cytotoxicity (CDC) and attracts and activates cytotoxic cells. It therefore represents an attractive mechanism for mAb in cancer immunotherapy development. The classical complement pathway is initiated by IgG molecules that have assembled into ordered hexamers after binding their Ag on the tumor cell surface. The requirements for CDC are further impacted by factors such as Ab epitope, valency, and affinity. Thus, mAb against well-validated solid tumor targets, such as the epidermal growth factor receptor (EGFR) that effectively induces complement activation and CDC, are highly sought after. The potency of complement activation by IgG Abs can be increased via several strategies. We identified single-point mutations in the Fc domain (e.g., E345K or E430G) enhancing Fc:Fc interactions, hexamer formation, and CDC after Ab binds cell-surface Ag. We show that EGFR Abs directed against clinically relevant epitopes can be converted into mAb with unprecedented CDC activity. Alternative strategies rely on increasing the affinity of monomeric IgG for C1q by introduction of a quadruple mutation at the C1q binding site or via generation of an IgG1/IgG3 chimera. In this study we show that selective enhancement of C1q binding via avidity modulation is superior to the unattended increase in C1q binding via affinity approaches, particularly for target cells with reduced EGFR expression levels. Improving Fc:Fc interactions of Ag-bound IgG therefore represents a highly promising and novel approach for potentiating the anti-tumor activity of therapeutic mAb against EGFR and potentially other tumor targets.

  2. Dissecting Virus Entry: Replication-Independent Analysis of Virus Binding, Internalization, and Penetration Using Minimal Complementation of β-Galactosidase

    PubMed Central

    Burkard, Christine; Bloyet, Louis-Marie; Wicht, Oliver; van Kuppeveld, Frank J.; Rottier, Peter J. M.; de Haan, Cornelis A. M.; Bosch, Berend Jan

    2014-01-01

    Studies of viral entry into host cells often rely on the detection of post-entry parameters, such as viral replication or the expression of a reporter gene, rather than on measuring entry per se. The lack of assays to easily detect the different steps of entry severely hampers the analysis of this key process in virus infection. Here we describe novel, highly adaptable viral entry assays making use of minimal complementation of the E. coli β-galactosidase in mammalian cells. Enzyme activity is reconstituted when a small intravirion peptide (α-peptide) is complementing the inactive mutant form ΔM15 of β-galactosidase. The method allows to dissect and to independently detect binding, internalization, and fusion of viruses during host cell entry. Here we use it to confirm and extend current knowledge on the entry process of two enveloped viruses: vesicular stomatitis virus (VSV) and murine hepatitis coronavirus (MHV). PMID:25025332

  3. Complement-mediated Opsonization of Invasive Group A Streptococcus pyogenes Strain AP53 Is Regulated by the Bacterial Two-component Cluster of Virulence Responder/Sensor (CovRS) System*

    PubMed Central

    Agrahari, Garima; Liang, Zhong; Mayfield, Jeffrey A.; Balsara, Rashna D.; Ploplis, Victoria A.; Castellino, Francis J.

    2013-01-01

    Group A Streptococcus pyogenes (GAS) strain AP53 is a primary isolate from a patient with necrotizing fasciitis. These AP53 cells contain an inactivating mutation in the sensor component of the cluster of virulence (cov) responder (R)/sensor (S) two-component gene regulatory system (covRS), which enhances the virulence of the primary strain, AP53/covR+S−. However, specific mechanisms by which the covRS system regulates the survival of GAS in humans are incomplete. Here, we show a key role for covRS in the regulation of opsonophagocytosis of AP53 by human neutrophils. AP53/covR+S− cells displayed potent binding of host complement inhibitors of C3 convertase, viz. Factor H (FH) and C4-binding protein (C4BP), which concomitantly led to minimal C3b deposition on AP53 cells, further showing that these plasma protein inhibitors are active on GAS cells. This resulted in weak killing of the bacteria by human neutrophils and a corresponding high death rate of mice after injection of these cells. After targeted allelic alteration of covS− to wild-type covS (covS+), a dramatic loss of FH and C4BP binding to the AP53/covR+S+ cells was observed. This resulted in elevated C3b deposition on AP53/covR+S+ cells, a high level of opsonophagocytosis by human neutrophils, and a very low death rate of mice infected with AP53/covR+S+. We show that covRS is a critical transcriptional regulator of genes directing AP53 killing by neutrophils and regulates the levels of the receptors for FH and C4BP, which we identify as the products of the fba and enn genes, respectively. PMID:23928307

  4. THE COMPLEMENT FIXATION TEST IN THE DIAGNOSIS OF VIRUS INFECTIONS OF THE CENTRAL NERVOUS SYSTEM.

    PubMed

    Casals, J; Palacios, R

    1941-10-31

    A specific complement fixation test can be obtained in various central nervous system virus infections by using as antigens emulsions of infected brain tissue, freezing and thawing the brain emulsion, and then centrifuging it in an angle head centrifuge at 3500 R.P.M. for 1 hour. The method has proved reliable in the case of rabies, St. Louis encephalitis, Japanese B encephalitis, lymphocytic choriomeningitis, Eastern equine encephalomyelitis, Western equine encephalomyelitis, louping ill, and spontaneous encephalomyelitis of mice (Theiler's disease). The specificity of the reaction, regardless of the virus involved, requires different temperatures of inactivation of the sera according to animal species: 56 degrees C. for guinea pig, 60 degrees C. for mouse, and 65 degrees C. for rabbit and dog sera, all heated for 20 minutes. For human sera a temperature of inactivation of 60 degrees C. also for 20 minutes has been adopted; at this temperature the reaction is in general specific. Complement-fixing antibodies in high titre were found in the sera of rabbits, guinea pigs, mice, and dogs immunized with rabies virus. Complement-fixing antibodies were present in high titre in sera drawn from two persons 8 years after an attack of louping ill, from five persons 2(1/2) years after an attack of Eastern equine encephalomyelitis, and from two persons 2(1/2) years after Western equine encephalomyelitis. In cases of St. Louis encephalitis and lymphocytic choriomeningitis, complement-fixing antibodies have been found shortly following infection but not after long periods.

  5. Variola virus immune evasion design: expression of a highly efficient inhibitor of human complement.

    PubMed

    Rosengard, Ariella M; Liu, Yu; Nie, Zhiping; Jimenez, Robert

    2002-06-25

    Variola virus, the most virulent member of the genus Orthopoxvirus, specifically infects humans and has no other animal reservoir. Variola causes the contagious disease smallpox, which has a 30-40% mortality rate. Conversely, the prototype orthopoxvirus, vaccinia, causes no disease in immunocompetent humans and was used in the global eradication of smallpox, which ended in 1977. However, the threat of smallpox persists because clandestine stockpiles of variola still exist. Although variola and vaccinia share remarkable DNA homology, the strict human tropism of variola suggests that its proteins are better suited than those of vaccinia to overcome the human immune response. Here, we demonstrate the functional advantage of a variola complement regulatory protein over that of its vaccinia homologue. Because authentic variola proteins are not available for study, we molecularly engineered and characterized the smallpox inhibitor of complement enzymes (SPICE), a homologue of a vaccinia virulence factor, vaccinia virus complement control protein (VCP). SPICE is nearly 100-fold more potent than VCP at inactivating human C3b and 6-fold more potent at inactivating C4b. SPICE is also more human complement-specific than is VCP. By inactivating complement components, SPICE serves to inhibit the formation of the C3/C5 convertases necessary for complement-mediated viral clearance. SPICE provides the first evidence that variola proteins are particularly adept at overcoming human immunity, and the decreased function of VCP suggests one reason why the vaccinia virus vaccine was associated with relatively low mortality. Disabling SPICE may be therapeutically useful if smallpox reemerges.

  6. Several Human Liver Cell Expressed Apolipoproteins Complement HCV Virus Production with Varying Efficacy Conferring Differential Specific Infectivity to Released Viruses

    PubMed Central

    Doepke, Mandy; Vieyres, Gabrielle; Todt, Daniel; Wölk, Benno; Vondran, Florian W. R.; Geffers, Robert; Lauber, Chris; Kaderali, Lars; Penin, François; Pietschmann, Thomas

    2015-01-01

    Apolipoprotein E (ApoE), an exchangeable apolipoprotein, is necessary for production of infectious Hepatitis C virus (HCV) particles. However, ApoE is not the only liver-expressed apolipoprotein and the role of other apolipoproteins for production of infectious HCV progeny is incompletely defined. Therefore, we quantified mRNA expression of human apolipoproteins in primary human hepatocytes. Subsequently, cDNAs encoding apolipoproteins were expressed in 293T/miR-122 cells to explore if they complement HCV virus production in cells that are non-permissive due to limiting endogenous levels of human apolipoproteins. Primary human hepatocytes expressed high mRNA levels of ApoA1, A2, C1, C3, E, and H. ApoA4, A5, B, D, F, J, L1, L2, L3, L4, L6, M, and O were expressed at intermediate levels, and C2, C4, and L5 were not detected. All members of the ApoA and ApoC family of lipoproteins complemented HCV virus production in HCV transfected 293T/miR-122 cells, albeit with significantly lower efficacy compared with ApoE. In contrast, ApoD expression did not support production of infectious HCV. Specific infectivity of released particles complemented with ApoA family members was significantly lower compared with ApoE. Moreover, the ratio of extracellular to intracellular infectious virus was significantly higher for ApoE compared to ApoA2 and ApoC3. Since apolipoproteins complementing HCV virus production share amphipathic alpha helices as common structural features we altered the two alpha helices of ApoC1. Helix breaking mutations in both ApoC1 helices impaired virus assembly highlighting a critical role of alpha helices in apolipoproteins supporting HCV assembly. In summary, various liver expressed apolipoproteins with amphipathic alpha helices complement HCV virus production in human non liver cells. Differences in the efficiency of virus assembly, the specific infectivity of released particles, and the ratio between extracellular and intracellular infectivity point to

  7. Replication of chicken anemia virus (CAV) requires apoptin and is complemented by VP3 of human torque teno virus (TTV).

    PubMed

    Prasetyo, Afiono Agung; Kamahora, Toshio; Kuroishi, Ayumu; Murakami, Kyoko; Hino, Shigeo

    2009-03-01

    To test requirement for apoptin in the replication of chicken anemia virus (CAV), an apoptin-knockout clone, pCAV/Ap(-), was constructed. DNA replication was completely abolished in cells transfected with replicative form of CAV/Ap(-). A reverse mutant competent in apoptin production regained the full level of DNA replication. DNA replication and virus-like particle (VLP) production of CAV/Ap(-) was fully complemented by supplementation of the wild-type apoptin. The virus yield of a point mutant, CAV/ApT(108)I, was 1/40 that of the wild type, even though its DNA replication level was full. The infectious titer of CAV was fully complemented by supplementing apoptin. Progeny virus was free from reverse mutation for T(108)I. To localize the domain within apoptin molecule inevitable for CAV replication, apoptin-mutant expressing plasmids, pAp1, pAp2, pAp3, and pAp4, were constructed by deleting amino acids 10-36, 31-59, 59-88 and 80-112, respectively. While Ap1 and Ap2 were preferentially localized in nuclei, Ap3 and Ap4 were mainly present in cytoplasm. Although complementation capacity of Ap3 and Ap4 was 1/10 of the wild type, neither of them completely lost its activity. VP3 of TTV did fully complement the DNA replication and VLP of CAV/Ap(-). These data suggest that apoptin is inevitable not only for DNA replication but also VLP of CAV. The common feature of apoptin and TTV-VP3 presented another evidence for close relatedness of CAV and TTV.

  8. Mutants deleted in the agnogene of simian virus 40 define a new complementation group.

    PubMed Central

    Mertz, J E; Murphy, A; Barkan, A

    1983-01-01

    Analysis of the DNA sequence of the late leader region of simian virus 40 indicates that it might encode a 61-amino acid, highly basic protein, LP-1. Mutants deleted in this region are viable, but they produce infectious progeny more slowly than wild-type virus in established monkey cells. On the basis of the rates of appearance and the sizes of mixed plaques formed after cotransfections with pairs of mutants, we found that mutants defective in the synthesis of LP-1 complementation was also observed in infections with virions and was bidirectional. Therefore, these mutants define a new complementation group, group G. In addition, a protein of the appropriate molecular weight for LP-1 (approximately 8 X 10(3) ) was synthesized by wild-type virus-infected cells but not by mock-infected or group G gene mutant-infected cells. This protein, whose identity has been established definitively by Jay et al. (Nature (London) 291:346-349, 1981), was synthesized at a high rate at late times after infection, was present predominantly in the cytoplasmic fraction of cells, possessed a fairly short half-life, and was absent from mature virions. Once formed, virions of group G gene mutants behaved biologically and physically like virions of wild-type virus. On the basis of these findings and other known properties of LP-1 and mutants defective in LP-1 synthesis, we hypothesize that LP-1 functions to facilitate virion assembly, possibly by serving as a nonreusable scaffolding protein. Images PMID:6296443

  9. Density of Infectious Virus and Complement-Fixing Antigens of Two Rhinovirus Strains

    PubMed Central

    Dans, P. E.; Forsyth, B. R.; Chanock, R. M.

    1966-01-01

    Dans, P. E. (National Institute of Allergy and Infectious Diseases, Bethesda, Md.), B. R. Forsyth, and R. M. Chanock. Density of infectious virus and complement-fixing antigens of two rhinovirus strains. J. Bacteriol. 91:1605–1611. 1966.—Two rhinovirus serotypes (echovirus 28 and HGP) and poliovirus type 1 were banded by isopycnic centrifugation in cesium chloride. The rhinovirus virions had a density of 1.41 g/ml, whereas that of poliovirus was 1.34. Since a number of other enteroviruses also have a density of 1.34 g/ml in cesium chloride, a basic difference in density may exist between the rhinovirus and enterovirus subgroups of the picornavirus family. Whether this difference reflects differences in ribonucleic acid content or binding of cesium ions remains to be determined. In tests with echovirus 28 two peaks of CF activity were detected: one in association with the virion (1.41 g/ml), and a larger peak of lower density (1.30 g/ml). With echovirus 28 antiserum, a heterotypically reactive complement-fixing (CF) antigen was detected in the HGP virus suspension at a density less than that of the virion (1.30 g/ml). This antigen corresponded in density to the less dense CF antigen of echovirus 28. PMID:4286454

  10. A complement-microglial axis drives synapse loss during virus-induced memory impairment.

    PubMed

    Vasek, Michael J; Garber, Charise; Dorsey, Denise; Durrant, Douglas M; Bollman, Bryan; Soung, Allison; Yu, Jinsheng; Perez-Torres, Carlos; Frouin, Arnaud; Wilton, Daniel K; Funk, Kristen; DeMasters, Bette K; Jiang, Xiaoping; Bowen, James R; Mennerick, Steven; Robinson, John K; Garbow, Joel R; Tyler, Kenneth L; Suthar, Mehul S; Schmidt, Robert E; Stevens, Beth; Klein, Robyn S

    2016-06-23

    Over 50% of patients who survive neuroinvasive infection with West Nile virus (WNV) exhibit chronic cognitive sequelae. Although thousands of cases of WNV-mediated memory dysfunction accrue annually, the mechanisms responsible for these impairments are unknown. The classical complement cascade, a key component of innate immune pathogen defence, mediates synaptic pruning by microglia during early postnatal development. Here we show that viral infection of adult hippocampal neurons induces complement-mediated elimination of presynaptic terminals in a murine WNV neuroinvasive disease model. Inoculation of WNV-NS5-E218A, a WNV with a mutant NS5(E218A) protein leads to survival rates and cognitive dysfunction that mirror human WNV neuroinvasive disease. WNV-NS5-E218A-recovered mice (recovery defined as survival after acute infection) display impaired spatial learning and persistence of phagocytic microglia without loss of hippocampal neurons or volume. Hippocampi from WNV-NS5-E218A-recovered mice with poor spatial learning show increased expression of genes that drive synaptic remodelling by microglia via complement. C1QA was upregulated and localized to microglia, infected neurons and presynaptic terminals during WNV neuroinvasive disease. Murine and human WNV neuroinvasive disease post-mortem samples exhibit loss of hippocampal CA3 presynaptic terminals, and murine studies revealed microglial engulfment of presynaptic terminals during acute infection and after recovery. Mice with fewer microglia (Il34(-/-) mice with a deficiency in IL-34 production) or deficiency in complement C3 or C3a receptor were protected from WNV-induced synaptic terminal loss. Our study provides a new murine model of WNV-induced spatial memory impairment, and identifies a potential mechanism underlying neurocognitive impairment in patients recovering from WNV neuroinvasive disease.

  11. Cloning and expression of the complement receptor glycoprotein C from Herpesvirus simiae (herpes B virus): protection from complement-mediated cell lysis.

    PubMed

    Huemer, Hartwig P; Wechselberger, Christian; Bennett, Alice M; Falke, Dietrich; Harrington, Lesley

    2003-05-01

    Simian herpes B virus (SHBV) is the herpes simplex virus (HSV) homologue for the species MACACA: Unlike in its natural host, and unlike other animal herpesviruses, SHBV causes high mortality in accidentally infected humans. SHBV-infected cells, like those infected with HSV-1 and equine herpesvirus types 1 and 4, express complement C3 receptor activity. To study immunoregulatory functions involved in susceptibility/resistance against interspecies transmission, the SHBV glycoprotein C (gC(SHBV)) gene (encoding 467 aa) was isolated. Sequence analysis revealed amino acid identity with gC proteins from HSV-2 (46.9 %), HSV-1 (44.5 %) and pseudorabies virus (21.2 %). Highly conserved cysteine residues were also noted. Similar to gC(HSV-2), gC(SHBV) is less glycosylated than gC(HSV-1), resulting in a molecular mass of 65 kDa if expressed in replication-deficient vaccinia virus Ankara. Stable transfectants expressing full-length gC(SHBV) on the cell surface induced C3 receptor activity and were substantially protected from complement-mediated lysis; no protection was observed with control constructs. This suggests that expression of the gC homologues on infected cell surfaces might also contribute to the survival of infected cells in addition to decreased virion inactivation. Interestingly, soluble gC(SHBV) isolated from protein-free culture supernatants did not interfere with the binding of the alternative complement pathway activator properdin to C3b, which is similar to our findings with gC(HSV-2) and could be attributed to major differences in the amino-terminal portion of the protein with extended deletions in both gC(SHBV) and gC(HSV-2). Binding of recombinant gC(SHBV) to polysulphates was observed. This, together with the heparin-sensitivity of the gC(SHBV)-C3 interaction on the infected cell surface, suggests a role in adherence to heparan sulphate, similar to the gC proteins of other herpesviruses.

  12. The Neutralizing Capacity of Antibodies Elicited by Parainfluenza Virus Infection of African Green Monkeys is Dependent on Complement

    PubMed Central

    Mayer, Anne E.; Johnson, John B.; Parks, Griffith D.

    2014-01-01

    The African Green Monkey (AGM) model was used to analyze the role of complement in neutralization of parainfluenza virus. Parainfluenza virus 5 (PIV5) and human parainfluenza virus type 2 were effectively neutralized in vitro by naïve AGM sera, but neutralizing capacity was lost by heat-inactivation. The mechanism of neutralization involved formation of massive aggregates, with no evidence of virion lysis. Following inoculation of the respiratory tract with a PIV5 vector expressing HIV gp160, AGM produced high levels of serum and tracheal antibodies against gp120 and the viral F and HN proteins. However, in the absence of complement these anti-PIV5 antibodies had very poor neutralizing capacity. Virions showed extensive deposition of IgG and C1q with post- but not pre-immune sera. These results highlight the importance of complement in the initial antibody response to parainfluenza viruses, with implications for understanding infant immune responses and design of vaccine strategies for these pediatric pathogens. PMID:25010267

  13. Virion-associated complement regulator CD55 is more potent than CD46 in mediating resistance of mumps virus and vesicular stomatitis virus to neutralization.

    PubMed

    Johnson, John B; Lyles, Douglas S; Alexander-Miller, Martha A; Parks, Griffith D

    2012-09-01

    Enveloped viruses can incorporate host cell membrane proteins during the budding process. Here we demonstrate that mumps virus (MuV) and vesicular stomatitis virus (VSV) assemble to include CD46 and CD55, two host cell regulators which inhibit propagation of complement pathways through distinct mechanisms. Using viruses which incorporated CD46 alone, CD55 alone, or both CD46 and CD55, we have tested the relative contribution of these regulators in resistance to complement-mediated neutralization. Virion-associated CD46 and CD55 were biologically active, with VSV showing higher levels of activity of both cofactors, which promoted factor I-mediated cleavage of C3b into iC3b as well as decay-accelerating factor (DAF) activity against the C3 convertase, than MuV. Time courses of in vitro neutralization with normal human serum (NHS) showed that both regulators could delay neutralization, but viruses containing CD46 alone were neutralized faster and more completely than viruses containing CD55 alone. A dominant inhibitory role for CD55 was most evident for VSV, where virus containing CD55 alone was not substantially different in neutralization kinetics from virus harboring both regulators. Electron microscopy showed that VSV neutralization proceeded through virion aggregation followed by lysis, with virion-associated CD55 providing a delay in both aggregation and lysis more substantial than that conferred by CD46. Our results demonstrate the functional significance of incorporation of host cell factors during virion envelope assembly. They also define pathways of virus complement-mediated neutralization and suggest the design of more effective viral vectors.

  14. Inhibition of the Membrane Attack Complex by Dengue Virus NS1 through Interaction with Vitronectin and Terminal Complement Proteins.

    PubMed

    Conde, Jonas Nascimento; da Silva, Emiliana Mandarano; Allonso, Diego; Coelho, Diego Rodrigues; Andrade, Iamara da Silva; de Medeiros, Luciano Neves; Menezes, Joice Lima; Barbosa, Angela Silva; Mohana-Borges, Ronaldo

    2016-11-01

    Dengue virus (DENV) infects millions of people worldwide and is a major public health problem. DENV nonstructural protein 1 (NS1) is a conserved glycoprotein that associates with membranes and is also secreted into the plasma in DENV-infected patients. The present study describes a novel mechanism by which NS1 inhibits the terminal complement pathway. We first identified the terminal complement regulator vitronectin (VN) as a novel DENV2 NS1 binding partner by using a yeast two-hybrid system. This interaction was further assessed by enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) assay. The NS1-VN complex was also detected in plasmas from DENV-infected patients, suggesting that this interaction occurs during DENV infection. We also demonstrated that the DENV2 NS1 protein, either by itself or by interacting with VN, hinders the formation of the membrane attack complex (MAC) and C9 polymerization. Finally, we showed that DENV2, West Nile virus (WNV), and Zika virus (ZIKV) NS1 proteins produced in mammalian cells inhibited C9 polymerization. Taken together, our results points to a role for NS1 as a terminal pathway inhibitor of the complement system.

  15. Effects of Opsonization and Gamma Interferon on Growth of Brucella Melitensis 16M in Mouse Peritoneal Macrophages In Vitro

    DTIC Science & Technology

    2000-01-01

    SUBTITLE Effects of Opsonization and Gamma Interferon on Growth of Brucella , melitensis 16M in Mouse Peritoneal Microphages rom In Vitro 3. REPORT...with Brucella melitensis 16M treated with complement- and/or antibody-rich serum. Mouse serum rich in antibody against Brucella lipopolysaccnaride...pathogens of humans and livestock. Brucella meli- tensis usually infects sheep, goats , and camels and is the most pathogenic species for humans (1). Like

  16. Keeping It All Going-Complement Meets Metabolism.

    PubMed

    Kolev, Martin; Kemper, Claudia

    2017-01-01

    The complement system is an evolutionary old and crucial component of innate immunity, which is key to the detection and removal of invading pathogens. It was initially discovered as a liver-derived sentinel system circulating in serum, the lymph, and interstitial fluids that mediate the opsonization and lytic killing of bacteria, fungi, and viruses and the initiation of the general inflammatory responses. Although work performed specifically in the last five decades identified complement also as a critical instructor of adaptive immunity-indicating that complement's function is likely broader than initially anticipated-the dominant opinion among researchers and clinicians was that the key complement functions were in principle defined. However, there is now a growing realization that complement activity goes well beyond "classic" immune functions and that this system is also required for normal (neuronal) development and activity and general cell and tissue integrity and homeostasis. Furthermore, the recent discovery that complement activation is not confined to the extracellular space but occurs within cells led to the surprising understanding that complement is involved in the regulation of basic processes of the cell, particularly those of metabolic nature-mostly via novel crosstalks between complement and intracellular sensor, and effector, pathways that had been overlooked because of their spatial separation. These paradigm shifts in the field led to a renaissance in complement research and provide new platforms to now better understand the molecular pathways underlying the wide-reaching effects of complement functions in immunity and beyond. In this review, we will cover the current knowledge about complement's emerging relationship with the cellular metabolism machinery with a focus on the functional differences between serum-circulating versus intracellularly active complement during normal cell survival and induction of effector functions. We will also

  17. Opsonization of encapsulated Cryptococcus neoformans by specific anticapsular antibody.

    PubMed Central

    Kozel, T R; Follette, J L

    1981-01-01

    Antisera prepared in rabbits against either whole encapsulated cells of Cryptococcus neoformans or purified cryptococcal polysaccharide were opsonic for the encapsulated yeast. The opsonic activity was removed by absorption with whole cryptococci and was inhibited by free polysaccharide. As little as 0.13 microgram of cryptococcal polysaccharide produced a 50% inhibition of opsonization. Various degrees of neutralization by polysaccharides from the four cryptococcal serotypes suggested that the opsonins were type specific. Fractionation of antiserum on Bio-Gel A-5m (Bio-Rad Laboratories) and diethylaminoethyl cellulose showed that the opsonins were antibodies of the immunoglobulin G class. These opsonizing antibodies did not require heat-labile serum components for optimal phagocytosis of the yeast. Inhibition studies using 2-deoxy-D-glucose demonstrated that ingestion of encapsulated cryptococci opsonized with anticapsular antibody was a 2-deoxy-D-glucose-inhibitable process. This result differed from similar studies with non-encapsulated cryptococci which showed that ingestion of non-encapsulated cryptococci opsonized with normal serum was not inhibited by 2-deoxy-D-glucose. PMID:7014468

  18. A detailed genetic analysis of the late complementation groups of simian virus 40.

    PubMed

    Mertz, J E

    1984-01-15

    A simple mixed-plaque assay procedure for determining complementation between pairs of SV40 mutants is described. Since the data obtained can be quantified with respect to both the relative numbers and sizes of plaques, this method is less likely than other complementation assay procedures to yield false-positive results and gives some indication as to the efficiency of the complementation. This quantitative assay procedure, which works with both viral DNA and virions, was used to examine the complementation properties of a variety of late region temperature-sensitive and deletion mutants of SV40. Conclusions reached from these studies included (i) the complementation observed between tsB and tsC mutants is definitely intragenic; (ii) D mutants define a true complementation group; (iii) sequences within the last 68 carboxyl-terminal amino acids of VP-3 are necessary for expression of the D function; and (iv) when linked to the last 19 carboxyl-terminal amino acids of VP-1, the first 136 amino-terminal amino acids of VP-2 are sufficient for expression of the E function. Lastly, the collection of deletion mutants described here may be useful in identifying both structural and regulatory functions of the virion proteins and in analyzing some aspects of viral mRNA biogenesis.

  19. In vitro inactivation of complement by a serum factor present in Junin-virus infected guinea-pigs.

    PubMed Central

    Rimoldi, M T; de Bracco, M M

    1980-01-01

    A serum factor(s) of guinea-pigs infected with Junin virus, the etiological agent of Argentine haemorrhagic fever, is endowed with a potent anticomplementary activity. It is resistant to heat (56 degrees, 30 min) and elutes from a Sephadex G-200 column between albumin and haemoglobin. It is ineffective in the presence of EDTA or EGTA and does not sediment at 82,000 g. It has no direct effect on C4 unless functional Cl is present. However, it induces Cl activation that consumes C4 haemolytic activity in normal human and guinea-pig sera. The evidence presented in this report demonstrates that the complement activation observed in experimental Argentine haemorrhagic fever is at least in part due to a direct effect of this serum factor on the classical complement pathway. PMID:6247264

  20. Rice ragged stunt virus segment S6-encoded nonstructural protein Pns6 complements cell-to-cell movement of Tobacco mosaic virus-based chimeric virus.

    PubMed

    Wu, Zujian; Wu, Jianguo; Adkins, Scott; Xie, Lianhui; Li, Weimin

    2010-09-01

    The protein(s) that support intercellular movement of Rice ragged stunt virus (RRSV) have not yet been identified. In this study, the role of three nonstructural proteins Pns6, Pns7 and Pns10 in cell-to-cell movement were determined with a movement-deficient Tobacco mosaic virus (TMV) vector. The results showed that only the Pns6 could complement the cell-to-cell movement of the movement-deficient TMV in Nicotiana tabacum Xanthi nc and N. benthamiana plants, and both N- and C-terminal 50 amino acids of Pns6 were essential for the cell-to-cell movement. Transient expression in epidermal cells from N. benthamiana showed that the Pns6-eGFP fusion protein was present predominantly along the cell wall as well as a few punctate sites perhaps indicating plasmodesmata. Taken together with previous finding that the Pns6 has nucleic acid-binding activity (Shao et al., 2004), the possible role of Pns6 in cell-to-cell movement of RRSV were discussed.

  1. The tubule-forming NSm protein from Tomato spotted wilt virus complements cell-to-cell and long-distance movement of Tobacco mosaic virus hybrids.

    PubMed

    Lewandowski, Dennis J; Adkins, Scott

    2005-11-10

    A Florida isolate of Tomato spotted wilt virus (TSWV) was able to complement cell-to-cell movement of a movement-defective Tobacco mosaic virus (TMV) vector expressing the jellyfish green fluorescent protein (GFP). To test for complementation of movement in the absence of other TSWV proteins, the open reading frame for the NSm protein was expressed from TMV constructs encoding only the TMV replicase proteins. NSm was expressed from either the coat protein or movement protein subgenomic promoter, creating virus hybrids that moved cell to cell in inoculated leaves of tobacco, providing the first functional demonstration that NSm is the TSWV movement protein. Furthermore, these CP-deficient hybrids moved into upper leaves of Nicotiana benthamiana, demonstrating that NSm can support long-distance movement of viral RNAs. Tubules, characteristic of the NSm protein, were also formed in tobacco protoplasts infected with the TMV-TSWV hybrids. The C-terminus of the NSm protein was shown to be required for movement. TMV-TSWV hybrids expressing NSm and GFP moved within inoculated leaves. Our combination of single-cell and intact plant experiments to examine multiple functions of a heterologous viral protein provides a generalized strategy with wider application to other viruses also lacking a reverse genetic system.

  2. Keeping It All Going—Complement Meets Metabolism

    PubMed Central

    Kolev, Martin; Kemper, Claudia

    2017-01-01

    The complement system is an evolutionary old and crucial component of innate immunity, which is key to the detection and removal of invading pathogens. It was initially discovered as a liver-derived sentinel system circulating in serum, the lymph, and interstitial fluids that mediate the opsonization and lytic killing of bacteria, fungi, and viruses and the initiation of the general inflammatory responses. Although work performed specifically in the last five decades identified complement also as a critical instructor of adaptive immunity—indicating that complement’s function is likely broader than initially anticipated—the dominant opinion among researchers and clinicians was that the key complement functions were in principle defined. However, there is now a growing realization that complement activity goes well beyond “classic” immune functions and that this system is also required for normal (neuronal) development and activity and general cell and tissue integrity and homeostasis. Furthermore, the recent discovery that complement activation is not confined to the extracellular space but occurs within cells led to the surprising understanding that complement is involved in the regulation of basic processes of the cell, particularly those of metabolic nature—mostly via novel crosstalks between complement and intracellular sensor, and effector, pathways that had been overlooked because of their spatial separation. These paradigm shifts in the field led to a renaissance in complement research and provide new platforms to now better understand the molecular pathways underlying the wide-reaching effects of complement functions in immunity and beyond. In this review, we will cover the current knowledge about complement’s emerging relationship with the cellular metabolism machinery with a focus on the functional differences between serum-circulating versus intracellularly active complement during normal cell survival and induction of effector functions

  3. Efficient, trans-complementing packaging systems for chimeric, pseudoinfectious dengue 2/yellow fever viruses

    SciTech Connect

    Shustov, Alexandr V.

    2010-04-25

    In our previous studies, we have stated to build a new strategy for developing defective, pseudoinfectious flaviviruses (PIVs) and applying them as a new type of vaccine candidates. PIVs combined the efficiency of live vaccines with the safety of inactivated or subunit vaccines. The results of the present work demonstrate further development of chimeric PIVs encoding dengue virus 2 (DEN2V) glycoproteins and yellow fever virus (YFV)-derived replicative machinery as potential vaccine candidates. The newly designed PIVs have synergistically functioning mutations in the prM and NS2A proteins, which abolish processing of the latter proteins and make the defective viruses capable of producing either only noninfectious, immature and/or subviral DEN2V particles. The PIV genomes can be packaged to high titers into infectious virions in vitro using the NS1-deficient YFV helper RNAs, and both PIVs and helpers can then be passaged as two-component genome viruses at an escalating scale.

  4. Soluble human complement receptor type 1 inhibits complement-mediated host defense.

    PubMed

    Swift, A J; Collins, T S; Bugelski, P; Winkelstein, J A

    1994-09-01

    Soluble complement receptor type 1 (sCR1) is a powerful inhibitor of complement activation. Because of this ability, sCR1 may prove to be an important therapeutic agent that can be used to block the immunopathologic effects of uncontrolled complement activation in a variety of clinically significant disorders. Although several previous studies have examined the ability of sCR1 to inhibit complemented-mediated immunopathologic damage, there is no information on its ability to interfere with the host's defense against infection. In the current experiments sCR1 exerted a concentration-dependent inhibitory effect on the phagocytosis of Streptococcus pneumoniae by human polymorphonuclear leukocytes in vitro. Not only di sCR1 inhibit complement-dependent opsonization of the pneumococcus but at higher concentrations it also inhibited the ingestion of bacteria which had been previously opsonized. Furthermore, when rats were injected with sCR1, it inhibited both their serum hemolytic activity and serum opsonic activity in a dose-dependent fashion. Finally, for rats treated with sCR1, the 50% lethal dose was S. pneumoniae and Pseudomonas aeruginosa. These data demonstrate that sCR1 significantly inhibits complement-mediated host against bacterial infection.

  5. Deletion of the Monkeypox Virus Inhibitor of Complement Enzymes Locus Impacts the Adaptive Immune Response to Monkeypox Virus in a Nonhuman Primate Model of Infection ▿ §

    PubMed Central

    Estep, Ryan D.; Messaoudi, Ilhem; O'Connor, Megan A.; Li, Helen; Sprague, Jerald; Barron, Alexander; Engelmann, Flora; Yen, Bonnie; Powers, Michael F.; Jones, John M.; Robinson, Bridget A.; Orzechowska, Beata U.; Manoharan, Minsha; Legasse, Alfred; Planer, Shannon; Wilk, Jennifer; Axthelm, Michael K.; Wong, Scott W.

    2011-01-01

    Monkeypox virus (MPXV) is an orthopoxvirus closely related to variola virus, the causative agent of smallpox. Human MPXV infection results in a disease that is similar to smallpox and can also be fatal. Two clades of MPXV have been identified, with viruses of the central African clade displaying more pathogenic properties than those within the west African clade. The monkeypox inhibitor of complement enzymes (MOPICE), which is not expressed by viruses of the west African clade, has been hypothesized to be a main virulence factor responsible for increased pathogenic properties of central African strains of MPXV. To gain a better understanding of the role of MOPICE during MPXV-mediated disease, we compared the host adaptive immune response and disease severity following intrabronchial infection with MPXV-Zaire (n = 4), or a recombinant MPXV-Zaire (n = 4) lacking expression of MOPICE in rhesus macaques (RM). Data presented here demonstrate that infection of RM with MPXV leads to significant viral replication in the peripheral blood and lungs and results in the induction of a robust and sustained adaptive immune response against the virus. More importantly, we show that the loss of MOPICE expression results in enhanced viral replication in vivo, as well as a dampened adaptive immune response against MPXV. Taken together, these findings suggest that MOPICE modulates the anti-MPXV immune response and that this protein is not the sole virulence factor of the central African clade of MPXV. PMID:21752919

  6. Giant virus with a remarkable complement of genes infects marine zooplankton

    PubMed Central

    Fischer, Matthias G.; Allen, Michael J.; Wilson, William H.; Suttle, Curtis A.

    2010-01-01

    As major consumers of heterotrophic bacteria and phytoplankton, microzooplankton are a critical link in aquatic foodwebs. Here, we show that a major marine microflagellate grazer is infected by a giant virus, Cafeteria roenbergensis virus (CroV), which has the largest genome of any described marine virus (≈730 kb of double-stranded DNA). The central 618-kb coding part of this AT-rich genome contains 544 predicted protein-coding genes; putative early and late promoter motifs have been detected and assigned to 191 and 72 of them, respectively, and at least 274 genes were expressed during infection. The diverse coding potential of CroV includes predicted translation factors, DNA repair enzymes such as DNA mismatch repair protein MutS and two photolyases, multiple ubiquitin pathway components, four intein elements, and 22 tRNAs. Many genes including isoleucyl-tRNA synthetase, eIF-2γ, and an Elp3-like histone acetyltransferase are usually not found in viruses. We also discovered a 38-kb genomic region of putative bacterial origin, which encodes several predicted carbohydrate metabolizing enzymes, including an entire pathway for the biosynthesis of 3-deoxy-d-manno-octulosonate, a key component of the outer membrane in Gram-negative bacteria. Phylogenetic analysis indicates that CroV is a nucleocytoplasmic large DNA virus, with Acanthamoeba polyphaga mimivirus as its closest relative, although less than one-third of the genes of CroV have homologs in Mimivirus. CroV is a highly complex marine virus and the only virus studied in genetic detail that infects one of the major groups of predators in the oceans. PMID:20974979

  7. Detection of type-specific antibody to herpes simplex virus type 1 and 2 in human sera by complement-fixation tests.

    PubMed

    Skinner, G R; Hartley, C H; Whitney, J E

    1976-01-01

    Type-specific antigens for herpes simplex virus type 1 and 2 were prepared by rigorous absorption of cell extracts with heterotypic immune sera. Type-specificity was demonstrated by immunodiffusion and complement-fixation tests against immune sera prepared in rabbits. Specific type 1 complement-fixing reactivity was detected in eleven of fifteen sera from Roman Catholic nuns and in two convalescent sera from patients with recurrent herpes labialis; these sera had been previously shown to contain neutralising and complement-fixing antibody to herpes simplex virus. Three of the non-reacting sera contained low or absent levels of type-common complement-fixing reactivity and other contained no type-specific neutralising antibody. With the exception of three "acute" sera, specific type 2 complement-fixing reactivity was detected in every convalescent or interim serum obtained from patients with a virologically-proven history of type 2 herpes virus infection. It is suggested that complement-fixation testing using these absorbed type-specific antigens preparations may provide a convenient and rapid method for the identification of type-specific antibody in human sera.

  8. CD8+ T cells complement antibodies in protecting against yellow fever virus.

    PubMed

    Bassi, Maria R; Kongsgaard, Michael; Steffensen, Maria A; Fenger, Christina; Rasmussen, Michael; Skjødt, Karsten; Finsen, Bente; Stryhn, Anette; Buus, Søren; Christensen, Jan P; Thomsen, Allan R

    2015-02-01

    The attenuated yellow fever (YF) vaccine (YF-17D) was developed in the 1930s, yet little is known about the protective mechanisms underlying its efficiency. In this study, we analyzed the relative contribution of cell-mediated and humoral immunity to the vaccine-induced protection in a murine model of YF-17D infection. Using different strains of knockout mice, we found that CD4(+) T cells, B cells, and Abs are required for full clinical protection of vaccinated mice, whereas CD8(+) T cells are dispensable for long-term survival after intracerebral challenge. However, by analyzing the immune response inside the infected CNS, we observed an accelerated T cell influx into the brain after intracerebral challenge of vaccinated mice, and this T cell recruitment correlated with improved virus control in the brain. Using mice deficient in B cells we found that, in the absence of Abs, YF vaccination can still induce some antiviral protection, and in vivo depletion of CD8(+) T cells from these animals revealed a pivotal role for CD8(+) T cells in controlling virus replication in the absence of a humoral response. Finally, we demonstrated that effector CD8(+) T cells also contribute to viral control in the presence of circulating YF-specific Abs. To our knowledge, this is the first time that YF-specific CD8(+) T cells have been demonstrated to possess antiviral activity in vivo.

  9. Synergy between the classical and alternative pathways of complement is essential for conferring effective protection against the pandemic influenza A(H1N1) 2009 virus infection

    PubMed Central

    Rattan, Ajitanuj; Pawar, Shailesh D.; Nawadkar, Renuka; Kulkarni, Neeraja

    2017-01-01

    The pandemic influenza A(H1N1) 2009 virus caused significant morbidity and mortality worldwide thus necessitating the need to understand the host factors that influence its control. Previously, the complement system has been shown to provide protection during the seasonal influenza virus infection, however, the role of individual complement pathways is not yet clear. Here, we have dissected the role of intact complement as well as of its individual activation pathways during the pandemic influenza virus infection using mouse strains deficient in various complement components. We show that the virus infection in C3-/- mice results in increased viral load and 100% mortality, which can be reversed by adoptive transfer of naïve wild-type (WT) splenocytes, purified splenic B cells, or passive transfer of immune sera from WT, but not C3-/- mice. Blocking of C3a and/or C5a receptor signaling in WT mice using receptor antagonists and use of C3aR-/- and C5aR-/- mice showed significant mortality after blocking/ablation of C3aR, with little or no effect after blocking/ablation of C5aR. Intriguingly, deficiency of C4 and FB in mice resulted in only partial mortality (24%-32%) suggesting a necessary cross-talk between the classical/lectin and alternative pathways for providing effective protection. In vitro virus neutralization experiments performed to probe the cross-talk between the various pathways indicated that activation of the classical and alternative pathways in concert, owing to coating of viral surface by antibodies, is needed for its efficient neutralization. Examination of the virus-specific complement-binding antibodies in virus positive subjects showed that their levels vary among individuals. Together these results indicate that cooperation between the classical and alternative pathways not only result in efficient direct neutralization of the pandemic influenza virus, but also lead to the optimum generation of C3a, which when sensed by the immune cells along

  10. Complement System Part II: Role in Immunity

    PubMed Central

    Merle, Nicolas S.; Noe, Remi; Halbwachs-Mecarelli, Lise; Fremeaux-Bacchi, Veronique; Roumenina, Lubka T.

    2015-01-01

    The complement system has been considered for a long time as a simple lytic cascade, aimed to kill bacteria infecting the host organism. Nowadays, this vision has changed and it is well accepted that complement is a complex innate immune surveillance system, playing a key role in host homeostasis, inflammation, and in the defense against pathogens. This review discusses recent advances in the understanding of the role of complement in physiology and pathology. It starts with a description of complement contribution to the normal physiology (homeostasis) of a healthy organism, including the silent clearance of apoptotic cells and maintenance of cell survival. In pathology, complement can be a friend or a foe. It acts as a friend in the defense against pathogens, by inducing opsonization and a direct killing by C5b–9 membrane attack complex and by triggering inflammatory responses with the anaphylatoxins C3a and C5a. Opsonization plays also a major role in the mounting of an adaptive immune response, involving antigen presenting cells, T-, and B-lymphocytes. Nevertheless, it can be also an enemy, when pathogens hijack complement regulators to protect themselves from the immune system. Inadequate complement activation becomes a disease cause, as in atypical hemolytic uremic syndrome, C3 glomerulopathies, and systemic lupus erythematosus. Age-related macular degeneration and cancer will be described as examples showing that complement contributes to a large variety of conditions, far exceeding the classical examples of diseases associated with complement deficiencies. Finally, we discuss complement as a therapeutic target. PMID:26074922

  11. Immunologic injury of cultured cells infected with measles virus. I. role of IfG antibody and the alternative complement pathway

    PubMed Central

    1975-01-01

    In these studies, a number of human cell lines including epithelial, neural, glial, and lymphoid cells infected with several strains of measles virus were found to be lysed upon incubation with fresh sera from humans containing antibody measles virus. In all instances, the cytolytic event was mediated by alternative complement (C) pathway without a significant contribution from classical pathway. In contrast, isolated measles virus in conjunction with antibody was found to selectively activate the classical C pathway. Measles antibodies of the IgG class, but not the IgA class, possessed cytolytic potential against cells infected with measles virus. Human IgG antibodies could directly activate the alternative C pathway. No defect was found in cytolytic measles antibody in sera or cerebrospinal fluid from patients with subacute sclerosing panencephalitis, nor was the alternative C pathway impaired in sera from these patients. Sera from newborn humans exhibited a functional alternative C pathway. PMID:1092789

  12. Sundanese Complementation

    ERIC Educational Resources Information Center

    Kurniawan, Eri

    2013-01-01

    The focus of this thesis is the description and analysis of clausal complementation in Sundanese, an Austronesian language spoken in Indonesia. The thesis examined a range of clausal complement types in Sundanese, which consists of (i) "yen/(wi)rehna" "that" complements, (ii) "pikeun" "for" complements,…

  13. Role of Streptococcus pneumoniae Proteins in Evasion of Complement-Mediated Immunity.

    PubMed

    Andre, Greiciely O; Converso, Thiago R; Politano, Walter R; Ferraz, Lucio F C; Ribeiro, Marcelo L; Leite, Luciana C C; Darrieux, Michelle

    2017-01-01

    The complement system plays a central role in immune defense against Streptococcus pneumoniae. In order to evade complement attack, pneumococci have evolved a number of mechanisms that limit complement mediated opsonization and subsequent phagocytosis. This review focuses on the strategies employed by pneumococci to circumvent complement mediated immunity, both in vitro and in vivo. At last, since many of the proteins involved in interactions with complement components are vaccine candidates in different stages of validation, we explore the use of these antigens alone or in combination, as potential vaccine approaches that aim at elimination or drastic reduction in the ability of this bacterium to evade complement.

  14. Role of Streptococcus pneumoniae Proteins in Evasion of Complement-Mediated Immunity

    PubMed Central

    Andre, Greiciely O.; Converso, Thiago R.; Politano, Walter R.; Ferraz, Lucio F. C.; Ribeiro, Marcelo L.; Leite, Luciana C. C.; Darrieux, Michelle

    2017-01-01

    The complement system plays a central role in immune defense against Streptococcus pneumoniae. In order to evade complement attack, pneumococci have evolved a number of mechanisms that limit complement mediated opsonization and subsequent phagocytosis. This review focuses on the strategies employed by pneumococci to circumvent complement mediated immunity, both in vitro and in vivo. At last, since many of the proteins involved in interactions with complement components are vaccine candidates in different stages of validation, we explore the use of these antigens alone or in combination, as potential vaccine approaches that aim at elimination or drastic reduction in the ability of this bacterium to evade complement. PMID:28265264

  15. Quantitation of enterovirus 70 antibody by microneutralization test and comparison with standard neutralization, hemagglutination inhibition, and complement fixation tests with different virus strains.

    PubMed Central

    Hierholzer, J C; Bingham, P G; Coombs, R A; Stone, Y O; Hatch, M H

    1984-01-01

    We describe here a microneutralization procedure for conveniently testing large numbers of specimens for antibodies to enterovirus 70. The test utilized human rhabdomyosarcoma cells and was read by staining with crystal violet after 4 days of incubation. The test compares well with other serological assays, being more sensitive than the standard tube neutralization test and the complement fixation test, but less sensitive than the hemagglutination inhibition test. However, the hemagglutination inhibition test required concentrated, partially purified virus as antigen, as did the complement fixation test, and was difficult to read, so that its greater sensitivity may not be of practical significance. By all four test procedures, a recent isolate of enterovirus 70 was a more sensitive antigen than the prototype strain, as shown by greater geometric mean titers in sera of patients from various epidemics. Images PMID:6206088

  16. Immunogenic Characterization of the Dengue Virus Specified Nonstructural Glycoprotein gp48 (NV3, Soluble Complement Fixing Antigen)

    DTIC Science & Technology

    1990-10-09

    and rabbit antisera produced against authentic and recombinant 17D YF NS1 (the latter prepared by Charles Rice) suggest that complement-mediated lysis...cell killing of flavivirus-infected targets are supportive in this regard (Kesson et al, 1987; Bukowski et al, 1989). However, antigen specificity of...the Tc cells does not appear to involve NS 1 ( Bukowski et al, 19-19). 2.2 In vivo evidence of a role for complement in protective anti-NS 1 antibody

  17. Modulation of anxiety behavior by intranasally administered vaccinia virus complement control protein and curcumin in a mouse model of Alzheimer's disease.

    PubMed

    Kulkarni, A P; Govender, D A; Kotwal, G J; Kellaway, L A

    2011-02-01

    Widespread neuroinflammation in the central nervous system (CNS) of Alzheimer's disease (AD) patients, involving pro-inflammatory mediators such as complement components, might be responsible for AD associated behavioral symptoms such as anxiety. Vaccinia virus complement control protein (VCP) and curcumin (Cur) are the bioactive compounds of natural origin shown to inhibit the in-vitro complement activation. In order to develop complement regulatory compounds which could be delivered to the CNS by a non-invasive route, VCP, its truncated version (tVCP), and Cur were administered to Wistar rats intranasally. The distribution of these compounds in cerebrospinal fluid (CSF) was studied using an enzyme linked immunosorbent assay (ELISA), using VCP and tVCP as antigens and a modified fluorimetric method (Cur). VCP and tVCP were also detected in the olfactory lobes of the rat brain using immunohistochemical analysis. These compounds were then compared for their ability to attenuate the anxiety levels in APPswePS1δE9 mice using an elevated plus maze (EPM) apparatus. VCP treatment significantly improved the exploratory behavior and reduced the anxiety behavior in APPswePS1δE9 mice. tVCP however showed an opposite effect to VCP, whereas Cur showed no effect on the anxiety behavior of these mice. When these mice were subsequently tested for their cognitive performance in the Morris water maze (MWM), they showed tendencies to collide with the periphery of the walls of MWM. This unusual activity was termed "kissperi" behavior. This newly defined index of anxiety was comparable to the anxiety profile of the VCP and tVCP treated groups on EPM. VCP can thus be delivered to the CNS effectively via intranasal route of administration to attenuate anxiety associated with AD.

  18. Immunogenic Characterization of the Dengue Virus Specified Nonstructural Glycoprotein GP48 (NV3, Soluble Complement Fixing Antigen)

    DTIC Science & Technology

    1988-09-09

    neuroblastoma (Neuro 2a) and human adenocarcinoma (SW13). Surface NS1 and E were detected on these cells by radiobinding and immuno- fluorescent...and complement Cell type Antibody Complement N2a SW13 PC5 .a 6 .3b 7.0 + 6.2 7.1 1A5 6.4 7.0 + 4.1 5.3 NRS 6.2 7. 1 + 6.1 7.1 R anti-YF NS1 - 6.3 7.P...from 17D YF- infected mouse neuroblastoma cells (Neuro 2a). -20- - r-O.a 7 (O|.O MTB > plot cl c3 %SURVIVE- - * .3* /,Q" - ?7975+ _ *999 - ,f

  19. Complement driven innate immune response to malaria: fuelling severe malarial diseases.

    PubMed

    Silver, Karlee L; Higgins, Sarah J; McDonald, Chloe R; Kain, Kevin C

    2010-08-01

    Severe malaria remains a major cause of global mortality. The innate immune response to infection is a key determinant of malaria severity and outcome. The complement system plays a key role in initiating and augmenting innate immune responses, including inflammation, endothelial activation, opsonization and coagulation, processes which have been implicated in malaria pathogenesis. In this review, we discuss the evidence supporting a role for excessive complement activation in the pathogenesis of severe malaria.

  20. Recombinant human monoclonal antibodies to human cytomegalovirus glycoprotein B neutralize virus in a complement-dependent manner.

    PubMed

    Ohta, Akane; Fujita, Ayano; Murayama, Tsugiya; Iba, Yoshitaka; Kurosawa, Yoshikazu; Yoshikawa, Tetsushi; Asano, Yoshizo

    2009-11-01

    Human antibodies specific for HCMV are currently considered as potential anti-HCMV therapeutic agents. In this study, we used a combinatorial human antibody library to isolate and characterize complete human monoclonal antibodies that effectively neutralize HCMV in a complement-dependent manner. One hundred and six clones were isolated in two independent screens using HCMV virions and recombinant glycoprotein B, gB654, as antigens. All of the clones recognized the same molecule gB and were classified into 14 groups based on the amino acid sequence of the V(H) region. Seven representative clones from these 14 groups had a strong gB654 binding affinity by surface plasmon resonance (SPR). A pairwise binding competition analysis suggested that there were three groups based on differences in the gB recognition sites. Although Fab fragments of the seven groups showed strong affinity for gB, none of the Fab fragments neutralized HCMV infectivity in vitro. In contrast, complete human IgG(1) antibodies of at least three groups neutralized HCMV in a complement-dependent manner. These data suggest that potent therapeutic antibodies can be obtained from a human antibody library, including most of the functional antibodies that mediate humoral immunity to the selected pathogen.

  1. Functional Interactions of the HHCC Domain of Moloney Murine Leukemia Virus Integrase Revealed by Nonoverlapping Complementation and Zinc-Dependent Dimerization

    PubMed Central

    Yang, Fan; Leon, Oscar; Greenfield, Norma J.; Roth, Monica J.

    1999-01-01

    The retroviral integrase (IN) is required for the integration of viral DNA into the host genome. The N terminus of IN contains an HHCC zinc finger-like motif, which is conserved among all retroviruses. To study the function of the HHCC domain of Moloney murine leukemia virus IN, the first N-terminal 105 residues were expressed independently. This HHCC domain protein is found to complement a completely nonoverlapping construct lacking the HHCC domain for strand transfer, 3′ processing and coordinated disintegration reactions, revealing trans interactions among IN domains. The HHCC domain protein binds zinc at a 1:1 ratio and changes its conformation upon binding to zinc. The presence of zinc within the HHCC domain stimulates selective integration processes. Zinc promotes the dimerization of the HHCC domain and protects it from N-ethylmaleimide modification. These studies dissect and define the requirement for the HHCC domain, the exact function of which remains unknown. PMID:9971758

  2. Molecular cloning of the cDNA encoding the Epstein-Barr virus/C3d receptor (complement receptor type 2) of human B lymphocytes

    SciTech Connect

    Moore, M.D.; Cooper, N.R.; Tack, B.F.; Nemerow, G.R.

    1987-12-01

    Complementary DNA clones for complement receptor type 2 (CR2), the B-lymphocyte membrane protein that serves as the receptor for Epstein-Barr virus and the C3d complement fragment, were obtained by screening a lambda gt11 library generated from Raji B lymphoblastoid cell mRNA. A 4.2-kilobase (kb) clone, representing the entire coding sequence of the protein plus untranslated 5' and 3' nucleotide sequences was obtained and sequenced. The 4.2-kb clone, which contains all but about 500 base pairs (bp) of the 5' untranslated region of the full-length CR2 mRNA, consists of 63 bp of 5' untranslated nucleotide sequence followed successively by a start codon, a 20-amino acid hydrophobic signal peptide, 1005 amino acids having a repeating motif, a 28-amino acid probable transmembrane domain, and a 34-amino acid cytoplasmic tail. The deduced amino acid sequence of the protein indicates that the extracellular domain consists entirely of 16 tandemly arranged repeating elements, each 60-75 amino acids in length, which are identified by multiple conserved residues. This repeating motif also occurs in the C3b/C4b receptor, several complement proteins, and a number of noncomplement proteins. In CR2, the 16 repeats occur in four clusters of four repeats each. Approximately 10% of the deduced amino acid sequence, including the amino and carboxyl termini, was confirmed by amino acid sequencing of tryptic peptides derived from purified CR2. The nucleotide and derived amino acid sequence of CR2 and related studies are presented here.

  3. Isolating the Epstein-Barr virus gp350/220 binding site on complement receptor type 2 (CR2/CD21).

    PubMed

    Young, Kendra A; Chen, Xiaojiang S; Holers, V Michael; Hannan, Jonathan P

    2007-12-14

    Complement receptor type 2 (CR2/CD21) is essential for the attachment of Epstein-Barr virus (EBV) to the surface of B-lymphocytes in an interaction mediated by the viral envelope glycoprotein gp350. The heavily glycosylated structure of EBV gp350 has recently been elucidated by x-ray crystallography, and the CR2 binding site on this protein has been characterized. To identify the corresponding gp350 binding site on CR2, we have undertaken a site-directed mutagenesis study targeting regions of CR2 that have previously been implicated in the binding of CR2 to the C3d/C3dg fragments of complement component C3. Wild-type or mutant forms of CR2 were expressed on K562 cells, and the ability of these CR2-expressing cells to bind gp350 was measured using flow cytometry. Mutations directed toward the two N-terminal extracellular domains of CR2 (SCR1-2) reveal that a large contiguous surface of CR2 SCR1-2 is involved in gp350 binding, including a number of positively charged residues (Arg-13, (Arg-28, (Arg-36, Lys-41, Lys-57, Lys-67, and Arg-83). These data appear to complement the CR2 binding site on gp350, which is characterized by a preponderance of negative charge. In addition to identifying the importance of charge in the formation of a CR2-gp350 complex, we also provide evidence that both SCR1 and SCR2 make contact with gp350. Specifically, two anti-CR2 monoclonal antibodies, designated as monoclonal antibodies 171 and 1048 whose primary epitopes are located within SCR2, inhibit binding of wild-type CR2 to EBV gp350; with regard to SCR1, both K562 cells expressing an S15P mutation and recombinant S15P CR2 proteins exhibit diminished gp350 binding.

  4. Complementation of a primer binding site-impaired murine leukemia virus-derived retroviral vector by a genetically engineered tRNA-like primer.

    PubMed Central

    Lund, A H; Duch, M; Lovmand, J; Jørgensen, P; Pedersen, F S

    1997-01-01

    Reverse transcription of retroviral genomes is primed by a tRNA annealed to an 18-nucleotide primer binding site. Here, we present a primer complementation system to study molecular interaction of the replication machinery with the primer and primer binding site in vivo. Introduction of eight base substitutions into the primer binding site of a murine leukemia virus-based vector allowed efficient RNA encapsidation but resulted in severely reduced vector replication capacity. Replication was restored upon complementation with a synthetic gene designed to encode a complementary tRNA-like primer, but not with a noncomplementary tRNA-like molecule. The engineered primer was shown to be involved in both the initiation of first-strand synthesis and second-strand transfer. These results provide an in vivo demonstration that the retroviral replication machinery may recognize sequence complementarity rather than actual primer binding site and 3' primer sequences. Use of mutated primer binding site vectors replicating via engineered primers may add additional control features to retroviral gene transfer technology. PMID:8995641

  5. The equine herpesvirus 1 gene 63 RING finger protein partially complements Vmw110, its herpes simplex virus type 1 counterpart.

    PubMed

    Everett, R; Orr, A; Elliott, M

    1995-09-01

    All alpha herpesviruses of known DNA sequence have been found to encode a protein with similarities to immediate early protein Vmw110 (ICP0) of herpes simplex virus type 1 (HSV-1). The conserved portion of this family of proteins is a characteristic zinc binding module, known as a RING finger or C3HC4 domain. Examples of RING finger domains occur in many other proteins of diverse evolutionary origin and function. Recently, the solution structure of the equine herpesvirus 1 (EHV-1) RING finger protein, encoded by gene 63, has been solved. To investigate whether this structure could be considered to be a paradigm of herpesvirus RING domains, we have constructed a recombinant HSV-1 which expresses the EHV-1 gene 63 protein (EHVg63) in place of Vmw110. Comparison of the growth properties of the recombinant with those of wild-type and Vmw110-defective viruses indicates that EHVg63 is able to fulfil partially, but not completely, the roles of Vmw110 during virus growth in tissue culture.

  6. Homotypic complement-fixing antibody in monkeys infected with type 2 poliomyelitis virus by the oral route.

    PubMed

    CASALS, J; OLITSKY, P K; SABIN, A B

    1952-07-01

    CF tests with Type 2 poliomyelitis antigen (MEF1) were performed on the pre- and postinfection sera of 20 cynomolgus monkeys which developed paralytic, non-paralytic, or inapparent infection following oral administration of a Type 2 strain of virus (Y-SK). All the monkeys developed neutralizing antibody, and 17 developed CF antibody in an original serum dilution titer of 1:4 or greater. The 3 monkeys which did not develop this level of CF antibody were in a group of 7 which died within 8 days after onset of paralysis. The CF titers were as high at 2 to 6 days after onset of paralysis in the other 4 moribund or dead monkeys as in the surviving animals tested 4 weeks after the first dose of virus and the CF titers were of the same order of magnitude in the groups with paralytic, non-paralytic, or inapparent infection. The Type 2 poliomyelitis CF titers developed in monkeys as a result of infection with homotypic virus were not greater than those found in human beings infected with heterotypic Type 1 poliomyelitis strains.

  7. Merozoite Antigens of Plasmodium falciparum Elicit Strain-Transcending Opsonizing Immunity

    PubMed Central

    Wilson, Danny W.; Sampaio, Natalia G.; Eriksson, Emily M.; Ryg-Cornejo, Victoria; Harrison, G. L. Abby; Uboldi, Alessandro D.; Robinson, Leanne J.; Beeson, James G.; Siba, Peter; Cowman, Alan F.; Hansen, Diana S.; Mueller, Ivo; Schofield, Louis

    2016-01-01

    It is unclear whether naturally acquired immunity to Plasmodium falciparum results from the acquisition of antibodies to multiple, diverse antigens or to fewer, highly conserved antigens. Moreover, the specific antibody functions required for malaria immunity are unknown, and hence informative immunological assays are urgently needed to address these knowledge gaps and guide vaccine development. In this study, we investigated whether merozoite-opsonizing antibodies are associated with protection from malaria in a strain-specific or strain-transcending manner by using a novel field isolate and an immune plasma-matched cohort from Papua New Guinea with our validated assay of merozoite phagocytosis. Highly correlated opsonization responses were observed across the 15 parasite strains tested, as were strong associations with protection (composite phagocytosis score across all strains in children uninfected at baseline: hazard ratio of 0.15, 95% confidence interval of 0.04 to 0.63). Opsonizing antibodies had a strong strain-transcending component, and the opsonization of transgenic parasites deficient for MSP3, MSP6, MSPDBL1, or P. falciparum MSP1-19 (PfMSP1-19) was similar to that of wild-type parasites. We have provided the first evidence that merozoite opsonization is predominantly strain transcending, and the highly consistent associations with protection against diverse parasite strains strongly supports the use of merozoite opsonization as a correlate of immunity for field studies and vaccine trials. These results demonstrate that conserved domains within merozoite antigens targeted by opsonization generate strain-transcending immune responses and represent promising vaccine candidates. PMID:27185785

  8. Polymeric antigen BLSOmp31 in aluminium hydroxide induces serum bactericidal and opsonic antibodies against Brucella canis in dogs.

    PubMed

    Clausse, Maria; Díaz, Alejandra G; Pardo, Romina P; Zylberman, Vanesa; Goldbaum, Fernando A; Estein, Silvia M

    2017-02-01

    Polymeric antigen BLSOmp31 is an immunogenic vaccine candidate that confers protection against Brucella canis in mice. In this preliminary study, the immunogenicity and safety of BLSOmp31 adsorbed to aluminum hydroxide gel (BLSOmp31-AH) were evaluated in Beagle dogs. In addition, the potential to elicit serum antibodies with complement-dependent bactericidal activity and/or to enhance phagocytosis by neutrophils were analyzed. Dogs were immunized three times with BLSOmp31-AH by subcutaneous route, followed by an annual booster. The vaccine elicited specific antibodies 3 weeks after the first immunization. Annual booster induced comparable antibody response as the primary series. Humoral immune response stimulated by BLSOmp31-AH did not interfere with routine agglutination test for canine brucellosis. Antibodies demonstrated a high complement-dependent bactericidal activity against B. canis. Moreover, opsonization by immune serum not only stimulated binding and uptake of the bacteria by neutrophils but effectively enhanced the destruction of B. canis. Specific IgG was detected in 3/4 immunized dogs in preputial secretions. The antibody profile corresponded to a marked Th2 response, since IgG1 prevailed over IgG2 and cellular immune response was not detected in vitro or in vivo. These results require further evaluation in larger field studies to establish the full prophylactic activity of BLSOmp31 against canine brucellosis.

  9. Encapsidation of poliovirus replicons encoding the complete human immunodeficiency virus type 1 gag gene by using a complementation system which provides the P1 capsid protein in trans.

    PubMed Central

    Porter, D C; Ansardi, D C; Morrow, C D

    1995-01-01

    Poliovirus genomes which contain small regions of the human immunodeficiency virus type 1 (HIV-1) gag, pol, and env genes substituted in frame for the P1 capsid region replicate and express HIV-1 proteins as fusion proteins with the P1 capsid precursor protein upon transfection into cells (W. S. Choi, R. Pal-Ghosh, and C. D. Morrow, J. Virol. 65:2875-2883, 1991). Since these genomes, referred to as replicons, do not express capsid proteins, a complementation system was developed to encapsidate the genomes by providing P1 capsid proteins in trans from a recombinant vaccinia virus, VV-P1. Virus stocks of encapsidated replicons were generated after serial passage of the replicon genomes into cells previously infected with VV-P1 (D. C. Porter, D. C. Ansardi, W. S. Choi, and C. D. Morrow, J. Virol. 67:3712-3719, 1993). Using this system, we have further defined the role of the P1 region in viral protein expression and RNA encapsidation. In the present study, we constructed poliovirus replicons which contain the complete 1,492-bp gag gene of HIV-1 substituted for the entire P1 region of poliovirus. To investigate whether the VP4 coding region was required for the replication and encapsidation of poliovirus RNA, a second replicon in which the complete gag gene was substituted for the VP2, VP3, and VP1 capsid sequences was constructed. Transfection of replicon RNA with and without the VP4 coding region into cells resulted in similar levels of expression of the HIV-1 Gag protein and poliovirus 3CD protein, as indicated by immunoprecipitation using specific antibodies. Northern (RNA) blot analysis of RNA from transfected cells demonstrated comparable levels of RNA replication for each replicon. Transfection of the replicon genomes into cells infected with VV-P1 resulted in the encapsidation of the genomes; serial passage in the presence of VV-P1 resulted in the generation of virus stocks of encapsidated replicons. Analysis of the levels of protein expression and encapsidated

  10. Detection of opsonic antibodies against Enterococcus faecalis cell wall carbohydrates in immune globulin preparations.

    PubMed

    Hufnagel, M; Sixel, K; Hammer, F; Kropec, A; Sava, I G; Theilacker, C; Berner, R; Huebner, J

    2014-08-01

    Three different commercially available polyvalent immune globulins (IG) were investigated for the existence of antibodies against cell wall carbohydrates of four different E. faecalis serotypes (using a cell wall carbohydrate-enzyme-linked immunosorbent assay), and whether these antibodies mediated opsonic killing (using an opsonic-killing assay). All three IG preparations contained antibodies against all four serotypes (CPS-A to CPS-D). However, only one of the three IG preparations showed opsonic killing against all four serotypes. Average killing was higher against serotypes A and B (72 and 79 %, respectively) than against serotypes C and D (30 and 37 %, respectively). Such IG preparations could play a role as an adjuvant therapeutic option in life-threatening infections with E. faecalis, particularly when resistant strains are involved.

  11. An AGM model for changes in complement during pregnancy: neutralization of influenza virus by serum is diminished in late third trimester.

    PubMed

    Mayer, Anne E; Parks, Griffith D

    2014-01-01

    Pregnant women in the third trimester are at increased risk of severe influenza disease relative to the general population, though mechanisms behind this are not completely understood. The immune response to influenza infection employs both complement (C') and antibody (Ab). The relative contributions of these components to the anti-viral response are difficult to dissect because most humans have pre-existing influenza-specific Abs. We developed the African green monkey (AGM) as a tractable nonhuman primate model to study changes in systemic innate immunity to influenza during pregnancy. Because the AGMs were influenza-naïve, we were able to examine the role of C' in influenza virus neutralization using serum from non-pregnant animals before and after influenza infection. We determined that serum from naïve AGMs neutralized influenza via C', while post-infection neutralization did not require C', suggesting an Ab-mediated mechanism. The latter mimicked neutralization using human serum. Further, we found that ex vivo neutralization of influenza with both naïve and influenza-immune AGM serum occurred by virus particle aggregation and lysis, with immune serum lysing virus at a much higher rate than naïve serum. We hypothesized that the anti-influenza C' response would diminish late in AGM pregnancy, corresponding with the time when pregnant women suffer increased influenza severity. We found that influenza neutralization capacity is significantly diminished in serum collected late in the third trimester. Strikingly, we found that circulating levels of C3, C3a, and C4 are diminished late in gestation relative to nonpregnant animals, and while neutralization capacity and serum C3a return to normal shortly after parturition, C3 and C4 levels do not. This AGM model system will enable further studies of the role of physiologic and hormonal changes in downregulating C'-mediated anti-viral immunity during pregnancy, and it will permit the identification of therapeutic

  12. Serodiversity of Opsonic Antibodies against Enterococcus faecalis —Glycans of the Cell Wall Revisited

    PubMed Central

    Theilacker, Christian; Kaczyński, Zbigniew; Kropec, Andrea; Sava, Irina; Ye, Libin; Bychowska, Anna; Holst, Otto; Huebner, Johannes

    2011-01-01

    In a typing system based on opsonic antibodies against carbohydrate antigens of the cell envelope, 60% of Enterococcus faecalis strains can be assigned to one of four serotypes (CPS-A to CPS-D). The structural basis for enterococcal serotypes, however, is still incompletely understood. Here we demonstrate that antibodies raised against lipoteichoic acid (LTA) from a CPS-A strain are opsonic to both CPS-A and CPS-B strains. LTA-specific antibodies also bind to LTA of CPS-C and CPS-D strains, but fail to opsonize them. From CPS-C and CPS-D strains resistant to opsonization by anti-LTA, we purified a novel diheteroglycan with a repeating unit of →6)-β-Galf-(1→3)- β-D-Glcp-(1→ with O-acetylation in position 5 and lactic acid substitution at position 3 of the Galf residue. The purified diheteroglycan, but not LTA absorbed opsonic antibodies from whole cell antiserum against E. faecalis type 2 (a CPS-C strain) and type 5 (CPS-D). Rabbit antiserum raised against purified diheteroglycan opsonized CPS-C and CPS-D strains and passive protection with diheteroglycan-specific antiserum reduced bacterial counts by 1.4 – 3.4 logs in mice infected with E. faecalis strains of the CPS-C and CPS-D serotype. Diheteroglycan-specific opsonic antibodies were absorbed by whole bacterial cells of E. faecalis FA2-2 (CPS-C) but not by its isogenic acapsular cpsI-mutant and on native PAGE purified diheteroglycan co-migrated with the gene product of the cps-locus, suggesting that it is synthesized by this locus. In summary, two polysaccharide antigens, LTA and a novel diheteroglycan, are targets of opsonic antibodies against typeable E. faecalis strains. These cell-wall associated polymers are promising candidates for active and passive vaccination and add to our armamentarium to fight this important nosocomial pathogen. PMID:21437253

  13. Familial opsonization defect associated with fatal infantile dermatitis, infections, and histiocytosis.

    PubMed Central

    Scott, H; Moynahan, E J; Risdon, R A; Harvey, B A; Soothill, J F

    1975-01-01

    Members of four generations of a family had a defect of serum opsonization for yeast phagocytosis consistent with dominant inheritance. 2 were healthy, one had chronic osteomyelitis, and the fourth developed a fatal illness in infancy characterized by exfoliative dermatitis, diarrhoea, multiple bacterial infections, and failure to thrive, which resembled the two prevously reported cases with this opsonization defect. At necropsy the infant also had lymphoid depletion, which was possibly secondary, and massive histiocytic infiltration. Images FIG. 1 FIG. 2 FIG. 3 PMID:1096830

  14. Spatiotemporal Dynamics of Complement C5a Production within Bacterial Extracellular Polymeric Substance

    PubMed Central

    Conrad, Erin C.; Hsu, Yueh-Ya; Bortz, David M.; Younger, John G.

    2013-01-01

    Opsonization and anaphylatoxin production are early events in innate response to bacterial pathogens. Opsonization alone is frequently not lethal and production of anaphylatoxins, especially C5a, allows for recruitment of cellular defenses. Complement biochemistry is extensively studied and computational models have been previously reported. However, a critical feature of complement mediated attack is its spatial dependence: diffusion of mediators into and away from a bacterium is central to understanding C5a generation. Spatial dependence is especially important in biofilms, where diffusion limitation is crucial to bacterial counterdefense. Here we develop a model of opsonization and C5a production in the presence of a common blood borne pathogen, Staphylococcus epidermidis. Our results indicate that when complement attacks a single cell, diffusion into the extracellular polymeric substance (EPS) is complete within 10 msec and that production of C5a peaks over the next 15 minutes. When longer diffusion lengths (as in an EPS-rich biofilm) are incorporated, diffusion limitation appears such that the intensity and duration of C5a production is increased. However, the amount of C5a produced under several likely clinical scenarios where single cells or sparse biofilms are present is below the kD of the C5a receptor suggesting that complement activation by a single bacterium may be difficult to detect when diffusion is taken into account. PMID:23328643

  15. Live cell imaging of interactions between replicase and capsid protein of Brome mosaic virus using Bimolecular Fluorescence Complementation: Implications for replication and genome packaging

    SciTech Connect

    Chaturvedi, Sonali; Rao, A.L.N.

    2014-09-15

    In Brome mosaic virus, it was hypothesized that a physical interaction between viral replicase and capsid protein (CP) is obligatory to confer genome packaging specificity. Here we tested this hypothesis by employing Bimolecular Fluorescent Complementation (BiFC) as a tool for evaluating protein–protein interactions in living cells. The efficacy of BiFC was validated by a known interaction between replicase protein 1a (p1a) and protein 2a (p2a) at the endoplasmic reticulum (ER) site of viral replication. Additionally, co-expression in planta of a bona fide pair of interacting protein partners of p1a and p2a had resulted in the assembly of a functional replicase. Subsequent BiFC assays in conjunction with mCherry labeled ER as a fluorescent cellular marker revealed that CP physically interacts with p2a, but not p1a, and this CP:p2a interaction occurs at the cytoplasmic phase of the ER. The significance of the CP:p2a interaction in BMV replication and genome packaging is discussed. - Highlights: • YFP fusion proteins of BMV p1a and p2a are biologically active. • Self-interaction was observed for p1a, p2a and CP. • CP interacts with p2a but not p1a. • Majority of reconstituted YFP resulting from bona fide fusion protein partners localized on ER.

  16. Commercially Available Complement Component-Depleted Sera Are Unexpectedly Codepleted of Ficolin-2

    PubMed Central

    Brady, Allison M.; Geno, K. Aaron; Dalecki, Alex G.; Cheng, Xiaogang

    2014-01-01

    The ficolins are a family of innate pattern recognition molecules that are known to bind acetylated compounds and activate complement through the association of mannose binding lectin (MBL)/ficolin-associated serine proteases (MASPs). Their importance has more recently become appreciated, as they have been shown to play a role in a variety of disease processes from infection to autoimmunity. While studying ficolin-2-mediated complement deposition on Streptococcus pneumoniae, we found that sera depleted of C1q or other complement components were also codepleted of ficolin-2 but not ficolin-1, ficolin-3, or MBL. MBL present in C1q-depleted sera was able to mediate complement deposition on Saccharomyces cerevisiae, suggesting the presence of MASPs. We found that complement was activated on pneumococci in C1q-depleted serum only after opsonization with exogenous recombinant ficolin-2 (rFicolin-2). Also, no complement deposition was observed in C1q-depleted serum when pneumococci were opsonized with rFicolin-2 mutated at its lysine-57 residue, where MASPs are known to associate. Thus, these depleted sera are a unique tool to study ficolin-2-mediated complement pathways; however, one should be aware that ficolin-2 is absent from complement component-depleted sera. PMID:25030054

  17. Animal and human antibodies to distinct Staphylococcus aureus antigens mutually neutralize opsonic killing and protection in mice

    PubMed Central

    Skurnik, David; Merighi, Massimo; Grout, Martha; Gadjeva, Mihaela; Maira-Litran, Tomas; Ericsson, Maria; Goldmann, Donald A.; Huang, Susan S.; Datta, Rupak; Lee, Jean C.; Pier, Gerald B.

    2010-01-01

    New prophylactic approaches are needed to control infection with the Gram-positive bacterium Staphylococcus aureus, which is a major cause of nosocomial and community-acquired infections. To develop these, greater understanding of protective immunity against S. aureus infection is needed. Human immunity to extracellular Gram-positive bacterial pathogens is primarily mediated by opsonic killing (OPK) via antibodies specific for surface polysaccharides. S. aureus expresses two such antigens, capsular polysaccharide (CP) and poly-N-acetyl glucosamine (PNAG). Here, we have shown that immunization-induced polyclonal animal antisera and monoclonal antibodies specific for either CP or PNAG antigens have excellent in vitro OPK activity in human blood but that when mixed together they show potent interference in OPK activity. In addition, reductions in antibody binding to the bacterial surface, complement deposition, and passive protection were seen in two mouse models of S. aureus infection. Electron microscopy, isothermal calorimetry, and surface plasmon resonance indicated that antibodies to CP and PNAG bound together via an apparent idiotype–anti-idiotype interaction. This interaction was also found in sera from humans with S. aureus bacteremia. These findings suggest that the lack of effective immunity to S. aureus infections in humans could be due, in part, to interference in OPK when antibodies to CP and PNAG antigens are both present. This information could be used to better design S. aureus vaccine components. PMID:20739753

  18. Hydrazinonicotinamide prolongs quantum dot circulation and reduces reticuloendothelial system clearance by suppressing opsonization and phagocyte engulfment

    NASA Astrophysics Data System (ADS)

    Jung, Kyung-Ho; Park, Jin Won; Paik, Jin-Young; Lee, Eun Jeong; Choe, Yearn Seong; Lee, Kyung-Han

    2012-12-01

    In this study, we investigated the effects of hydrazinonicotinamide (HYNIC)—a bifunctional crosslinker widely used to 99mTc radiolabel protein and nanoparticles for imaging studies—on quantum dot opsonization, macrophage engulfment and in vivo kinetics. In streptavidin-coated quantum dots (SA-QDots), conjugation with HYNIC increased the net negative charge without affecting the zeta potential. Confocal microscopy and fluorescence-activated cell sorting showed HYNIC attachment to suppress SA-QDot engulfment by macrophages. Furthermore, HYNIC conjugation suppressed surface opsonization by serum protein including IgG. When intravenously injected into mice, HYNIC conjugation significantly prolonged the circulation of SA-QDots and reduced their hepatosplenic uptake. Diminished reticuloendothelial system clearance of SA-QDots and aminoPEG-QDots by HYNIC conjugation was also demonstrated by in vivo and ex vivo optical imaging. The effects of HYNIC on the opsonization, phagocytosis and in vivo kinetics of quantum dots were reversed by removal of the hydrazine component from HYNIC. Thus, surface functionalization with HYNIC can improve the in vivo kinetics of quantum dots by reducing phagocytosis via suppression of surface opsonization.

  19. Chemiluminescence of neutrophiles stimulated by opsonized Zymosan in children with bronchial asthma and pneumonia

    NASA Astrophysics Data System (ADS)

    Lewandowicz-Uszynska, A.; Jankowski, A.

    2004-08-01

    Oxygen metabolism of neutrophils after stimulation with opsonized zymosan was examined using chemiluminescence test (in the presence of the patient serum or pooled serum). Into the study 37 children aged from 2 to 12 years were enrolled (20 girls and 17 boys). 10 healthy volunteers comprised the control group (group III). Two groups of patients were established: group I -- children with bronchial asthma (without infection), group II -- children with pneumonia. The examination in both groups was performed twice -- in acute phase and in remission period. The group I in acute phase comprised 16 children and in remission phase 9 children, group II - 21 children in acute phase and 9 children in remission phase, respectively. The following parameters of CL were estimated average value of so called spontaneous CL, maximal excitation of neutrophils after stimulation by zymogen (CLmax), time of zymosan opsonization. The following results were obtained: increased spontaneous CL and CLmax (at the presence of both sera) in acute phase of bronchial asthma and pneumonia in comparison to the control group. In the period of remission both these parameters were insignificantly decreased. The longest time of zymosan opsonization in acute period of disease was observed in children with pneumonia (18 min.). This time did not change during remission phase. Only slightly longer time of opsonization was observed in the patients from group I (in exacerbation) (15 min) than in the control group (13,1 min). This time was prolonged in the clinical remission (20 min).

  20. Complement Interaction with Trypanosomatid Promastigotes in Normal Human Serum

    PubMed Central

    Domínguez, Mercedes; Moreno, Inmaculada; López-Trascasa, Margarita; Toraño, Alfredo

    2002-01-01

    In normal human serum (NHS), axenic promastigotes of Crithidia, Phytomonas, and Leishmania trigger complement activation, and from 1.2 to 1.8 × 105 C3 molecules are deposited per promastigote within 2.5 min. In Leishmania, promastigote C3 binding capacity remains constant during in vitro metacyclogenesis. C3 deposition on promastigotes activated through the classical complement pathway reaches a 50% maximum after ∼50 s, and represents >85% of total C3 bound. In C1q- and C2-deficient human sera, promastigotes cannot activate the classical pathway (CP) unless purified C1q or C2 factors, respectively, are supplemented, demonstrating a requirement for CP factor in promastigote C3 opsonization. NHS depleted of natural anti-Leishmania antibodies cannot trigger promastigote CP activation, but IgM addition restores C3 binding. Furthermore, Leishmania binds natural antibodies in ethylenediaminetetracetic acid (EDTA)-treated NHS; after EDTA removal, promastigote-bound IgM triggers C3 deposition in natural antibody-depleted NHS. Serum collectins and pentraxins thus do not participate significantly in NHS promastigote C3 opsonization. Real-time kinetic analysis of promastigote CP-mediated lysis indicates that between 85–95% of parasites are killed within 2.5 min of serum contact. These data indicate that successful Leishmania infection in man must immediately follow promastigote transmission, and that Leishmania evasion strategies are shaped by the selective pressure exerted by complement. PMID:11854358

  1. Epstein-Barr virus glycoprotein gH/gL antibodies complement IgA-viral capsid antigen for diagnosis of nasopharyngeal carcinoma.

    PubMed

    Li, Rui-Chen; Du, Yong; Zeng, Qiu-Yao; Tang, Lin-Quan; Zhang, Hua; Li, Yan; Liu, Wan-Li; Zhong, Qian; Zeng, Mu-Sheng; Huang, Xiao-Ming

    2016-03-29

    To determine whether measuring antibodies against Epstein-Barr virus (EBV) glycoprotein gH/gL in serum could improve diagnostic accuracy in nasopharyngeal carcinoma (NPC) cases, gH/gL expressed in a recombinant baculovirus system was used in an enzyme-linked immunosorbent assay (ELISA) to detect antibodies in two independent cohorts. Binary logistic regression analyses were performed using results from a training cohort (n = 406) to establish diagnostic mathematical models, which were validated in a second independent cohort (n = 279). Levels of serum gH/gL antibodies were higher in NPC patients than in healthy controls (p < 0.001). In the training cohort, the IgA-gH/gL ELISA had a sensitivity of 83.7%, specificity of 82.3% and area under the curve (AUC) of 0.893 (95% CI, 0.862-0.924) for NPC diagnosis. Furthermore, gH/gL maintained diagnostic capacity in IgA-VCA negative NPC patients (sensitivity = 78.1%, specificity = 82.3%, AUC = 0.879 [95% CI, 0.820 - 0.937]). Combining gH/gL and viral capsid antigen (VCA) detection improved diagnostic capacity as compared to individual tests alone in both the training cohort (sensitivity = 88.5%, specificity = 97%, AUC = 0.98 [95% CI, 0.97 - 0.991]), and validation cohort (sensitivity = 91.2%, specificity = 96.5%, AUC = 0.97 [95% CI, 0.951-0.988]). These findings suggest that EBV gH/gL detection complements VCA detection in the diagnosis of NPC and aids in the identification of patients with VCA-negative NPC.

  2. Deficiency of the Complement Component 3 but Not Factor B Aggravates Staphylococcus aureus Septic Arthritis in Mice.

    PubMed

    Na, Manli; Jarneborn, Anders; Ali, Abukar; Welin, Amanda; Magnusson, Malin; Stokowska, Anna; Pekna, Marcela; Jin, Tao

    2016-04-01

    The complement system plays an essential role in the innate immune response and protection against bacterial infections. However, detailed knowledge regarding the role of complement in Staphylococcus aureus septic arthritis is still largely missing. In this study, we elucidated the roles of selected complement proteins in S. aureus septic arthritis. Mice lacking the complement component 3 (C3(-/-)), complement factor B (fB(-/-)), and receptor for C3-derived anaphylatoxin C3a (C3aR(-/-)) and wild-type (WT) control mice were intravenously or intra-articularly inoculated with S. aureus strain Newman. The clinical course of septic arthritis, as well as histopathological and radiological changes in joints, was assessed. After intravenous inoculation, arthritis severity and frequency were significantly higher in C3(-/-)mice than in WT controls, whereas fB(-/-)mice displayed intermediate arthritis severity and frequency. This was in accordance with both histopathological and radiological findings. C3, but not fB, deficiency was associated with greater weight loss, more frequent kidney abscesses, and higher bacterial burden in kidneys. S. aureus opsonized with C3(-/-)sera displayed decreased uptake by mouse peritoneal macrophages compared with bacteria opsonized with WT or fB(-/-)sera. C3aR deficiency had no effect on the course of hematogenous S. aureus septic arthritis. We conclude that C3 deficiency increases susceptibility to hematogenous S. aureus septic arthritis and impairs host bacterial clearance, conceivably due to diminished opsonization and phagocytosis of S. aureus.

  3. Herpes virus entry mediator synergizes with Toll-like receptor mediated neutrophil inflammatory responses

    PubMed Central

    Haselmayer, Philipp; Tenzer, Stefan; Kwon, Byoung S; Jung, Gundram; Schild, Hansjörg; Radsak, Markus P

    2006-01-01

    In microbial infections polymorphnuclear neutrophils (PMN) constitute a major part of the innate host defence, based upon their ability to rapidly accumulate in inflamed tissues and clear the site of infection from microbial pathogens by their potent effector mechanisms. The recently described transmembrane receptor herpes virus entry mediator (HVEM) is a member of the tumour necrosis factor receptor super family and is expressed on many haematopoietic cells, including T cells, B cells, natural killer cells, monocytes and PMN. Interaction of HVEM with the natural ligand LIGHT on T cells has a costimulatory effect, and increases the bactericidal activity of PMN. To further characterize the function of HVEM on PMN, we evaluated the effect of receptor ligation on human PMN effector functions using an agonistic monoclonal antibody. Here we demonstrate that activation of HVEM causes activation of neutrophil effector functions, including respiratory burst, degranulation and release of interleukin-8 in synergy with ligands for Toll-like receptors or GM-CSF. In addition, stimulation via HVEM enhanced neutrophil phagocytic activity of complement opsonized, but not of non-opsonized, particles. In conclusion, these results indicate a new, as yet unknown, participation of HVEM in the innate immune response and points to a new link between innate and adaptive immunity. PMID:17067315

  4. RIAM (Rap1-interacting adaptor molecule) regulates complement-dependent phagocytosis.

    PubMed

    Medraño-Fernandez, Iria; Reyes, Raquel; Olazabal, Isabel; Rodriguez, Elena; Sanchez-Madrid, Francisco; Boussiotis, Vassiliki A; Reche, Pedro A; Cabañas, Carlos; Lafuente, Esther M

    2013-07-01

    Phagocytosis mediated by the complement receptor CR3 (also known as integrin αMß2 or Mac-1) is regulated by the recruitment of talin to the cytoplasmic tail of the ß2 integrin subunit. Talin recruitment to this integrin is dependent on Rap1 activation. However, the mechanism by which Rap1 regulates this event and CR3-dependent phagocytosis remains largely unknown. In the present work, we examined the role of the Rap1 effector RIAM, a talin-binding protein, in the regulation of complement-mediated phagocytosis. Using the human myeloid cell lines HL-60 and THP-1, we determined that knockdown of RIAM impaired αMß2 integrin affinity changes induced by stimuli fMLP and LPS. Phagocytosis of complement-opsonized RBC particles, but not of IgG-opsonized RBC particles, was impaired in RIAM knockdown cells. Rap1 activation via EPAC induced by 8-pCPT-2'-O-Me-cAMP resulted in an increase of complement-mediated phagocytosis that was abrogated by knockdown of RIAM in HL-60 and THP-1 cell lines and in macrophages derived from primary monocytes. Furthermore, recruitment of talin to ß2 integrin during complement-mediated phagocytosis was reduced in RIAM knockdown cells. These results indicate that RIAM is a critical component of the phagocytosis machinery downstream of Rap1 and mediates its function by recruiting talin to the phagocytic complement receptors.

  5. Opsonic activity of anti-flagellar serum against Clostridium chauvoei by mouse polymorphonuclear leucocytes.

    PubMed

    Tamura, Y; Tanaka, M

    1987-05-01

    The role of anti-flagellar serum against Clostridium chauvoei in phagocytosis by mouse polymorphonuclear leucocytes was examined. Anti-flagellar serum markedly increased phagocytic rate against the flagellated strain Okinawa but not against a non-flagellated mutant (NFM) derived from the same strain, while anti-NFM serum increased the phagocytic rate against both strains. These results indicate that anti-flagellar serum exerts its protective effect by opsonic activity.

  6. Opsonic Antibodies to Enterococcus faecalis Strain 12030 Are Directed against Lipoteichoic Acid

    PubMed Central

    Theilacker, Christian; Kaczynski, Zbigniew; Kropec, Andrea; Fabretti, Francesca; Sange, Tatjana; Holst, Otto; Huebner, Johannes

    2006-01-01

    A teichoic acid (TA)-like polysaccharide in Enterococcus faecalis has previously been shown to induce opsonic antibodies that protect against bacteremia after active and passive immunization. Here we present new data providing a corrected structure of the antigen and the epitope against which the opsonic antibodies are directed. Capsular polysaccharide isolated from E. faecalis strain 12030 by enzymatic digestion of peptidoglycan and chromatography (enzyme-TA) was compared with lipoteichoic acid (LTA) extracted using butanol and purified by hydrophobic-interaction chromatography (BuOH-LTA). Structural determinations were carried out by chemical analysis and nuclear magnetic resonance spectroscopy. Antibody specificity was assessed by enzyme-linked immunosorbent assay and the opsonophagocytosis assay. After alanine ester hydrolysis, there was structural identity between enzyme-TA and BuOH-LTA of the TA-parts of the two molecules. The basic enterococcal LTA structure was confirmed: 1,3-poly(glycerol phosphate) nonstoichiometrically substituted at position C-2 of the glycerol residues with d-Ala and kojibiose. We also detected a novel substituent at position C-2, [d-Ala→6]-α-d-Glcp-(1→2-[d-Ala→6]-α-d-Glcp-1→). Antiserum raised against enzyme-TA bound equally well to BuOH-LTA and dealanylated BuOH-LTA as to the originally described enzyme-TA antigen. BuOH-LTA was a potent inhibitor of opsonophagocytic killing by the antiserum to enzyme-TA. Immunization with antibiotic-killed whole bacterial cells did not induce a significant proportion of antibodies directed against alanylated epitopes on the TA, and opsonic activity was inhibited completely by both alanylated and dealanylated BuOH-LTA. In summary, the E. faecalis strain 12030 enzyme-TA is structurally and immunologically identical to dealanylated LTA. Opsonic antibodies to E. faecalis 12030 are directed predominantly to nonalanylated epitopes on the LTA molecule. PMID:16988246

  7. Analysis of a Novel Spore Antigen in Bacillus anthracis That Contributes to Spore Opsonization

    DTIC Science & Technology

    2008-01-01

    primarily on production of antibodies against the protective antigen component of the anthrax toxins, which are secreted by the bacilli. It has been... production . A spore-associated protein was identified that was specific to the B. cereus group of bacteria and referred to as spore opsonization-associated...in the Ames strain of B. anthracis appeared to increase the phagocytic uptake of the spores in the presence of anti-spore antibodies , since, unlike

  8. Molecular basis of the interaction between complement receptor type 2 (CR2/CD21) and Epstein-Barr virus glycoprotein gp350.

    PubMed

    Young, Kendra A; Herbert, Andrew P; Barlow, Paul N; Holers, V Michael; Hannan, Jonathan P

    2008-11-01

    The binding of the Epstein-Barr virus glycoprotein gp350 by complement receptor type 2 (CR2) is critical for viral attachment to B lymphocytes. We set out to test hypotheses regarding the molecular nature of this interaction by developing an enzyme-linked immunosorbent assay (ELISA) for the efficient analysis of the gp350-CR2 interaction by utilizing wild-type and mutant forms of recombinant gp350 and also of the CR2 N-terminal domains SCR1 and SCR2 (designated CR2 SCR1-2). To delineate the CR2-binding site on gp350, we generated 17 gp350 single-site substitutions targeting an area of gp350 that has been broadly implicated in the binding of both CR2 and the major inhibitory anti-gp350 monoclonal antibody (MAb) 72A1. These site-directed mutations identified a novel negatively charged CR2-binding surface described by residues Glu-21, Asp-22, Glu-155, Asp-208, Glu-210, and Asp-296. We also identified gp350 amino acid residues involved in non-charge-dependent interactions with CR2, including Tyr-151, Ile-160, and Trp-162. These data were supported by experiments in which phycoerythrin-conjugated wild-type and mutant forms of gp350 were incubated with CR2-expressing K562 cells and binding was assessed by flow cytometry. The ELISA was further utilized to identify several positively charged residues (Arg-13, Arg-28, Arg-36, Lys-41, Lys-57, Lys-67, Arg-83, and Arg-89) within SCR1-2 of CR2 that are involved in the binding interaction with gp350. These experiments allowed a comparison of those CR2 residues that are important for binding gp350 to those that define the epitope for an effective inhibitory anti-CR2 MAb, 171 (Asn-11, Arg-13, Ser-32, Thr-34, Arg-36, and Tyr-64). The mutagenesis data were used to calculate a model of the CR2-gp350 complex using the soft-docking program HADDOCK.

  9. Intracranial administration of vaccinia virus complement control protein in Mo/Hu APPswe PS1dE9 transgenic mice at an early age shows enhanced performance at a later age using a cheese board maze test.

    PubMed

    Kulkarni, Amod P; Pillay, Nirvana S; Kellaway, Lauriston A; Kotwal, Girish J

    2008-12-01

    One of the key pro-inflammatory mediators activated by amyloid protein in neurodegenerative disorders of the brain, such as Alzheimer's disease is the complement system. Vaccinia virus complement control protein secreted by vaccinia virus, commonly known as VCP, was found to inhibit amyloid protein mediated up-regulation of complement system in vitro. In the current research investigation, VCP was administered twice (First dose at 3 weeks and the second dose at 6-7 months) intracranially into the parietal cortical area of Mo/Hu APPswe transgenic mice. At the age of 2 years or more, the same mice were subjected to cued-learning, spatial learning, probe and reverse probe trial paradigms of cheese board maze tasks for cognitive assessment. A significant difference was observed between VCP treated mice and the transgenic controls on days two and three of the cued trials and probe trials. The VCP treated group showed a similar trend as revealed during the spatial learning trial and reverse probe trial. A differential pattern of thioflavine S staining was observed in the VCP treated group. These results suggest that administration of VCP at an early age in transgenic mice may be effective in regulating the progression to the familial form of Alzheimer's disease at a later age.

  10. Serological and Genetic Evidence for Altered Complement System Functionality in Systemic Lupus Erythematosus: Findings of the GAPAID Consortium

    PubMed Central

    Prechl, József; Papp, Krisztián; Hérincs, Zoltán; Péterfy, Hajna; Lóránd, Veronika; Szittner, Zoltán; Estonba, Andone; Rovero, Paolo; Paolini, Ilaria; del Amo, Jokin; Uribarri, Maria; Alcaro, Maria Claudia; Ruiz-Larrañaga, Otsanda; Migliorini, Paola; Czirják, László

    2016-01-01

    Systemic lupus erythematosus is a chronic autoimmune disease with multifactorial ethiopathogenesis. The complement system is involved in both the early and late stages of disease development and organ damage. To better understand autoantibody mediated complement consumption we examined ex vivo immune complex formation on autoantigen arrays. We recruited patients with SLE (n = 211), with other systemic autoimmune diseases (n = 65) and non-autoimmune control subjects (n = 149). Standard clinical and laboratory data were collected and serum complement levels were determined. The genotype of SNP rs1143679 in the ITGAM gene was also determined. Ex vivo formation of immune complexes, with respect to IgM, IgG, complement C4 and C3 binding, was examined using a functional immunoassay on autoantigen microarray comprising nucleic acids, proteins and lipids. Complement consumption of nucleic acids increased upon binding of IgM and IgG even when serum complement levels were decreased due to consumption in SLE patients. A negative correlation between serum complement levels and ex vivo complement deposition on nucleic acid autoantigens is demonstrated. On the contrary, complement deposition on tested protein and lipid autoantigens showed positive correlation with C4 levels. Genetic analysis revealed that the non-synonymous variant rs1143679 in complement receptor type 3 is associated with an increased production of anti-dsDNA IgG antibodies. Notwithstanding, homozygous carriers of the previously reported susceptible allele (AA) had lower levels of dsDNA specific IgM among SLE patients. Both the non-synonymous variant rs1143679 and the high ratio of nucleic acid specific IgG/IgM were associated with multiple organ involvement. In summary, secondary complement deficiency in SLE does not impair opsonization of nucleic-acid-containing autoantigens but does affect other antigens and potentially other complement dependent processes. Dysfunction of the receptor recognizing complement

  11. Serological and Genetic Evidence for Altered Complement System Functionality in Systemic Lupus Erythematosus: Findings of the GAPAID Consortium.

    PubMed

    Prechl, József; Papp, Krisztián; Hérincs, Zoltán; Péterfy, Hajna; Lóránd, Veronika; Szittner, Zoltán; Estonba, Andone; Rovero, Paolo; Paolini, Ilaria; Del Amo, Jokin; Uribarri, Maria; Alcaro, Maria Claudia; Ruiz-Larrañaga, Otsanda; Migliorini, Paola; Czirják, László

    2016-01-01

    Systemic lupus erythematosus is a chronic autoimmune disease with multifactorial ethiopathogenesis. The complement system is involved in both the early and late stages of disease development and organ damage. To better understand autoantibody mediated complement consumption we examined ex vivo immune complex formation on autoantigen arrays. We recruited patients with SLE (n = 211), with other systemic autoimmune diseases (n = 65) and non-autoimmune control subjects (n = 149). Standard clinical and laboratory data were collected and serum complement levels were determined. The genotype of SNP rs1143679 in the ITGAM gene was also determined. Ex vivo formation of immune complexes, with respect to IgM, IgG, complement C4 and C3 binding, was examined using a functional immunoassay on autoantigen microarray comprising nucleic acids, proteins and lipids. Complement consumption of nucleic acids increased upon binding of IgM and IgG even when serum complement levels were decreased due to consumption in SLE patients. A negative correlation between serum complement levels and ex vivo complement deposition on nucleic acid autoantigens is demonstrated. On the contrary, complement deposition on tested protein and lipid autoantigens showed positive correlation with C4 levels. Genetic analysis revealed that the non-synonymous variant rs1143679 in complement receptor type 3 is associated with an increased production of anti-dsDNA IgG antibodies. Notwithstanding, homozygous carriers of the previously reported susceptible allele (AA) had lower levels of dsDNA specific IgM among SLE patients. Both the non-synonymous variant rs1143679 and the high ratio of nucleic acid specific IgG/IgM were associated with multiple organ involvement. In summary, secondary complement deficiency in SLE does not impair opsonization of nucleic-acid-containing autoantigens but does affect other antigens and potentially other complement dependent processes. Dysfunction of the receptor recognizing complement

  12. Naturally occurring anti-band-3 antibodies and complement together mediate phagocytosis of oxidatively stressed human erythrocytes

    SciTech Connect

    Lutz, H.U.; Bussolino, F.; Flepp, R.; Fasler, S.; Stammler, P.; Kazatchkine, M.D.; Arese, P.

    1987-11-01

    Treatment of erythrocytes with the thiol-specific oxidant azodicarboxylic acid bis(dimethylamide) (diamide) enhances their phagocytosis by adherent monocytes. Phagocytosis of diamide-treated erythrocytes required that the cells were opsonized with whole serum, since complement inactivation abolished phagocytosis. Opsonization with whole serum containing 20-100 times the physiological concentration of naturally occurring anti-band-3- antibodies enhanced phagocytosis of diamide-treated erythrocytes. High inputs of anti-band-3 also restored phagocytosis of erythrocytes that had been incubated with complement-inactivated serum. Elevated concentrations of anti-spectrin antibodies were ineffective in whole and complement-inactivated serum. Specific recognition of diamide-treated erythrocytes by anti-band-3 antibodies may be due to generation of anti-band-3 reactive protein oligomers on intact diamide-treated erythrocytes. Generation of such oligomers was dose-dependent with respect to diamide. Bound anti-band-3 alone was not sufficient to mediate phagocytosis. It resulted in deposition of complement component C3b on the cells through activation of the alternative complement pathway in amounts exceeding that of bound antibodies by two orders of magnitude. Thus, anti-band-3 and complement together mediate phagocytosis of oxidatively stressed erythrocytes, which simulate senescent erythrocytes with respect to bound antibody and complement.

  13. Naturally produced opsonizing antibodies restrict the survival of Mycobacterium tuberculosis in human macrophages by augmenting phagosome maturation

    PubMed Central

    Kumar, Shashi Kant; Singh, Padam; Sinha, Sudhir

    2015-01-01

    This study investigated the hypothesis that serum antibodies against Mycobacterium tuberculosis present in naturally infected healthy subjects of a tuberculosis (TB) endemic area could create and/or sustain the latent form of infection. All five apparently healthy Indian donors showed high titres of serum antibodies against M. tuberculosis cell membrane antigens, including lipoarabinomannan and alpha crystallin. Uptake and killing of bacilli by the donor macrophages was significantly enhanced following their opsonization with antibody-rich, heat-inactivated autologous sera. However, the capability to opsonize was apparent for antibodies against some and not other antigens. High-content cell imaging of infected macrophages revealed significantly enhanced colocalization of the phagosome maturation marker LAMP-1, though not of calmodulin, with antibody-opsonized compared with unopsonized M. tuberculosis. Key enablers of macrophage microbicidal action—proinflammatory cytokines (IFN-γ and IL-6), phagosome acidification, inducible NO synthase and nitric oxide—were also significantly enhanced following antibody opsonization. Interestingly, heat-killed M. tuberculosis also elevated these mediators to the levels comparable to, if not higher than, opsonized M. tuberculosis. Results of the study support the emerging view that an efficacious vaccine against TB should, apart from targeting cell-mediated immunity, also generate ‘protective’ antibodies. PMID:26674415

  14. Immunoglobulin levels, opsonic activity and phagocytic power in Egyptian thalassemic children.

    PubMed

    Khalifa, A S; Fattah, S A; Maged, Z; Sabry, F; Mohamed, H A

    1983-01-01

    Serum IgG, IgM and IgA were determined in 25 patients with homozygous beta thalassemia and 7 with the trait. The levels were increased in homozygous patients and increased further after splenectomy. Serum opsonic activity against Salmonella typhi and staphylococci was impaired in homozygous patients. Splenectomy caused more impairment against salmonella only. Similarly, phagocytic power against both organisms was lower in beta thalassemia. Further decrease against salmonella occurred after splenectomy. Patients with thalassemia trait did not differ from normal controls.

  15. The presence of complement fixing antibodies to Rous sarcoma virus (Schmidt-Ruppin strain) in patients with various forms of neoplasia.

    PubMed

    Nastac, E; Stoian, M; Lungu, M; Ionescu, T; Athanasiu, P

    1975-01-01

    The presence in men of antibodies to Rous sarcoma virus, an oncogenic virus of avian origin, was demonstrated. The highest antibody incidence was found in patients with various forms of cancer (34.4%, as against the value of 12% recorded in blood donors); these patients also showed an increased antibody level - 1/64 titers were detected in 43 out of 7 patients. The possibility of a human infection with animal oncogenic viruses is discussed, without excluding the hypothesis of a paraimmune reaction.

  16. On the Functional Overlap between Complement and Anti-Microbial Peptides

    PubMed Central

    Zimmer, Jana; Hobkirk, James; Mohamed, Fatima; Browning, Michael J.; Stover, Cordula M.

    2015-01-01

    Intriguingly, activated complement and anti-microbial peptides share certain functionalities; lytic, phagocytic, and chemo-attractant activities and each may, in addition, exert cell instructive roles. Each has been shown to have distinct LPS detoxifying activity and may play a role in the development of endotoxin tolerance. In search of the origin of complement, a functional homolog of complement C3 involved in opsonization has been identified in horseshoe crabs. Horseshoe crabs possess anti-microbial peptides able to bind to acyl chains or phosphate groups/saccharides of endotoxin, LPS. Complement activity as a whole is detectable in marine invertebrates. These are also a source of anti-microbial peptides with potential pharmaceutical applicability. Investigating the locality for the production of complement pathway proteins and their role in modulating cellular immune responses are emerging fields. The significance of local synthesis of complement components is becoming clearer from in vivo studies of parenchymatous disease involving specifically generated, complement-deficient mouse lines. Complement C3 is a central component of complement activation. Its provision by cells of the myeloid lineage varies. Their effector functions in turn are increased in the presence of anti-microbial peptides. This may point to a potentiating range of activities, which should serve the maintenance of health but may also cause disease. Because of the therapeutic implications, this review will consider closely studies dealing with complement activation and anti-microbial peptide activity in acute inflammation (e.g., dialysis-related peritonitis, appendicitis, and ischemia). PMID:25646095

  17. Increased sensitivity of early apoptotic cells to complement-mediated lysis.

    PubMed

    Attali, Gitit; Gancz, Dana; Fishelson, Zvi

    2004-11-01

    Opsonization of apoptotic cells with complement proteins contributes to their clearance by phagocytes. Little is known about the lytic effects of complement on apoptotic cells. Sensitivity of cells treated with anti-Fas antibody (Jurkat cells), staurosporine or etoposide (Raji cells) to lysis by complement was examined. As shown here, early apoptotic cells are more sensitive to lysis by antibody and complement than control cells. More complement C3 and C9 bound to apoptotic than to control cells, even though antibody binding was similar. Enhanced killing and C3/C9 deposition were blocked by benzyloxy-Val-Ala-Asp-fluoromethylketone, a pan-caspase inhibitor. Complement-mediated lysis of early apoptotic cells was also prevented by inhibitors of caspases 6, 8, 9 or 10. In contrast, caspase inhibitors had no effect on the lysis of non-apoptotic Jurkat and Raji cells. Early apoptotic Jurkat cells were also more sensitive to lysis by the pore formers streptolysin O and melittin. Sensitivity of Jurkat Bcl-2 transfectants to lysis by complement was analyzed. Enhanced Bcl-2 expression was associated with reduced C3 deposition and lower sensitivity to complement-mediated lysis. These results demonstrate that at an early stage in apoptosis, following caspase activation, cells become sensitive to necrotic-type death by complement and other pore formers. Furthermore, they suggest that Bcl-2 is actively protecting Jurkat cells from complement-mediated lysis.

  18. Real-time polymerase chain reaction detection of cauliflower mosaic virus to complement the 35S screening assay for genetically modified organisms.

    PubMed

    Cankar, Katarina; Ravnikar, Maja; Zel, Jana; Gruden, Kristina; Toplak, Natasa

    2005-01-01

    Labeling of genetically modified organisms (GMOs) is now in place in many countries, including the European Union, in order to guarantee the consumer's choice between GM and non-GM products. Screening of samples is performed by polymerase chain reaction (PCR) amplification of regulatory sequences frequently introduced into genetically modified plants. Primers for the 35S promoter from Cauliflower mosaic virus (CaMV) are those most frequently used. In virus-infected plants or in samples contaminated with plant material carrying the virus, false-positive results can consequently occur. A system for real-time PCR using a TaqMan minor groove binder probe was designed that allows recognition of virus coat protein in the sample, thus allowing differentiation between transgenic and virus-infected samples. We measured the efficiency of PCR amplification, limits of detection and quantification, range of linearity, and repeatability of the assay in order to assess the applicability of the assay for routine analysis. The specificity of the detection system was tested on various virus isolates and plant species. All 8 CaMV isolates were successfully amplified using the designed system. No cross-reactivity was detected with DNA from 3 isolates of the closely related Carnation etched ring virus. Primers do not amplify plant DNA from available genetically modified maize and soybean lines or from different species of Brassicaceae or Solanaceae that are natural hosts for CaMV. We evaluated the assay for different food matrixes by spiking CaMV DNA into DNA from food samples and have successfully amplified CaMV from all samples. The assay was tested on rapeseed samples from routine GMO testing that were positive in the 35S screening assay, and the presence of the virus was confirmed.

  19. 7-Day Biodefense: Engineered Nanoparticle for Virus Elimination by Opsonization (ENVELOP)

    DTIC Science & Technology

    2013-12-10

    Pilot batches of liposomes produced by Northern Lipids using this process had the same physical properties as similar batches produced at UCSB and...a lipid anchor to create a glycolipid that could be incorporated into liposomes. Alternatives were to conjugate the carbohydrate to a different...molecules such as sucrose when exposed to protein and lipid surfactants in the airway. The pharmacokinetic profile was not dependent on the liposome

  20. Activation of Human Complement System by Dextran-Coated Iron Oxide Nanoparticles Is Not Affected by Dextran/Fe Ratio, Hydroxyl Modifications, and Crosslinking

    PubMed Central

    Wang, Guankui; Chen, Fangfang; Banda, Nirmal K.; Holers, V. Michael; Wu, LinPing; Moghimi, S. Moein; Simberg, Dmitri

    2016-01-01

    While having tremendous potential as therapeutic and imaging tools, the clinical use of engineered nanoparticles has been associated with serious safety concerns. Activation of the complement cascade and the release of proinflammatory factors C3a and C5a may contribute to infusion-related reactions, whereas opsonization with C3 fragments promotes rapid recognition and clearance of nanomaterials by mononuclear phagocytes. We used dextran-coated superparamagnetic iron oxide nanoparticles (SPIO), which are potent activators of the complement system, to study the role of nanoparticle surface chemistry in inciting complement in human serum. Using complement inhibitors and measuring levels of fluid phase markers (sC5b-9, C5a, and Bb), we found that the majority of human complement activation by SPIO is through the alternative pathways (AP). SPIO prepared with high dextran/iron ratio showed some complement activation via calcium-sensitive pathways, but the AP was responsible for the bulk of complement activation and amplification. Activation via the AP required properdin, the positive regulator of the alternative C3bBb convertase. Modification of sugar alcohols of dextran with alkylating, acylating, or crosslinking agents did not overcome complement activation and C3 opsonization. These data demonstrate that human complement activation is independent of dextran modification of SPIO and suggest a crucial role of the AP in immune recognition of nano-assemblies in human serum. PMID:27777575

  1. Opsonic antibody activity against Actinobacillus actinomycetemcomitans in patients with rapidly progressive periodontitis.

    PubMed Central

    Sjöström, K; Darveau, R; Page, R; Whitney, C; Engel, D

    1992-01-01

    Actinobacillus actinomycetemcomitans has been closely associated with early-onset, severe periodontitis, and such patients often have serum immunoglobulin G (IgG) antibodies reactive with antigens of this gram-negative pathogen. We examined the functionality and potential importance of these antibodies. The opsonic activity against A. actinomycetemcomitans of sera from 30 patients with rapidly progressive periodontitis (RPP) and from 28 periodontally normal subjects was tested by using polymorphonuclear leukocyte (PMN) chemiluminescence and bactericidal assays. Peak chemiluminescence values correlated strongly with killing observed in the PMN-dependent bactericidal assay (r = 0.88; P < 0.001). Neither the mean IgG titer nor the mean peak chemiluminescence differed significantly between the two groups. However, when the relationship between chemiluminescence and titer was examined, regression analysis showed that antibodies present in low-titer normal sera were significantly more effective at opsonizing A. actinomycetemcomitans than antibodies present in low-titer RPP patient sera (P = 0.04). Thus, periodontally normal individuals may be better able than RPP patients to clear A. actinomycetemcomitans in early stages of colonization, and anti-A. actinomycetemcomitans antibodies in RPP patients may be relatively ineffective in preventing infection by this organism. PMID:1398993

  2. Neutrophils extracellular traps damage Naegleria fowleri trophozoites opsonized with human IgG.

    PubMed

    Contis-Montes de Oca, A; Carrasco-Yépez, M; Campos-Rodríguez, R; Pacheco-Yépez, J; Bonilla-Lemus, P; Pérez-López, J; Rojas-Hernández, S

    2016-08-01

    Naegleria fowleri infects humans through the nasal mucosa causing a disease in the central nervous system known as primary amoebic meningoencephalitis (PAM). Polymorphonuclear cells (PMNs) play a critical role in the early phase of N. fowleri infection. Recently, a new biological defence mechanism called neutrophil extracellular traps (NETs) has been attracting attention. NETs are composed of nuclear DNA combined with histones and antibacterial proteins, and these structures are released from the cell to direct its antimicrobial attack. In this work, we evaluate the capacity of N. fowleri to induce the liberation of NETs by human PMN cells. Neutrophils were cocultured with unopsonized or IgG-opsonized N. fowleri trophozoites. DNA, histone, myeloperoxidase (MPO) and neutrophil elastase (NE) were stained, and the formation of NETs was evaluated by confocal microscopy and by quantifying the levels of extracellular DNA. Our results showed N. fowleri induce the liberation of NETs including release of MPO and NE by human PMN cells as exposure interaction time is increased, but N. fowleri trophozoites evaded killing. However, when trophozoites were opsonized, they were susceptible to the neutrophils activity. Therefore, our study suggests that antibody-mediated PMNs activation through NET formation may be crucial for antimicrobial responses against N. fowleri.

  3. Kinetics of staphylococcal opsonization, attachment, ingestion and killing by human polymorphonuclear leukocytes: a quantitative assay using [3H]thymidine labeled bacteria.

    PubMed

    Verhoef, J; Peterson, P K; Quie, P G

    1977-01-01

    A method has been developed for studying quantitatively the separate processes of bacterial opsonization, phagocytosis, and killing by human polymorphonuclear leukocytes using [3H]thymidine labeled Staphylococcus aureus. Phagocytosis is determined by assaying for leukocytes-associated radioactivity after differential centrifugation and washing the leukocytes. Opsonization is studied by incubating bacteria with an opsonic source for varying durations and then adding leukocytes. By treatment of samples with the muralytic enzyme, lysostaphin, the attachment and ingestion phases of phagocytosis can be separated. Sampling for colony forming units after disruption of the leukocytes permits the measurement of bacterial killing. Using this method, differences in the kinetics of staphylococcal opsonization by normal and C2 deficient sera were defined, opsonic influences on the attachment and ingestion phases of pH agocytosis were delineated, and the influences of different opsonins and leukocyte populations on killing were determined.

  4. Partial Protection against Porcine Influenza A Virus by a Hemagglutinin-Expressing Virus Replicon Particle Vaccine in the Absence of Neutralizing Antibodies

    PubMed Central

    Ricklin, Meret E.; Vielle, Nathalie J.; Python, Sylvie; Brechbühl, Daniel; Zumkehr, Beatrice; Posthaus, Horst; Zimmer, Gert; Summerfield, Artur

    2016-01-01

    This work was initiated by previous reports demonstrating that mismatched influenza A virus (IAV) vaccines can induce enhanced disease, probably mediated by antibodies. Our aim was, therefore, to investigate if a vaccine inducing opsonizing but not neutralizing antibodies against the hemagglutinin (HA) of a selected heterologous challenge virus would enhance disease or induce protective immune responses in the pig model. To this end, we immunized pigs with either whole inactivated virus (WIV)-vaccine or HA-expressing virus replicon particles (VRP) vaccine based on recombinant vesicular stomatitis virus (VSV). Both types of vaccines induced virus neutralizing and opsonizing antibodies against homologous virus as shown by a highly sensitive plasmacytoid dendritic cell-based opsonization assay. Opsonizing antibodies showed a broader reactivity against heterologous IAV compared with neutralizing antibodies. Pigs immunized with HA-recombinant VRP vaccine were partially protected from infection with a mismatched IAV, which was not neutralized but opsonized by the immune sera. The VRP vaccine reduced lung lesions, lung inflammatory cytokine responses, serum IFN-α responses, and viral loads in the airways. Only the VRP vaccine was able to prime IAV-specific IFNγ/TNFα dual secreting CD4+ T cells detectable in the peripheral blood. In summary, this work demonstrates that with the virus pair selected, a WIV vaccine inducing opsonizing antibodies against HA which lack neutralizing activity, is neither protective nor does it induce enhanced disease in pigs. In contrast, VRP-expressing HA is efficacious vaccines in swine as they induced both potent antibodies and T-cell immunity resulting in a broader protective value. PMID:27446083

  5. Binding and Phagocytosis by Opsonized and Nonopsonized Channel Catfish Macrophages of Viable DsRed-fluorescent-labeled Edwardsiella ictaluri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phagocyte-mediated killing of bacterial pathogens is one of the major defensive mechanisms in fish. The binding, uptake and destruction of recombinant fluorescent protein DsRed transformed Edwardsiella ictaluri by opsonized and nonopsonized channel catfish (Ictalurus punctatus) macrophages was chara...

  6. Human neutrophils mediate trogocytosis rather than phagocytosis of CLL B-cells opsonized with anti-CD20 antibodies.

    PubMed

    Valgardsdottir, Rut; Cattaneo, Irene; Klein, Christian; Introna, Martino; Figliuzzi, Marina; Golay, Josée

    2017-03-13

    Polymorphonuclear neutrophils (PMN) have previously been reported to mediate phagocytosis of anti-CD20 opsonized B-cells from CLL patients. However recent data have suggested that PMN, like macrophages, can also mediate trogocytosis. We have performed experiments to more precisely investigate this point and discriminate between trogocytosis and phagocytosis. In live cell time-lapse microscopy experiments, we could not detect any significant phagocytosis by purified PMN of anti-CD20-opsonized CLL B-cells, but only the repeated close contact between effectors and targets, suggesting trogocytosis. Similarly, in flow cytometry assays using CLL B-cell targets labeled with the membrane dye PKH67 and opsonized with rituximab or obinutuzumab, we could show that a mean of 50% and 75% of PMN had taken a fraction of the dye from CLL B-cells at 3 and 20 hours, respectively, with no significant decrease in absolute live or total CLL B-cell numbers, confirming that trogocytosis takes place, rather than phagocytosis. Trogocytosis was accompanied by loss of membrane CD20 from CLL B-cells, which was evident with rituximab but not obinutuzumab. We conclude that PMN mediate mostly trogocytosis rather than phagocytosis of anti-CD20-opsonized CLL B-cells and discuss the implications of this finding in CLL patients treated with rituximab or obinutuzumab in vivo.

  7. Choristoneura fumiferana multiple nucleopolyhedrovirus LEF-3-P143 complex can complement DNA replication and budded virus in an AcMNPV LEF-3-P143 double knockout bacmid.

    PubMed

    Yu, Mei; Carstens, Eric B

    2012-02-01

    Transient replication assays using Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and Choristoneura fumiferana multiple nucleopolyhedrovirus (CfMNPV) genes suggested that the interactions between P143, the viral helicase and LEF-3, a ssDNA-binding protein, may represent virus species specificity determinants. P143 and LEF-3 are essential for DNA replication in these assays and together with IE-1, the major immediate-early transcription factor, may be part of the viral replisome. In the current report, a lef-3/p143 double-knockout AcMNPV bacmid was constructed that was defective for viral DNA replication and late gene expression. When the homologous lef-3/p143 CfMNPV genes were introduced into this double-knockout bacmid, DNA replication was restored but the level of replication was lower, budded virus production was delayed, and the yields were reduced from those in an AcMNPV-rescue bacmid. These results suggest that to maximize virus replication, baculovirus replisome assembly and function requires protein-protein interactions between P143 and LEF-3, and other viral proteins.

  8. Complement in autoimmune diseases.

    PubMed

    Vignesh, Pandiarajan; Rawat, Amit; Sharma, Madhubala; Singh, Surjit

    2017-02-01

    The complement system is an ancient and evolutionary conserved element of the innate immune mechanism. It comprises of more than 20 serum proteins most of which are synthesized in the liver. These proteins are synthesized as inactive precursor proteins which are activated by appropriate stimuli. The activated forms of these proteins act as proteases and cleave other components successively in amplification pathways leading to exponential generation of final effectors. Three major pathways of complement pathways have been described, namely the classical, alternative and lectin pathways which are activated by different stimuli. However, all the 3 pathways converge on Complement C3. Cleavage of C3 and C5 successively leads to the production of the membrane attack complex which is final common effector. Excessive and uncontrolled activation of the complement has been implicated in the host of autoimmune diseases. But the complement has also been bemusedly described as the proverbial "double edged sword". On one hand, complement is the final effector of tissue injury in autoimmune diseases and on the other, deficiencies of some components of the complement can result in autoimmune diseases. Currently available tools such as enzyme based immunoassays for functional assessment of complement pathways, flow cytometry, next generation sequencing and proteomics-based approaches provide an exciting opportunity to study this ancient yet mysterious element of innate immunity.

  9. Targeting complement in therapy.

    PubMed

    Kirschfink, M

    2001-04-01

    With increasing evidence that complement activation significantly contributes to the pathogenesis of a large number of inflammatory diseases, strategies that interfere with its deleterious action have become a major focus in pharmacological research. Endogenous soluble complement inhibitors (C1 inhibitor, recombinant soluble complement receptor 1, antibodies) blocking key proteins of the cascade reaction, neutralizing the action of the complement-derived anaphylatoxin C5a, or interfering with complement receptor 3 (CR3, CD18/11b)-mediated adhesion of inflammatory cells to the vascular endothelium have successfully been tested in various animal models over the past years. Promising results consequently led to clinical trials. Furthermore, incorporation of membrane-bound complement regulators (decay-accelerating factor (CD55), membrane co-factor protein (CD46), CD59) in transgenic animals has provided a major step forward in protecting xenografts from hyperacute rejection. At the same time, the poor contribution of complement to the antitumor response, which is caused by multiple resistance mechanisms that hamper the efficacy of antibody-based tumor therapy, is increasingly recognized and requires pharmacologic intervention. First attempts have now been made to interfere with the resistance mechanisms, thereby improving complement-mediated tumor cell destruction.

  10. Complement and HIV-I infection/ HIV-associated neurocognitive disorders

    PubMed Central

    Liu, Fengming; Dai, Shen; Gordon, Jennifer; Qin, Xuebin

    2014-01-01

    The various neurological complications associated with HIV-1 infection, specifically HIV-associated neurocognitive disorders (HAND) persist as a major public health burden worldwide. Despite the widespread use of anti-retroviral therapy, the prevalence of HAND is significantly high. HAND results from the direct effects of an HIV-1 infection as well as secondary effects of HIV-1-induced immune reaction and inflammatory response. Complement, a critical mediator of innate and acquired immunity, plays important roles in defeating many viral infections by the formation of a lytic pore or indirectly by opsonization and recruitment of phagocytes. While the role of complement in the pathogenesis of HIV-1 infection and HAND has been previously recognized for over fifteen years, it has been largely underestimated thus far. Complement can be activated through HIV-1 envelope proteins, mannose binding lectins (MBL) and anti-HIV-1 antibodies. Complement not only fights against HIV-1 infection but also enhances HIV-1 infection. Also, HIV-1 can hijack complement regulators such as CD59 and CD55 and can utilize these regulators and factor H to escape from complement attack. Normally, complement levels in brain are much lower than plasma levels and there is no or little complement deposition in brain cells. Interestingly, local production and deposition of complement are dramatically increased in HIV-1-infected brain, indicating that complement may contribute to the pathogenesis of HAND. Here, we review the current understanding of the role of complement in HIV-1 infection and HAND as well as potential therapeutic approaches targeting to the complement system for the treatment and eradications of HIV-1 infection. PMID:24639397

  11. The Lectin Pathway of Complement and Rheumatic Heart Disease

    PubMed Central

    Beltrame, Marcia Holsbach; Catarino, Sandra Jeremias; Goeldner, Isabela; Boldt, Angelica Beate Winter; de Messias-Reason, Iara José

    2014-01-01

    The innate immune system is the first line of host defense against infection and is comprised of humoral and cellular mechanisms that recognize potential pathogens within minutes or hours of entry. The effector components of innate immunity include epithelial barriers, phagocytes, and natural killer cells, as well as cytokines and the complement system. Complement plays an important role in the immediate response against microorganisms, including Streptococcus sp. The lectin pathway is one of three pathways by which the complement system can be activated. This pathway is initiated by the binding of mannose-binding lectin (MBL), collectin 11 (CL-K1), and ficolins (Ficolin-1, Ficolin-2, and Ficolin-3) to microbial surface oligosaccharides and acetylated residues, respectively. Upon binding to target molecules, MBL, CL-K1, and ficolins form complexes with MBL-associated serine proteases 1 and 2 (MASP-1 and MASP-2), which cleave C4 and C2 forming the C3 convertase (C4b2a). Subsequent activation of complement cascade leads to opsonization, phagocytosis, and lysis of target microorganisms through the formation of the membrane-attack complex. In addition, activation of complement may induce several inflammatory effects, such as expression of adhesion molecules, chemotaxis and activation of leukocytes, release of reactive oxygen species, and secretion of cytokines and chemokines. In this chapter, we review the general aspects of the structure, function, and genetic polymorphism of lectin-pathway components and discuss most recent understanding on the role of the lectin pathway in the predisposition and clinical progression of Rheumatic Fever. PMID:25654073

  12. Deletion of the Complement Phagocytic Receptors CR3 and CR4 Does Not Alter Susceptibility to Experimental Cerebral Malaria

    PubMed Central

    Ramos, T.N.; Bullard, Dan C.; Barnum, S.R.

    2015-01-01

    Summary Complement receptors for C3-derived fragments (CR1-4) play critical roles in innate and adaptive immune responses. Of these receptors, CR3 and CR4 are important in binding and phagocytosis of complement-opsonized pathogens including parasites. The role of CR3 and CR4 in malaria or in cerebral malaria has received little attention and remains poorly understood in both human disease and rodent models of malaria. CR3 and CR4 are members of the β2-integrin family of adhesion molecules and are expressed on all leukocytes that participate in the development of cerebral malaria (CM), most importantly as it relates to parasite phagocytosis (monocytes/macrophages) and antigen processing and presentation (dendritic cells). Thus it is possible that these receptors might play an important role in disease development. To address this question, we examined the role of CR3-/- and CR4-/- mice in experimental cerebral malaria (ECM). We found that both CR3-/- and CR4-/- mice were fully susceptible to ECM and developed disease comparable to wild type mice. Our results indicate that CR3 and CR4 are not critical to the pathogenesis of ECM despite their role in elimination of complement-opsonized pathogens. These findings support recent studies indicating the importance of the terminal complement pathway and the membrane attack complex in ECM pathogenesis. PMID:22882618

  13. Deletion of the complement phagocytic receptors CR3 and CR4 does not alter susceptibility to experimental cerebral malaria.

    PubMed

    Ramos, T N; Bullard, D C; Barnum, S R

    2012-11-01

    Complement receptors for C3-derived fragments (CR1-4) play critical roles in innate and adaptive immune responses. Of these receptors, CR3 and CR4 are important in binding and phagocytosis of complement-opsonized pathogens including parasites. The role of CR3 and CR4 in malaria or in cerebral malaria (CM) has received little attention and remains poorly understood in both human disease and rodent models of malaria. CR3 and CR4 are members of the β(2) -integrin family of adhesion molecules and are expressed on all leucocytes that participate in the development of CM, most importantly as it relates to parasite phagocytosis (monocytes/macrophages) and antigen processing and presentation (dendritic cells). Thus, it is possible that these receptors might play an important role in disease development. To address this question, we examined the role of CR3(-/-) and CR4(-/-) in experimental cerebral malaria (ECM). We found that both CR3(-/-) and CR4(-/-) mice were fully susceptible to ECM and developed disease comparable to wild-type mice. Our results indicate that CR3 and CR4 are not critical to the pathogenesis of ECM despite their role in elimination of complement-opsonized pathogens. These findings support recent studies indicating the importance of the terminal complement pathway and the membrane attack complex in ECM pathogenesis.

  14. Factor C acts as a lipopolysaccharide-responsive C3 convertase in horseshoe crab complement activation.

    PubMed

    Ariki, Shigeru; Takahara, Shusaku; Shibata, Toshio; Fukuoka, Takaaki; Ozaki, Aya; Endo, Yuichi; Fujita, Teizo; Koshiba, Takumi; Kawabata, Shun-ichiro

    2008-12-01

    The complement system in vertebrates plays an important role in host defense against and clearance of invading microbes, in which complement component C3 plays an essential role in the opsonization of pathogens, whereas the molecular mechanism underlying C3 activation in invertebrates remains unknown. In an effort to understand the molecular activation mechanism of invertebrate C3, we isolated and characterized an ortholog of C3 (designated TtC3) from the horseshoe crab Tachypleus tridentatus. Flow cytometric analysis using an Ab against TtC3 revealed that the horseshoe crab complement system opsonizes both Gram-negative and Gram-positive bacteria. Evaluation of the ability of various pathogen-associated molecular patterns to promote the proteolytic conversion of TtC3 to TtC3b in hemocyanin-depleted plasma indicated that LPS, but not zymosan, peptidoglycan, or laminarin, strongly induces this conversion, highlighting the selective response of the complement system to LPS stimulation. Although originally characterized as an LPS-sensitive initiator of hemolymph coagulation stored within hemocytes, we identified factor C in hemolymph plasma. An anti-factor C Ab inhibited various LPS-induced phenomena, including plasma amidase activity, the proteolytic activation of TtC3, and the deposition of TtC3b on the surface of Gram-negative bacteria. Moreover, activated factor C present on the surface of Gram-negative bacteria directly catalyzed the proteolytic conversion of the purified TtC3, thereby promoting TtC3b deposition. We conclude that factor C acts as an LPS-responsive C3 convertase on the surface of invading Gram-negative bacteria in the initial phase of horseshoe crab complement activation.

  15. Source and role of diacylglycerol formed during phagocytosis of opsonized yeast particles and associated respiratory burst in human neutrophils

    SciTech Connect

    Della Bianca, V.; Grzeskowiak, M.; Lissandrini, D.; Rossi, F. )

    1991-06-28

    The results presented in this paper demonstrate that in human neutrophils phagocytosis of C3b/bi and IgG-opsonized yeast particles is associated with activation of phospholipase D and that this reaction is the main source of diglycerides. The demonstration is based upon the following findings: (1) the challenge of neutrophils with these opsonized particles was followed by a rapid formation of (3H)alkyl-phosphatidic acid (( 3H)alkyl-PA) and (3H)alkyl-diglyceride (( 3H)alkyl-DG) in cells labeled with (3H)alkyl-lyso-phosphatidylcholine; (2) in the presence of ethanol (3H)alkyl-phosphatidylethanol was formed, and accumulation of (3H)alkyl-PA and (3H)alkyl-DG was depressed; (3) propranolol, by inhibiting the dephosphorylation of (3H)alkyl-PA, completely inhibited the accumulation of (3H)alkyl-DG and depressed by about 75% the formation of diglyceride mass. Evidence is also presented that phagocytosis of C3b/bi and IgG-opsonized yeast particles and associated respiratory burst can take place independently of diglyceride formation and of the activity of this second messenger on protein kinase C. In fact: (a) propranolol while completely inhibited the formation of diglyceride mass did not modify either the phagocytosis or respiratory burst; (b) these two processes were insensitive to staurosporine.

  16. Interaction between complement receptor gC1qR and hepatitis C virus core protein inhibits T-lymphocyte proliferation

    PubMed Central

    Kittlesen, David J.; Chianese-Bullock, Kimberly A.; Yao, Zhi Qiang; Braciale, Thomas J.; Hahn, Young S.

    2000-01-01

    Hepatitis C virus (HCV) is an important human pathogen that is remarkably efficient at establishing persistent infection. The HCV core protein is the first protein expressed during the early phase of HCV infection. Our previous work demonstrated that the HCV core protein suppresses host immune responses, including anti-viral cytotoxic T-lymphocyte responses in a murine model. To investigate the mechanism of HCV core-mediated immunosuppression, we searched for host proteins capable of associating with the core protein using a yeast two-hybrid system. Using the core protein as bait, we screened a human T cell–enriched expression library and identified a gene encoding the gC1q receptor (gC1qR). C1q is a ligand of gC1qR and is involved in the early host defense against infection. Like C1q, HCV core can inhibit T-cell proliferative responses in vitro. This core-induced anti–T-cell proliferation is reversed by addition of anti-gC1qR Ab in a T-cell proliferation assay. Furthermore, biochemical analysis of the interaction between core and gC1qR indicates that HCV core binds the region spanning amino acids 188 to 259 of gC1qR, a site distinct from the binding region of C1q. The inhibition of T-cell responsiveness by HCV core may have important implications for HCV persistence in humans. PMID:11086025

  17. Membrane ruffles capture C3bi-opsonized particles in activated macrophages.

    PubMed

    Patel, Prerna C; Harrison, Rene E

    2008-11-01

    A widespread belief in phagocyte biology is that FcgammaR-mediated phagocytosis utilizes membrane pseudopods, whereas Mac-1-mediated phagocytosis does not involve elaborate plasma membrane extensions. Here we report that dynamic membrane ruffles in activated macrophages promote binding of C3bi-opsonized particles. We identify these ruffles as components of the macropinocytosis machinery in both PMA- and LPS-stimulated macrophages. C3bi-particle capture is facilitated by enrichment of high-affinity Mac-1 and the integrin-regulating protein talin in membrane ruffles. Membrane ruffle formation and C3bi-particle binding are cytoskeleton dependent events, having a strong requirement for F-actin and microtubules (MTs). MT disruption blunts ruffle formation and PMA- and LPS-induced up-regulation of surface Mac-1 expression. Furthermore, the MT motor, kinesin participates in ruffle formation implicating a requirement for intracellular membrane delivery to active membrane regions during Mac-1-mediated phagocytosis. We observed colocalization of Rab11-positive vesicles with CLIP-170, a MT plus-end binding protein, at sites of particle adherence using TIRF imaging. Rab11 has been implicated in recycling endosome dynamics and mutant Rab11 expression inhibits both membrane ruffle formation and C3bi-sRBC adherence to macrophages. Collectively these findings represent a novel membrane ruffle "capture" mechanism for C3bi-particle binding during Mac-1-mediated phagocytosis. Importantly, this work also demonstrates a strong functional link between integrin activation, macropinocytosis and phagocytosis in macrophages.

  18. Stealth nanotubes: strategies of shielding carbon nanotubes to evade opsonization and improve biodistribution.

    PubMed

    Kotagiri, Nalinikanth; Kim, Jin-Woo

    2014-01-01

    Carbon nanotubes (CNTs) have recently been in the limelight for their potential role in disease diagnostics and therapeutics, as well as in tissue engineering. Before these medical applications can be realized, there is a need to address issues like opsonization, phagocytosis by macrophages, and sequestration to the liver and spleen for eventual elimination from the body; along with equally important issues such as aqueous solubility, dispersion, biocompatibility, and biofunctionalization. CNTs have not been shown to be able to evade such biological obstacles, which include their nonspecific attachments to cells and other biological components in the bloodstream, before reaching target tissues and cells in vivo. This will eventually determine their longevity in circulation and clearance rate from the body. This review article discusses the current status, challenges, practical strategies, and implementations of coating CNTs with biocompatible and opsonin-resistant moieties, rendering CNTs transparent to opsonins and deceiving the innate immune response to make believe that the CNTs are not foreign. A holistic approach to the development of such "stealth" CNTs is presented, which encompasses not only several biophysicochemical factors that are not limited to surface treatment of CNTs, but also extraneous biological factors such as the protein corona formation that inevitably controls the in vivo fate of the particles. This review also discusses the present and potential applications, along with the future directions, of CNTs and their hybrid-based nanotheranostic agents for multiplex, multimodal molecular imaging and therapy, as well as in other applications, such as drug delivery and tissue engineering.

  19. Stealth nanotubes: strategies of shielding carbon nanotubes to evade opsonization and improve biodistribution

    PubMed Central

    Kotagiri, Nalinikanth; Kim, Jin-Woo

    2014-01-01

    Carbon nanotubes (CNTs) have recently been in the limelight for their potential role in disease diagnostics and therapeutics, as well as in tissue engineering. Before these medical applications can be realized, there is a need to address issues like opsonization, phagocytosis by macrophages, and sequestration to the liver and spleen for eventual elimination from the body; along with equally important issues such as aqueous solubility, dispersion, biocompatibility, and biofunctionalization. CNTs have not been shown to be able to evade such biological obstacles, which include their nonspecific attachments to cells and other biological components in the bloodstream, before reaching target tissues and cells in vivo. This will eventually determine their longevity in circulation and clearance rate from the body. This review article discusses the current status, challenges, practical strategies, and implementations of coating CNTs with biocompatible and opsonin-resistant moieties, rendering CNTs transparent to opsonins and deceiving the innate immune response to make believe that the CNTs are not foreign. A holistic approach to the development of such “stealth” CNTs is presented, which encompasses not only several biophysicochemical factors that are not limited to surface treatment of CNTs, but also extraneous biological factors such as the protein corona formation that inevitably controls the in vivo fate of the particles. This review also discusses the present and potential applications, along with the future directions, of CNTs and their hybrid-based nanotheranostic agents for multiplex, multimodal molecular imaging and therapy, as well as in other applications, such as drug delivery and tissue engineering. PMID:24872705

  20. [Effects of periodontitis and opsonized zymosan on chemiluminescence of blood neutrophils].

    PubMed

    Zekonis, Gediminas; Ivanauskiene, Egle

    2002-01-01

    The objective of the present investigation was to explore oxidative function of parodontitis patient's blood neutrophils stimulated with opsonized zymosan by method of luminol- and lucigenin-dependent chemiluminescence. The leukocytes for this study were obtained from peripheral venous blood of 16 parodontitis patients and 10 healthy subjects. The luminol-dependent chemiluminescence of stimulated neutrophils of parodontitis patients did not differ (p > 0.05) from control subjects (66,849 +/- 6372 cpm and 61,243 +/- 5240 cpm, respectively). Lucigenin-dependent chemiluminescence of stimulated neutrophils of parodontitis patients was increased (p < or = 0.001) comparing with control subjects (1361 +/- 169 cpm and 492 +/- 56 cpm respectively). The luminol- and lucigenin-dependent chemiluminescence (381 +/- 63 cpm, and 389 +/- 52 cpm, respectively) of nonstimulated neutrophils of parodontitis patients was significantly higher (p < or = 0.001) than analogous Cl (134 +/- 22 cpm and 138 +/- 16 cpm respectively) of control subjects. The results indicate that increased oxidative function of neutrophils of parodontitis patients possibly can affect parodontal health.

  1. Multi-faceted proteomic characterization of host protein complement of Rift Valley fever virus virions and identification of specific heat shock proteins, including HSP90, as important viral host factors.

    PubMed

    Nuss, Jonathan E; Kehn-Hall, Kylene; Benedict, Ashwini; Costantino, Julie; Ward, Michael; Peyser, Brian D; Retterer, Cary J; Tressler, Lyal E; Wanner, Laura M; McGovern, Hugh F; Zaidi, Anum; Anthony, Scott M; Kota, Krishna P; Bavari, Sina; Hakami, Ramin M

    2014-01-01

    Rift Valley fever is a potentially fatal disease of humans and domestic animals caused by Rift Valley fever virus (RVFV). Infection with RVFV in ruminants can cause near 100% abortion rates and recent outbreaks in naïve human populations have suggested case fatality rates of greater than thirty percent. To elucidate the roles that host proteins play during RVFV infection, proteomic analysis of RVFV virions was conducted using complementary analytical approaches, followed by functional validation studies of select identified host factors. Coupling the more traditional Gel LC/MS/MS approach (SDS PAGE followed by liquid chromatography tandem mass spectrometry) with an alternative technique that preserves protein complexes allowed the protein complement of these viral particles to be thoroughly examined. In addition to viral proteins present within the virions and virion-associated host proteins, multiple macromolecular complexes were identified. Bioinformatic analysis showed that host chaperones were among over-represented protein families associated with virions, and functional experiments using siRNA gene silencing and small molecule inhibitors identified several of these heat shock proteins, including heat shock protein 90 (HSP90), as important viral host factors. Further analysis indicated that HSP inhibition effects occur during the replication/transcription phase of the virus life cycle, leading to significant lowering of viral titers without compromising the functional capacity of released virions. Overall, these studies provide much needed further insight into interactions between RVFV and host cells, increasing our understanding of the infection process and suggesting novel strategies for anti-viral development. In particular, considering that several HSP90 inhibitors have been advancing through clinical trials for cancer treatment, these results also highlight the exciting potential of repurposing HSP90 inhibitors to treat RVF.

  2. High-Sensitivity C-Reactive Protein Complements Plasma Epstein-Barr Virus Deoxyribonucleic Acid Prognostication in Nasopharyngeal Carcinoma: A Large-Scale Retrospective and Prospective Cohort Study

    SciTech Connect

    Tang, Lin-Quan; Li, Chao-Feng; Chen, Qiu-Yan; Zhang, Lu; Lai, Xiao-Ping; He, Yun; Xu, Yun-Xiu-Xiu; Hu, Dong-Peng; Wen, Shi-Hua; Peng, Yu-Tuan; Chen, Wen-Hui; Liu, Huai; Guo, Shan-Shan; Liu, Li-Ting; Li, Jing; Zhang, Jing-Ping; and others

    2015-02-01

    Purpose: To evaluate the effects of combining the assessment of circulating high-sensitivity C-reactive protein (hs-CRP) with that of Epstein-Barr virus DNA (EBV DNA) in the pretherapy prognostication of nasopharyngeal carcinoma (NPC). Patients and Methods: Three independent cohorts of NPC patients (training set of n=3113, internal validation set of n=1556, and prospective validation set of n=1668) were studied. Determinants of disease-free survival, distant metastasis–free survival, and overall survival were assessed by multivariate analysis. Hazard ratios and survival probabilities of the patient groups, segregated by clinical stage (T1-2N0-1M0, T3-4N0-1M0, T1-2N2-3M0, and T3-4N2-3M0) and EBV DNA load (low or high) alone, and also according to hs-CRP level (low or high), were compared. Results: Elevated hs-CRP and EBV DNA levels were significantly correlated with poor disease-free survival, distant metastasis–free survival, and overall survival in both the training and validation sets. Associations were similar and remained significant after excluding patients with cardiovascular disease, diabetes, and chronic hepatitis B. Patients with advanced-stage disease were segregated by high EBV DNA levels and high hs-CRP level into a poorest-risk group, and participants with either high EBV DNA but low hs-CRP level or high hs-CRP but low EBV DNA values had poorer survival compared with the bottom values for both biomarkers. These findings demonstrate a significant improvement in the prognostic ability of conventional advanced NPC staging. Conclusion: Baseline plasma EBV DNA and serum hs-CRP levels were significantly correlated with survival in NPC patients. The combined interpretation of EBV DNA with hs-CRP levels led to refinement of the risks for the patient subsets, with improved risk discrimination in patients with advanced-stage disease.

  3. Group G streptococcal IgG binding molecules FOG and protein G have different impacts on opsonization by C1q.

    PubMed

    Nitsche-Schmitz, D Patric; Johansson, Helena M; Sastalla, Inka; Reissmann, Silvana; Frick, Inga-Maria; Chhatwal, Gursharan S

    2007-06-15

    Recent epidemiological data on diseases caused by beta-hemolytic streptococci belonging to Lancefield group C and G (GCS, GGS) underline that they are an emerging threat to human health. Among various virulence factors expressed by GCS and GGS isolates from human infections, M and M-like proteins are considered important because of their anti-phagocytic activity. In addition, protein G has been implicated in the accumulation of IgG on the bacterial surface through non-immune binding. The function of this interaction, however, is still unknown. Using isogenic mutants lacking protein G or the M-like protein FOG (group G streptococci), respectively, we could show that FOG contributes substantially to IgG binding. A detailed characterization of the interaction between IgG and FOG revealed its ability to bind the Fc region of human IgG and its binding to the subclasses IgG1, IgG2, and IgG4. FOG was also found to bind IgG of several animal species. Surface plasmon resonance measurements indicate a high affinity to human IgG with a dissociation constant of 2.4 pm. The binding site was localized in a central motif of FOG. It has long been speculated about anti-opsonic functions of streptococcal Fc-binding proteins. The presented data for the first time provide evidence and, furthermore, indicate functional differences between protein G and FOG. By obstructing the interaction between IgG and C1q, protein G prevented recognition by the classical pathway of the complement system. In contrast, IgG that was bound to FOG remained capable of binding C1q, an effect that may have important consequences in the pathogenesis of GGS infections.

  4. Characterization of the complement inhibitory function of rhesus rhadinovirus complement control protein (RCP).

    PubMed

    Okroj, Marcin; Mark, Linda; Stokowska, Anna; Wong, Scott W; Rose, Nicola; Blackbourn, David J; Villoutreix, Bruno O; Spiller, O Brad; Blom, Anna M

    2009-01-02

    Rhesus rhadinovirus (RRV) is currently the closest known, fully sequenced homolog of human Kaposi sarcoma-associated herpesvirus. Both these viruses encode complement inhibitors as follows: Kaposi sarcoma-associated herpesvirus-complement control protein (KCP) and RRV-complement control protein (RCP). Previously we characterized in detail the functional properties of KCP as a complement inhibitor. Here, we performed comparative analyses for two variants of RCP protein, encoded by RRV strains H26-95 and 17577. Both RCP variants and KCP inhibited human and rhesus complement when tested in hemolytic assays measuring all steps of activation via the classical and the alternative pathway. RCP variants from both RRV strains supported C3b and C4b degradation by factor I and decay acceleration of the classical C3 convertase, similar to KCP. Additionally, the 17577 RCP variant accelerated decay of the alternative C3 convertase, which was not seen for KCP. In contrast to KCP, RCP showed no affinity to heparin and is the first described complement inhibitor in which the binding site for C3b/C4b does not interact with heparin. Molecular modeling shows a structural disruption in the region of RCP that corresponds to the KCP-heparin-binding site. This makes RRV a superior model for future in vivo investigations of complement evasion, as RCP does not play a supportive role in viral attachment as KCP does.

  5. Uncoupling complement C1s activation from C1q binding in apoptotic cell phagocytosis and immunosuppressive capacity.

    PubMed

    Colonna, Lucrezia; Parry, Graham C; Panicker, Sandip; Elkon, Keith B

    2016-02-01

    Complement activation contributes to inflammation in many diseases, yet it also supports physiologic apoptotic cells (AC) clearance and its downstream immunosuppressive effects. The roles of individual complement components in AC phagocytosis have been difficult to dissect with artificially depleted sera. Using human in vitro systems and the novel antibody complement C1s inhibitor TNT003, we uncoupled the role of the enzymatic activation of the classical pathway from the opsonizing role of C1q in mediating a) the phagocytosis of early and late AC, and b) the immunosuppressive capacity of early AC. We found that C1s inhibition had a small impact on the physiologic clearance of early AC, leaving their immunosuppressive properties entirely unaffected, while mainly inhibiting the phagocytosis of late apoptotic/secondary necrotic cells. Our data suggest that C1s inhibition may represent a valuable therapeutic strategy to control classical pathway activation without causing significant AC accumulation in diseases without defects in AC phagocytosis.

  6. Sialylation of neurites inhibits complement-mediated macrophage removal in a human macrophage-neuron Co-Culture System.

    PubMed

    Linnartz-Gerlach, Bettina; Schuy, Christine; Shahraz, Anahita; Tenner, Andrea J; Neumann, Harald

    2016-01-01

    The complement system has been implicated in the removal of dysfunctional synapses and neurites during development and in disease processes in the mouse, but it is unclear how far the mouse data can be transferred to humans. Here, we co-cultured macrophages derived from human THP1 monocytes and neurons derived from human induced pluripotent stem cells, to study the role of the complement system in a human model. Components of the complement system were expressed by the human macrophages and human neuronal culture, while receptors of the complement cascade were expressed by human macrophages as shown via gene transcript analysis and flow cytometry. We mimicked pathological conditions leading to an altered glycocalyx by treatment of human neurons with sialidases. Desialylated human neurites were opsonized by the complement component C1q. Furthermore, human neurites with an intact sialic acid cap remained untouched, while desialylated human neurites were removed and ingested by human macrophages. While blockage of the complement receptor 1 (CD35) had no effect, blockage of CD11b as part of the complement receptor 3 (CR3) reversed the effect on macrophage phagocytosis of desialylated human neurites. Data demonstrate that in the human system sialylation of the neuronal glycocalyx serves as an inhibitory flag for complement binding and CR3-mediated phagocytosis by macrophages.

  7. Outline of Hungarian Complementation.

    ERIC Educational Resources Information Center

    Szamosi, Michael

    This study presents a preliminary analysis of Hungarian complement constructions and the syntactic operations needed to account for them. The expository framework (and the implicit framework of the research itself) is based upon that of Rosenbaum (1967). The aim of the paper is to arrive at a rough picture of the kinds of structures and syntactic…

  8. Verbal Complementizers in Arabic

    ERIC Educational Resources Information Center

    Ahmed, Hossam Eldin Ibrahim

    2015-01-01

    A class of Modern Standard Arabic complementizers known as "'?inna' and its sisters" demonstrate unique case and word order restrictions. While CPs in Arabic allow both Subject-Verb (SV) and Verb-Subject (VS) word order and their subjects show nominative morphology, CPs introduced by "?inna" ban a verb from directly following…

  9. Anti-glycoprotein g antibodies of herpes simplex virus 2 contribute to complete protection after vaccination in mice and induce antibody-dependent cellular cytotoxicity and complement-mediated cytolysis.

    PubMed

    Görander, Staffan; Ekblad, Maria; Bergström, Tomas; Liljeqvist, Jan-Åke

    2014-11-12

    We investigated the role of antibodies against the mature portion of glycoprotein G (mgG-2) of herpes simplex virus 2 (HSV-2) in protective immunity after vaccination. Mice were immunized intramuscularly with mgG-2 and oligodeoxynucleotides containing two CpG motifs plus alum as adjuvant. All C57BL/6 mice survived and presented no genital or systemic disease. High levels of immunoglobulin G subclass 1 (IgG1) and IgG2 antibodies were detected and re-stimulated splenic CD4+ T cells proliferated and produced IFN-γ. None of the sera from immunized mice exhibited neutralization, while all sera exerted antibody-dependent cellular cytotoxicity (ADCC) and complement-mediated cytolysis (ACMC) activity. Passive transfer of anti-mgG-2 monoclonal antibodies, or immune serum, to naive C57BL/6 mice did not limit disease progression. Immunized B‑cell KO mice presented lower survival rate and higher vaginal viral titers, as compared with vaccinated B-cell KO mice after passive transfer of immune serum and vaccinated C57BL/6 mice. Sera from mice that were vaccinated subcutaneously and intranasally with mgG-2 presented significantly lower titers of IgG antibodies and lower ADCC and ACMC activity. We conclude that anti-mgG-2 antibodies were of importance to limit genital HSV‑2 infection. ADCC and ACMC activity are potentially important mechanisms in protective immunity, and could tentatively be evaluated in future animal vaccine studies and in clinical trials.

  10. Systemic Lupus Erythematosus and Deficiencies of Early Components of the Complement Classical Pathway

    PubMed Central

    Macedo, Ana Catarina Lunz; Isaac, Lourdes

    2016-01-01

    The complement system plays an important role in the innate and acquired immune response against pathogens. It consists of more than 30 proteins found in soluble form or attached to cell membranes. Most complement proteins circulate in inactive forms and can be sequentially activated by the classical, alternative, or lectin pathways. Biological functions, such as opsonization, removal of apoptotic cells, adjuvant function, activation of B lymphocytes, degranulation of mast cells and basophils, and solubilization and clearance of immune complex and cell lysis, are dependent on complement activation. Although the activation of the complement system is important to avoid infections, it also can contribute to the inflammatory response triggered by immune complex deposition in tissues in autoimmune diseases. Paradoxically, the deficiency of early complement proteins from the classical pathway (CP) is strongly associated with development of systemic lupus erythematous (SLE) – mainly C1q deficiency (93%) and C4 deficiency (75%). The aim of this review is to focus on the deficiencies of early components of the CP (C1q, C1r, C1s, C4, and C2) proteins in SLE patients. PMID:26941740

  11. Opsonic effect of jacalin and human immunoglobulin A on type II group B streptococci.

    PubMed Central

    Payne, N R; Concepcion, N F; Anthony, B F

    1990-01-01

    This study examined the effect of immunoglobulin A (IgA) and the IgA-binding lectin jacalin on the phagocytosis of type II group B streptococci (GBS). Strains possessing the trypsin-sensitive and trypsin-resistant components of the c protein (II/c) and type II GBS lacking the c protein (II) were examined by radiolabeled bacterial uptake, bactericidal assays, and electron microscopy. Type II/c GBS resisted phagocytosis by monocytes (4.9% +/- 0.8% uptake, mean +/- SE, n = 25) compared with type II GBS (8.5% +/- 1.4% uptake, n = 14, P = 0.03). Phagocytic killing by polymorphonuclear leukocytes was also less for the type II/c strain 78-471 than for the type II strain 79-176 (68% +/- 5% versus 86% +/- 4% reduction in CFU at 45 min, P = 0.03). IgA binding did not explain the resistance of type II/c GBS to phagocytosis. The uptake of type II/c GBS was not significantly different after opsonization in cord sera lacking endogenous IgA (5.93% +/- 1.4%) than in the same cord sera after addition of exogenous IgA (5.48% +/- 1.4%, P = 0.69, n = 9). Attempts to remove serum IgA with the IgA-binding lectin jacalin resulted in the binding of IgA-jacalin complexes to II/c GBS. This combination of nonspecific IgA and jacalin increased uptake of II/c GBS from 4.9% +/- 0.8% to 11.8% +/- 1.9% (P = 0.002). Jacalin also combined with specific, immune, monoclonal IgA bound to the surface of Haemophilus influenzae and promoted the uptake of these bacteria. Jacalin and IgA mediated phagocytosis of II/c GBS via receptors that were not dependent on divalent cations and that were not modulated by plating monocytes on antigen-antibody complexes. Images PMID:2228238

  12. Complements do not lie.

    PubMed

    Robert, Stefanie Christina; Forbes, Suzanne Helen; Soleimanian, Surusch; Hadley, Julia S

    2011-12-13

    A 74-year-old patient presented with constitutional symptoms and was found to have acute kidney injury. He was known to have a prosthetic aortic valve. He was febrile with splenomegaly and vasculitic lesions on both hands. Nephritic screen revealed strongly positive cytoplasmic-antineutrophil cytoplasmic antibodies (c-ANCA). Differential diagnosis thus included a small vessel vasculitis or infective endocarditis. Transoesophageal echocardiography demonstrated no vegetations and serial blood cultures were negative. Immunosuppression for presumed granulomatosis with polyangiitis (Wegeners granulomatosis) was therefore instituted. The patient deteriorated, requiring multi-organ support. Renal biopsy showed a proliferative glomerulopathy and complements were low. Atypical screen for culture negative endocarditis revealed a strongly positive IgG-antibody titre against Bartonella henselae. Immunosuppression was discontinued and treatment for chronic Bartonellosis commenced. The patient made a remarkable recovery. His renal function quickly returned to normal, and ANCA titres and complements normalised. He was discharged home after completing a 6 week course of antibiotic therapy.

  13. Complements do not lie

    PubMed Central

    Robert, Stefanie Christina; Forbes, Suzanne Helen; Soleimanian, Surusch; Hadley, Julia S

    2011-01-01

    A 74-year-old patient presented with constitutional symptoms and was found to have acute kidney injury. He was known to have a prosthetic aortic valve. He was febrile with splenomegaly and vasculitic lesions on both hands. Nephritic screen revealed strongly positive cytoplasmic-antineutrophil cytoplasmic antibodies (c-ANCA). Differential diagnosis thus included a small vessel vasculitis or infective endocarditis. Transoesophageal echocardiography demonstrated no vegetations and serial blood cultures were negative. Immunosuppression for presumed granulomatosis with polyangiitis (Wegeners granulomatosis) was therefore instituted. The patient deteriorated, requiring multi-organ support. Renal biopsy showed a proliferative glomerulopathy and complements were low. Atypical screen for culture negative endocarditis revealed a strongly positive IgG-antibody titre against Bartonella henselae. Immunosuppression was discontinued and treatment for chronic Bartonellosis commenced. The patient made a remarkable recovery. His renal function quickly returned to normal, and ANCA titres and complements normalised. He was discharged home after completing a 6 week course of antibiotic therapy. PMID:22674942

  14. Complements do not lie.

    PubMed

    Robert, Stefanie Christina; Forbes, Suzanne Helen; Soleimanian, Surusch; Hadley, Julia S

    2011-12-01

    A 74-year-old patient presented with constitutional symptoms and was found to have acute kidney injury. He was known to have a prosthetic aortic valve. He was febrile with splenomegaly and vasculitic lesions on both hands. Nephritic screen revealed strongly positive cytoplasmic-antineutrophil cytoplasmic antibodies (c-ANCA). Differential diagnosis thus included a small vessel vasculitis or infective endocarditis. Transoesophageal echocardiography demonstrated no vegetations and serial blood cultures were negative. Immunosuppression for presumed granulomatosis with polyangiitis (Wegeners granulomatosis) was therefore instituted. The patient deteriorated, requiring multi-organ support. Renal biopsy showed a proliferative glomerulopathy and complements were low. Atypical screen for culture negative endocarditis revealed a strongly positive IgG-antibody titre against Bartonella henselae. Immunosuppression was discontinued and treatment for chronic Bartonellosis commenced. The patient made a remarkable recovery. His renal function quickly returned to normal, and ANCA titres and complements normalised. He was discharged home after completing a 6 week course of antibiotic therapy.

  15. IXO: The Instrument Complement

    NASA Astrophysics Data System (ADS)

    Nousek, John A.; IWG, IXO

    2009-01-01

    The International X-ray Observatory (IXO) has recently been created as a mission concept by a joint team of NASA, ESA and JAXA scientists, based on the previous Constellation-X and XEUS concepts. Definition of the IXO instruments is still under evolution, but the core instrument complement will include a Wide Field X-ray Imager, an X-ray Calorimeter / Narrow Field X-ray Imager, and an X-ray Grating Spectrometer. Other, modest additional instruments (such as a hard X-ray capability, a polarimeter, and a high time resolution detector) will also be considered. We present the current status of the IXO instrument complement and offer the opportunity for discussion of ideas relevant to the IXO mission concept process.

  16. Effect of oxidatively modified and non-modified human serum albumin on luminol-dependent chemiluminescence of human peripheral blood leukocytes stimulated with opsonized zymosan.

    PubMed

    Piryazev, A P; Azizova, A P; Aseichev, A V; Sergienko, V I

    2014-07-01

    We studied the effects of native and oxidized human serum albumin on luminol-dependent chemiluminescence of human peripheral blood leukocytes stimulated with opsonized zymosan. Human serum albumin was added simultaneously with opsonized zymosan at the beginning of the chemiluminescent reaction. Otherwise, leukocytes were incubated with human serum albumin at 37°C for various periods before addition of opsonized zymosan. Oxidized human serum albumin was obtained by the method of metal-catalyzed oxidation. In control to non-modified albumin, oxidized albumin produced an inhibitory effect on luminol-dependent chemiluminescence of leukocytes. These changes were observed in experiments with addition of oxidized albumin at the beginning of a chemiluminescent reaction and after incubation of study agent with cells.

  17. IgM-Dependent Phagocytosis in Microglia Is Mediated by Complement Receptor 3, Not Fcα/μ Receptor.

    PubMed

    Weinstein, Jonathan R; Quan, Yi; Hanson, Josiah F; Colonna, Lucrezia; Iorga, Michael; Honda, Shin-ichiro; Shibuya, Kazuko; Shibuya, Akira; Elkon, Keith B; Möller, Thomas

    2015-12-01

    Microglia play an important role in receptor-mediated phagocytosis in the CNS. In brain abscess and other CNS infections, invading bacteria undergo opsonization with Igs or complement. Microglia recognize these opsonized pathogens by Fc or complement receptors triggering phagocytosis. In this study, we investigated the role of Fcα/μR, the less-studied receptor for IgM and IgA, in microglial phagocytosis. We showed that primary microglia, as well as N9 microglial cells, express Fcα/μR. We also showed that anti-Staphylococcus aureus IgM markedly increased the rate of microglial S. aureus phagocytosis. To unequivocally test the role of Fcα/μR in IgM-mediated phagocytosis, we performed experiments in microglia from Fcα/μR(-/-) mice. Surprisingly, we found that IgM-dependent phagocytosis of S. aureus was similar in microglia derived from wild-type or Fcα/μR(-/-) mice. We hypothesized that IgM-dependent activation of complement receptors might contribute to the IgM-mediated increase in phagocytosis. To test this, we used immunologic and genetic inactivation of complement receptor 3 components (CD11b and CD18) as well as C3. IgM-, but not IgG-mediated phagocytosis of S. aureus was reduced in wild-type microglia and macrophages following preincubation with an anti-CD11b blocking Ab. IgM-dependent phagocytosis of S. aureus was also reduced in microglia derived from CD18(-/-) and C3(-/-) mice. Taken together, our findings implicate complement receptor 3 and C3, but not Fcα/μR, in IgM-mediated phagocytosis of S. aureus by microglia.

  18. Plasma fibronectin (opsonic glycoprotein): its synthesis by vascular endothelial cells and role in cardiopulmonary integrity after trauma as related to reticuloendothelial function.

    PubMed

    Saba, T M; Jaffe, E

    1980-04-01

    Progressive multiple organ failure in association with septic complications in the surgical, trauma and burn patient is of major clinical importance. Reticuloendothelial system host defense mechanisms are abnormal following severe trauma and burn. Failure in systemic host defense is, in part, mediated by a deficiency in a circulating opsonic alpha 2 surface binding (SB) glycoprotein. This opsonic deficiency and reticuloendothelial host defense failure appears etiologic in the genesis of organ failure with sepsis. Opsonic alpha 2SB glycoprotein is identical to cold-insoluble globulin or plasma fibronectin. Plasma fibronectin is antigenically related to cell surface fibronectin which appears to be synthesized by both fibroblasts and vascular endothelial cells. Although these two proteins are antigenically related, they may or may not be identical with respect to biochemical properties and function. Cell surface fibronectin appears to be an adhesive glycoprotein mediating cell-cell interaction and cell adhesion to a substratum. Plasma fibronectin is a more soluble form which mediates reticuloendothelial or macrophage clearance of particulates such as fibrin microaggregates, collagenous debris, perhaps other bacterial or nonbacterial particulates. Since opsonic glycoprotein is identical to cold-insoluble globulin which can be readily concentrated in plasma cryoprecipitate, it has been shown that cryoprecipitate infusion can reverse opsonic deficiency in the injured patient with sepsis. Reversal of opsonic deficiency by cryoprecipitate infusion results in a marked improvement in cardiopulmonary function which includes a decline in the pulmonary shunt, a decrease in the physiologic dead space, an increase in limb blood flow, an increase in reactive hyperemia of the peripheral circulation and an increase in limb oxygen consumption. This cardiopulmonary response is paralleled by a decline in the septic state and normalization of other hematologic parameters. These studies

  19. Complement: A primer for the coming therapeutic revolution.

    PubMed

    Barnum, Scott R

    2017-04-01

    The complement system is an important part of the innate and adaptive immune systems. Originally characterized as a single serum component contributing to the killing of bacteria, we now know that there are close to sixty complement proteins, multiple activation pathways and a wide range of effector functions mediated by complement. The system plays a critical role in host defense against bacteria, viruses, fungi and other pathogens. However, inappropriate complement activation contributes to the pathophysiology of autoimmune diseases and many inflammatory syndromes. Over the last several decades, therapeutic approaches to inhibit complement activation at various steps in the pathways have met with initial success, particularly at the level of the terminal pathway. This success, combined with insight from animal model studies, has lead to an unprecedented effort by biotech and pharmaceutical companies to begin developing complement inhibitors. As a result, complement has been brought for the first time to the attention of pharmacologists, toxicologists, project managers and others in the drug development industry, as well as those in the investment world. The purpose of this primer is to provide a broad overview of complement immunobiology to help those new to complement understand the rationale behind the current therapeutic directions and the investment potential of these new therapeutics.

  20. Binding of complement component C3b to glycoprotein gC of herpes simplex virus type 1: mapping of gC-binding sites and demonstration of conserved C3b binding in low-passage clinical isolates.

    PubMed Central

    Friedman, H M; Glorioso, J C; Cohen, G H; Hastings, J C; Harris, S L; Eisenberg, R J

    1986-01-01

    The sites on glycoprotein gC of herpes simplex virus type 1 (HSV-1) which bind complement component C3b were evaluated by using anti-gC monoclonal antibodies and mutants which have alterations at defined regions of the glycoprotein. Monoclonal antibodies were incubated with HSV-1-infected cells in a competitive assay to block C3b binding. Each of 12 different monoclonals, which recognize the four major antigenic sites of gC, completely inhibited C3b binding. With this approach, no one antigenic group on gC could be assigned as the C3b-binding region. Next, 21 gC mutants were evaluated for C3b binding, including 1 which failed to synthesize gC, 4 which synthesized truncated forms of the glycoprotein such that gC did not insert into the cell's membrane, and 16 which expressed gC on the cell's surface but which had mutations in various antigenic groups. Eleven strains did not bind C3b. This included the 1 strain which did not synthesize gC, the 4 strains which secreted gC without inserting the glycoprotein into the cell membrane, and 6 of 16 strains which expressed gC on the cell surface. In these six strains, the mutations were at three different antigenic sites. One hypothesis to explain these findings is that C3b binding is modified by changes in the conformation of gC which develop either after antibodies bind to gC or as a result of mutations in the gC gene. Attachment of C3b to gC was also evaluated in 31 low-passage clinical isolates of HSV-1. Binding was detected with each HSV-1 isolate, but not with nine HSV-2 isolates. Therefore, although mutants that lack C3b binding are readily selected in vitro, the C3b-binding function of gC is maintained in vivo. These results indicate that the sites on gC that bind C3b are different from those that bind monoclonal antibodies, that antibodies directed against all sites on gC block C3b binding, and that C3b binding is a conserved function of gC in vivo. PMID:3021981

  1. Virulence of Group A Streptococci Is Enhanced by Human Complement Inhibitors

    PubMed Central

    Ermert, David; Shaughnessy, Jutamas; Joeris, Thorsten; Kaplan, Jakub; Pang, Catherine J.; Kurt-Jones, Evelyn A.; Rice, Peter A.; Ram, Sanjay; Blom, Anna M.

    2015-01-01

    Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is an important human bacterial pathogen that can cause invasive infections. Once it colonizes its exclusively human host, GAS needs to surmount numerous innate immune defense mechanisms, including opsonization by complement and consequent phagocytosis. Several strains of GAS bind to human-specific complement inhibitors, C4b-binding protein (C4BP) and/or Factor H (FH), to curtail complement C3 (a critical opsonin) deposition. This results in diminished activation of phagocytes and clearance of GAS that may lead to the host being unable to limit the infection. Herein we describe the course of GAS infection in three human complement inhibitor transgenic (tg) mouse models that examined each inhibitor (human C4BP or FH) alone, or the two inhibitors together (C4BPxFH or ‘double’ tg). GAS infection with strains that bound C4BP and FH resulted in enhanced mortality in each of the three transgenic mouse models compared to infection in wild type mice. In addition, GAS manifested increased virulence in C4BPxFH mice: higher organism burdens and greater elevations of pro-inflammatory cytokines and they died earlier than single transgenic or wt controls. The effects of hu-C4BP and hu-FH were specific for GAS strains that bound these inhibitors because strains that did not bind the inhibitors showed reduced virulence in the ‘double’ tg mice compared to strains that did bind; mortality was also similar in wild-type and C4BPxFH mice infected by non-binding GAS. Our findings emphasize the importance of binding of complement inhibitors to GAS that results in impaired opsonization and phagocytic killing, which translates to enhanced virulence in a humanized whole animal model. This novel hu-C4BPxFH tg model may prove invaluable in studies of GAS pathogenesis and for developing vaccines and therapeutics that rely on human complement activation for efficacy. PMID:26200783

  2. Annexin A2 Enhances Complement Activation by Inhibiting Factor H1

    PubMed Central

    Renner, Brandon; Tong, Hua Hua; Laskowski, Jennifer; Jonscher, Karen; Goetz, Lindsey; Woolaver, Rachel; Hannan, Jonathan; Li, Yong Xing; Hourcade, Dennis; Pickering, Matthew C.; Holers, V. Michael; Thurman, Joshua M.

    2015-01-01

    Factor H is a circulating protein that regulates activation of the alternative pathway (AP) of complement. Mutations and genetic variations of factor H are associated with several AP-mediated diseases, highlighting the critical role of factor H in AP regulation. AP-mediated inflammation is typically triggered by illness or tissue injury, however, and tissue injury can trigger AP activation in individuals with fully functional factor H. This suggests that factor H function is affected by local conditions within tissues. We hypothesized that inducible proteins impair the ability of factor H to locally control the AP, thereby increasing AP activation. We used purified murine factor H to immunoprecipitate binding partners from mouse kidneys. Using immunoaffinity liquid chromatography-mass spectrometry we then identified annexin A2 as a factor H binding partner. Further experiments showed that annexin A2 reduces the binding of factor H to cell surfaces. Recombinant annexin A2 impaired complement regulation by factor H, and increased complement activation on renal cell surfaces in vitro and in vivo. In a murine model of acute pneumococcal otitis media the administration of annexin A2 increased AP-mediated bacterial opsonization and clearance. In conclusion, the local production of annexin A2 within tissues suppresses regulation of the AP by factor H. Annexin A2 can contribute to AP-mediated tissue inflammation by locally impairing factor H function, but annexin A2 can also improve complement-mediated bacterial clearance. PMID:26729803

  3. Compstatin: a C3-targeted complement inhibitor reaching its prime for bedside intervention.

    PubMed

    Mastellos, Dimitrios C; Yancopoulou, Despina; Kokkinos, Petros; Huber-Lang, Markus; Hajishengallis, George; Biglarnia, Ali R; Lupu, Florea; Nilsson, Bo; Risitano, Antonio M; Ricklin, Daniel; Lambris, John D

    2015-04-01

    There is a growing awareness that complement plays an integral role in human physiology and disease, transcending its traditional perception as an accessory system for pathogen clearance and opsonic cell killing. As the list of pathologies linked to dysregulated complement activation grows longer, it has become clear that targeted modulation of this innate immune system opens new windows of therapeutic opportunity for anti-inflammatory drug design. Indeed, the introduction of the first complement-targeting drugs has reignited a vibrant interest in the clinical translation of complement-based inhibitors. Compstatin was discovered as a cyclic peptide that inhibits complement activation by binding C3 and interfering with convertase formation and C3 cleavage. As the convergence point of all activation pathways and a molecular hub for crosstalk with multiple pathogenic pathways, C3 represents an attractive target for therapeutic modulation of the complement cascade. A multidisciplinary drug optimization effort encompassing rational 'wet' and in silico synthetic approaches and an array of biophysical, structural and analytical tools has culminated in an impressive structure-function refinement of compstatin, yielding a series of analogues that show promise for a wide spectrum of clinical applications. These new derivatives have improved inhibitory potency and pharmacokinetic profiles and show efficacy in clinically relevant primate models of disease. This review provides an up-to-date survey of the drug design effort placed on the compstatin family of C3 inhibitors, highlighting the most promising drug candidates. It also discusses translational challenges in complement drug discovery and peptide drug development and reviews concerns related to systemic C3 interception.

  4. The terminal pathway of the complement system is activated in focal penetrating but not in mild diffuse traumatic brain injury.

    PubMed

    Rostami, Elham; Davidsson, Johan; Gyorgy, Andrea; Agoston, Denes V; Risling, Mårten; Bellander, Bo-Michael

    2013-12-01

    The complement system plays an important role in the inflammatory response activated by many central nervous system disorders. However, its significance in traumatic diffuse traumatic axonal injury (TAI) is not fully known. Here we analyze the complement activity in two rat models of traumatic brain injury (TBI); a focal penetration injury (pen-TBI) and a rotational acceleration injury (rot-TBI) that leads to a mild TAI. We used in situ hybridization to examine the distribution of mRNA for C1q and C3 and immunohistochemistry to examine the presence of the C3 protein and C5b-9 complex at 1-5 days after injury. We found a time-dependent complement activity in both models. However, the responses caused by the two models were different. We detected C5b-9 surrounding the cavity in pen-TBI, but C5b-9 was not found in the rot-TBI. Our findings suggest that the terminal complement pathway is progressed to the formation of the C5b-9 membrane attack complex only in the penetrating TBI but not in isolated TAI model. This indicates that the complement activation does not lead to membrane-damaging effects and a subsequent secondary axotomy in TAI by the terminal complex C5b-9. The role of complement activation in TAI is unclear, but might indicate an alternative function following rot-TBI, such as opsonizing the synapses for elimination.

  5. Complementing Gender Analysis Methods.

    PubMed

    Kumar, Anant

    2016-01-01

    The existing gender analysis frameworks start with a premise that men and women are equal and should be treated equally. These frameworks give emphasis on equal distribution of resources between men and women and believe that this will bring equality which is not always true. Despite equal distribution of resources, women tend to suffer and experience discrimination in many areas of their lives such as the power to control resources within social relationships, and the need for emotional security and reproductive rights within interpersonal relationships. These frameworks believe that patriarchy as an institution plays an important role in women's oppression, exploitation, and it is a barrier in their empowerment and rights. Thus, some think that by ensuring equal distribution of resources and empowering women economically, institutions like patriarchy can be challenged. These frameworks are based on proposed equality principle which puts men and women in competing roles. Thus, the real equality will never be achieved. Contrary to the existing gender analysis frameworks, the Complementing Gender Analysis framework proposed by the author provides a new approach toward gender analysis which not only recognizes the role of economic empowerment and equal distribution of resources but suggests to incorporate the concept and role of social capital, equity, and doing gender in gender analysis which is based on perceived equity principle, putting men and women in complementing roles that may lead to equality. In this article the author reviews the mainstream gender theories in development from the viewpoint of the complementary roles of gender. This alternative view is argued based on existing literature and an anecdote of observations made by the author. While criticizing the equality theory, the author offers equity theory in resolving the gender conflict by using the concept of social and psychological capital.

  6. Infections of People with Complement Deficiencies and Patients Who Have Undergone Splenectomy

    PubMed Central

    Ram, Sanjay; Lewis, Lisa A.; Rice, Peter A.

    2010-01-01

    Summary: The complement system comprises several fluid-phase and membrane-associated proteins. Under physiological conditions, activation of the fluid-phase components of complement is maintained under tight control and complement activation occurs primarily on surfaces recognized as “nonself” in an attempt to minimize damage to bystander host cells. Membrane complement components act to limit complement activation on host cells or to facilitate uptake of antigens or microbes “tagged” with complement fragments. While this review focuses on the role of complement in infectious diseases, work over the past couple of decades has defined several important functions of complement distinct from that of combating infections. Activation of complement in the fluid phase can occur through the classical, lectin, or alternative pathway. Deficiencies of components of the classical pathway lead to the development of autoimmune disorders and predispose individuals to recurrent respiratory infections and infections caused by encapsulated organisms, including Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. While no individual with complete mannan-binding lectin (MBL) deficiency has been identified, low MBL levels have been linked to predisposition to, or severity of, several diseases. It appears that MBL may play an important role in children, who have a relatively immature adaptive immune response. C3 is the point at which all complement pathways converge, and complete deficiency of C3 invariably leads to severe infections, including those caused by meningococci and pneumococci. Deficiencies of the alternative and terminal complement pathways result in an almost exclusive predisposition to invasive meningococcal disease. The spleen plays an important role in antigen processing and the production of antibodies. Splenic macrophages are critical in clearing opsonized encapsulated bacteria (such as pneumococci, meningococci, and Escherichia coli

  7. Anti-Pseudomonas aeruginosa IgY antibodies promote bacterial opsonization and augment the phagocytic activity of polymorphonuclear neutrophils

    PubMed Central

    Thomsen, Kim; Christophersen, Lars; Jensen, Peter Østrup; Bjarnsholt, Thomas; Moser, Claus; Høiby, Niels

    2016-01-01

    ABSTRACT Moderation of polymorphonuclear neutrophils (PMNs) as part of a critical defense against invading pathogens may offer a promising therapeutic approach to supplement the antibiotic eradication of Pseudomonas aeruginosa infection in non-chronically infected cystic fibrosis (CF) patients. We have observed that egg yolk antibodies (IgY) harvested from White leghorn chickens that target P. aeruginosa opsonize the pathogen and enhance the PMN-mediated respiratory burst and subsequent bacterial killing in vitro. The effects on PMN phagocytic activity were observed in different Pseudomonas aeruginosa strains, including clinical isolates from non-chronically infected CF patients. Thus, oral prophylaxis with anti-Pseudomonas aeruginosa IgY may boost the innate immunity against Pseudomonas aeruginosa in the CF setting by facilitating a rapid and prompt bacterial clearance by PMNs. PMID:26901841

  8. Complement inhibition in cancer therapy.

    PubMed

    Pio, Ruben; Ajona, Daniel; Lambris, John D

    2013-02-01

    For decades, complement has been recognized as an effector arm of the immune system that contributes to the destruction of tumor cells. In fact, many therapeutic strategies have been proposed that are based on the intensification of complement-mediated responses against tumors. However, recent studies have challenged this paradigm by demonstrating a tumor-promoting role for complement. Cancer cells seem to be able to establish a convenient balance between complement activation and inhibition, taking advantage of complement initiation without suffering its deleterious effects. Complement activation may support chronic inflammation, promote an immunosuppressive microenvironment, induce angiogenesis, and activate cancer-related signaling pathways. In this context, inhibition of complement activation would be a therapeutic option for treating cancer. This concept is relatively new and deserves closer attention. In this article, we summarize the mechanisms of complement activation on cancer cells, the cancer-promoting effect of complement initiation, and the rationale behind the use of complement inhibition as a therapeutic strategy against cancer.

  9. Non-opsonic phagocytosis of homologous non-toxigenic and toxigenic Corynebacterium diphtheriae strains by human U-937 macrophages.

    PubMed

    dos Santos, Cíntia Silva; dos Santos, Louisy Sanches; de Souza, Monica Cristina; dos Santos Dourado, Fernanda; de Souza de Oliveira Dias, Alexandre Alves; Sabbadini, Priscila Soares; Pereira, Gabriela Andrade; Cabral, Maulori Curié; Hirata Junior, Raphael; de Mattos-Guaraldi, Ana Luíza

    2010-01-01

    As interactions between bacteria and macrophages dictate the outcome of most infectious diseases, analyses of molecular mechanisms of non-opsonic phagocytosis should lead to new approaches for the prevention of diphtheria and systemic Corynebacterium diphtheriae infections. The present study aimed to evaluate human macrophage-bacteria interactions in the absence of opsonin antibodies and the influence of the tox gene on this process. Homologous C. diphtheriae tox+ and tox- strains were evaluated for adhesion, entering and survival within U-937 human macrophages at different incubation periods. Higher numbers of viable bacteria associated with and internalized by macrophages were demonstrated for the tox+ strain. However, viable intracellular bacteria were detected at T-24 hr only for the tox- strain. Cytoskeletal inhibitors, cytochalasin E, genistein and colchicine, inhibited intracellular viability of both strains at different levels. Bacterial replication was evidenced at T-24 hr in supernatants of monolayers infected with the tox- strain. Host cell death and nuclear alterations were evidenced by the Trypan blue exclusion assay and DAPI fluorescence microscopy. ELISA of histone-associated DNA fragments allowed detection of apoptosis and necrosis induced by tox+ and tox- strains at T-1 hr and T-3 hr. In conclusion, human macrophages in the absence of opsonins may not be promptly effective at killing diphtheria bacilli. The presence of the tox gene influences the susceptibility of C. diphtheriae to human macrophages and the outcome of non-opsonic phagocytosis. C. diphtheriae strains exhibit strategies to survive within macrophages and to exert apoptosis and necrosis in human phagocytic cells, independent of the tox gene.

  10. Type IV pilus glycosylation mediates resistance of Pseudomonas aeruginosa to opsonic activities of the pulmonary surfactant protein A.

    PubMed

    Tan, Rommel M; Kuang, Zhizhou; Hao, Yonghua; Lee, Francis; Lee, Timothy; Lee, Ryan J; Lau, Gee W

    2015-04-01

    Pseudomonas aeruginosa is a major bacterial pathogen commonly associated with chronic lung infections in cystic fibrosis (CF). Previously, we have demonstrated that the type IV pilus (Tfp) of P. aeruginosa mediates resistance to antibacterial effects of pulmonary surfactant protein A (SP-A). Interestingly, P. aeruginosa strains with group I pilins are O-glycosylated through the TfpO glycosyltransferase with a single subunit of O-antigen (O-ag). Importantly, TfpO-mediated O-glycosylation is important for virulence in mouse lungs, exemplified by more frequent lung infection in CF with TfpO-expressing P. aeruginosa strains. However, the mechanism underlying the importance of Tfp glycosylation in P. aeruginosa pathogenesis is not fully understood. Here, we demonstrated one mechanism of increased fitness mediated by O-glycosylation of group 1 pilins on Tfp in the P. aeruginosa clinical isolate 1244. Using an acute pneumonia model in SP-A+/+ versus SP-A-/- mice, the O-glycosylation-deficient ΔtfpO mutant was found to be attenuated in lung infection. Both 1244 and ΔtfpO strains showed equal levels of susceptibility to SP-A-mediated membrane permeability. In contrast, the ΔtfpO mutant was more susceptible to opsonization by SP-A and by other pulmonary and circulating opsonins, SP-D and mannose binding lectin 2, respectively. Importantly, the increased susceptibility to phagocytosis was abrogated in the absence of opsonins. These results indicate that O-glycosylation of Tfp with O-ag specifically confers resistance to opsonization during host-mediated phagocytosis.

  11. Complement System in Lung Disease

    PubMed Central

    Pandya, Pankita H.

    2014-01-01

    In addition to its established contribution to innate immunity, recent studies have suggested novel roles for the complement system in the development of various lung diseases. Several studies have demonstrated that complement may serve as a key link between innate and adaptive immunity in a variety of pulmonary conditions. However, the specific contributions of complement to lung diseases based on innate and adaptive immunity are just beginning to emerge. Elucidating the role of complement-mediated immune regulation in these diseases will help to identify new targets for therapeutic interventions. PMID:24901241

  12. Viruses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lytic bacteriophages, viruses which infect and lyse bacterial cells, can provide a natural method to reduce bacterial pathogens on produce commodities. The use of multi-phage cocktails is most likely to be effective against bacterial pathogens on produce commodities, and minimize the development of...

  13. The Complement System in Flavivirus Infections.

    PubMed

    Conde, Jonas N; Silva, Emiliana M; Barbosa, Angela S; Mohana-Borges, Ronaldo

    2017-01-01

    The incidence of flavivirus infections has increased dramatically in recent decades in tropical and sub-tropical climates worldwide, affecting hundreds of millions of people each year. The Flaviviridae family includes dengue, West Nile, Zika, Japanese encephalitis, and yellow fever viruses that are typically transmitted by mosquitoes or ticks, and cause a wide range of symptoms, such as fever, shock, meningitis, paralysis, birth defects, and death. The flavivirus genome is composed of a single positive-sense RNA molecule encoding a single viral polyprotein. This polyprotein is further processed by viral and host proteases into three structural proteins (C, prM/M, E) and seven non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, NS5) that are involved in viral replication and pathogenicity. The complement system has been described to play an important role in flavivirus infection either by protecting the host and/or by influencing disease pathogenesis. In this mini-review, we will explore the role of complement system inhibition and/or activation against infection by the Flavivirus genus, with an emphasis on dengue and West Nile viruses.

  14. The Complement System in Flavivirus Infections

    PubMed Central

    Conde, Jonas N.; Silva, Emiliana M.; Barbosa, Angela S.; Mohana-Borges, Ronaldo

    2017-01-01

    The incidence of flavivirus infections has increased dramatically in recent decades in tropical and sub-tropical climates worldwide, affecting hundreds of millions of people each year. The Flaviviridae family includes dengue, West Nile, Zika, Japanese encephalitis, and yellow fever viruses that are typically transmitted by mosquitoes or ticks, and cause a wide range of symptoms, such as fever, shock, meningitis, paralysis, birth defects, and death. The flavivirus genome is composed of a single positive-sense RNA molecule encoding a single viral polyprotein. This polyprotein is further processed by viral and host proteases into three structural proteins (C, prM/M, E) and seven non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, NS5) that are involved in viral replication and pathogenicity. The complement system has been described to play an important role in flavivirus infection either by protecting the host and/or by influencing disease pathogenesis. In this mini-review, we will explore the role of complement system inhibition and/or activation against infection by the Flavivirus genus, with an emphasis on dengue and West Nile viruses. PMID:28261172

  15. Extravascular hemolysis and complement consumption in Paroxysmal Nocturnal Hemoglobinuria patients undergoing eculizumab treatment.

    PubMed

    Subías Hidalgo, Marta; Martin Merinero, Hector; López, Alicia; Anter, Jaouad; García, Sheila Pinto; Ataúlfo Gonzalez-Fernández, Fernando; Forés, Rafael; Lopez-Trascasa, Margarita; Villegas, Ana; Ojeda, Emilio; Rodríguez de Córdoba, Santiago

    2017-02-01

    Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia characterized by complement-mediated intravascular hemolysis that is effectively treated with eculizumab. However, treatment responses are reported heterogeneous with some patients presenting residual hemolysis and requiring RBC transfusions. Recent reports have shown that both extravascular hemolysis and incomplete C5 blockade can explain these suboptimal hematological responses. Here we have tested our eculizumab-treated PNH patients (n=12) for signs of hemolysis and assessed complement biomarkers. Patients were also genotyped for complement receptor 1 (CR1, CD35) and C5 polymorphisms and evaluated for free eculizumab in plasma. We report that 10 patients (83%) present parameters suggesting persistent hemolysis, although they did not require additional transfusions. Seven of them (58%) become direct Coombs-test positive as a consequence of treatment, including all patients carrying the low-expression CR1-L allele. CH50 and sC5b-9 assays demonstrate that the persistent low-level hemolysis identified in our treated patients is not a consequence of incomplete C5 blockade, supporting that this hemolysis, as has been suggested previously, results from the extravascular removal of C3 opsonized PNH erythrocytes. We also show that continuous alternative pathway activation in eculizumab-treated individuals carrying the CR1-L allele results in abnormally decreased levels of C3 in plasma that could, potentially, increase their susceptibility to bacterial infections. Finally, we encourage a routine evaluation of free eculizumab levels and terminal pathway activity to personalize eculizumab administration.

  16. Phagocytosis escape by a Staphylococcus aureus protein that connects complement and coagulation proteins at the bacterial surface.

    PubMed

    Ko, Ya-Ping; Kuipers, Annemarie; Freitag, Claudia M; Jongerius, Ilse; Medina, Eva; van Rooijen, Willemien J; Spaan, András N; van Kessel, Kok P M; Höök, Magnus; Rooijakkers, Suzan H M

    2013-01-01

    Upon contact with human plasma, bacteria are rapidly recognized by the complement system that labels their surface for uptake and clearance by phagocytic cells. Staphylococcus aureus secretes the 16 kD Extracellular fibrinogen binding protein (Efb) that binds two different plasma proteins using separate domains: the Efb N-terminus binds to fibrinogen, while the C-terminus binds complement C3. In this study, we show that Efb blocks phagocytosis of S. aureus by human neutrophils. In vitro, we demonstrate that Efb blocks phagocytosis in plasma and in human whole blood. Using a mouse peritonitis model we show that Efb effectively blocks phagocytosis in vivo, either as a purified protein or when produced endogenously by S. aureus. Mutational analysis revealed that Efb requires both its fibrinogen and complement binding residues for phagocytic escape. Using confocal and transmission electron microscopy we show that Efb attracts fibrinogen to the surface of complement-labeled S. aureus generating a 'capsule'-like shield. This thick layer of fibrinogen shields both surface-bound C3b and antibodies from recognition by phagocytic receptors. This information is critical for future vaccination attempts, since opsonizing antibodies may not function in the presence of Efb. Altogether we discover that Efb from S. aureus uniquely escapes phagocytosis by forming a bridge between a complement and coagulation protein.

  17. Nouns, Verbs and NP Complements.

    ERIC Educational Resources Information Center

    Platt, J. T.

    This paper investigates restrictions on three types of noun-phrase complements (gerundive, infinitive, clause) in English and seeks to point out some parallels between the occurrence of these three types in object positions. The author first presents a list of verbs which may be followed by noun-phrase complements; he then considers the occurrence…

  18. Complement in health and disease.

    PubMed

    Carroll, Maria V; Sim, Robert B

    2011-09-16

    The complement system consists of about 35-40 proteins and glycoproteins present in blood plasma or on cell surfaces. Its main biological function is to recognise "foreign" particles and macromolecules, and to promote their elimination either by opsonisation or lysis. Although historically complement has been studied as a system for immune defence against bacteria, it has an important homeostatic role in which it recognises damaged or altered "self" components. Thus complement has major roles in both immune defence against microorganisms, and in clearance of damaged or "used" host components. Since complement proteins opsonise or lyse cells, complement can damage healthy host cells and tissues. The system is regulated by many endogenous regulatory proteins. Regulation is sometimes imperfect and both too much and too little complement activation is associated with many diseases. Excessive or inappropriate activation can cause tissue damage in diseases such as rheumatoid arthritis, age-related macular degeneration (AMD), multiple sclerosis, ischemia-reperfusion injury (e.g. ischemic stroke). Insufficient complement activity is associated with susceptibility to infection (mainly bacterial) and development of autoimmune disease, like SLE (systemic lupus erythematosus).

  19. Complement Evasion by Pathogenic Leptospira.

    PubMed

    Fraga, Tatiana Rodrigues; Isaac, Lourdes; Barbosa, Angela Silva

    2016-01-01

    Leptospirosis is a neglected infectious disease caused by spirochetes from the genus Leptospira. Pathogenic microorganisms, notably those which reach the blood circulation such as Leptospira, have evolved multiple strategies to escape the host complement system, which is important for innate and acquired immunity. Leptospira avoid complement-mediated killing through: (i) recruitment of host complement regulators; (ii) acquisition of host proteases that cleave complement proteins on the bacterial surface; and, (iii) secretion of proteases that inactivate complement proteins in the Leptospira surroundings. The recruitment of host soluble complement regulatory proteins includes the acquisition of Factor H (FH) and FH-like-1 (alternative pathway), C4b-binding protein (C4BP) (classical and lectin pathways), and vitronectin (Vn) (terminal pathway). Once bound to the leptospiral surface, FH and C4BP retain cofactor activity of Factor I in the cleavage of C3b and C4b, respectively. Vn acquisition by leptospires may result in terminal pathway inhibition by blocking C9 polymerization. The second evasion mechanism lies in plasminogen (PLG) binding to the leptospiral surface. In the presence of host activators, PLG is converted to enzymatically active plasmin, which is able to degrade C3b, C4b, and C5 at the surface of the pathogen. A third strategy used by leptospires to escape from complement system is the active secretion of proteases. Pathogenic, but not saprophytic leptospires, are able to secrete metalloproteases that cleave C3 (central complement molecule), Factor B (alternative pathway), and C4 and C2 (classical and lectin pathways). The purpose of this review is to fully explore these complement evasion mechanisms, which act together to favor Leptospira survival and multiplication in the host.

  20. Complement Evasion by Pathogenic Leptospira

    PubMed Central

    Fraga, Tatiana Rodrigues; Isaac, Lourdes; Barbosa, Angela Silva

    2016-01-01

    Leptospirosis is a neglected infectious disease caused by spirochetes from the genus Leptospira. Pathogenic microorganisms, notably those which reach the blood circulation such as Leptospira, have evolved multiple strategies to escape the host complement system, which is important for innate and acquired immunity. Leptospira avoid complement-mediated killing through: (i) recruitment of host complement regulators; (ii) acquisition of host proteases that cleave complement proteins on the bacterial surface; and, (iii) secretion of proteases that inactivate complement proteins in the Leptospira surroundings. The recruitment of host soluble complement regulatory proteins includes the acquisition of Factor H (FH) and FH-like-1 (alternative pathway), C4b-binding protein (C4BP) (classical and lectin pathways), and vitronectin (Vn) (terminal pathway). Once bound to the leptospiral surface, FH and C4BP retain cofactor activity of Factor I in the cleavage of C3b and C4b, respectively. Vn acquisition by leptospires may result in terminal pathway inhibition by blocking C9 polymerization. The second evasion mechanism lies in plasminogen (PLG) binding to the leptospiral surface. In the presence of host activators, PLG is converted to enzymatically active plasmin, which is able to degrade C3b, C4b, and C5 at the surface of the pathogen. A third strategy used by leptospires to escape from complement system is the active secretion of proteases. Pathogenic, but not saprophytic leptospires, are able to secrete metalloproteases that cleave C3 (central complement molecule), Factor B (alternative pathway), and C4 and C2 (classical and lectin pathways). The purpose of this review is to fully explore these complement evasion mechanisms, which act together to favor Leptospira survival and multiplication in the host. PMID:28066433

  1. Factor H and factor H-related protein 1 bind to human neutrophils via complement receptor 3, mediate attachment to Candida albicans, and enhance neutrophil antimicrobial activity.

    PubMed

    Losse, Josephine; Zipfel, Peter F; Józsi, Mihály

    2010-01-15

    The host complement system plays an important role in protection against infections. Several human-pathogenic microbes were shown to acquire host complement regulators, such as factor H (CFH), that downregulate complement activation at the microbial surface and protect the pathogens from the opsonic and lytic effects of complement. Because CFH can also bind to host cells, we addressed the role of CFH and CFH-related proteins as adhesion ligands in host-pathogen interactions. We show that the CFH family proteins CFH, CFH-like protein 1 (CFHL1), CFH-related protein (CFHR) 1, and CFHR4 long isoform bind to human neutrophil granulocytes and to the opportunistic human-pathogenic yeast Candida albicans. Two major binding sites, one within the N-terminus and one in the C-terminus of CFH, were found to mediate binding to neutrophils. Complement receptor 3 (CD11b/CD18; alpha(M)beta2 integrin) was identified as the major cellular receptor on neutrophils for CFH, CFHL1, and CFHR1, but not for CFHR4 long isoform. CFH and CFHR1 supported cell migration. Furthermore, CFH, CFHL1, and CFHR1 increased attachment of neutrophils to C. albicans. Adhesion of neutrophils to plasma-opsonized yeasts was reduced when CFH binding was inhibited by specific Abs or when using CFH-depleted plasma. Yeast-bound CFH and CFHR1 enhanced the generation of reactive oxygen species and the release of the antimicrobial protein lactoferrin by human neutrophils, and resulted in a more efficient killing of the pathogen. Thus, CFH and CFHR1, when bound on the surface of C. albicans, enhance antimicrobial activity of human neutrophils.

  2. How antibodies alter the cell entry pathway of dengue virus particles in macrophages

    PubMed Central

    Ayala-Nunez, Nilda V.; Hoornweg, Tabitha E.; van de Pol, Denise P.I.; Sjollema, Klaas A.; Flipse, Jacky; van der Schaar, Hilde M.; Smit, Jolanda M.

    2016-01-01

    Antibody-dependent enhancement of dengue virus (DENV) infection plays an important role in the exacerbation of DENV-induced disease. To understand how antibodies influence the fate of DENV particles, we explored the cell entry pathway of DENV in the absence and presence of antibodies in macrophage-like P388D1 cells. Recent studies unraveled that both mature and immature DENV particles contribute to ADE, hence, both particles were studied. We observed that antibody-opsonized DENV enters P388D1 cells through a different pathway than non-opsonized DENV. Antibody-mediated DENV entry was dependent on FcγRs, pH, Eps15, dynamin, actin, PI3K, Rab5, and Rab7. In the absence of antibodies, DENV cell entry was FcγR, PI3K, and Rab5-independent. Live-cell imaging of fluorescently-labeled particles revealed that actin-mediated membrane protrusions facilitate virus uptake. In fact, actin protrusions were found to actively search and capture antibody-bound virus particles distantly located from the cell body, a phenomenon that is not observed in the absence of antibodies. Overall, similar results were seen for antibody-opsonized standard and antibody-bound immature DENV preparations, indicating that the maturation status of the virus does not control the entry pathway. Collectively, our findings suggest that antibodies alter the cell entry pathway of DENV and trigger a novel mechanism of initial virus-cell contact. PMID:27385443

  3. Genetics of the complement system.

    PubMed Central

    Lachmann, P

    1975-01-01

    The complement system, unlike the coagulation system, was largely characterized by in-vitro techniques which did not make use of genetically deficient plasmas. The existence of the genetically deficient plasmas. The existence of the genetically deficient subjects therefore has served largely to increase our knowledge of the in-vivo role of complement. At the present time its clearest role is in the resistance to infection; obviously in the case of C3 deficiency and bacterial infection and possibly more subtly in the case of deficiency of the early active complement components and low virulence organisms. There is so far no evidence that genetic complement deficiency interferes with antibody formation or with the generation of tolerance as has been suggested in the pas (Azar et al, 1968; Dukor and Hartmann, 1973). PMID:768477

  4. Myelin-reactive antibodies initiate T cell-mediated CNS autoimmune disease by opsonization of endogenous antigen.

    PubMed

    Kinzel, Silke; Lehmann-Horn, Klaus; Torke, Sebastian; Häusler, Darius; Winkler, Anne; Stadelmann, Christine; Payne, Natalie; Feldmann, Linda; Saiz, Albert; Reindl, Markus; Lalive, Patrice H; Bernard, Claude C; Brück, Wolfgang; Weber, Martin S

    2016-07-01

    In the pathogenesis of central nervous system (CNS) demyelinating disorders, antigen-specific B cells are implicated to act as potent antigen-presenting cells (APC), eliciting waves of inflammatory CNS infiltration. Here, we provide the first evidence that CNS-reactive antibodies (Ab) are similarly capable of initiating an encephalitogenic immune response by targeting endogenous CNS antigen to otherwise inert myeloid APC. In a transgenic mouse model, constitutive production of Ab against myelin oligodendrocyte glycoprotein (MOG) was sufficient to promote spontaneous experimental autoimmune encephalomyelitis (EAE) in the absence of B cells, when mice endogenously contained MOG-recognizing T cells. Adoptive transfer studies corroborated that anti-MOG Ab triggered activation and expansion of peripheral MOG-specific T cells in an Fc-dependent manner, subsequently causing EAE. To evaluate the underlying mechanism, anti-MOG Ab were added to a co-culture of myeloid APC and MOG-specific T cells. At otherwise undetected concentrations, anti-MOG Ab enabled Fc-mediated APC recognition of intact MOG; internalized, processed and presented MOG activated naïve T cells to differentiate in an encephalitogenic manner. In a series of translational experiments, anti-MOG Ab from two patients with an acute flare of CNS inflammation likewise facilitated detection of human MOG. Jointly, these observations highlight Ab-mediated opsonization of endogenous CNS auto-antigen as a novel disease- and/or relapse-triggering mechanism in CNS demyelinating disorders.

  5. Complement Activation Alters Platelet Function

    DTIC Science & Technology

    2013-10-01

    mice and mice transfused with Syk inhibitor-treated platelets . Platelet lodging was remarkably decreased in lungs of mice transfused with Syk...AD_________________ Award Number: W81XWH-12-1-0523 TITLE: Complement Activation Alters Platelet ...30September2012–29September2013 4. TITLE AND SUBTITLE Complement Activation Alters Platelet Function 5a. CONTRACT NUMBER W81XWH-12-1-0523 5b. GRANT NUMBER

  6. Dengue virus compartmentalization during antibody-enhanced infection

    PubMed Central

    Ong, Eugenia Z.; Zhang, Summer L.; Tan, Hwee Cheng; Gan, Esther S.; Chan, Kuan Rong; Ooi, Eng Eong

    2017-01-01

    Secondary infection with a heterologous dengue virus (DENV) serotype increases the risk of severe dengue, through a process termed antibody-dependent enhancement (ADE). During ADE, DENV is opsonized with non- or sub-neutralizing antibody levels that augment entry into monocytes and dendritic cells through Fc-gamma receptors (FcγRs). We previously reported that co-ligation of leukocyte immunoglobulin-like receptor-B1 (LILRB1) by antibody-opsonized DENV led to recruitment of SH2 domain-containing phosphatase-1 (SHP-1) to dephosphorylate spleen tyrosine kinase (Syk) and reduce interferon stimulated gene induction. Here, we show that LILRB1 also signals through SHP-1 to attenuate the otherwise rapid acidification for lysosomal enzyme activation following FcγR-mediated uptake of DENV. Reduced or slower trafficking of antibody-opsonized DENV to lytic phagolysosomal compartments, demonstrates how co-ligation of LILRB1 also permits DENV to overcome a cell-autonomous immune response, enhancing intracellular survival of DENV. Our findings provide insights on how antiviral drugs that modify phagosome acidification should be used for viruses such as DENV. PMID:28084461

  7. FACIN, a Double-Edged Sword of the Emerging Periodontal Pathogen Filifactor alocis: A Metabolic Enzyme Moonlighting as a Complement Inhibitor.

    PubMed

    Jusko, Monika; Miedziak, Beata; Ermert, David; Magda, Michal; King, Ben C; Bielecka, Ewa; Riesbeck, Kristian; Eick, Sigrun; Potempa, Jan; Blom, Anna M

    2016-10-15

    Periodontal disease is one of the most common inflammatory infectious diseases worldwide and it is associated with other syndromes, such as cardiovascular disease or rheumatoid arthritis. Recent advances in sequencing allowed for identification of novel periodontopathogens such as Gram-positive Filifactor alocis, but its virulence mechanisms remain largely unknown. We confirmed that F. alocis is a prevalent species in periodontitis patients, and we also observed strong correlation of this bacterium with clinical parameters, highlighting its role in the pathogenesis of the disease. Further, we found that preincubation of human serum with F. alocis resulted in abolished bactericidal activity and that F. alocis was surviving readily in full blood. We demonstrated that one of the key contributors to F. alocis complement resistance is a unique protein, FACIN (F. alocis complement inhibitor), which binds to C3, resulting in suppression of all complement pathways. Interestingly, FACIN is a nonclassical cell surface protein, a cytosolic enzyme acetylornithine transaminase, for which we now identified a moonlighting function. FACIN binds to C3 alone, but more importantly it also captures activated complement factor 3 within the complex with factor B, thereby locking in the convertase in an inactive state. Because of the indispensable role of alternative pathway convertase in amplifying complement cascades, its inhibition by FACIN results in a very potent downregulation of activated complement factor 3 opsonization on the pathogen surface, accompanied by reduction of downstream C5 cleavage.

  8. Mycoplasma polysaccharide protects against complement

    PubMed Central

    Bolland, Jeffrey R.; Simmons, Warren L.; Daubenspeck, James M.

    2012-01-01

    Although they lack a cell wall, mycoplasmas do possess a glycocalyx. The interactions between the glycocalyx, mycoplasmal surface proteins and host complement were explored using the murine pathogen Mycoplasma pulmonis as a model. It was previously shown that the length of the tandem repeat region of the surface lipoprotein Vsa is associated with susceptibility to complement-mediated killing. Cells producing a long Vsa containing about 40 repeats are resistant to complement, whereas strains that produce a short Vsa of five or fewer repeats are susceptible. We show here that the length of the Vsa protein modulates the affinity of the M. pulmonis EPS-I polysaccharide for the mycoplasma cell surface, with more EPS-I being associated with mycoplasmas producing a short Vsa protein. An examination of mutants that lack EPS-I revealed that planktonic mycoplasmas were highly susceptible to complement killing even when the Vsa protein was long, demonstrating that both EPS-I and Vsa length contribute to resistance. In contrast, the mycoplasmas were resistant to complement even in the absence of EPS-I when the cells were encased in a biofilm. PMID:22504437

  9. N-truncation and pyroglutaminylation enhances the opsonizing capacity of Aβ-peptides and facilitates phagocytosis by macrophages and microglia.

    PubMed

    Condic, Mateja; Oberstein, Timo Jan; Herrmann, Martin; Reimann, Mareike Carola; Kornhuber, Johannes; Maler, Juan Manuel; Spitzer, Philipp

    2014-10-01

    Abnormal accumulations of amyloid-β (Aβ)-peptides are one of the pathological hallmarks of Alzheimer's disease (AD). The precursor of the Aβ-peptides, the amyloid precursor protein (APP), is also found in peripheral blood cells, but its function in these cells remains elusive. We previously observed that mononuclear phagocytes release Aβ-peptides during activation and phagocytosis, suggesting a physiologic role in inflammatory processes. Here, we show that supplementing the media with soluble N-terminally truncated Aβ(2-40) and Aβ(2-42) as well as Aβ(1-42) induced the phagocytosis of polystyrene particles (PSPs) by primary human monocytes. If the PSPs were pre-incubated with Aβ-peptides, phagocytosis was induced by all tested Aβ-peptide species. N-terminally truncated Aβ(x-42) induced the phagocytosis of PSPs significantly more effectively than did Aβ(x-40). Similarly, the phagocytosis of Escherichia coli by GM-CSF- and M-CSF-elicited macrophages as well as microglia was particularly facilitated by pre-incubation with N-terminally truncated Aβ(x-42). The proinflammatory polarization of monocytes was indicated by the reduced MSRI expression and IL-10 secretion after phagocytosis of PSPs coated with Aβ(1-42), Aβ(2-42) and Aβ(3p-42). Polarization of the macrophages by GM-CSF reduced the phagocytic activity, but it did not affect the capabilities of Aβ-peptides to opsonize prey. Taken together, Aβ-peptides support phagocytosis as soluble factors and act as opsonins. Differential effects among the Aβ-peptide variants point to distinct mechanisms of interaction among monocytes/macrophages, prey and Aβ-peptides. A proinflammatory polarization induced by the phagocytosis of Aβ-peptide coated particles may provide a model for the chronic inflammatory reaction and sustained plaque deposition in AD.

  10. Improvisation: A Complement to Curriculum

    ERIC Educational Resources Information Center

    Ronald, Green A.

    2006-01-01

    With the growth of standardized assessment benchmarks in both the public and private paradigms, testing performance matters to institutions more than ever. In an attempt to take as many hindering variables out of this process, such as test anxiety, socioeconomic influences, and latency in cognition, Improvisation: A Complement to Curriculum seeks…

  11. Role of complement in xenotransplantation.

    PubMed

    Mollnes, Tom Eirik; Fiane, A E

    2002-01-01

    The xenotransplantation research is driven by the increasing gap between the number of patients with end-stage organ failure on waiting lists for transplantation and the supply of allografts. The lack of success in developing suitable artificial organs for permanent treatment of organ failure has further strengthened the need for xenotransplantation research. Pigs are now generally accepted to be the source animal of choice. Transplantation of pig organs to humans faces several barriers which have to be overcome before it comes to clinical application: (1) anatomical and physiological conditions; (2) immunological rejection mechanisms; (3) molecular compatibility between signal molecules of the two species; (4) risk of transmission of microorganisms, particularly pig endogenous retroviruses; and (5) legal and ethical aspects both with respect to the animal and the recipient. Here we will focus on the role of the complement system in the rejection of immediately vascularized pig-to-primate xenografts. The hyperacute rejection occurring within minutes after transplantation is mediated by binding of natural antibodies to the Galalpha(l-3)Gal epitope on the endothelial cells with subsequent complement activation. Whereas inhibition of complement activation protects against hyperacute rejection, the role of complement in the later rejection phases is less clarified.

  12. Sentential Complementation--An Overview.

    ERIC Educational Resources Information Center

    Nuessel, Frank H., Jr.

    A review of traditional and transformational studies on the phenomenon of sentential complementation (noun clauses) reveals many areas of agreement. Although some adherents of generative grammar may have occasionally obscured this aspect because of the offensive nature of their criticism of other modes of analysis, it is seen that, in several…

  13. Structural insights on complement activation.

    PubMed

    Alcorlo, Martín; López-Perrote, Andrés; Delgado, Sandra; Yébenes, Hugo; Subías, Marta; Rodríguez-Gallego, César; Rodríguez de Córdoba, Santiago; Llorca, Oscar

    2015-10-01

    The proteolytic cleavage of C3 to generate C3b is the central and most important step in the activation of complement, a major component of innate immunity. The comparison of the crystal structures of C3 and C3b illustrates large conformational changes during the transition from C3 to C3b. Exposure of a reactive thio-ester group allows C3b to bind covalently to surfaces such as pathogens or apoptotic cellular debris. The displacement of the thio-ester-containing domain (TED) exposes hidden surfaces that mediate the interaction with complement factor B to assemble the C3-convertase of the alternative pathway (AP). In addition, the displacement of the TED and its interaction with the macroglobulin 1 (MG1) domain generates an extended surface in C3b where the complement regulators factor H (FH), decay accelerating factor (DAF), membrane cofactor protein (MCP) and complement receptor 1 (CR1) can bind, mediating accelerated decay of the AP C3-convertase and proteolytic inactivation of C3b. In the last few years, evidence has accumulated revealing that the structure of C3b in solution is significantly more flexible than anticipated. We review our current knowledge on C3b structural flexibility to propose a general model where the TED can display a collection of conformations around the MG ring, as well as a few specialized positions where the TED is held in one of several fixed locations. Importantly, this conformational heterogeneity in C3b impacts complement regulation by affecting the interaction with regulators.

  14. Complement activation on platelets correlates with a decrease in circulating immature platelets in patients with immune thrombocytopenic purpura.

    PubMed

    Peerschke, Ellinor I B; Andemariam, Biree; Yin, Wei; Bussel, James B

    2010-02-01

    The role of the complement system in immune thrombocytopenic purpura (ITP) is not well defined. We examined plasma from 79 patients with ITP, 50 healthy volunteers, and 25 patients with non-immune mediated thrombocytopenia, to investigate their complement activation/fixation capacity (CAC) on immobilized heterologous platelets. Enhanced CAC was found in 46 plasma samples (59%) from patients with ITP, but no samples from patients with non-immune mediated thrombocytopenia. Plasma from healthy volunteers was used for comparison. In patients with ITP, an enhanced plasma CAC was associated with a decreased circulating absolute immature platelet fraction (A-IPF) (<15 x 10(9)/l) (P = 0.027) and thrombocytopenia (platelet count < 100 x 10(9)/l) (P = 0.024). The positive predictive value of an enhanced CAC for a low A-IPF was 93%, with a specificity of 77%. The specificity and positive predictive values increased to 100% when plasma CAC was defined strictly by enhanced C1q and/or C4d deposition on test platelets. Although no statistically significant correlation emerged between CAC and response to different pharmacological therapies, an enhanced response to splenectomy was noted (P < 0.063). Thus, complement fixation may contribute to the thrombocytopenia of ITP by enhancing clearance of opsonized platelets from the circulation, and/or directly damaging platelets and megakaryocytes.

  15. Allele mining in the pepper gene pool provided new complementation effects between pvr2-eIF4E and pvr6-eIF(iso)4E alleles for resistance to pepper veinal mottle virus.

    PubMed

    Rubio, Manuel; Nicolaï, Maryse; Caranta, Carole; Palloix, Alain

    2009-11-01

    Molecular cloning of recessive resistance genes to potyviruses in a large range of host species identified the eukaryotic translation initiation factor 4E (eIF4E) as an essential determinant in the outcome of potyvirus infection. Resistance results from a few amino acid changes in the eIF4E protein encoded by the recessive resistance allele that disrupt the direct interaction with the potyviral protein VPg. In plants, several loci encode two protein subfamilies, eIF4E and eIF(iso)4E. While most eIF4E-mediated resistance to potyviruses depends on mutations in a single eIF4E protein, simultaneous mutations in eIF4E (corresponding to the pvr2 locus) and eIF(iso)4E (corresponding to the pvr6 locus) are required to prevent pepper veinal mottle virus (PVMV) infection in pepper. We used this model to look for additional alleles at the pvr2-eIF4E locus that result in resistance when combined with the pvr6-eIF(iso)4E resistant allele. Among the 12 pvr2-eIF4E resistance alleles sequenced in the pepper gene pool, three were shown to have a complementary effect with pvr6-eIF(iso)4E for resistance. Two amino acid changes were exclusively shared by these three alleles and were systematically associated with a second amino acid change, suggesting that these substitutions are associated with resistance expression. The availability of new resistant allele combinations increases the possibility for the durable deployment of resistance against this pepper virus which is prevalent in Africa.

  16. Influence of minor thermal injury on expression of complement receptor CR3 on human neutrophils.

    PubMed Central

    Nelson, R. D.; Hasslen, S. R.; Ahrenholz, D. H.; Haus, E.; Solem, L. D.

    1986-01-01

    Thermal injury is well known to inhibit functions of the circulating neutrophil related to its role in host defense against infection, but the mechanism(s) of this phenomenon are not fully understood. To gain further clues to these mechanisms, the authors have studied patients with thermal injury in terms of altered expression of neutrophil cell membrane receptors for the opsonic complement-derived ligand C3bi--complement receptor Type 3, or CR3. CR3 expression was selected for study because an increase in the number of receptors on the cell surface can be stimulated by products of complement activation known to accumulate after thermal injury and because of the role of CR3 in phagocytic and adherence functions of the neutrophil. Expression of CR3 was monitored semiquantitatively by flow cytometry with the use of a murine monoclonal antibody (OKM1) specific for an antigen (CD11) associated with this receptor. Patients evaluated were limited in this study to those with minor degrees of thermal injury (second-degree burn involving less than 20% of total body surface area) so that possible confounding effects of major injury and its complications could be eliminated. It was observed that patient neutrophil CR3 becomes significantly up-regulated during the first week, as early as 1 day after injury. The maximum level of expression of CR3 averaged greater than 150% (range, 70-314%) of the respective minimum level observed for each patient. The minimum levels of expression of CR3 on patient neutrophils, reached 11-37 days after injury for 7 of 8 patients, were comparable to the level of expression of CR3 on unstimulated control neutrophils. Such temporal up-regulation of patient neutrophil CR3 suggests the early generation of stimuli of CR3 mobilization in response to thermal injury. Increased numbers of CR3 on patient neutrophils may augment microbicidal function and enhance or inhibit delivery of cells to the burn site. PMID:3541642

  17. A metalloproteinase karilysin present in the majority of Tannerella forsythia isolates inhibits all pathways of the complement system.

    PubMed

    Jusko, Monika; Potempa, Jan; Karim, Abdulkarim Y; Ksiazek, Miroslaw; Riesbeck, Kristian; Garred, Peter; Eick, Sigrun; Blom, Anna M

    2012-03-01

    Tannerella forsythia is a poorly studied pathogen despite being one of the main causes of periodontitis, which is an inflammatory disease of the supporting structures of the teeth. We found that despite being recognized by all complement pathways, T. forsythia is resistant to killing by human complement, which is present at up to 70% of serum concentration in gingival crevicular fluid. Incubation of human serum with karilysin, a metalloproteinase of T. forsythia, resulted in a decrease in bactericidal activity of the serum. T. forsythia strains expressing karilysin at higher levels were more resistant than low-expressing strains. Furthermore, the low-expressing strain was significantly more opsonized with activated complement factor 3 and membrane attack complex from serum compared with the other strains. The high-expressing strain was more resistant to killing in human blood. The protective effect of karilysin against serum bactericidal activity was attributable to its ability to inhibit complement at several stages. The classical and lectin complement pathways were inhibited because of the efficient degradation of mannose-binding lectin, ficolin-2, ficolin-3, and C4 by karilysin, whereas inhibition of the terminal pathway was caused by degradation of C5. Interestingly, karilysin was able to release biologically active C5a peptide in human plasma and induce migration of neutrophils. Importantly, we detected the karilysin gene in >90% of gingival crevicular fluid samples containing T. forsythia obtained from patients with periodontitis. Taken together, the newly characterized karilysin appears to be an important virulence factor of T. forsythia and might have several important implications for immune evasion.

  18. The Complement System and Adverse Pregnancy Outcomes

    PubMed Central

    Regal, Jean F.; Gilbert, Jeffrey S.; Burwick, Richard M.

    2015-01-01

    Adverse pregnancy outcomes significantly contribute to morbidity and mortality for mother and child, with lifelong health consequences for both. The innate and adaptive immune system must be regulated to insure survival of the feta allograft, and the complement system is no exception. An intact complement system optimizes placental development and function and is essential to maintain host defense and fetal survival. Complement regulation is apparent at the placental interface from early pregnancy with some degree of complement activation occurring normally throughout gestation. However, a number of pregnancy complications including early pregnancy loss, fetal growth restriction, hypertensive disorders of pregnancy and preterm birth are associated with excessive or misdirected complement activation, and are more frequent in women with inherited or acquired complement system disorders or complement gene mutations. Clinical studies employing complement biomarkers in plasma and urine implicate dysregulated complement activation in components of each of the adverse pregnancy outcomes. In addition, mechanistic studies in rat and mouse models of adverse pregnancy outcomes address the complement pathways or activation products of importance and allow critical analysis of the pathophysiology. Targeted complement therapeutics are already in use to control adverse pregnancy outcomes in select situations. A clearer understanding of the role of the complement system in both normal pregnancy and complicated or failed pregnancy will allow a rational approach to future therapeutic strategies for manipulating complement with the goal of mitigating adverse pregnancy outcomes, preserving host defense, and improving long term outcomes for both mother and child. PMID:25802092

  19. Genetics Home Reference: complement component 8 deficiency

    MedlinePlus

    ... the membranes surrounding the brain and spinal cord (meningitis). Although meningitis can be life-threatening, individuals with complement component ... leaves affected individuals prone to recurrent episodes of meningitis. Learn more about the genes associated with complement ...

  20. Complement fixation test to C. burnetii

    MedlinePlus

    ... ency/article/003520.htm Complement fixation test to C burnetii To use the sharing features on this ... JavaScript. The complement fixation test to Coxiella burnetii ( C burnetti ) is a blood test that checks for ...

  1. An Integrated Theory of Complement Control.

    ERIC Educational Resources Information Center

    Sag, Ivan A.; Pollard, Carl

    1991-01-01

    Presents an integrated theory of the syntactic and semantic representation of complements where the unexpressed subjects of the embedded verb-phrase complement are subject to certain interpretation restrictions. It is argued that the grammar of English controlled complements can be derived from the interaction of semantically based principles of…

  2. CD44 Antibody Inhibition of Macrophage Phagocytosis Targets Fcγ Receptor- and Complement Receptor 3-Dependent Mechanisms.

    PubMed

    Amash, Alaa; Wang, Lin; Wang, Yawen; Bhakta, Varsha; Fairn, Gregory D; Hou, Ming; Peng, Jun; Sheffield, William P; Lazarus, Alan H

    2016-04-15

    Targeting CD44, a major leukocyte adhesion molecule, using specific Abs has been shown beneficial in several models of autoimmune and inflammatory diseases. The mechanisms contributing to the anti-inflammatory effects of CD44 Abs, however, remain poorly understood. Phagocytosis is a key component of immune system function and can play a pivotal role in autoimmune states where CD44 Abs have shown to be effective. In this study, we show that the well-known anti-inflammatory CD44 Ab IM7 can inhibit murine macrophage phagocytosis of RBCs. We assessed three selected macrophage phagocytic receptor systems: Fcγ receptors (FcγRs), complement receptor 3 (CR3), and dectin-1. Treatment of macrophages with IM7 resulted in significant inhibition of FcγR-mediated phagocytosis of IgG-opsonized RBCs. The inhibition of FcγR-mediated phagocytosis was at an early stage in the phagocytic process involving both inhibition of the binding of the target RBC to the macrophages and postbinding events. This CD44 Ab also inhibited CR3-mediated phagocytosis of C3bi-opsonized RBCs, but it did not affect the phagocytosis of zymosan particles, known to be mediated by the C-type lectin dectin-1. Other CD44 Abs known to have less broad anti-inflammatory activity, including KM114, KM81, and KM201, did not inhibit FcγR-mediated phagocytosis of RBCs. Taken together, these findings demonstrate selective inhibition of FcγR and CR3-mediated phagocytosis by IM7 and suggest that this broadly anti-inflammatory CD44 Ab inhibits these selected macrophage phagocytic pathways. The understanding of the immune-regulatory effects of CD44 Abs is important in the development and optimization of therapeutic strategies for the potential treatment of autoimmune conditions.

  3. Distinct recognition of complement iC3b by integrins αXβ2 and αMβ2.

    PubMed

    Xu, Shutong; Wang, Jianchuan; Wang, Jia-Huai; Springer, Timothy A

    2017-03-28

    Recognition by the leukocyte integrins αXβ2 and αMβ2 of complement iC3b-opsonized targets is essential for effector functions including phagocytosis. The integrin-binding sites on iC3b remain incompletely characterized. Here, we describe negative-stain electron microscopy and biochemical studies of αXβ2 and αMβ2 in complex with iC3b. Despite high homology, the two integrins bind iC3b at multiple distinct sites. αXβ2 uses the αX αI domain to bind iC3b on its C3c moiety at one of two sites: a major site at the interface between macroglobulin (MG) 3 and MG4 domains, and a less frequently used site near the C345C domain. In contrast, αMβ2 uses its αI domain to bind iC3b at the thioester domain and simultaneously interacts through a region near the αM β-propeller and β2 βI domain with a region of the C3c moiety near the C345C domain. Remarkably, there is no overlap between the primary binding site of αXβ2 and the binding site of αMβ2 on iC3b. Distinctive binding sites on iC3b by integrins αXβ2 and αMβ2 may be biologically beneficial for leukocytes to more efficiently capture opsonized pathogens and to avoid subversion by pathogen factors.

  4. The Semantics of Complementation in English: A Cognitive Semantic Account of Two English Complement Constructions

    ERIC Educational Resources Information Center

    Smith, Michael B.

    2009-01-01

    Studies on complementation in English and other languages have traditionally focused on syntactic issues, most notably on the constituent structures of different complement types. As a result, they have neglected the role of meaning in the choice of different complements. This paper investigates the semantics of complementation within the…

  5. Meningococcal disease and the complement system

    PubMed Central

    Lewis, Lisa A; Ram, Sanjay

    2014-01-01

    Despite considerable advances in the understanding of the pathogenesis of meningococcal disease, this infection remains a major cause of morbidity and mortality globally. The role of the complement system in innate immune defenses against invasive meningococcal disease is well established. Individuals deficient in components of the alternative and terminal complement pathways are highly predisposed to invasive, often recurrent meningococcal infections. Genome-wide analysis studies also point to a central role for complement in disease pathogenesis. Here we review the pathophysiologic events pertinent to the complement system that accompany meningococcal sepsis in humans. Meningococci use several often redundant mechanisms to evade killing by human complement. Capsular polysaccharide and lipooligosaccharide glycan composition play critical roles in complement evasion. Some of the newly described protein vaccine antigens interact with complement components and have sparked considerable research interest. PMID:24104403

  6. Phagocytosis via Complement or Fc-Gamma Receptors Is Compromised in Monocytes from Type 2 Diabetes Patients with Chronic Hyperglycemia

    PubMed Central

    Restrepo, Blanca I.; Twahirwa, Marcel; Rahbar, Mohammad H.; Schlesinger, Larry S.

    2014-01-01

    Type 2 diabetes patients (DM2) have a higher risk of tuberculosis (TB) that may be attributed to functional defects in their mononuclear phagocytes given the critical role of these cells in Mycobacterium tuberculosis containment. Our previous findings suggest that monocytes from DM2 have reduced association with serum-opsonized M. tuberculosis. To determine if this alteration is due to defects in phagocytosis via complement or Fc-gamma receptors (FcγRs), in this study we evaluated the uptake of sheep red blood cells coated with IgG or complement, respectively, by monocytes from individuals with and without DM2. We found that chronic hyperglycemia was significantly associated with reduced phagocytosis via either receptor by univariable and multivariable analyses. This defect was independent of host serum opsonins and flow cytometry data indicated this was not attributed to reduced expression of these phagocytic receptors on DM2 monocytes. The positive correlation between both pathways (R = 0.64; p = 0.003) indicate that monocytes from individuals with chronic hyperglycemia have a defect in the two predominant phagocytic pathways of these cells. Given that phagocytosis is linked to activation of effector mechanisms for bacterial killing, it is likely that this defect is one factor contributing to the higher susceptibility of DM2 patients to pathogens like M. tuberculosis. PMID:24671137

  7. Neisseria meningitidis and Escherichia coli are protected from leukocyte phagocytosis by binding to erythrocyte complement receptor 1 in human blood.

    PubMed

    Brekke, Ole-Lars; Hellerud, Bernt Christian; Christiansen, Dorte; Fure, Hilde; Castellheim, Albert; Nielsen, Erik Waage; Pharo, Anne; Lindstad, Julie Katrine; Bergseth, Grethe; Leslie, Graham; Lambris, John D; Brandtzaeg, Petter; Mollnes, Tom Eirik

    2011-09-01

    The initial interaction of Gram-negative bacteria with erythrocytes and its implications on leukocyte phagocytosis and oxidative burst in human whole blood were examined. Alexa-labeled Escherichia coli, wild-type H44/76 N. meningitidis and the H44/76lpxA lipopolysaccharide (LPS)-deficient mutant were incubated with whole blood using lepirudin as anticoagulant which has no adverse effects on complement. Bacteria free in plasma, bound to erythrocytes or phagocytized by granulocytes and monocytes were quantified using flow cytometry. The effects of the C3 inhibitor compstatin, a C5a receptor antagonist (C5aRa) and a complement receptor 1 (CR1)-blocking antibody (3D9) were examined. Most bacteria (80%) immediately bound to erythrocytes. The binding gradually declined over time, with a parallel increase in phagocytosis. Complement inhibition with compstatin reduced erythrocyte binding and bacterial C3 opsonization. In contrast, the C5aRa efficiently reduced phagocytosis, but did not affect the binding of bacteria to erythrocytes. The anti-CR1 blocking mAb dose-dependently reduced bacterial binding to erythrocytes to nil, with subsequent increased phagocytosis and oxidative burst. LPS had no effect on these processes since similar results were obtained using an LPS-deficient N. meningitidis mutant. In vivo experiments in a pig model of sepsis showed limited binding of bacteria to erythrocytes, consistent with the facts that erythrocyte CR1 receptors are absent in non-primates and that the bacteria were mainly found in the lungs. In conclusion, complement-dependent binding of Gram-negative bacteria to erythrocyte CR1 decreases phagocytosis and oxidative burst by leukocytes in human whole blood.

  8. Neisseria meningitidis and Escherichia coli are protected from leukocyte phagocytosis by binding to erythrocyte complement receptor 1 in human blood

    PubMed Central

    Brekke, Ole-Lars; Hellerud, Bernt Christian; Christiansen, Dorte; Fure, Hilde; Castellheim, Albert; Nielsen, Erik Waage; Pharo, Anne; Lindstad, Julie Katrine; Bergseth, Grethe; Leslie, Graham; Lambris, John D.; Brandtzaeg, Petter; Mollnes, Tom Eirik

    2011-01-01

    The initial interaction of Gram-negative bacteria with erythrocytes and its implications on leukocyte phagocytosis and oxidative burst in human whole blood were examined. Alexa-labeled Escherichia coli, wild-type H44/76 Neisseria meningitidis (N. meningitidis) and the H44/76lpxA lipopolysaccharide (LPS)-deficient mutant were incubated with whole blood using lepirudin as anticoagulant which has no adverse effects on complement. Bacteria free in plasma, bound to erythrocytes or phagocytized by granulocytes and monocytes were quantified using flow cytometry. The effects of the C3 inhibitor compstatin, a C5a receptor antagonist (C5aRa) and a complement receptor 1 (CR1)-blocking antibody (3D9) were examined. Most bacteria (80%) immediately bound to erythrocytes. The binding gradually declined over time, with a parallel increase in phagocytosis. Complement inhibition with compstatin reduced erythrocyte binding and bacterial C3 opsonization. In contrast, the C5aRa efficiently reduced phagocytosis, but did not affect the binding of bacteria to erythrocytes. The anti-CR1 blocking mAb dose-dependently reduced bacterial binding to erythrocytes to nil, with subsequent increased phagocytosis and oxidative burst. LPS had no effect on these processes since similar results were obtained using an LPS-deficient N. meningitidis mutant. In vivo experiments in a pig model of sepsis showed limited binding of bacteria to erythrocytes, consistent with the facts that erythrocyte CR1 receptors are absent in non-primates and that the bacteria were mainly found in the lungs. In conclusion, complement-dependent binding of Gram-negative bacteria to erythrocyte CR1 decreases phagocytosis and oxidative burst by leukocytes in human whole blood. PMID:21839519

  9. Functional and structural characterization of four mouse monoclonal antibodies to complement C3 with potential therapeutic and diagnostic applications.

    PubMed

    Subías Hidalgo, Marta; Yébenes, Hugo; Rodríguez-Gallego, César; Martín-Ambrosio, Adrián; Domínguez, Mercedes; Tortajada, Agustin; Rodríguez de Córdoba, Santiago; Llorca, Oscar

    2017-03-01

    C3 is the central component of the complement system. Upon activation, C3 sequentially generates various proteolytic fragments, C3a, C3b, iC3b, C3dg, each of them exposing novel surfaces, which are sites of interaction with other proteins. C3 and its fragments are therapeutic targets and markers of complement activation. We report the structural and functional characterization of four monoclonal antibodies (mAbs) generated by immunizing C3-deficient mice with a mixture of human C3b, iC3b and C3dg fragments, and discuss their potential applications. This collection includes three mAbs interacting with native C3 and inhibiting AP complement activation; two of them by blocking the cleavage of C3 by the AP C3-converase and one by impeding formation of the AP C3-convertase. The interaction sites of these mAbs in the target molecules were determined by resolving the structures of Fab fragments bound to C3b and/or iC3b using electron microscopy. A fourth mAb specifically recognizes the iC3b, C3dg, and C3d fragments. It binds to an evolutionary-conserved neoepitope generated after C3b cleavage by FI, detecting iC3b/C3dg deposition over opsonized surfaces by flow cytometry and immunohistochemistry in human and other species. Because well-characterized anti-complement mAbs are uncommon, the mAbs reported here may offer interesting therapeutic and diagnostic opportunities.

  10. Exogenous leukotriene B4 (LTB4) inhibits human neutrophil generation of LTB4 from endogenous arachidonic acid during opsonized zymosan phagocytosis.

    PubMed

    Fiedler, J; Wheelan, P; Henson, P M; Murphy, R C

    1998-10-01

    The effect of exogenous leukotriene B4 (LTB4) on opsonized zymosan-stimulated human neutrophil formation of 5-lipoxygenase products and arachidonic acid release was directly assessed using reverse-phase HPLC/tandem mass spectrometric methods for quantitation. Stable isotopically labeled LTB4, [1,2-13C2]LTB4, caused a dose-dependent inhibition of LTB4 production in isolated human neutrophils with significant inhibition (60 +/- 7% of control levels) when 0.12 nM [13C2]LTB4 was present. Production of 5-hydroxy-6,8,11,14-eicosatetraenoic acid and release of free arachidonic acid were also dose-dependently inhibited by exogenous LTB4. Metabolites of LTB4, 20-hydroxy-LTB4 and 3(S)-hydroxy-LTB4, also significantly reduced LTB4 production to levels as low as 10 +/- 6% and 10 +/- 7% of control levels, respectively, when present exogenously at 10 nM. Exogenous 5-hydroxy-6,8,11,14-eicosatetraenoic acid at concentrations as high as 10 nM produced no significant reduction in LTB4 biosynthesis during zymosan-stimulated human neutrophil production of LTB4. The inhibitory effect of LTB4 could be partially reversed by the LTB4 receptor antagonist U 75302. Furthermore, an alternative stimulus, N-formyl-methionyl-leucyl-phenylalanine (100 nM), did not inhibit the production of LTB4 in opsonized zymosan-stimulated human neutrophils. These results suggest that activation of the LTB4 receptor on the human neutrophil during phagocytosis limits the ultimate biosynthesis of LTB4. This autocrine effect is opposite to that observed when neutrophils have much of the signal transduction pathways bypassed when stimulated with calcium ionophore A23187 or treated with exogenous free arachidonic acid.

  11. Complement Activation and Inhibition in Wound Healing

    PubMed Central

    Cazander, Gwendolyn; Jukema, Gerrolt N.; Nibbering, Peter H.

    2012-01-01

    Complement activation is needed to restore tissue injury; however, inappropriate activation of complement, as seen in chronic wounds can cause cell death and enhance inflammation, thus contributing to further injury and impaired wound healing. Therefore, attenuation of complement activation by specific inhibitors is considered as an innovative wound care strategy. Currently, the effects of several complement inhibitors, for example, the C3 inhibitor compstatin and several C1 and C5 inhibitors, are under investigation in patients with complement-mediated diseases. Although (pre)clinical research into the effects of these complement inhibitors on wound healing is limited, available data indicate that reduction of complement activation can improve wound healing. Moreover, medicine may take advantage of safe and effective agents that are produced by various microorganisms, symbionts, for example, medicinal maggots, and plants to attenuate complement activation. To conclude, for the development of new wound care strategies, (pre)clinical studies into the roles of complement and the effects of application of complement inhibitors in wound healing are required. PMID:23346185

  12. Dynamics of interaction between complement-fixing antibody/dsDNA immune complexes and erythrocytes. In vitro studies and potential general applications to clinical immune complex testing

    SciTech Connect

    Taylor, R.P.; Horgan, C.; Hooper, M.; Burge, J.

    1985-01-01

    Soluble antibody//sub 3/H-double-stranded PM2 DNA (dsDNA) immune complexes were briefly opsonized with complement and then allowed to bind to human erythrocytes (via complement receptors). The cells were washed and subsequently a volume of autologous blood in a variety of media was added, and the release of the bound immune complexes from the erythrocytes was studied as a function of temperature and time. After 1-2 h, the majority of the bound immune complexes were not released into the serum during blood clotting at either 37 degrees C or room temperature, but there was a considerably greater release of the immune complexes into the plasma of blood that was anticoagulated with EDTA. Similar results were obtained using various conditions of opsonization and also using complexes that contained lower molecular weight dsDNA. Thus, the kinetics of release of these antibody/dsDNA immune complexes differed substantially from the kinetics of release of antibody/bovine serum albumin complexes that was reported by others. Studies using the solution phase C1q immune complex binding assay confirmed that in approximately half of the SLE samples that were positive for immune complexes, there was a significantly higher level of detectable immune complexes in plasma vs. serum. Freshly drawn erythrocytes from some SLE patients exhibiting this plasma/serum discrepancy had IgG antigen on their surface that was released by incubation in EDTA plasma. Thus, the higher levels of immune complexes observed in EDTA plasma vs. serum using the C1q assay may often reflect the existence of immune complexes circulating in vivo bound to erythrocytes.

  13. prM-antibody renders immature West Nile virus infectious in vivo.

    PubMed

    Colpitts, Tonya M; Rodenhuis-Zybert, Izabela; Moesker, Bastiaan; Wang, Penghua; Fikrig, Erol; Smit, Jolanda M

    2011-10-01

    West Nile virus (WNV) is a member of the family Flaviviridae and is a neurotropic pathogen responsible for severe human disease. Flavivirus-infected cells release virus particles that contain variable numbers of precursor membrane (prM) protein molecules at the viral surface. Consequently, antibodies are produced against the prM protein. These antibodies have been shown to activate the infectious potential of fully immature flavivirus particles in vitro. Here, we provide in vivo proof that prM antibodies render immature WNV infectious. Infection with antibody-opsonized immature WNV particles caused disease and death of mice, and infectious WNV was found in the brains and sera.

  14. Complement Protein C1q Interacts with DC-SIGN via Its Globular Domain and Thus May Interfere with HIV-1 Transmission

    PubMed Central

    Pednekar, Lina; Pandit, Hrishikesh; Paudyal, Basudev; Kaur, Anuvinder; Al-Mozaini, Maha Ahmed; Kouser, Lubna; Ghebrehiwet, Berhane; Mitchell, Daniel A.; Madan, Taruna; Kishore, Uday

    2016-01-01

    Dendritic cells (DCs) are the most potent antigen-presenting cells capable of priming naïve T-cells. Its C-type lectin receptor, DC-SIGN, regulates a wide range of immune functions. Along with its role in HIV-1 pathogenesis through complement opsonization of the virus, DC-SIGN has recently emerged as an adaptor for complement protein C1q on the surface of immature DCs via a trimeric complex involving gC1qR, a receptor for the globular domain of C1q. Here, we have examined the nature of interaction between C1q and DC-SIGN in terms of domain localization, and implications of C1q–DC-SIGN-gC1qR complex formation on HIV-1 transmission. We first expressed and purified recombinant extracellular domains of DC-SIGN and its homologue DC-SIGNR as tetramers comprising of the entire extra cellular domain including the α-helical neck region and monomers comprising of the carbohydrate recognition domain only. Direct binding studies revealed that both DC-SIGN and DC-SIGNR were able to bind independently to the recombinant globular head modules ghA, ghB, and ghC, with ghB being the preferential binder. C1q appeared to interact with DC-SIGN or DC-SIGNR in a manner similar to IgG. Mutational analysis using single amino acid substitutions within the globular head modules showed that TyrB175 and LysB136 were critical for the C1q–DC-SIGN/DC-SIGNR interaction. Competitive studies revealed that gC1qR and ghB shared overlapping binding sites on DC-SIGN, implying that HIV-1 transmission by DCs could be modulated due to the interplay of gC1qR-C1q with DC-SIGN. Since C1q, gC1qR, and DC-SIGN can individually bind HIV-1, we examined how C1q and gC1qR modulated HIV-1–DC-SIGN interaction in an infection assay. Here, we report, for the first time, that C1q suppressed DC-SIGN-mediated transfer of HIV-1 to activated pooled peripheral blood mononuclear cells, although the globular head modules did not. The protective effect of C1q was negated by the addition of gC1qR. In fact, gC1qR enhanced

  15. Complement Protein C1q Interacts with DC-SIGN via Its Globular Domain and Thus May Interfere with HIV-1 Transmission.

    PubMed

    Pednekar, Lina; Pandit, Hrishikesh; Paudyal, Basudev; Kaur, Anuvinder; Al-Mozaini, Maha Ahmed; Kouser, Lubna; Ghebrehiwet, Berhane; Mitchell, Daniel A; Madan, Taruna; Kishore, Uday

    2016-01-01

    Dendritic cells (DCs) are the most potent antigen-presenting cells capable of priming naïve T-cells. Its C-type lectin receptor, DC-SIGN, regulates a wide range of immune functions. Along with its role in HIV-1 pathogenesis through complement opsonization of the virus, DC-SIGN has recently emerged as an adaptor for complement protein C1q on the surface of immature DCs via a trimeric complex involving gC1qR, a receptor for the globular domain of C1q. Here, we have examined the nature of interaction between C1q and DC-SIGN in terms of domain localization, and implications of C1q-DC-SIGN-gC1qR complex formation on HIV-1 transmission. We first expressed and purified recombinant extracellular domains of DC-SIGN and its homologue DC-SIGNR as tetramers comprising of the entire extra cellular domain including the α-helical neck region and monomers comprising of the carbohydrate recognition domain only. Direct binding studies revealed that both DC-SIGN and DC-SIGNR were able to bind independently to the recombinant globular head modules ghA, ghB, and ghC, with ghB being the preferential binder. C1q appeared to interact with DC-SIGN or DC-SIGNR in a manner similar to IgG. Mutational analysis using single amino acid substitutions within the globular head modules showed that Tyr(B175) and Lys(B136) were critical for the C1q-DC-SIGN/DC-SIGNR interaction. Competitive studies revealed that gC1qR and ghB shared overlapping binding sites on DC-SIGN, implying that HIV-1 transmission by DCs could be modulated due to the interplay of gC1qR-C1q with DC-SIGN. Since C1q, gC1qR, and DC-SIGN can individually bind HIV-1, we examined how C1q and gC1qR modulated HIV-1-DC-SIGN interaction in an infection assay. Here, we report, for the first time, that C1q suppressed DC-SIGN-mediated transfer of HIV-1 to activated pooled peripheral blood mononuclear cells, although the globular head modules did not. The protective effect of C1q was negated by the addition of gC1qR. In fact, gC1qR enhanced DC

  16. Role of Complement in Autoimmune Hemolytic Anemia

    PubMed Central

    Berentsen, Sigbjørn

    2015-01-01

    Summary The classification of autoimmune hemolytic anemias and the complement system are reviewed. In autoimmune hemolytic anemia of the warm antibody type, complement-mediated cell lysis is clinically relevant in a proportion of the patients but is hardly essential for hemolysis in most patients. Cold antibody-mediated autoimmune hemolytic anemias (primary cold agglutinin disease, secondary cold agglutinin syndrome and paroxysmal cold hemoglobinuria) are entirely complement-mediated disorders. In cold agglutinin disease, efficient therapies have been developed in order to target the pathogenic B-cell clone, but complement modulation remains promising in some clinical situations. No established therapy exists for secondary cold agglutinin syndrome and paroxysmal cold hemoglobinuria, and the possibility of therapeutic complement inhibition is interesting. Currently, complement modulation is not clinically documented in any autoimmune hemolytic anemia. The most relevant candidate drugs and possible target levels of action are discussed. PMID:26696798

  17. Subversion of complement by hematophagous parasites

    PubMed Central

    Schroeder, Hélène; Skelly, Patrick; Zipfel, Peter F.; Losson, Bertrand; Vanderplasschen, Alain

    2008-01-01

    The complement system is a crucial part of innate and adaptive immunity which exerts a significant evolutionary pressure on pathogens. It has selected for those pathogens, mainly micro-organisms but also parasites, that have evolved countermeasures. The characterization of how pathogens evade complement attack is a rapidly developing field of current research. In recent years, multiple complement evasion strategies have been characterized. In this review, we focus on complement escape mechanisms expressed by hematophagous parasites, a heterogeneous group of metazoan parasites that share the property of ingesting the whole blood of their host. Complement inhibition is crucial for parasite survival within the host tissue or to facilitate blood feeding. Finally, complement inhibition by hematophagous parasites may also contribute to their success as pathogen vectors. PMID:18762211

  18. Role of Complement in Autoimmune Hemolytic Anemia.

    PubMed

    Berentsen, Sigbjørn

    2015-09-01

    The classification of autoimmune hemolytic anemias and the complement system are reviewed. In autoimmune hemolytic anemia of the warm antibody type, complement-mediated cell lysis is clinically relevant in a proportion of the patients but is hardly essential for hemolysis in most patients. Cold antibody-mediated autoimmune hemolytic anemias (primary cold agglutinin disease, secondary cold agglutinin syndrome and paroxysmal cold hemoglobinuria) are entirely complement-mediated disorders. In cold agglutinin disease, efficient therapies have been developed in order to target the pathogenic B-cell clone, but complement modulation remains promising in some clinical situations. No established therapy exists for secondary cold agglutinin syndrome and paroxysmal cold hemoglobinuria, and the possibility of therapeutic complement inhibition is interesting. Currently, complement modulation is not clinically documented in any autoimmune hemolytic anemia. The most relevant candidate drugs and possible target levels of action are discussed.

  19. Serum complement and immunoconglutinin in malnutrition.

    PubMed Central

    Chandra, R K

    1975-01-01

    Serum haemolytic complement activity and C3 were significantly decreased in 35 malnourished children. The changes were more pronounced in those with infection. Electrophoretically altered forms of complement C were detected in 14. There was an inverse correlation between C3 levels and immunoconglutinin titres. Nutritional rehabilitation and eradication of infection reversed the abnormalities. It is suggested that reduced complement function in malnutrition is the combined result of impaired synthesis, complement activation in vivo, and changes in plasma volume, and that it may contribute to an increased susceptibility to infection in undernourished individuals. PMID:807166

  20. NEUTRALIZING AND COMPLEMENT-FIXING ANTIBODY PRODUCTION AND RESISTANCE FOLLOWING VACCINATION IN EXPERIMENTAL ENCEPHALITIS INFECTIONS

    PubMed Central

    Casals, J.

    1943-01-01

    In mice vaccinated subcutaneously with different doses of virulent W.E.E. virus or with formolized vaccine, neutralizing and complement-fixing antibodies paralleled resistance to some extent yet appeared in groups in which resistance remained undetectable, persisted at a similar maximum level in spite of different titers of resistance, and after resistance had become negligible. In mice vaccinated subcutaneously with different doses of virulent St. Louis encephalitis virus or with formolized vaccine, neutralizing and complement-fixing antibodies bore little relation to resistance. Neutralizing antibodies appeared only in the group showing resistance but not until resistance was diminishing. Complement-fixing antibodies developed equally well in groups with or without resistance. PMID:19871341

  1. Infectious diseases associated with complement deficiencies.

    PubMed Central

    Figueroa, J E; Densen, P

    1991-01-01

    The complement system consists of both plasma and membrane proteins. The former influence the inflammatory response, immune modulation, and host defense. The latter are complement receptors, which mediate the cellular effects of complement activation, and regulatory proteins, which protect host cells from complement-mediated injury. Complement activation occurs via either the classical or the alternative pathway, which converge at the level of C3 and share a sequence of terminal components. Four aspects of the complement cascade are critical to its function and regulation: (i) activation of the classical pathway, (ii) activation of the alternative pathway, (iii) C3 convertase formation and C3 deposition, and (iv) membrane attack complex assembly and insertion. In general, mechanisms evolved by pathogenic microbes to resist the effects of complement are targeted to these four steps. Because individual complement proteins subserve unique functional activities and are activated in a sequential manner, complement deficiency states are associated with predictable defects in complement-dependent functions. These deficiency states can be grouped by which of the above four mechanisms they disrupt. They are distinguished by unique epidemiologic, clinical, and microbiologic features and are most prevalent in patients with certain rheumatologic and infectious diseases. Ethnic background and the incidence of infection are important cofactors determining this prevalence. Although complement undoubtedly plays a role in host defense against many microbial pathogens, it appears most important in protection against encapsulated bacteria, especially Neisseria meningitidis but also Streptococcus pneumoniae, Haemophilus influenzae, and, to a lesser extent, Neisseria gonorrhoeae. The availability of effective polysaccharide vaccines and antibiotics provides an immunologic and chemotherapeutic rationale for preventing and treating infection in patients with these deficiencies. PMID

  2. APP, APOE, complement receptor 1, clusterin and PICALM and their involvement in the herpes simplex life cycle.

    PubMed

    Carter, C J

    2010-10-11

    The major Alzheimer's disease susceptibility genes (APOE, clusterin, complement receptor 1 (CR1) and phosphatidylinositol binding clathrin assembly protein, PICALM) can be implicated directly (APOE, CR1) or indirectly (clusterin and PICALM) in the herpes simplex life cycle. The virus binds to proteoliposomes containing APOE or APOA1 and also to CR1, and both clusterin and PICALM are related to a mannose-6-phosphate receptor used by the virus for cellular entry and intracellular transport. PICALM also binds to a nuclear exportin used by the virus for nuclear egress. Clusterin and complement receptor 1 are both related to the complement pathways and play a general role in pathogen defence. In addition, the amyloid precursor protein APP is involved in herpes viral transport and gamma-secretase cleaves a number of receptors used by the virus for cellular entry. APOE, APOA1 and clusterin, or alpha 2-macroglobulin, insulysin and caspase 3, which also bind to the virus, are involved in beta-amyloid clearance or degradation, as are the viral binding complement components, C3 and CR1. There are multiple ways in which the products of key susceptibility genes might be able to modify the viral life cycle and in turn the virus interacts with key proteins involved in APP and beta-amyloid processing. These interactions support a role for the herpes simplex virus in Alzheimer's disease pathology and suggest that antiviral agents or vaccination might be considered as viable therapeutic strategies in Alzheimer's disease.

  3. Interaction between complement regulators and Streptococcus pyogenes: binding of C4b-binding protein and factor H/factor H-like protein 1 to M18 strains involves two different cell surface molecules.

    PubMed

    Pérez-Caballero, David; García-Laorden, Isabel; Cortés, Guadalupe; Wessels, Michael R; de Córdoba, Santiago Rodríguez; Albertí, Sebastián

    2004-12-01

    Streptococcus pyogenes, or group A Streptococcus, is one of the most frequent causes of pharyngitis and skin infections in humans. Many virulence mechanisms have been suggested to be involved in the infectious process. Among them is the binding to the bacterial cell surface of the complement regulatory proteins factor H, factor H-like protein 1 (FHL-1), and C4b-binding protein. Previous studies indicate that binding of these three regulators to the streptococcal cell involves the M protein encoded by the emm gene. M-type 18 strains are prevalent among clinical isolates and have been shown to interact with all three complement regulators simultaneously. Using isogenic strains lacking expression of the Emm18 or the Enn18 proteins, we demonstrate in this study that, in contradistinction to previously described S. pyogenes strains, M18 strains bind the complement regulators factor H, FHL-1, and C4b-binding protein through two distinct cell surface proteins. Factor H and FHL-1 bind to the Emm18 protein, while C4BP binds to the Enn18 protein. We propose that expression of two distinct surface structures that bind complement regulatory proteins represents a unique adaptation of M18 strains that enhances their resistance to opsonization by human plasma and increases survival of this particular S. pyogenes strain in the human host. These new findings illustrate that S. pyogenes has evolved diverse mechanisms for recruitment of complement regulatory proteins to the bacterial surface to evade immune clearance in the human host.

  4. Nonopsonic binding of Mycobacterium tuberculosis to complement receptor type 3 is mediated by capsular polysaccharides and is strain dependent.

    PubMed Central

    Cywes, C; Hoppe, H C; Daffé, M; Ehlers, M R

    1997-01-01

    The choice of host cell receptor and the mechanism of binding (opsonic versus nonopsonic) may influence the intracellular fate of Mycobacterium tuberculosis. We have identified two substrains of M. tuberculosis H37Rv, designated H37Rv-CC and -HH, that differed in their modes of binding to complement receptor type 3 (CR3) expressed in transfected Chinese hamster ovary (CHO-Mac-1) cells: H37Rv-CC bound nonopsonically, whereas H37Rv-HH bound only after opsonization in fresh serum. H37Rv-CC also bound nonopsonically to untransfected CHO cells, whereas H37Rv-HH binding was enhanced by serum and was mediated by the 1D1 antigen, a bacterial adhesin previously identified as a polar phosphatidylinositol mannoside. H37Rv-CC and -HH had identical IS6110 DNA fingerprint patterns. Of five M. tuberculosis clinical isolates examined, four displayed the same binding phenotype as H37Rv-CC, as did the Erdman strain, whereas one isolate, as well as Mycobacterium smegmatis, behaved like H37Rv-HH. Nonopsonic binding of H37Rv-CC to CHO cell-expressed CR3 was apparently to the beta-glucan lectin site, as it was cation independent and inhibited by laminarin (seaweed beta-glucan) and N-acetylglucosamine; laminarin also inhibited the binding of H37Rv-CC to monocyte-derived macrophages. Further, binding of H37Rv-CC to CHO-Mac-1 cells was inhibited by prior agitation of bacteria with glass beads (which strips outer capsular polysaccharides) and by preincubation with amyloglucosidase, as well as by the presence of capsular D-glucan and D-mannan from M. tuberculosis Erdman, but not by Erdman D-arabino-D-mannan, yeast mannan, or capsular components from H37Rv-HH. Analysis of capsular carbohydrates revealed that H37Rv-CC expressed 5-fold more glucose and 2.5-fold more arabinose and mannose than H37Rv-HH. Flow cytometric detection of surface epitopes indicated that H37Rv-CC displayed twofold less surface-exposed phosphatidylinositol mannoside and bound complement C3 less efficiently than H37Rv

  5. Review on complement analysis method and the roles of glycosaminoglycans in the complement system.

    PubMed

    Li, Lian; Li, Yan; Ijaz, Muhammad; Shahbaz, Muhammad; Lian, Qianqian; Wang, Fengshan

    2015-12-10

    Complement system is composed of over 30 proteins and it plays important roles in self-defence and inflammation. There are three activation pathways, including classical pathway, alternative pathway and lectin pathway, in complement system, and they are associated with many diseases such as osteoarthritis and age-related macular degeneration. Modulation of the complement system may be a promising strategy in the treatment of related diseases. Glycosaminoglycans are anionic linear polysaccharides without branches. They are one kind of multi-functional macromolecules which have great potential in regulating complement system. This review is organized around two aspects between the introduction of complement system and the interaction of glycosaminoglycans with complement system. Three complement activation pathways and the biological significance were introduced first. Then functional analysis methods were compared to provide a strategy for potential glycosaminoglycans screen. Finally, the roles of glycosaminoglycans played in the complement system were summed up.

  6. Complement associated pathogenic mechanisms in myasthenia gravis.

    PubMed

    Tüzün, Erdem; Christadoss, Premkumar

    2013-07-01

    The complement system is profoundly involved in the pathogenesis of acetylcholine receptor (AChR) antibody (Ab) related myasthenia gravis (MG) and its animal model experimental autoimmune myasthenia gravis (EAMG). The most characteristic finding of muscle pathology in both MG and EAMG is the abundance of IgG and complement deposits at the nerve-muscle junction (NMJ), suggesting that AChR-Ab induces muscle weakness by complement pathway activation and consequent membrane attack complex (MAC) formation. This assumption has been supported with EAMG resistance of complement factor C3 knockout (KO), C4 KO and C5 deficient mice and amelioration of EAMG symptoms following treatment with complement inhibitors such as cobra venom factor, soluble complement receptor 1, anti-C1q, anti-C5 and anti-C6 Abs. Moreover, the complement inhibitor decay accelerating factor (DAF) KO mice exhibit increased susceptibility to EAMG. These findings have brought forward improvisation of novel therapy methods based on inhibition of classical and common complement pathways in MG treatment.

  7. The role of complement in AMD.

    PubMed

    Zipfel, Peter F; Lauer, Nadine; Skerka, Christine

    2010-01-01

    Age related macular degeneration (AMD) is a common form of blindness in the western world and genetic variations of several complement genes, including the complement regulator Factor H, the central complement component C3, Factor B, C2, and also Factor I confer a risk for the disease. However deletion of a chromosomal segment in the Factor H gene cluster on human chromosome 1, which results in the deficiency of the terminal pathway regulator CFHR1, and of the putative complement regulator CFHR3 has a protective effect for development of AMD. The Factor H gene encodes two proteins Factor H and FHL1 which are derived from alternatively processed transcripts. In particular a sequence variation at position 402 of both Factor H and FHL1 is associated with a risk for AMD. A tyrosine residue at position 402 represents the protective and a histidine residue the risk variant. AMD is considered a chronic inflammatory disease, which can be caused by defective and inappropriate regulation of the continuously activated alternative complement pathway. This activation generates complement effector products and inflammatory mediators that stimulate further inflammatory reactions. Defective regulation can lead to formation of immune deposits, drusen and ultimately translate into damage of retinal pigment epithelial cells, rupture of the interface between these epithelial cells and the Bruch's membrane and vision loss. Here we describe the role of complement in the retina and summarize the current concept how defective or inappropriate local complement control contributes to inflammation and the pathophysiology of AMD.

  8. Progress and Trends in Complement Therapeutics

    PubMed Central

    Ricklin, Daniel; Lambris, John D.

    2012-01-01

    The past few years have proven to be a highly successful and exciting period for the field of complement-directed drug discovery and development. Driven by promising experiences with the first marketed complement drugs, increased knowledge about the involvement of complement in health and disease, and improvements in structural and analytical techniques as well as animal models of disease, the field has seen a surge in creative approaches to therapeutically intervene at various stages of the cascade. An impressive panel of compounds that show promise in clinical trials is meanwhile being lined up in the pipelines of both small biotechnology and big pharmaceutical companies. Yet with this new focus on complement-targeted therapeutics, important questions concerning target selection, point and length of intervention, safety, and drug delivery emerge. In view of the diversity of the clinical disorders involving abnormal complement activity or regulation, which include both acute and chronic diseases and affect a wide range of organs, diverse yet specifically tailored therapeutic approaches may be needed to shift complement back into balance. This chapter highlights the key changes in the field that shape our current perception of complement-targeted drugs and provides a brief overview of recent strategies and emerging trends. Selected examples of complement-related diseases and inhibitor classes are highlighted to illustrate the diversity and creativity in field. PMID:22990692

  9. Effect of Complement on HIV-2 Plasma Antiviral Activity Is Intratype Specific and Potent

    PubMed Central

    Özkaya Şahin, Gülşen; Holmgren, Birgitta; Sheik-Khalil, Enas; da Silva, Zacarias; Nielsen, Jens; Nowroozalizadeh, Salma; Månsson, Fredrik; Norrgren, Hans; Aaby, Peter; Fenyö, Eva Maria

    2013-01-01

    Human immunodeficiency virus type 2 (HIV-2)-infected individuals develop immunodeficiency with a considerable delay and transmit the virus at rates lower than HIV-1-infected persons. Conceivably, comparative studies on the immune responsiveness of HIV-1- and HIV-2-infected hosts may help to explain the differences in pathogenesis and transmission between the two types of infection. Previous studies have shown that the neutralizing antibody response is more potent and broader in HIV-2 than in HIV-1 infection. In the present study, we have examined further the function of the humoral immune response and studied the effect of complement on the antiviral activity of plasma from singly HIV-1- or HIV-2-infected individuals, as well as HIV-1/HIV-2 dually infected individuals. The neutralization and antibody-dependent complement-mediated inactivation of HIV-1 and HIV-2 isolates were tested in a plaque reduction assay using U87.CD4.CCR5 cells. The results showed that the addition of complement increased intratype antiviral activities of both HIV-1 and HIV-2 plasma samples, although the complement effect was more pronounced with HIV-2 than HIV-1 plasma. Using an area-under-the-curve (AUC)-based readout, multivariate statistical analysis confirmed that the type of HIV infection was independently associated with the magnitude of the complement effect. The analyses carried out with purified IgG indicated that the complement effect was largely exerted through the classical complement pathway involving IgG in both HIV-1 and HIV-2 infections. In summary, these findings suggest that antibody binding to HIV-2 structures facilitates the efficient use of complement and thereby may be one factor contributing to a strong antiviral activity present in HIV-2 infection. PMID:23077299

  10. Mechanical properties of viruses.

    PubMed

    de Pablo, Pedro J; Mateu, Mauricio G

    2013-01-01

    Structural biology techniques have greatly contributed to unveil the relationships between structure, properties and functions of viruses. In recent years, classic structural approaches are being complemented by single-molecule techniques such as atomic force microscopy and optical tweezers to study physical properties and functions of viral particles that are not accessible to classic structural techniques. Among these features are mechanical properties such as stiffness, intrinsic elasticity, tensile strength and material fatigue. The field of virus mechanics is contributing to materials science by investigating some physical parameters of "soft" biological matter and biological nano-objects. Virus mechanics studies are also starting to unveil the biological implications of physical properties of viruses. Growing evidence indicate that viruses are subjected to internal and external forces, and that they may have adapted to withstand and even use those forces. This chapter describes what is known on the mechanical properties of virus particles, their structural determinants, and possible biological implications, of which several examples are provided.

  11. A Homology Model Reveals Novel Structural Features and an Immunodominant Surface Loop/Opsonic Target in the Treponema pallidum BamA Ortholog TP_0326

    PubMed Central

    Luthra, Amit; Anand, Arvind; Hawley, Kelly L.; LeDoyt, Morgan; La Vake, Carson J.; Caimano, Melissa J.; Cruz, Adriana R.; Salazar, Juan C.

    2015-01-01

    ABSTRACT We recently demonstrated that TP_0326 is a bona fide rare outer membrane protein (OMP) in Treponema pallidum and that it possesses characteristic BamA bipartite topology. Herein, we used immunofluorescence analysis (IFA) to show that only the β-barrel domain of TP_0326 contains surface-exposed epitopes in intact T. pallidum. Using the solved structure of Neisseria gonorrhoeae BamA, we generated a homology model of full-length TP_0326. Although the model predicts a typical BamA fold, the β-barrel harbors features not described in other BamAs. Structural modeling predicted that a dome comprised of three large extracellular loops, loop 4 (L4), L6, and L7, covers the barrel's extracellular opening. L4, the dome's major surface-accessible loop, contains mainly charged residues, while L7 is largely neutral and contains a polyserine tract in a two-tiered conformation. L6 projects into the β-barrel but lacks the VRGF/Y motif that anchors L6 within other BamAs. IFA and opsonophagocytosis assay revealed that L4 is surface exposed and an opsonic target. Consistent with B cell epitope predictions, immunoblotting and enzyme-linked immunosorbent assay (ELISA) confirmed that L4 is an immunodominant loop in T. pallidum-infected rabbits and humans with secondary syphilis. Antibody capture experiments using Escherichia coli expressing OM-localized TP_0326 as a T. pallidum surrogate further established the surface accessibility of L4. Lastly, we found that a naturally occurring substitution (Leu593 → Gln593) in the L4 sequences of T. pallidum strains affects antibody binding in sera from syphilitic patients. Ours is the first study to employ a “structure-to-pathogenesis” approach to map the surface topology of a T. pallidum OMP within the context of syphilitic infection. IMPORTANCE Previously, we reported that TP_0326 is a bona fide rare outer membrane protein (OMP) in Treponema pallidum and that it possesses the bipartite topology characteristic of a BamA ortholog

  12. Properdin in Complement Activation and Tissue Injury

    PubMed Central

    Lesher, AM; B, Nilsson; Song, W-C

    2013-01-01

    The plasma protein properdin is the only known positive regulator of complement activation. Although regarded as an initiator of the alternative pathway of complement activation at the time of its discovery more than a half century ago, the role and mechanism of action of properdin in the complement cascade has undergone significant conceptual evolution since then. Despite the long history of research on properdin, however, new insight and unexpected findings on the role of properdin in complement activation, pathogen infection and host tissue injury are still being revealed by ongoing investigations. In this article, we provide a brief review on recent studies that shed new light on properdin biology, focusing on the following three topics: 1) its role as a pattern recognition molecule to direct and trigger complement activation, 2) its context-dependent requirement in complement activation on foreign and host cell surfaces, and 3) its involvement in alternative pathway complement-mediated immune disorders and considerations of properdin as a potential therapeutic target in human diseases. PMID:23816404

  13. Infections Revealing Complement Deficiency in Adults

    PubMed Central

    Audemard-Verger, A.; Descloux, E.; Ponard, D.; Deroux, A.; Fantin, B.; Fieschi, C.; John, M.; Bouldouyre, A.; Karkowsi, L.; Moulis, G.; Auvinet, H.; Valla, F.; Lechiche, C.; Davido, B.; Martinot, M.; Biron, C.; Lucht, F.; Asseray, N.; Froissart, A.; Buzelé, R.; Perlat, A.; Boutboul, D.; Fremeaux-Bacchi, V.; Isnard, S.; Bienvenu, B.

    2016-01-01

    Abstract Complement system is a part of innate immunity, its main function is to protect human from bacterial infection. As genetic disorders, complement deficiencies are often diagnosed in pediatric population. However, complement deficiencies can also be revealed in adults but have been poorly investigated. Herein, we describe a case series of infections revealing complement deficiency in adults to study clinical spectrum and management of complement deficiencies. A nationwide retrospective study was conducted in French university and general hospitals in departments of internal medicine, infectious diseases enrolling patients older than 15 years old who had presented at least one infection leading to a complement deficiency diagnosis. Forty-one patients included between 2002 and 2015 in 19 different departments were enrolled in this study. The male-to-female ratio was 1.3 and the mean age at diagnosis was 28 ± 14 (15–67) years. The main clinical feature was Neisseria meningitidis meningitis 75% (n = 31/41) often involving rare serotype: Y (n = 9) and W 135 (n = 7). The main complement deficiency observed was the common final pathway deficiency 83% (n = 34/41). Half of the cohort displayed severe sepsis or septic shock at diagnosis (n = 22/41) but no patient died. No patient had family history of complement deficiency. The mean follow-up was 1.15 ± 1.95 (0.1–10) years. Half of the patients had already suffered from at least one infection before diagnosis of complement deficiency: meningitis (n = 13), pneumonia (n = 4), fulminans purpura (n = 1), or recurrent otitis (n = 1). Near one-third (n = 10/39) had received prophylactic antibiotics (cotrimoxazole or penicillin) after diagnosis of complement deficiency. The vaccination coverage rate, at the end of the follow-up, for N meningitidis, Streptococcus pneumonia, and Haemophilius influenzae were, respectively, 90% (n = 33/37), 47% (n = 17/36), and 35

  14. CD46: the 'multitasker' of complement proteins.

    PubMed

    Yamamoto, Hidekazu; Fara, Antonella Francesca; Dasgupta, Prokar; Kemper, Claudia

    2013-12-01

    Complement is undeniably quintessential for innate immunity by detecting and eliminating infectious microorganisms. Recent work, however, highlights an equally profound impact of complement on the induction and regulation of a wide range of immune cells. In particular, the complement regulator CD46 emerges as a key sensor of immune activation and a vital modulator of adaptive immunity. In this review, we summarize the current knowledge of CD46-mediated signalling events and their functional consequences on immune-competent cells with a specific focus on those in CD4(+) T cells. We will also discuss the promises and challenges that potential therapeutic modulation of CD46 may hold and pose.

  15. Antibodies to the Plasmodium falciparum Proteins MSPDBL1 and MSPDBL2 Opsonize Merozoites, Inhibit Parasite Growth, and Predict Protection From Clinical Malaria.

    PubMed

    Chiu, Chris Y H; Hodder, Anthony N; Lin, Clara S; Hill, Danika L; Li Wai Suen, Connie S N; Schofield, Louis; Siba, Peter M; Mueller, Ivo; Cowman, Alan F; Hansen, Diana S

    2015-08-01

    Increasing evidence suggests that antibodies against merozoite surface proteins (MSPs) play an important role in clinical immunity to malaria. Two unusual members of the MSP-3 family, merozoite surface protein duffy binding-like (MSPDBL)1 and MSPDBL2, have been shown to be extrinsically associated to MSP-1 on the parasite surface. In addition to a secreted polymorphic antigen associated with merozoite (SPAM) domain characteristic of MSP-3 family members, they also contain Duffy binding-like (DBL) domain and were found to bind to erythrocytes, suggesting that they play a role in parasite invasion. Antibody responses to these proteins were investigated in a treatment-reinfection study conducted in an endemic area of Papua New Guinea to determine their contribution to naturally acquired immunity. Antibodies to the SPAM domains of MSPDBL1 and MSPDBL2 as well as the DBL domain of MSPDBL1 were found to be associated with protection from Plasmodium falciparum clinical episodes. Moreover, affinity-purified anti-MSPDBL1 and MSPDBL2 were found to inhibit in vitro parasite growth and had strong merozoite opsonizing capacity, suggesting that protection targeting these antigens results from ≥2 distinct effector mechanisms. Together these results indicate that MSPDBL1 and MSPDBL2 are important targets of naturally acquired immunity and might constitute potential vaccine candidates.

  16. In vitro effects of aqueous seeds extract of Acacia cyanophylla on the opsonized zymosan-induced superoxide anions production by rat polymorphonuclear leukocytes.

    PubMed

    El Abbouyi, Ahmed; Toumi, Mina; El Hachimi, Youssef; Jossang, Akino

    2004-03-01

    In vitro studies were carried out in rat pleural polymorphonuclear leukocytes (PMNs) activated by opsonized zymosan (OZ) to investigate the effects of aqueous extract from Acacia cyanophylla seeds on superoxide anions generation. PMNs were collected, after induction of an acute inflammatory reaction, by injection in the rat pleural cavity, of a suspension of calcium pyrophosphate (CaPP) crystals (pleurisy with CaPP) or serum (pleurisy with serum). The results obtained indicate that Acacia cyanophylla aqueous seeds extract had, in vitro, a significant stimulatory effect, in a dose dependent manner, on the PMN superoxide anions generation. It also corrected the diminution of superoxide anions production induced by diclofenac pre-treated PMNs. It could be concluded from the results of this study that the stimulatory properties of Acacia cyanophylla seeds aqueous extract may at least be due to the presence of polyphenols such tannins and/or lignins. Further investigations are needed to determine clearly the mechanisms mediating the generation of superoxide radicals in this phenomenon.

  17. F-type lectin from the sea bass (Dicentrarchus labrax): purification, cDNA cloning, tissue expression and localization, and opsonic activity.

    PubMed

    Salerno, G; Parisi, M G; Parrinello, D; Benenati, G; Vizzini, A; Vazzana, M; Vasta, G R; Cammarata, M

    2009-08-01

    Recently described biochemical and structural aspects of fucose-binding lectins from the European eel (Anguilla anguilla) and striped bass (Morone saxatilis) led to the identification of a novel lectin family ("F-type" lectins) characterized by a unique sequence motif and a characteristic structural fold. The F-type fold is shared not only with other members of this lectin family, but also with apparently unrelated proteins ranging from prokaryotes to vertebrates. Here we describe the purification, biochemical and molecular properties, and the opsonic activity of an F-type lectin (DlFBL) isolated from sea bass (Dicentrarchus labrax) serum. DlFBL exhibits two tandemly arranged carbohydrate-recognition domains that display the F-type sequence motif. In situ hybridization and immunohistochemical analysis revealed that DlFBL is specifically expressed and localized in hepatocytes and intestinal cells. Exposure of formalin-killed Escherichia coli to DlFBL enhanced their phagocytosis by D. labrax peritoneal macrophages relative to the unexposed controls, suggesting that DlFBL may function as an opsonin in plasma and intestinal mucus.

  18. Efficient internalization of mesoporous silica particles of different sizes by primary human macrophages without impairment of macrophage clearance of apoptotic or antibody-opsonized target cells

    SciTech Connect

    Witasp, Erika; Kupferschmidt, Natalia; Bengtsson, Linnea; Hultenby, Kjell; Smedman, Christian; Paulie, Staffan; Garcia-Bennett, Alfonso E.; Fadeel, Bengt

    2009-09-15

    Macrophage recognition and ingestion of apoptotic cell corpses, a process referred to as programmed cell clearance, is of considerable importance for the maintenance of tissue homeostasis and in the resolution of inflammation. Moreover, macrophages are the first line of defense against microorganisms and other foreign materials including particles. However, there is sparse information on the mode of uptake of engineered nanomaterials by primary macrophages. In this study, mesoporous silica particles with cubic pore geometries and covalently fluorescein-grafted particles were synthesized through a novel route, and their interactions with primary human monocyte-derived macrophages were assessed. Efficient and active internalization of mesoporous silica particles of different sizes was observed by transmission electron microscopic and flow cytometric analysis and studies using pharmacological inhibitors suggested that uptake occurred through a process of endocytosis. Moreover, uptake of silica particles was independent of serum factors. The silica particles with very high surface areas due to their porous structure did not impair cell viability or function of macrophages, including the ingestion of different classes of apoptotic or opsonized target cells. The current findings are relevant to the development of mesoporous materials for drug delivery and other biomedical applications.

  19. Autocrine Effects of Tumor-Derived Complement

    PubMed Central

    Cho, Min Soon; Vasquez, Hernan G.; Rupaimoole, Rajesha; Pradeep, Sunila; Wu, Sherry; Zand, Behrouz; Han, Hee-Dong; Rodriguez-Aguayo, Cristian; Bottsford-Miller, Justin; Huang, Jie; Miyake, Takahito; Choi, Hyun-Jin; Dalton, Heather J.; Ivan, Cristina; Baggerly, Keith; Lopez-Berestein, Gabriel; Sood, Anil K.; Afshar-Kharghan, Vahid

    2014-01-01

    SUMMARY We describe a role for the complement system in enhancing cancer growth. Cancer cells secrete complement proteins that stimulate tumor growth upon activation. Complement promotes tumor growth via a direct autocrine effect that is partially independent of tumor-infiltrating cytotoxic T cells. Activated C5aR and C3aR signal through the PI3K/AKT pathway in cancer cells, and silencing the PI3K or AKT gene in cancer cells eliminates the progrowth effects of C5aR and C3aR stimulation. In patients with ovarian or lung cancer, higher tumoral C3 or C5aR mRNA levels were associated with decreased overall survival. These data identify a role for tumor-derived complement proteins in promoting tumor growth, and they therefore have substantial clinical and therapeutic implications. PMID:24613353

  20. Regulation of humoral immunity by complement.

    PubMed

    Carroll, Michael C; Isenman, David E

    2012-08-24

    The complement system of innate immunity is important in regulating humoral immunity largely through the complement receptor CR2, which forms a coreceptor on B cells during antigen-induced activation. However, CR2 also retains antigens on follicular dendritic cells (FDCs). Display of antigen on FDCs is critical for clonal selection and affinity maturation of activated B cells. This review will discuss the role of complement in adaptive immunity in general with a focus on the interplay between CR2-associated antigen on B cells with CR2 expressed on FDCs. This latter interaction provides an opportunity for memory B cells to sample antigen over prolonged periods. The cocrystal structure of CR2 with its ligand C3d provides insight into how the complement system regulates access of antigen by B cells with implications for therapeutic manipulations to modulate aberrant B cell responses in the case of autoimmunity.

  1. On complements of coradicals of finite groups

    NASA Astrophysics Data System (ADS)

    Vedernikov, V. A.; Sorokina, M. M.

    2016-06-01

    Let F be an ω-local Fitting formation, and G a finite group that can be represented in the form of a product of n subnormal subgroups whose F-coradicals are ω-soluble, and whose Sylow p-subgroups are abelian for any p\\inω. It is established that there exist ω-complements of the F-coradical of G. New theorems on the existence of complements of coradicals of a group are obtained as corollaries. For an ω-local formation F, conditions are established for the existence of complements and ω-complements of the F-coradical of a group in any of its extensions. Bibliography: 21 titles.

  2. Complement activation by a B cell superantigen.

    PubMed

    Kozlowski, L M; Soulika, A M; Silverman, G J; Lambris, J D; Levinson, A I

    1996-08-01

    Staphylococcal protein A (SpA), acting as a B cell superantigen, binds to the Fab region of human VH3+ Igs. Using SpA abrogated of its IgG Fc binding activity (Mod SpA) as a model B cell superantigen, we determined whether such an interaction causes complement activation. Addition of Mod SpA to human serum led to complement consumption and the generation of C3a. To determine whether this complement activation 1) was due to an interaction between VH3+ Igs and the Fab binding site of SpA and 2) proceeded via the classical complement pathway, we tested a panel of monoclonal IgM proteins for the ability to hind C1q following interaction with SpA. C1q binding was restricted to SpA-reactive, VH3+ IgM proteins. To formally determine whether the binding of SpA to the reactive VH3+ IgM proteins led to complement activation, we reconstituted the serum from a hypogammaglobulinemic patient with monoclonal IgM proteins and measured complement consumption and C3a generation following the addition of Mod SpA. We observed complement consumption and C3a production only in Mod SpA-treated serum reconstituted with a VH3+, SpA-binding, IgM protein. Taken together, these results provide compelling evidence that the interaction of the Fab binding site of SpA and VH3+ Igs can lead to complement activation via the classical pathway. This novel interaction may have significant implications for the in vivo properties of a B cell superantigen.

  3. Oral Vaccination with Heat Inactivated Mycobacterium bovis Activates the Complement System to Protect against Tuberculosis

    PubMed Central

    Garrido, Joseba M.; Aranaz, Alicia; Sevilla, Iker; Villar, Margarita; Boadella, Mariana; Galindo, Ruth C.; Pérez de la Lastra, José M.; Moreno-Cid, Juan A.; Fernández de Mera, Isabel G.; Alberdi, Pilar; Santos, Gracia; Ballesteros, Cristina; Lyashchenko, Konstantin P.; Minguijón, Esmeralda; Romero, Beatriz; de Juan, Lucía; Domínguez, Lucas; Juste, Ramón; Gortazar, Christian

    2014-01-01

    Tuberculosis (TB) remains a pandemic affecting billions of people worldwide, thus stressing the need for new vaccines. Defining the correlates of vaccine protection is essential to achieve this goal. In this study, we used the wild boar model for mycobacterial infection and TB to characterize the protective mechanisms elicited by a new heat inactivated Mycobacterium bovis vaccine (IV). Oral vaccination with the IV resulted in significantly lower culture and lesion scores, particularly in the thorax, suggesting that the IV might provide a novel vaccine for TB control with special impact on the prevention of pulmonary disease, which is one of the limitations of current vaccines. Oral vaccination with the IV induced an adaptive antibody response and activation of the innate immune response including the complement component C3 and inflammasome. Mycobacterial DNA/RNA was not involved in inflammasome activation but increased C3 production by a still unknown mechanism. The results also suggested a protective mechanism mediated by the activation of IFN-γ producing CD8+ T cells by MHC I antigen presenting dendritic cells (DCs) in response to vaccination with the IV, without a clear role for Th1 CD4+ T cells. These results support a role for DCs in triggering the immune response to the IV through a mechanism similar to the phagocyte response to PAMPs with a central role for C3 in protection against mycobacterial infection. Higher C3 levels may allow increased opsonophagocytosis and effective bacterial clearance, while interfering with CR3-mediated opsonic and nonopsonic phagocytosis of mycobacteria, a process that could be enhanced by specific antibodies against mycobacterial proteins induced by vaccination with the IV. These results suggest that the IV acts through novel mechanisms to protect against TB in wild boar. PMID:24842853

  4. Complement and thrombosis in the antiphospholipid syndrome.

    PubMed

    Oku, Kenji; Nakamura, Hiroyuki; Kono, Michihiro; Ohmura, Kazumasa; Kato, Masaru; Bohgaki, Toshiyuki; Horita, Tetsuya; Yasuda, Shinsuke; Amengual, Olga; Atsumi, Tatsuya

    2016-10-01

    The involvement of complement activation in the pathophysiology of antiphospholipid syndrome (APS) was first reported in murine models of antiphospholipid antibody (aPL)-related pregnancy morbidities. We previously reported that complement activation is prevalent and may function as a source of procoagulant cell activation in the sera of APS patients. Recently, autoantibodies against C1q, a component of complement 1, were reported to be correlated with complement activation in systemic lupus erythematosus. These antibodies target neoepitopes of deformed C1q bound to various molecules (i.e., anionic phospholipids) and induce accelerated complement activation. We found that anti-C1q antibodies are more frequently detected in primary APS patients than in control patients and in refractory APS patients with repeated thrombotic events. The titer of anti-C1q antibodies was significantly higher in refractory APS patients than in APS patients without flare. The binding of C1q to anionic phospholipids may be associated with the surge in complement activation in patients with anti-C1q antibodies when triggered by 'second-hit' biological stressors such as infection. Such stressors will induce overexpression of anionic phospholipids, with subsequent increases in deformed C1q that is targeted by anti-C1q antibodies.

  5. Fc receptors for IgG (Fc gamma Rs) on human monocytes and macrophages are not infectivity receptors for human immunodeficiency virus type 1 (HIV-1): studies using bispecific antibodies to target HIV-1 to various myeloid cell surface molecules, including the Fc gamma R.

    PubMed Central

    Connor, R I; Dinces, N B; Howell, A L; Romet-Lemonne, J L; Pasquali, J L; Fanger, M W

    1991-01-01

    Fc gamma Rs (Fc gamma RI, Fc gamma RII, and Fc gamma RIII) are highly expressed on human mononuclear phagocytes and function in the clearance of immune complexes and opsonized pathogens. We have examined the role of Fc gamma R in mediating antibody-dependent clearance of HIV-1 by human monocytes and monocyte-derived macrophages by using bispecific antibodies (BsAbs) to independently target the virus to Fc gamma RI, Fc gamma RII, or Fc gamma RIII. Virus production was markedly reduced in monocytes cultured with strain HIV-1IIIB opsonized with BsAbs that target the virus to either Fc gamma RI or Fc gamma RII compared to monocytes cultured with virus in the absence of BsAbs or in the presence of BsAbs that target the virus to non-Fc gamma R surface antigens (CD33 and HLA-A,B,C). These results were confirmed using the monotropic isolate HIV-1JRFL. Interaction of HIV-1JRFL with Fc gamma RI or Fc gamma RII on human monocytes and Fc gamma RI, Fc gamma RII, or Fc gamma RIII on monocyte-derived macrophages resulted in markedly reduced levels of virus production in these cultures. Moreover, HIV-1 infection of monocytes and monocyte-derived macrophages was completely blocked by anti-CD4 monoclonal antibodies, indicating that interaction with CD4 is required for infectivity even under conditions of antibody-mediated binding of HIV-1 to Fc gamma R. Thus, we propose that highly opsonized HIV-1 initiates high-affinity multivalent interactions with Fc gamma R that trigger endocytosis and intracellular degradation of the antibody-virus complex. At lower levels of antibody opsonization, there are two few interactions with Fc gamma R to initiate endocytosis and intracellular degradation of the antibody-virus complex, but there are enough interactions to stabilize the virus at the cell surface, allowing antibody-dependent enhancement of HIV-1 infection through high-affinity CD4 interactions. However, our results suggest that interaction of highly opsonized HIV-1 with Fc gamma Rs

  6. Complement in therapy and disease: Regulating the complement system with antibody-based therapeutics.

    PubMed

    Melis, Joost P M; Strumane, Kristin; Ruuls, Sigrid R; Beurskens, Frank J; Schuurman, Janine; Parren, Paul W H I

    2015-10-01

    Complement is recognized as a key player in a wide range of normal as well as disease-related immune, developmental and homeostatic processes. Knowledge of complement components, structures, interactions, and cross-talk with other biological systems continues to grow and this leads to novel treatments for cancer, infectious, autoimmune- or age-related diseases as well as for preventing transplantation rejection. Antibodies are superbly suited to be developed into therapeutics with appropriate complement stimulatory or inhibitory activity. Here we review the design, development and future of antibody-based drugs that enhance or dampen the complement system.

  7. Inhibition of Complement Retards Ankylosing Spondylitis Progression

    PubMed Central

    Yang, Chaoqun; Ding, Peipei; Wang, Qingkai; Zhang, Long; Zhang, Xin; Zhao, Jianquan; Xu, Enjie; Wang, Na; Chen, Jianfeng; Yang, Guang; Hu, Weiguo; Zhou, Xuhui

    2016-01-01

    Ankylosing spondylitis (AS) is a chronic axial spondyloarthritis (SpA) resulting in back pain and progressive spinal ankyloses. Currently, there are no effective therapeutics targeting AS largely due to elusive pathogenesis mechanisms, even as potential candidates such as HLA-B27 autoantigen have been identified. Herein, we employed a proteoglycan (PG)-induced AS mouse model together with clinical specimens, and found that the complement system was substantially activated in the spinal bone marrow, accompanied by a remarkable proportion alteration of neutrophils and macrophage in bone marrow and spleen, and by the significant increase of TGF-β1 in serum. The combined treatment with a bacteria-derived complement inhibitor Efb-C (C-terminal of extracellular fibrinogen-binding protein of Staphylococcus aureus) remarkably retarded the progression of mouse AS by reducing osteoblast differentiation. Furthermore, we demonstrated that two important modulators involved in AS disease, TGF-β1 and RANKL, were elevated upon in vitro complement attack in osteoblast and/or osteoclast cells. These findings further unravel that complement activation is closely related with the pathogenesis of AS, and suggest that complement inhibition may hold great potential for AS therapy. PMID:27698377

  8. Binding of IgG-opsonized particles to Fc gamma R is an active stage of phagocytosis that involves receptor clustering and phosphorylation.

    PubMed

    Sobota, Andrzej; Strzelecka-Kiliszek, Agnieszka; Gładkowska, Ewelina; Yoshida, Kiyotsugu; Mrozińska, Kazimiera; Kwiatkowska, Katarzyna

    2005-10-01

    Fc gammaR mediate the phagocytosis of IgG-coated particles and the clearance of IgG immune complexes. By dissecting binding from internalization of the particles, we found that the binding stage, rather than particle internalization, triggered tyrosine phosphorylation of Fc gammaR and accompanying proteins. High amounts of Lyn kinase were found to associate with particles isolated at the binding stage from J774 cells. PP2 (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine), an Src kinase inhibitor, but not piceatannol, an inhibitor of Syk kinase, reduced the amount of Lyn associated with the bound particles and simultaneously diminished the binding of IgG-coated particles. Studies of baby hamster kidney cells transfected with wild-type and mutant Fc gammaRIIA revealed that the ability of the receptor to bind particles was significantly reduced when phosphorylation of the receptor was abrogated by Y298F substitution in the receptor signaling motif. Under these conditions, binding of immune complexes of aggregated IgG was depressed to a lesser extent. A similar effect was exerted on the binding ability of wild-type Fc gammaRIIA by PP2. Moreover, expression of mutant kinase-inactive Lyn K275R inhibited both Fc gammaRIIA phosphorylation and IgG-opsonized particle binding. To gain insight into the mechanism by which protein tyrosine phosphorylation can control Fc gammaR-mediated binding, we investigated the efficiency of clustering of wild-type and Y298F-substituted Fc gammaRIIA upon binding of immune complexes. We found that a lack of Fc gammaRIIA phosphorylation led to an impairment of receptor clustering. The results indicate that phosphorylation of Fc gammaR and accompanying proteins, dependent on Src kinase activity, facilitates the clustering of activated receptors that is required for efficient particle binding.

  9. State of Büchi Complementation

    NASA Astrophysics Data System (ADS)

    Tsai, Ming-Hsien; Fogarty, Seth; Vardi, Moshe Y.; Tsay, Yih-Kuen

    Büchi complementation has been studied for five decades since the formalism was introduced in 1960. Known complementation constructions can be classified into Ramsey-based, determinization-based, rank-based, and slice-based approaches. For the performance of these approaches, there have been several complexity analyses but very few experimental results. What especially lacks is a comparative experiment on all the four approaches to see how they perform in practice. In this paper, we review the state of Büchi complementation, propose several optimization heuristics, and perform comparative experimentation on the four approaches. The experimental results show that the determinization-based Safra-Piterman construction outperforms the other three and our heuristics substantially improve the Safra-Piterman construction and the slice-based construction.

  10. Applying Complement Therapeutics to Rare Diseases

    PubMed Central

    Reis, Edimara S.; Mastellos, Dimitrios C.; Yancopoulou, Despina; Risitano, Antonio M.; Ricklin, Daniel; Lambris, John D.

    2015-01-01

    Around 350 million people worldwide suffer from rare diseases. These may have a genetic, infectious, or autoimmune basis, and several include an inflammatory component. Launching of effective treatments can be very challenging when there is a low disease prevalence and limited scientific insights into the disease mechanisms. As a key trigger of inflammatory processes, complement has been associated with a variety of diseases and has become an attractive therapeutic target for conditions involving inflammation. In view of the clinical experience acquired with drugs licensed for the treatment of rare diseases such as hereditary angioedema and paroxysmal nocturnal hemoglobinuria, growing evidence supports the safety and efficacy of complement therapeutics in restoring immune balance and preventing aggravation of clinical outcomes. This review provides an overview of the candidates currently in the pharmaceutical pipeline with potential to treat orphan diseases and discusses the molecular mechanisms triggered by complement involved with the disease pathogenesis. PMID:26341313

  11. Applying complement therapeutics to rare diseases.

    PubMed

    Reis, Edimara S; Mastellos, Dimitrios C; Yancopoulou, Despina; Risitano, Antonio M; Ricklin, Daniel; Lambris, John D

    2015-12-01

    Around 350 million people worldwide suffer from rare diseases. These may have a genetic, infectious, or autoimmune basis, and several include an inflammatory component. Launching of effective treatments can be very challenging when there is a low disease prevalence and limited scientific insights into the disease mechanisms. As a key trigger of inflammatory processes, complement has been associated with a variety of diseases and has become an attractive therapeutic target for conditions involving inflammation. In view of the clinical experience acquired with drugs licensed for the treatment of rare diseases such as hereditary angioedema and paroxysmal nocturnal hemoglobinuria, growing evidence supports the safety and efficacy of complement therapeutics in restoring immune balance and preventing aggravation of clinical outcomes. This review provides an overview of the candidates currently in the pharmaceutical pipeline with potential to treat orphan diseases and discusses the molecular mechanisms triggered by complement involved with the disease pathogenesis.

  12. Complement activation in chronic liver disease.

    PubMed Central

    Munoz, L E; De Villiers, D; Markham, D; Whaley, K; Thomas, H C

    1982-01-01

    Patients with HBsAg positive chronic active liver disease (CALD) and primary biliary cirrhosis (PBC) exhibit increased C3d concentrations and changes in the serum concentrations of the complement components consistent with activation of the classical and alternative pathways. In these patients the concentrations of the regulatory proteins, C3b inactivator (C3bINA) and beta IH globulin, are normal. Patients with HBsAg negative CALD and alcohol induced liver disease (ALD) exhibit no evidence of an increased level of complement system activation. In these patients diminished serum concentrations of complement components appear to be related to diminished hepatic synthetic function. C4 synthesis may be specifically reduced in autoimmune chronic active liver disease. PMID:7083631

  13. The extracellular RNA complement of Escherichia coli

    PubMed Central

    Ghosal, Anubrata; Upadhyaya, Bimal Babu; Fritz, Joëlle V; Heintz-Buschart, Anna; Desai, Mahesh S; Yusuf, Dilmurat; Huang, David; Baumuratov, Aidos; Wang, Kai; Galas, David; Wilmes, Paul

    2015-01-01

    The secretion of biomolecules into the extracellular milieu is a common and well-conserved phenomenon in biology. In bacteria, secreted biomolecules are not only involved in intra-species communication but they also play roles in inter-kingdom exchanges and pathogenicity. To date, released products, such as small molecules, DNA, peptides, and proteins, have been well studied in bacteria. However, the bacterial extracellular RNA complement has so far not been comprehensively characterized. Here, we have analyzed, using a combination of physical characterization and high-throughput sequencing, the extracellular RNA complement of both outer membrane vesicle (OMV)-associated and OMV-free RNA of the enteric Gram-negative model bacterium Escherichia coli K-12 substrain MG1655 and have compared it to its intracellular RNA complement. Our results demonstrate that a large part of the extracellular RNA complement is in the size range between 15 and 40 nucleotides and is derived from specific intracellular RNAs. Furthermore, RNA is associated with OMVs and the relative abundances of RNA biotypes in the intracellular, OMV and OMV-free fractions are distinct. Apart from rRNA fragments, a significant portion of the extracellular RNA complement is composed of specific cleavage products of functionally important structural noncoding RNAs, including tRNAs, 4.5S RNA, 6S RNA, and tmRNA. In addition, the extracellular RNA pool includes RNA biotypes from cryptic prophages, intergenic, and coding regions, of which some are so far uncharacterised, for example, transcripts mapping to the fimA-fimL and ves-spy intergenic regions. Our study provides the first detailed characterization of the extracellular RNA complement of the enteric model bacterium E. coli. Analogous to findings in eukaryotes, our results suggest the selective export of specific RNA biotypes by E. coli, which in turn indicates a potential role for extracellular bacterial RNAs in intercellular communication. PMID:25611733

  14. Therapeutic complement inhibition in complement-mediated hemolytic anemias: Past, present and future.

    PubMed

    Risitano, Antonio M; Marotta, Serena

    2016-06-01

    The introduction in the clinic of anti-complement agents represented a major achievement which gave to physicians a novel etiologic treatment for different human diseases. Indeed, the first anti-complement agent eculizumab has changed the treatment paradigm of paroxysmal nocturnal hemoglobinuria (PNH), dramatically impacting its severe clinical course. In addition, eculizumab is the first agent approved for atypical Hemolytic Uremic Syndrome (aHUS), a life-threatening inherited thrombotic microangiopathy. Nevertheless, such remarkable milestone in medicine has brought to the fore additional challenges for the scientific community. Indeed, the list of complement-mediated anemias is not limited to PNH and aHUS, and other human diseases can be considered for anti-complement treatment. They include other thrombotic microangiopathies, as well as some antibody-mediated hemolytic anemias. Furthermore, more than ten years of experience with eculizumab led to a better understanding of the individual steps of the complement cascade involved in the pathophysiology of different human diseases. Based on this, new unmet clinical needs are emerging; a number of different strategies are currently under development to improve current anti-complement treatment, trying to address these specific clinical needs. They include: (i) alternative anti-C5 agents, which may improve the heaviness of eculizumab treatment; (ii) broad-spectrum anti-C3 agents, which may improve the efficacy of anti-C5 treatment by intercepting the complement cascade upstream (i.e., preventing C3-mediated extravascular hemolysis in PNH); (iii) targeted inhibitors of selective complement activating pathways, which may prevent early pathogenic events of specific human diseases (e.g., anti-classical pathway for antibody-mediated anemias, or anti-alternative pathway for PNH and aHUS). Here we briefly summarize the status of art of current and future complement inhibition for different complement-mediated anemias

  15. Inhibition of complement-mediated cytolysis by the terminal complement inhibitor of herpesvirus saimiri.

    PubMed

    Rother, R P; Rollins, S A; Fodor, W L; Albrecht, J C; Setter, E; Fleckenstein, B; Squinto, S P

    1994-02-01

    Herpesvirus saimiri (HVS) is a lymphotropic herpesvirus that induces T-cell transformation in vitro and causes lymphomas and leukemias in New World primates other than its natural host, the squirrel monkey. Nucleotide sequence analysis of the HVS genome revealed two open reading frames with significant homology to genes for human complement regulatory molecules. One of these genes encodes a predicted protein (designated HVSCD59) with 48% amino acid sequence identity to the human terminal complement regulatory protein CD59 (HuCD59). The CD59 homolog from squirrel monkey (SMCD59) was cloned, and the corresponding amino acid sequence showed 69% identity with HVSCD59. BALB/3T3 cells stably expressing HVSCD59, SMCD59, or HuCD59 were equally protected from complement-mediated lysis by human serum. However, only HVSCD59-expressing cells were effectively protected from complement-mediated lysis when challenged with rat serum, suggesting that HVSCD59 was less species restrictive. The complement regulatory activity of HVSCD59 and SMCD59 occurred after C3b deposition, indicating terminal complement inhibition. Treatment of BALB/3T3 stable transfectants with phosphatidylinositol-specific phospholipase C prior to complement attack decreased the complement regulatory function of HVSCD59, suggesting cell surface attachment via a glycosyl-phosphatidylinositol anchor. Cells expressing HVSCD59 effectively inhibited complement-mediated lysis by squirrel monkey serum in comparison with SMCD59-expressing cells. Finally HVSCD59-specific transcripts were detected in owl monkey cells permissive for lytic HVS replication but not in T cells transformed by HVS, which failed to produce virions. These data are the first to demonstrate a functional, virally encoded terminal complement inhibitor and suggest that HVSCD59 represents a humoral immune evasion mechanism supporting the lytic life cycle of HVS.

  16. Complement fixation and neutralization RS antibodies in maternal and neonatal sera.

    PubMed Central

    Heijtink, R. A.; Backx, G.; Van Der Horst, J. M.; Masurel, N.

    1977-01-01

    RSV complement fixation antibodies were established in 200 paired maternal and cord blood sera. Geometric mean titres in cord sera were significantly higher than in matermal sera. The differences did not depend on the virus strain used. Half of the paired sera (taken at random) were also submitted to microneutralization tests. No differences were found between geometric mean titres in maternal and cord sera. PMID:266541

  17. 21 CFR 866.4100 - Complement reagent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Complement reagent. 866.4100 Section 866.4100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  18. 21 CFR 866.4100 - Complement reagent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Complement reagent. 866.4100 Section 866.4100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  19. 21 CFR 866.4100 - Complement reagent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Complement reagent. 866.4100 Section 866.4100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  20. 21 CFR 866.4100 - Complement reagent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Complement reagent. 866.4100 Section 866.4100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  1. 21 CFR 866.4100 - Complement reagent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Complement reagent. 866.4100 Section 866.4100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  2. The complement system: an evolution in progress

    PubMed Central

    Ghebrehiwet, Berhane

    2016-01-01

    The complement system, which consists of three independent but interacting pathways, constitutes a powerful arm of innate immunity. Its major function is to recognize and destroy pathogenic microorganisms as well as eliminate modified self-antigens. Although it is a fine-tuned system with innate capacity to discriminate self from non-self as well as danger from non-danger signals, an unwarranted activation can nonetheless occur and cause tissue destruction. To prevent such activation, specific regulators present both in plasma and on the cell surface tightly control it. Data accumulated over the past four decades have also shown that the complement system is capable of not only cross-talk with the activation cascades of plasma––i.e. blood coagulation, contact activation, and the kinin/kallikrein system––but also serving as a bridge between innate and adaptive immunity. It is for these reasons that the various activation steps of the complement system have been recently targeted for therapy to treat diseases in which the role of complement is beyond doubt. This trend will certainly continue for years to come, especially as novel concepts guiding the field into areas never contemplated before are continuing to be discovered. PMID:27990282

  3. Emai Sentence Complements in Typological Perspective.

    ERIC Educational Resources Information Center

    Schaefer, Ronald P.; Egbokhare, Francis O.

    This paper explores the syntactic and semantic character of previously undescribed sentence complements (SCs) in Emai, a Benue-Congo language of Nigeria's Edoid group. Data come from ongoing documentation incorporating oral narrative texts as well as dictionary and grammar descriptions. To delineate the grammatical properties of SCs, the paper…

  4. Genetics Home Reference: complement component 2 deficiency

    MedlinePlus

    ... Page Jönsson G, Sjöholm AG, Truedsson L, Bengtsson AA, Braconier JH, Sturfelt G. Rheumatological manifestations, organ damage ... 31. Review. Citation on PubMed Truedsson L, Bengtsson AA, Sturfelt G. Complement deficiencies and systemic lupus erythematosus. ...

  5. Complement Constructions in English: Fairly Difficult for EFL Language Learners

    ERIC Educational Resources Information Center

    Fazeli, Fatemeh; Shokrpour, Nasrin

    2012-01-01

    Complement constructions vary significantly in English and Persian. There are more complementation structures in English than in Persian and a complement structure in Persian might have more than one equivalent in English. Producing complement structures (CSs) in English is very difficult for native speakers of Persian, especially in an EFL…

  6. Targeted Inhibition of Complement Using Complement Receptor 2-Conjugated Inhibitors Attenuates EAE

    PubMed Central

    Hu, Xianzhen; Tomlinson, Stephen; Barnum, Scott R.

    2012-01-01

    Multiple sclerosis (MS) is the most common autoimmune demyelinating disease, affecting millions of individuals worldwide. In the last two decades, many therapeutic options for the treatment of MS have become available, however they are limited in terms of effectiveness and some remain plagued by safety issues. The currently available treatment options target relapsing remitting forms of MS and are not effective against the more progressive forms of the disease. These limitations highlight a significant unmet treatment need for MS. In experimental autoimmune encephalomyelitis (EAE) studies from our laboratory, we have previously shown, using a number of complement mutant and transgenic mice, that inhibition of the alternative complement pathway and the C3 convertase confers significant protection from disease. We report here that targeted inhibition of complement activation using complement receptor 2 (CR2)-conjugated inhibitors significantly attenuates EAE. Administration of CR2-Crry (blocks all complement pathways at C3 activation) and CR2-fH (specifically blocks the alternative pathway) just prior to and during the onset of EAE blocks progression of both acute and chronic disease. These data indicate that inhibition of complement may offer an effective therapeutic approach to treating both acute and chronic forms of demyelinating disease through blocking the alternative pathway or complement convertases. PMID:23079547

  7. Targeted inhibition of complement using complement receptor 2-conjugated inhibitors attenuates EAE.

    PubMed

    Hu, Xianzhen; Tomlinson, Stephen; Barnum, Scott R

    2012-11-30

    Multiple sclerosis (MS) is the most common autoimmune demyelinating disease, affecting millions of individuals worldwide. In the last two decades, many therapeutic options for the treatment of MS have become available, however they are limited in terms of effectiveness and some remain plagued by safety issues. The currently available treatment options target relapsing remitting forms of MS and are not effective against the more progressive forms of the disease. These limitations highlight a significant unmet treatment need for MS. In experimental autoimmune encephalomyelitis (EAE) studies from our laboratory, we have previously shown, using a number of complement mutant and transgenic mice, that inhibition of the alternative complement pathway and the C3 convertase confers significant protection from disease. We report here that targeted inhibition of complement activation using complement receptor 2 (CR2)-conjugated inhibitors significantly attenuates EAE. Administration of CR2-Crry (blocks all complement pathways at C3 activation) and CR2-fH (specifically blocks the alternative pathway) just prior to and during the onset of EAE blocks progression of both acute and chronic disease. These data indicate that inhibition of complement may offer an effective therapeutic approach to treating both acute and chronic forms of demyelinating disease through blocking the alternative pathway or complement convertases.

  8. The effects of soluble recombinant complement receptor 1 on complement-mediated experimental glomerulonephritis.

    PubMed

    Couser, W G; Johnson, R J; Young, B A; Yeh, C G; Toth, C A; Rudolph, A R

    1995-05-01

    Complement is a major mediator of tissue injury in several types of glomerulonephritis. However, no therapeutic agents that inhibit complement activation are available for human use. sCR1 (TP10, BRL 55736) is a recombinant, soluble human complement receptor 1 (CR1) molecule lacking transmembrane and cytoplasmic domains that inhibits C3 and C5 convertase activity by preferentially binding C4b and C3b. To test the efficacy of sCR1 on complement-mediated glomerulonephritis, rats were pretreated with sCR1 (60 mg/kg per day) before and during the induction of three models of complement-dependent glomerulonephritis (concanavalin A and antithymocyte serum models of proliferative glomerulonephritis, passive Heyman nephritis). Daily sCR1 and complement hemolytic activity levels were measured, and renal histology and urine protein excretion were examined. Mean serum sCR1 levels of 100 to 200 micrograms/mL were maintained with a reduction in complement hemolytic activity to less than 15% in most animals. In the antithymocyte serum model, sCR1-treated animals had significant reductions in mesangiolysis, glomerular platelet and macrophage infiltrates, and proteinuria at 48 h. In the concanavalin A model, sCR1 significantly reduced glomerular C3 and fibrin deposits, platelet infiltrates, and proteinuria at 48 h. In passive Heymann nephritis, proteinuria was also significantly reduced (199 +/- 8.5 versus 125 +/- 16 mg/day, P < 0.002) at 5 days. It was concluded that sCR1 significantly reduces both morphologic and functional consequences of several different types of complement-mediated glomerulonephritis and deserves evaluation as a potential therapeutic agent in complement-mediated immune glomerular disease in humans.

  9. Complementation of a DNA repair defect in xeroderma pigmentosum cells by transfer of human chromosome 9

    SciTech Connect

    Kaur, G.P.; Athwal, R.S. )

    1989-11-01

    Complementation of the repair defect in xeroderma pigmentosum cells of complementation group A was achieved by the transfer of human chromosome 9. A set of mouse-human hybrid cell lines, each containing a single Ecogpt-marked human chromosome, was used as a source of donor chromosomes. Chromosome transfer to XPTG-1 cells, a hypoxanthine/guanine phosphoribosyltransferase-deficient mutant of simian virus 40-transformed complementation group A cells, was achieved by microcell fusion and selection for Ecogpt. Chromosome-transfer clones of XPTG-1 cells, each containing a different human donor chromosome, were analyzed for complementation of sensitivity to UV irradiation. Among all the clones, increased levels of resistance to UV was observed only in clones containing chromosome 9. Since our recipient cell line XPTG-1 is hypoxanthine/guanine phosphoribosyltransferase deficient, cultivation of Ecogpt+ clones in medium containing 6-thioguanine permits selection of cells for loss of the marker and, by inference, transferred chromosome 9. Clones isolated for growth in 6-thioguanine, which have lost the Ecogpt-marked chromosome, exhibited a UV-sensitive phenotype, confirming the presence of the repair gene(s) for complementation group A on chromosome 9.

  10. DEVELOPMENT, PERSISTENCE, AND SIGNIFICANCE OF TYPE 2, POLIOMYELITIS COMPLEMENT-FIXING ANTIBODY IN MAN

    PubMed Central

    Casals, Jordi; Olitsky, Peter K.; Sabin, Albert B.

    1952-01-01

    Sera from 81 patients with a diagnosis of paralytic or non-paralytic poliomyelitis, and from 159 individuals of similar age groups giving no history of the disease, were tested with a high titered, complement-fixing poliomyelitis antigen of Type 2 (Lansing-like). The antigen consisted of brain tissue from newborn mice injected with the MEF1 strain of virus as previously adapted to these animals. The presence or absence of Type 2 neutralizing antibody in the sera under test was found not to affect the complement fixation. Positive reactions were obtained with 57 per cent of the sera deriving from non-paralytic patients and in 70 per cent from paralytics, when the specimens were tested at a dilution of 1:16. The complement-fixing antibody was often present in highest titer as early as 24 hours after the onset of poliomyelitis, and in almost all instances within 7 days. In about half of the patients a 4-fold or greater drop in titer occurred within 3 months, with little or no change in the others. The incidence of titers of 1:16 or higher with the control sera varied with the season of the year at which they were procured, 3 per cent of the winter samples proving positive and 13 per cent of the summer. The tests of sera from the group of patients from whom poliomyelitis virus was recovered, disclosed no significant differences between those having the paralytic and those having the non-paralytic disease. Type 1 (Brunhilde-like) strains of virus were recovered from many of the patients yielding positive tests, although they presented no evidence of previous or concurrent infection with Type 2 virus. This finding shows that Type 1 virus can give rise in patients to Type 2 complement-fixing antibody. The application of these data to the serologic diagnosis of poliomyelitis infection in man will of necessity be limited until information is obtained on the development, persistence, and significance of complement-fixation reactions with antigens deriving from Type 1 and

  11. Development, persistence, and significance of type 2, poliomyelitis complement-fixing antibody in man.

    PubMed

    CASALS, J; OLITSKY, P K; SABIN, A B

    1952-07-01

    Sera from 81 patients with a diagnosis of paralytic or non-paralytic poliomyelitis, and from 159 individuals of similar age groups giving no history of the disease, were tested with a high titered, complement-fixing poliomyelitis antigen of Type 2 (Lansing-like). The antigen consisted of brain tissue from newborn mice injected with the MEF1 strain of virus as previously adapted to these animals. The presence or absence of Type 2 neutralizing antibody in the sera under test was found not to affect the complement fixation. Positive reactions were obtained with 57 per cent of the sera deriving from non-paralytic patients and in 70 per cent from paralytics, when the specimens were tested at a dilution of 1:16. The complement-fixing antibody was often present in highest titer as early as 24 hours after the onset of poliomyelitis, and in almost all instances within 7 days. In about half of the patients a 4-fold or greater drop in titer occurred within 3 months, with little or no change in the others. The incidence of titers of 1:16 or higher with the control sera varied with the season of the year at which they were procured, 3 per cent of the winter samples proving positive and 13 per cent of the summer. The tests of sera from the group of patients from whom poliomyelitis virus was recovered, disclosed no significant differences between those having the paralytic and those having the non-paralytic disease. Type 1 (Brunhilde-like) strains of virus were recovered from many of the patients yielding positive tests, although they presented no evidence of previous or concurrent infection with Type 2 virus. This finding shows that Type 1 virus can give rise in patients to Type 2 complement-fixing antibody. The application of these data to the serologic diagnosis of poliomyelitis infection in man will of necessity be limited until information is obtained on the development, persistence, and significance of complement-fixation reactions with antigens deriving from Type 1 and

  12. Can Cell Bound Complement Activation Products Predict Inherited Complement Deficiency in Systemic Lupus Erythematosus?

    PubMed Central

    Waters, Barry

    2016-01-01

    Activation of the classical pathway complement system has long been implicated in stimulating immune complex mediated tissue destruction in systemic lupus erythematosus (SLE). C3 and C4 complement levels are utilized as part of SLE diagnosis and monitoring criteria. Recently, cell bound complement activation products (CBCAPs) have shown increased sensitivity in diagnosing and monitoring lupus activity, compared to traditional markers. CBCAPs are increasingly utilized in rheumatology practice as additional serological markers in evaluating SLE patients. We report a case of a patient diagnosed with SLE that had chronically low C3 and C4, along with negative CBCAPs. We surmise that the patient has an inherited complement deficiency as the etiology of her SLE and that CBCAPs could be used to predict such deficiency. PMID:28074166

  13. Heartland Virus

    MedlinePlus

    ... Vector-Borne Diseases (DVBD) NCEZID Share Compartir Heartland virus On this Page What is Heartland virus? How ... Do I Need to Know? What is Heartland virus? Heartland virus belongs to a family of viruses ...

  14. Direct Complement Restriction of Flavivirus Infection Requires Glycan Recognition by Mannose Binding Lectin

    PubMed Central

    Fuchs, Anja; Lin, Tsai-Yu; Beasley, David W.; Stover, Cordula M.; Schwaeble, Wilhelm J.; Pierson, Theodore C.; Diamond, Michael S.

    2010-01-01

    SUMMARY An intact complement system is crucial for limiting West Nile virus (WNV) dissemination. Herein, we define how complement directly restricts flavivirus infection in an antibody-independent fashion. Mannose binding lectin (MBL) recognized N-linked glycans on the structural proteins of WNV and Dengue virus (DENV), resulting in neutralization through a C3 and C4-dependent mechanism that utilized both the canonical and bypass lectin activation pathways. For WNV, neutralization occurred with virus produced in insect cells, whereas for DENV, neutralization of insect and mammalian cell-derived virus was observed. Mechanism of action studies suggested that the MBL-dependent neutralization occurred in part, by blocking viral fusion. Experiments in mice showed an MBL-dependent accelerated intravascular clearance of DENV or a WNV mutant with two N-linked glycans on its E protein, but not with wild type WNV. Our studies show that MBL recognizes terminal mannose containing carbohydrates on flaviviruses, resulting in neutralization and efficient clearance in vivo. PMID:20709295

  15. Tanker avionics and aircrew complement evaluation.

    PubMed

    Moss, R W; Barbato, G J

    1982-11-01

    This paper describes an effort to determine control and display criteria for operating SAC's KC-135 tanker with a reduced crew complement. The Tanker Avionics and Aircrew Complement Evaluation (TAACE) Program was a four-phase effort addressing the control and display design issues associated with operating the tanker without the navigator position. Discussed are: the mission analysis phase, during which the tanker's operational responsibilities were defined and documented; the design phase, during which alternative crew station design concepts were developed; the mockup evaluation phase, which accomplished initial SAC crew member assessment of cockpit designs; and the simulation phase, which validated the useability of the crew system redesign. The paper also describes a recommended crew station configuration and discusses some of the philosophy underlying the selection of cockpit hardware and systems.

  16. COMPLEMENT REGULATION IN RENAL DISEASE MODELS

    PubMed Central

    Naik, Abhijit; Sharma, Shweta; Quigg, Richard J.

    2014-01-01

    Activation of the complement system is tightly regulated by plasma and cell-associated complement regulatory proteins (CRPs), such as factor H (fH), decay-accelerating factor (DAF), and membrane cofactor protein (MCP). Animal models of disease have provided considerable insights into the important roles for CRPs in the kidney. Mice deficient in fH have excessive fluid phase C3 activation and inactivation leading to deposition of iC3b in glomerular capillary walls (GCW), comparable to dense deposit disease. In contrast, when fH lacks C-terminal surface targeting regions, local activation on the GCW leads to a disease reminiscent of thrombotic microangiopathy. The uniquely rodent protein, CR1-related y (Crry), has features analogous to human MCP. Defective Crry leads to unrestricted alternative pathway activation in the tubulointerstitium (TI) resulting in pathological features ranging from TMA, acute kidney injury and TI nephritis. In the presence of initiators of the classical or lectin pathways, commonly in the form of immune complexes in human glomerular diseases, complement regulation on self is stressed, with the potential for recruitment of the spontaneously active alternative pathway. The threshold for this activation is set by CRPs; pathology is more likely when complement regulation is defective. Within the endocapillary region of the GCW, fH is key, while DAF and Crry are protective on mesangial cells and podocytes. Arguably, acquired alterations in these CRPs is a more common event, extending from pathological states of cellular injury or production of inhibitory antibodies, to physiological fine tuning of the adaptive immune response. PMID:24161042

  17. Microbe-specific C3b deposition in the horseshoe crab complement system in a C2/factor B-dependent or -independent manner.

    PubMed

    Tagawa, Keisuke; Yoshihara, Toyoki; Shibata, Toshio; Kitazaki, Kazuki; Endo, Yuichi; Fujita, Teizo; Koshiba, Takumi; Kawabata, Shun-ichiro

    2012-01-01

    Complement C3 plays an essential role in the opsonization of pathogens in the mammalian complement system, whereas the molecular mechanism underlying C3 activation in invertebrates remains unknown. To understand the molecular mechanism of C3b deposition on microbes, we characterized two types of C2/factor B homologs (designated TtC2/Bf-1 and TtC2/Bf-2) identified from the horseshoe crab Tachypleus tridentatus. Although the domain architectures of TtC2/Bf-1 and TtC2/Bf-2 were identical to those of mammalian homologs, they contained five-repeated and seven-repeated complement control protein domains at their N-terminal regions, respectively. TtC2/Bf-1 and TtC2/Bf-2 were synthesized and glycosylated in hemocytes and secreted to hemolymph plasma, which existed in a complex with C3 (TtC3), and their activation by microbes was absolutely Mg(2+)-dependent. Flow cytometric analysis revealed that TtC3b deposition was Mg(2+)-dependent on Gram-positive bacteria or fungi, but not on Gram-negative bacteria. Moreover, this analysis demonstrated that Ca(2+)-dependent lectins (C-reactive protein-1 and tachylectin-5A) were required for TtC3b deposition on Gram-positive bacteria, and that a Ca(2+)-independent lectin (Tachypleus plasma lectin-1) was definitely indispensable for TtC3b deposition on fungi. In contrast, a horseshoe crab lipopolysaccharide-sensitive protease factor C was necessary and sufficient to deposit TtC3b on Gram-negative bacteria. We conclude that plasma lectins and factor C play key roles in microbe-specific TtC3b deposition in a C2/factor B-dependent or -independent manner.

  18. Detection of complement activation by counterimmunoelectrophoresis (CIE).

    PubMed

    Arroyave, C M; Tan, E M

    1976-01-01

    Counterimmunoelectrophoresis (CIE) was used as a method of detecting activation of the third component of the complement system (C3). Highly purified C3, normal human serum (NHS), EDTA-treated plasma and serum activated with aggregated human immunoglobulin (agg-IgG) or inulin were used as sources of C3 and/or C3 split products. Activation of the alternative pathway of complement was assayed in the presence of EGTA (10 mM) and MgCl2 (0.3 mM), conditions which block activation of the classical pathway. When purified native C3, fresh NHS and fresh EDTA-plasma were tested in CIE against either antisera to whole C3 or to C3 split products, only one precipitin line was found, which was identified as native C3. However, when serum activated with agg-IgG or inulin were tested against the same reagents, two precipitin lines were seen. The first, with more cathodal mobility was identical to that of native C3. The second line had a more anodal mobility, was distinctly separated from the first and contained C3c and C3d as shown immunochemically with specific antisera. Native C3 and split products of C3 were identified by this CIE method in patients showing evidence of activated complement by having subnormal total complement (CH50) levels. When C3 split products were identified, the C3c-C3d precipitin line could always be distinguished from native C3 by its different electrophoretic mobility, even when C3 concentrations in serum varied from 0.25 mg/ml to 1.5 mg/ml. The sensitivity of CIE was compared to that of CH50 by asssaying at different time intervals after agg-IgG was added to fresh NHS. C3c-C3d split products were detected by CIE before any fall in CH50 and at all times when a significant decrease in CH50 was present. This study shows that the CIE technique is a highly sensitive, specific and rapid method for detecting activation of the complement system via classical or alternative pathways in human disease.

  19. P2X7 Receptor-mediated Scavenger Activity of Mononuclear Phagocytes toward Non-opsonized Particles and Apoptotic Cells Is Inhibited by Serum Glycoproteins but Remains Active in Cerebrospinal Fluid*

    PubMed Central

    Gu, Ben J.; Duce, James A.; Valova, Valentina A.; Wong, Bruce; Bush, Ashley I.; Petrou, Steven; Wiley, James S.

    2012-01-01

    Rapid phagocytosis of non-opsonized particles including apoptotic cells is an important process that involves direct recognition of the target by multiple scavenger receptors including P2X7 on the phagocyte surface. Using a real-time phagocytosis assay, we studied the effect of serum proteins on this phagocytic process. Inclusion of 1–5% serum completely abolished phagocytosis of non-opsonized YG beads by human monocytes. Inhibition was reversed by pretreatment of serum with 1–10 mm tetraethylenepentamine, a copper/zinc chelator. Inhibitory proteins from the serum were determined as negatively charged glycoproteins (pI < 6) with molecular masses between 100 and 300 kDa. A glycoprotein-rich inhibitory fraction of serum not only abolished YG bead uptake but also inhibited phagocytosis of apoptotic lymphocytes or neuronal cells by human monocyte-derived macrophages. Three copper- and/or zinc-containing serum glycoproteins, ceruloplasmin, serum amyloid P-component, and amyloid precursor protein, were identified, and the purified proteins were shown to inhibit the phagocytosis of beads by monocytes as well as phagocytosis of apoptotic neuronal cells by macrophages. Human adult cerebrospinal fluid, which contains very little glycoprotein, had no inhibitory effect on phagocytosis of either beads or apoptotic cells. These data suggest for the first time that metal-interacting glycoproteins present within serum are able to inhibit the scavenger activity of mononuclear phagocytes toward insoluble debris and apoptotic cells. PMID:22461619

  20. The contribution of both oxygen and nitrogen intermediates to the intracellular killing mechanisms of C1q-opsonized Listeria monocytogenes by the macrophage-like IC-21 cell line.

    PubMed

    Alvarez-Domínguez, C; Carrasco-Marín, E; López-Mato, P; Leyva-Cobián, F

    2000-09-01

    Listeria monocytogenes is a facultative intracellular pathogen which is internalized by host mammalian cells upon binding to their surface. Further listerial growth occurs in the cytosol after escape from the phagosomal-endosomal compartment. We have previously reported that C1q is able to potentiate L. monocytogenes phagocytosis upon bacterial opsonization by ingestion through C1q-binding structures. In this report, we analysed the post-phagocytic events upon internalization of C1q-opsonized L. monocytogenes and found an induction of macrophage (Mphi)-like IC-21 cell bactericidal mechanisms displayed by the production of oxygen and nitrogen metabolites. Both types of molecules are effective in L. monocytogenes killing. Further analysis of the cellular responses promoted by interaction of C1q with its surface binding structures, leads us to consider C1q as a collaborative molecule involved in Mphi activation. Upon interaction with surface binding structures, C1q was able to trigger and/or amplify the production of reactive oxygen and nitrogen intermediates induced by stimuli such as interferon-gamma and L. monocytogenes phagocytosis.

  1. Age-related macular degeneration: Complement in action.

    PubMed

    van Lookeren Campagne, Menno; Strauss, Erich C; Yaspan, Brian L

    2016-06-01

    The complement system plays a key role in host-defense against common pathogens but must be tightly controlled to avoid inflammation and tissue damage. Polymorphisms in genes encoding two important negative regulators of the alternative complement pathway, complement factor H (CFH) and complement factor I (CFI), are associated with the risk for Age-Related Macular Degeneration (AMD), a leading cause of vision impairment in the ageing population. In this review, we will discuss the genetic basis of AMD and the potential impact of complement de-regulation on disease pathogenesis. Finally, we will highlight recent therapeutic approaches aimed at controlling complement activation in patients with AMD.

  2. A Gammaherpesvirus Complement Regulatory Protein Promotes Initiation of Infection by Activation of Protein Kinase Akt/PKB

    PubMed Central

    Steer, Beatrix; Adler, Barbara; Jonjic, Stipan; Stewart, James P.; Adler, Heiko

    2010-01-01

    Background Viruses have evolved to evade the host's complement system. The open reading frames 4 (ORF4) of gammaherpesviruses encode homologs of regulators of complement activation (RCA) proteins, which inhibit complement activation at the level of C3 and C4 deposition. Besides complement regulation, these proteins are involved in heparan sulfate and glycosaminoglycan binding, and in case of MHV-68, also in viral DNA synthesis in macrophages. Methodology/Principal Findings Here, we made use of MHV-68 to study the role of ORF4 during infection of fibroblasts. While attachment and penetration of virions lacking the RCA protein were not affected, we observed a delayed delivery of the viral genome to the nucleus of infected cells. Analysis of the phosphorylation status of a variety of kinases revealed a significant reduction in phosphorylation of the protein kinase Akt in cells infected with ORF4 mutant virus, when compared to cells infected with wt virus. Consistent with a role of Akt activation in initial stages of infection, inhibition of Akt signaling in wt virus infected cells resulted in a phenotype resembling the phenotype of the ORF4 mutant virus, and activation of Akt by addition of insulin partially reversed the phenotype of the ORF4 mutant virus. Importantly, the homologous ORF4 of KSHV was able to rescue the phenotype of the MHV-68 ORF4 mutant, indicating that ORF4 is functionally conserved and that ORF4 of KSHV might have a similar function in infection initiation. Conclusions/Significance In summary, our studies demonstrate that ORF4 contributes to efficient infection by activation of the protein kinase Akt and thus reveal a novel function of a gammaherpesvirus RCA protein. PMID:20657771

  3. Complementing asteroseismology with 4MOST spectroscopy

    NASA Astrophysics Data System (ADS)

    de Jong, R. S.; 4MOST Consortium; 4MOST Spectroscopy Consortium

    2016-09-01

    4MOST is a wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of the European Southern Observatory (ESO). Its main science drivers are in the areas of galactic archeology, high-energy physics, galaxy evolution and cosmology. 4MOST will in particular provide the spectroscopic complements to the large area surveys coming from space missions like Gaia, eROSITA, Euclid, and PLATO. 4MOST will have an unique operations concept in which 5-years public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure, resulting in more than 25 million spectra of targets spread over a large fraction of the southern sky. As a dedicated spectroscopic survey facility with a large field-of-view, a high multiplex that can be reconfigured quickly, and with a broad wavelength coverage, 4MOST is particularly well suited to complement the upcoming asteroseismology space missions like TESS and PLATO. Here we show that, by dedicating the observing time during twilight and poor observing conditions to bright stars, 4MOST will obtain resolution {R>18 000} spectra of nearly all stars brighter than ˜ 12th magnitude at Dec < 30o every ˜ 2 years. 4MOST is also expected to spectroscopically complement any fainter asteroseismology target to be observed with PLATO. These observations will provide a chemical characterization of nearly all stars to be observed with the TESS and PLATO missions and place any planets found in a full chemo-dynamical context of the star formation history of the Galaxy, yield very accurate ages and masses for all stars that can be characterized with asteroseismology, and allow removal of contaminants from target samples (e.g., spectroscopic binaries).

  4. VISUALIZATION OF MOLECULAR INTERACTIONS BY FLUORESCENCE COMPLEMENTATION

    PubMed Central

    Kerppola, Tom K.

    2008-01-01

    The visualization of protein complexes in living cells enables validation of protein interactions in their normal environment and determination of their subcellular localization. The bimolecular fluorescence complementation (BiFC) assay has been used to visualize interactions among multiple proteins in many cell types and organisms. This assay is based on the association between two fluorescent-protein fragments when they are brought together by an interaction between proteins fused to the fragments. Modified forms of this assay have been used to visualize the competition between alternative interaction partners and the covalent modification of proteins by ubiquitin family peptides. PMID:16625152

  5. Versatile microfluidic complement fixation test for disease biomarker detection.

    PubMed

    Li, Man; Shi, ZhuanZhuan; Fang, Can; Gao, AnXiu; Li, Chang Ming; Yu, Ling

    2016-04-15

    The complement fixation test (CFT) is a serological test that can be used to detect the presence of specific antibodies or antigens to diagnose infections, particularly diseases caused by microbes that are not easily detected by standard culture methods. We report here, for the first time, a poly(dimethylsiloxane) (PDMS)/glass slide hybrid microfluidic device that was used to manipulate the solution compartment and communication within the microchannel to establish sampler and indicator systems of CFT. Two types of on-chip CFT, solution-based and solid phase agar-based assays, were successfully demonstrated for biomarker carcinoembryonic antigen (CEA) and recombinant avian influenza A (rH7N9) virus protein detection. In addition, the feasibility of the on-chip CFT in assaying real biopsy was successfully demonstrated by specifically detecting rH7N9 and CEA in human serum. The results demonstrated that the miniaturized assay format significantly reduced the assay time and sample consumption. Exemption from protein immobilization, blocking, complicated washing steps and expensive enzyme/fluorescein conjugates highlights the merits of on-chip CFT over ELISA. Most attractively, the on-chip agar-based CFT results can be imaged and analysed by smartphone, strengthening its point-of-care application potential. We anticipate that the on-chip CFT reported herein will be a useful supplemental or back-up tool for on-chip immunoassays such as ELISA for disease diagnosis and food inspection.

  6. Soluble complement receptor 1 inhibits both complement and granulocyte activation during ex vivo hemodialysis.

    PubMed

    Himmelfarb, J; McMonagle, E; Holbrook, D; Toth, C

    1995-10-01

    Hemodialysis with cellulosic membranes results in both complement and granulocyte activation. We investigated the effects of soluble complement receptor 1 (sCR1), a potent complement inhibitor, on both complement and granulocyte activation in an ex vivo model of dialysis. Measurements were made of complement activation (radioimmunoassay for C3a desArg) as well as granulocyte activation (flow cytometric measurements of reactive oxygen species production, granulocyte CD11b/CD18 (MAC-1) expression and CD62L (L-selectin) expression). sCR1 completely abolished the generation of plasma C3a desArg during ex vivo hemodialysis. Without sCR1, C3a desArg levels rose from 968 +/- 373 ng/ml to 4961 +/- 40 ng/ml by the end of the ex vivo procedure (p < 0.001). sCR1 also completely inhibited MAC-1 upregulation and L-selectin shedding from granulocytes during ex vivo hemodialysis. With sCR1 there was still a statistically significant increase in granulocyte reactive oxygen species production (from 2.42 +/- 0.1 fluorescence channels to 6.47 +/- 0.7 fluorescence channels, p < 0.01) but a 50% inhibition when compared with experiments without sCR1 (3.15 +/- 0.5 to 11.2 +/- 1.9, p < 0.01). We conclude that sCR1 completely abolishes complement activation and changes in granulocyte cell adhesion molecules during ex vivo hemodialysis with cellulosic membranes. sCR1 partially inhibits granulocyte reactive oxygen species formation.

  7. The Production of Complement Clauses in Children with Language Impairment

    ERIC Educational Resources Information Center

    Steel, Gillian; Rose, Miranda; Eadie, Patricia

    2016-01-01

    Purpose: The purpose of this research was to provide a comprehensive description of complement-clause production in children with language impairment. Complement clauses were examined with respect to types of complement structure produced, verb use, and both semantic and syntactic accuracy. Method: A group of 17 children with language impairment…

  8. Antibodies against the Envelope Glycoprotein Promote Infectivity of Immature Dengue Virus Serotype 2

    PubMed Central

    da Silva Voorham, Júlia M.; Rodenhuis-Zybert, Izabela A.; Ayala Nuñez, Nilda Vanesa; Colpitts, Tonya M.; van der Ende-Metselaar, Heidi; Fikrig, Erol; Diamond, Michael S.; Wilschut, Jan; Smit, Jolanda M.

    2012-01-01

    Cross-reactive dengue virus (DENV) antibodies directed against the envelope (E) and precursor membrane (prM) proteins are believed to contribute to the development of severe dengue disease by facilitating antibody-dependent enhancement of infection. We and others recently demonstrated that anti-prM antibodies render essentially non-infectious immature DENV infectious in Fcγ-receptor-expressing cells. Immature DENV particles are abundantly present in standard (st) virus preparations due to inefficient processing of prM to M during virus maturation. Structural analysis has revealed that the E protein is exposed in immature particles and this prompted us to investigate whether antibodies to E render immature particles infectious. To this end, we analyzed the enhancing properties of 27 anti-E antibodies directed against distinct structural domains. Of these, 23 bound to immature particles, and 15 enhanced infectivity of immature DENV in a furin-dependent manner. The significance of these findings was subsequently tested in vivo using the well-established West Nile virus (WNV) mouse model. Remarkably, mice injected with immature WNV opsonized with anti-E mAbs or immune serum produced a lethal infection in a dose-dependent manner, whereas in the absence of antibody immature WNV virions caused no morbidity or mortality. Furthermore, enhancement infection studies with standard (st) DENV preparations opsonized with anti-E mAbs in the presence or absence of furin inhibitor revealed that prM-containing particles present within st virus preparations contribute to antibody-dependent enhancement of infection. Taken together, our results support the notion that antibodies against the structural proteins prM and E both can promote pathogenesis by enhancing infectivity of prM-containing immature and partially mature flavivirus particles. PMID:22431958

  9. Virus - tumor cell relationships. In vivo cocultivation of para-influenza type 1 (Sendai) virus and of Rous sarcoma virus (Schmidt-Ruppin strain) in mouse Ehrlich ascites carcinoma.

    PubMed

    Nastac, E; Chira, M; Suru, M; Repanovici, R; Anghelescu, S

    1985-01-01

    Co-infection of Ehrlich ascites carcinoma (EAC)-bearing mice with Sendai virus and Rous sarcoma virus (RSV) did not result in the formation of complete RSV. Sendai virus could be, however, propagated in this system over 8 serial passages. As demonstrated by immunofluorescence and complement fixation reactions, antigens specific to each virus were synthesized in EAC cells following either single or mixed virus infection. The virus progens also contained antigenic fractions incorporated from the host cell. The incomplete progens synthesized when RSV inoculation preceded that of Sendai virus possessed three polypeptide fractions characteristic of Sendai virus and one RSV-specific fraction.

  10. Complement related kidney diseases: Recurrence after transplantation.

    PubMed

    Salvadori, Maurizio; Bertoni, Elisabetta

    2016-12-24

    The recurrence of renal disease after renal transplantation is becoming one of the main causes of graft loss after kidney transplantation. This principally concerns some of the original diseases as the atypical hemolytic uremic syndrome (HUS), the membranoproliferative glomerulonephritis (MPGN), in particular the MPGN now called C3 glomerulopathy. Both this groups of renal diseases are characterized by congenital (genetic) or acquired (auto-antibodies) modifications of the alternative pathway of complement. These abnormalities often remain after transplantation because they are constitutional and poorly influenced by the immunosuppression. This fact justifies the high recurrence rate of these diseases. Early diagnosis of recurrence is essential for an optimal therapeutically approach, whenever possible. Patients affected by end stage renal disease due to C3 glomerulopathies or to atypical HUS, may be transplanted with extreme caution. Living donor donation from relatives is not recommended because members of the same family may be affected by the same gene mutation. Different therapeutically approaches have been attempted either for recurrence prevention and treatment. The most promising approach is represented by complement inhibitors. Eculizumab, a monoclonal antibody against C5 convertase is the most promising drug, even if to date is not known how long the therapy should be continued and which are the best dosing. These facts face the high costs of the treatment. Eculizumab resistant patients have been described. They could benefit by a C3 convertase inhibitor, but this class of drugs is by now the object of randomized controlled trials.

  11. Complement related kidney diseases: Recurrence after transplantation

    PubMed Central

    Salvadori, Maurizio; Bertoni, Elisabetta

    2016-01-01

    The recurrence of renal disease after renal transplantation is becoming one of the main causes of graft loss after kidney transplantation. This principally concerns some of the original diseases as the atypical hemolytic uremic syndrome (HUS), the membranoproliferative glomerulonephritis (MPGN), in particular the MPGN now called C3 glomerulopathy. Both this groups of renal diseases are characterized by congenital (genetic) or acquired (auto-antibodies) modifications of the alternative pathway of complement. These abnormalities often remain after transplantation because they are constitutional and poorly influenced by the immunosuppression. This fact justifies the high recurrence rate of these diseases. Early diagnosis of recurrence is essential for an optimal therapeutically approach, whenever possible. Patients affected by end stage renal disease due to C3 glomerulopathies or to atypical HUS, may be transplanted with extreme caution. Living donor donation from relatives is not recommended because members of the same family may be affected by the same gene mutation. Different therapeutically approaches have been attempted either for recurrence prevention and treatment. The most promising approach is represented by complement inhibitors. Eculizumab, a monoclonal antibody against C5 convertase is the most promising drug, even if to date is not known how long the therapy should be continued and which are the best dosing. These facts face the high costs of the treatment. Eculizumab resistant patients have been described. They could benefit by a C3 convertase inhibitor, but this class of drugs is by now the object of randomized controlled trials. PMID:28058212

  12. Immune inhibition of virus release from herpes simplex virus-infected cells.

    PubMed

    Skinner, G R; Mushi, E Z; Whitney, J E

    By treatment of herpes simplex virus-infected cells with virus antiserum with or without complement, the yield of infectious extracellular virus was significantly reduced. This was shown to be due to an immune alteration of the cell membrane which inhibited release of virus particles from the infected cells and not due to neutralization; both type-common and type-specific antigens of herpes simplex virus were involved. The phenomenon was also evident with antisera directed against cell determinants. The experimental findings are presented and their significance in the immunological defense mechanisms of the body and in viral immunotherapy is discussed.

  13. A versatile assay for the identification of RNA silencing suppressors based on complementation of viral movement.

    PubMed

    Powers, Jason G; Sit, Tim L; Qu, Feng; Morris, T Jack; Kim, Kook-Hyung; Lommel, Steven A

    2008-07-01

    The cell-to-cell movement of Turnip crinkle virus (TCV) in Nicotiana benthamiana requires the presence of its coat protein (CP), a known suppressor of RNA silencing. RNA transcripts of a TCV construct containing a reporter gene (green fluorescent protein) (TCV-sGFP) in place of the CP open reading frame generated foci of three to five cells. TCV CP delivered in trans by Agrobacterium tumefaciens infiltration potentiated movement of TCV-sGFP and increased foci diameter, on average, by a factor of four. Deletion of the TCV movement proteins in TCV-sGFP (construct TCVDelta92-sGFP) abolished the movement complementation ability of TCV CP. Other known suppressors of RNA silencing from a wide spectrum of viruses also complemented the movement of TCV-sGFP when delivered in trans by Agrobacterium tumefaciens. These include suppressors from nonplant viruses with no known plant movement function, demonstrating that this assay is based solely on RNA silencing suppression. While the TCV-sGFP construct is primarily used as an infectious RNA transcript, it was also subcloned for direct expression from Agrobacterium tumefaciens for simple quantification of suppressor activity based on fluorescence levels in whole leaves. Thus, this system provides the flexibility to assay for suppressor activity in either the cytoplasm or nucleus, depending on the construct employed.

  14. Hijacking Complement Regulatory Proteins for Bacterial Immune Evasion

    PubMed Central

    Hovingh, Elise S.; van den Broek, Bryan; Jongerius, Ilse

    2016-01-01

    The human complement system plays an important role in the defense against invading pathogens, inflammation and homeostasis. Invading microbes, such as bacteria, directly activate the complement system resulting in the formation of chemoattractants and in effective labeling of the bacteria for phagocytosis. In addition, formation of the membrane attack complex is responsible for direct killing of Gram-negative bacteria. In turn, bacteria have evolved several ways to evade complement activation on their surface in order to be able to colonize and invade the human host. One important mechanism of bacterial escape is attraction of complement regulatory proteins to the microbial surface. These molecules are present in the human body for tight regulation of the complement system to prevent damage to host self-surfaces. Therefore, recruitment of complement regulatory proteins to the bacterial surface results in decreased complement activation on the microbial surface which favors bacterial survival. This review will discuss recent advances in understanding the binding of complement regulatory proteins to the bacterial surface at the molecular level. This includes, new insights that have become available concerning specific conserved motives on complement regulatory proteins that are favorable for microbial binding. Finally, complement evasion molecules are of high importance for vaccine development due to their dominant role in bacterial survival, high immunogenicity and homology as well as their presence on the bacterial surface. Here, the use of complement evasion molecules for vaccine development will be discussed. PMID:28066340

  15. Targeted complement inhibition and microvasculature in transplants: a therapeutic perspective.

    PubMed

    Khan, M A; Hsu, J L; Assiri, A M; Broering, D C

    2016-02-01

    Active complement mediators play a key role in graft-versus-host diseases, but little attention has been given to the angiogenic balance and complement modulation during allograft acceptance. The complement cascade releases the powerful proinflammatory mediators C3a and C5a anaphylatoxins, C3b, C5b opsonins and terminal membrane attack complex into tissues, which are deleterious if unchecked. Blocking complement mediators has been considered to be a promising approach in the modern drug discovery plan, and a significant number of therapeutic alternatives have been developed to dampen complement activation and protect host cells. Numerous immune cells, especially macrophages, develop both anaphylatoxin and opsonin receptors on their cell surface and their binding affects the macrophage phenotype and their angiogenic properties. This review discusses the mechanism that complement contributes to angiogenic injury, and the development of future therapeutic targets by antagonizing activated complement mediators to preserve microvasculature in rejecting the transplanted organ.

  16. Interpain A, a cysteine proteinase from Prevotella intermedia, inhibits complement by degrading complement factor C3.

    PubMed

    Potempa, Michal; Potempa, Jan; Kantyka, Tomasz; Nguyen, Ky-Anh; Wawrzonek, Katarzyna; Manandhar, Surya P; Popadiak, Katarzyna; Riesbeck, Kristian; Eick, Sigrun; Blom, Anna M

    2009-02-01

    Periodontitis is an inflammatory disease of the supporting structures of the teeth caused by, among other pathogens, Prevotella intermedia. Many strains of P. intermedia are resistant to killing by the human complement system, which is present at up to 70% of serum concentration in gingival crevicular fluid. Incubation of human serum with recombinant cysteine protease of P. intermedia (interpain A) resulted in a drastic decrease in bactericidal activity of the serum. Furthermore, a clinical strain 59 expressing interpain A was more serum-resistant than another clinical strain 57, which did not express interpain A, as determined by Western blotting. Moreover, in the presence of the cysteine protease inhibitor E64, the killing of strain 59 by human serum was enhanced. Importantly, we found that the majority of P. intermedia strains isolated from chronic and aggressive periodontitis carry and express the interpain A gene. The protective effect of interpain A against serum bactericidal activity was found to be attributable to its ability to inhibit all three complement pathways through the efficient degradation of the alpha-chain of C3 -- the major complement factor common to all three pathways. P. intermedia has been known to co-aggregate with P. gingivalis, which produce gingipains to efficiently degrade complement factors. Here, interpain A was found to have a synergistic effect with gingipains on complement degradation. In addition, interpain A was able to activate the C1 complex in serum, causing deposition of C1q on inert and bacterial surfaces, which may be important at initial stages of infection when local inflammatory reaction may be beneficial for a pathogen. Taken together, the newly characterized interpain A proteinase appears to be an important virulence factor of P. intermedia.

  17. Complement components in Nigerians with bronchial asthma.

    PubMed

    Onyemelukwe, G C

    1989-10-01

    Serum complement components C1q, C3, C4, factor B, and C3d breakdown products were measured in asthmatic Nigerians and in age-matched and sex-matched controls. C3 mean level was higher than in controls while C1q and C4 mean levels were lower than in controls. High levels of C3d in asthmatic patients suggest the possible role of C3a and C5a anaphylatoxins in the etiopathogenesis of perennial asthma in Nigerian patients in a tropical environment with ubiquitous airborne allergens and infective agents. The significantly elevated levels of IgM and IgG may suggest recurrent respiratory challenge of perennial antigens in our environment.

  18. Virus meningo-encephalitis in Slovenia

    PubMed Central

    Vesenjak-Zmijanac, J.; Bedjanič, M.; Rus, S.; Kmet, J.

    1955-01-01

    An organism was isolated from the blood of a patient clinically diagnosed as suffering from virus meningo-encephalitis; the organism causes illness and death in white mice. The antigen prepared from the brains of mice infected with this organism fixes complement with sera from typical cases of virus meningo-encephalitis. From its biological and serological characteristics, the isolated organism appears to belong to the group of neurotropic viruses and to be the causative agent of virus meningo-encephalitis in Slovenia. PMID:14378996

  19. Another Really, Really Big Virus

    PubMed Central

    Van Etten, James L.

    2011-01-01

    Viruses with genomes larger than 300 kb and up to 1.2 Mb, which encode hundreds of proteins, are being discovered and characterized with increasing frequency. Most, but not all, of these large viruses (often referred to as giruses) infect protists that live in aqueous environments. Bioinformatic analyses of metagenomes of aqueous samples indicate that large DNA viruses are quite common in nature and await discovery. One issue that is perhaps not appreciated by the virology community is that large viruses, even those classified in the same family, can differ significantly in morphology, lifestyle, and gene complement. This brief commentary, which will mention some of these unique properties, was stimulated by the characterization of the newest member of this club, virus CroV (Fischer, M.G.; Allen, M.J.; Wilson, W.H.; Suttle, C.A. Giant virus with a remarkable complement of genes infects marine zooplankton. Proc. Natl. Acad. Sci. USA 2010, 107, 19508–19513 [1]). CroV has a 730 kb genome (with ∼544 protein-encoding genes) and infects the marine microzooplankton Cafeteria roenbergensis producing a lytic infection. PMID:21994725

  20. Replication-defective viruses as vaccines and vaccine vectors.

    PubMed

    Dudek, Tim; Knipe, David M

    2006-01-05

    The classical viral vaccine approaches using inactivated virus or live-attenuated virus have not been successful for some viruses, such as human immunodeficiency virus or herpes simplex virus. Therefore, new types of vaccines are needed to combat these infections. Replication-defective mutant viruses are defective for one or more functions that are essential for viral genome replication or synthesis and assembly of viral particles. These viruses are propagated in complementing cell lines expressing the missing gene product; however, in normal cells, they express viral gene products but do not replicate to form progeny virions. As vaccines, these mutant viruses have advantages of both classical types of viral vaccines in being as safe as inactivated virus but expressing viral antigens inside infected cells so that MHC class I and class II presentation can occur efficiently. Replication-defective viruses have served both as vaccines for the virus itself and as a vector for the expression of heterologous antigens. The potential advantages and disadvantages of these vaccines are discussed as well as contrasting them with single-cycle mutant virus vaccines and replicon/amplicon versions of vaccines. Replication-defective viruses have also served as important probes of the host immune response in helping to define the importance of the first round of infected cells in the host immune response, the mechanisms of activation of innate immune response, and the role of the complement pathway in humoral immune responses to viruses.

  1. Complement inhibition: a promising concept for cancer treatment

    PubMed Central

    Pio, Ruben; Ajona, Daniel; Lambris, John D.

    2013-01-01

    For decades, complement has been recognized as an effector arm of the immune system that contributes to the destruction of tumor cells. In fact, many therapeutic strategies have been proposed that are based on the intensification of complement-mediated responses against tumors. However, recent studies have challenged this paradigm by demonstrating a tumor-promoting role for complement. Cancer cells seem to be able to establish a convenient balance between complement activation and inhibition, taking advantage of complement initiation without suffering its deleterious effects. Complement activation may support chronic inflammation, promote an immunosuppressive microenvironment, induce angiogenesis, and activate cancer-related signaling pathways. In this context, inhibition of complement activation would be a therapeutic option for treating cancer. This concept is relatively novel and deserves closer attention. In this paper, we will summarize the mechanisms of complement activation on cancer cells, the cancer-promoting effect of complement initiation, and the rationale behind the use of complement inhibition as a therapeutic strategy against cancer. PMID:23706991

  2. Complement-mediated regulation of metabolism and basic cellular processes

    PubMed Central

    Hess, Christoph; Kemper, Claudia

    2016-01-01

    Complement is well appreciated as critical arm of innate immunity. It is required for the removal of invading pathogens and functions by direct pathogen destruction and through the activation of innate and adaptive immune cells. However, complement activation and function is not confined to the extracellular space but also occurs within cells. Recent work indicates that complement activation regulates key metabolic pathways and thus can impact fundamental processes of the cell, such as survival, proliferation, and autophagy. Novel identified functions of complement include a key role in shaping metabolic reprogramming, which underlies T cell effector differentiation, and a role as a nexus for interactions with other effector systems, in particular the inflammasome and Notch transcription factor networks. This review focuses on the contributions of complement to basic processes of the cell, in particular the integration of complement with cellular metabolism, and the potential implications in infection and other disease settings. PMID:27533012

  3. Protein ultrastructure and the nanoscience of complement activation.

    PubMed

    Vorup-Jensen, Thomas; Boesen, Thomas

    2011-09-16

    The complement system constitutes an important barrier to infection of the human body. Over more than four decades structural properties of the proteins of the complement system have been investigated with X-ray crystallography, electron microscopy, small-angle scattering, and atomic force microscopy. Here, we review the accumulated evidence that the nm-scaled dimensions and conformational changes of these proteins support functions of the complement system with regard to tissue distribution, molecular crowding effects, avidity binding, and conformational regulation of complement activation. In the targeting of complement activation to the surfaces of nanoparticulate material, such as engineered nanoparticles or fragments of the microbial cell wall, these processes play intimately together. This way the complement system is an excellent example where nanoscience may serve to unravel the molecular biology of the immune response.

  4. Complement-Mediated Regulation of Metabolism and Basic Cellular Processes.

    PubMed

    Hess, Christoph; Kemper, Claudia

    2016-08-16

    Complement is well appreciated as a critical arm of innate immunity. It is required for the removal of invading pathogens and works by directly destroying them through the activation of innate and adaptive immune cells. However, complement activation and function is not confined to the extracellular space but also occurs within cells. Recent work indicates that complement activation regulates key metabolic pathways and thus can impact fundamental cellular processes, such as survival, proliferation, and autophagy. Newly identified functions of complement include a key role in shaping metabolic reprogramming, which underlies T cell effector differentiation, and a role as a nexus for interactions with other effector systems, in particular the inflammasome and Notch transcription-factor networks. This review focuses on the contributions of complement to basic processes of the cell, in particular the integration of complement with cellular metabolism and the potential implications in infection and other disease settings.

  5. C1q binding to Dengue Virus inhibits infection of THP-1 and cellular inflammatory responses

    PubMed Central

    Douradinha, Bruno; McBurney, Sean P.; de Melo, Klecia M. Soares; Smith, Amanda P.; Krishna, Neel K.; Barratt-Boyes, Simon M.; Evans, Jared D.; Nascimento, Eduardo J. M.; Marques, Ernesto T. A

    2014-01-01

    Summary Dengue virus infection elicits a spectrum of clinical presentations ranging from asymptomatic to severe disease. The mechanisms leading to severe dengue are not known, however it has been reported that the complement system is hyper-activated in severe dengue. Screening of complement proteins demonstrated that C1q, a pattern recognition molecule, can bind directly to Dengue Virus Envelope protein and to whole Dengue Virus serotype 2. Incubation of Dengue Virus serotype 2 with C1q prior to infection of THP-1 cells led to decreased virus infectivity and modulation of mRNA expression of immunoregulatory molecules suggesting reduced inflammatory responses. PMID:24246304

  6. Altmetrics - a complement to conventional metrics.

    PubMed

    Melero, Remedios

    2015-01-01

    Emerging metrics based on article-level does not exclude traditional metrics based on citations to the journal, but complements them. Both can be employed in conjunction to offer a richer picture of an article use from immediate to long terms. Article-level metrics (ALM) is the result of the aggregation of different data sources and the collection of content from multiple social network services. Sources used for the aggregation can be broken down into five categories: usage, captures, mentions, social media and citations. Data sources depend on the tool, but they include classic metrics indicators based on citations, academic social networks (Mendeley, CiteULike, Delicious) and social media (Facebook, Twitter, blogs, or Youtube, among others). Altmetrics is not synonymous with alternative metrics. Altmetrics are normally early available and allow to assess the social impact of scholarly outputs, almost at the real time. This paper overviews briefly the meaning of altmetrics and describes some of the existing tools used to apply this new metrics: Public Library of Science--Article-Level Metrics, Altmetric, Impactstory and Plum.

  7. Complement activation in very early Alzheimer disease.

    PubMed

    Zanjani, H; Finch, C E; Kemper, C; Atkinson, J; McKeel, D; Morris, J C; Price, J L

    2005-01-01

    The activation of the classical complement (C)-system in early-stage Alzheimer disease (AD) and nondemented aging was examined with immunohistochemistry in subjects assessed by the Clinical Dementia Rating (CDR). Activation (staining for C3 and C4 fragments) was found in all brains with amyloid deposits, including all nondemented (CDR 0) cases, with either small numbers of diffuse plaques or with sufficient plaques and tangles to indicate preclinical AD. Staining for C3 and C4 increased in parallel with plaque density in very mild to severe clinical AD. A subset of very mild AD (CDR 0.5) cases also showed C1q (on plaques) and C5b-9 (on neuritic plaques and tangles), whereas these C-fragments were consistently found in severe AD (CDR 3). Mirror section (split-face) analysis showed that C1q, C3, and apoJ (clusterin) occurred on the same plaques. However, C-system regulators CD59, CR1, DAF, and MCP were not detected on plaques or tangles at any stage, indicating that C-activation related to AD is incompletely controlled.

  8. Altmetrics – a complement to conventional metrics

    PubMed Central

    Melero, Remedios

    2015-01-01

    Emerging metrics based on article-level does not exclude traditional metrics based on citations to the journal, but complements them. Both can be employed in conjunction to offer a richer picture of an article use from immediate to long terms. Article-level metrics (ALM) is the result of the aggregation of different data sources and the collection of content from multiple social network services. Sources used for the aggregation can be broken down into five categories: usage, captures, mentions, social media and citations. Data sources depend on the tool, but they include classic metrics indicators based on citations, academic social networks (Mendeley, CiteULike, Delicious) and social media (Facebook, Twitter, blogs, or Youtube, among others). Altmetrics is not synonymous with alternative metrics. Altmetrics are normally early available and allow to assess the social impact of scholarly outputs, almost at the real time. This paper overviews briefly the meaning of altmetrics and describes some of the existing tools used to apply this new metrics: Public Library of Science - Article-Level Metrics, Altmetric, Impactstory and Plum. PMID:26110028

  9. Complement component 5 promotes lethal thrombosis

    PubMed Central

    Mizuno, Tomohiro; Yoshioka, Kengo; Mizuno, Masashi; Shimizu, Mie; Nagano, Fumihiko; Okuda, Tomoyuki; Tsuboi, Naotake; Maruyama, Shoichi; Nagamatsu, Tadashi; Imai, Masaki

    2017-01-01

    Extracellular histones promote platelet aggregation and thrombosis; this is followed by induction of coagulation disorder, which results in exhaustion of coagulation factors. Complement component 5 (C5) is known to be associated with platelet aggregation and coagulation system activation. To date, the pathological mechanism underlying liver injury has remained unclear. Here, we investigated whether C5 promotes liver injury associated with histone-induced lethal thrombosis. C5-sufficient and C5-deficient mice received single tail vein injections of purified, unfractionated histones obtained from calf thymus (45–75 μg/g). Subsequently, the mice were monitored for survival for up to 72 h. Based on the survival data, the 45 μg/g dose was used for analysis of blood cell count, liver function, blood coagulation ability, and promotion of platelet aggregation and platelet/leukocyte aggregate (PLA) production by extracellular histones. C5-deficient mice were protected from lethal thrombosis and had milder thrombocytopenia, consumptive coagulopathy, and liver injury with embolism and lower PLA production than C5-sufficient mice. These results indicate that C5 is associated with coagulation disorders, PLA production, and embolism-induced liver injury. In conclusion, C5 promotes liver injury associated with histone-induced lethal thrombosis. PMID:28205538

  10. Genetic complementation studies of multiple sulfatase deficiency.

    PubMed

    Horwitz, A L

    1979-12-01

    Cultured fibroblasts from two individuals with multiple sulfatase deficiency (MSD) were found to have decreased activities of arylsulfatases (aryl-sulfate sulfohydrolase, EC 3.1.6.1) A, B, and C as well as iduronate-sulfate sulfatase, sulfamidase, and N-acetylglucosamine-6-sulfate sulfatase. The activity of N-acetylgalactosamine-6-sulfate sulfatase was decreased in one line but not in the other. Mixtures of MSD cell extracts with extracts from normal cells did not result in inhibition of normal sulfatase activities. Mixtures of MSD cell extracts with extracts of fibroblasts from patients with Hunter or Sanfilippo A syndrome did not activate iduronate-sulfate sulfatase or sulfamidase activity. Heterokaryons formed by fusion of MSD cells with Sanfilippo A fibroblasts demonstrated a partial correction of the enzyme deficiency. In similar manner, MSD-Hunter heterokaryons showed a significant increase in iduronate-sulfate-sulfatase activity. Genetic complementation in heterokaryons of MSD fibroblasts and cells of either Sanfilippo A or Hunter syndrome implies a genetic defect in MSD different from that causing specific sulfatase deficiencies.

  11. 21 CFR 866.5240 - Complement components immunological test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... tissues. Complement is a group of serum proteins which destroy infectious agents. Measurements of these proteins aids in the diagnosis of immunologic disorders, especially those associated with deficiencies...

  12. 21 CFR 866.5240 - Complement components immunological test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... tissues. Complement is a group of serum proteins which destroy infectious agents. Measurements of these proteins aids in the diagnosis of immunologic disorders, especially those associated with deficiencies...

  13. 21 CFR 866.5240 - Complement components immunological test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... tissues. Complement is a group of serum proteins which destroy infectious agents. Measurements of these proteins aids in the diagnosis of immunologic disorders, especially those associated with deficiencies...

  14. Complement response after experimental bacterial infection in various nutritional states.

    PubMed Central

    Sakamoto, M; Ishii, S; Nishioka, K; Shimada, K

    1979-01-01

    In malnourished rats, nutritionally rehabilitated rats at various stages, and in well nourished rats, levels of serum complement after bacterial infection caused by Staphylococcus aureus, as well as tuberculin reactivity, were examined. The elevation of complement showed a peak 2--3 days after infection, herein called the first complement response. A reelevation occurred at a later stage, 7--14 days after infection, and is referred to as the second complement response. The first complement response was observed in all the rats after Staphylococcus aureus infection but it was greater in well nourished rats. In malnourished rats, only the first complement response was observed and the tuberculin reaction and second complement response were lacking. After 1 week of nutritional rehabilitation, 40% of the rats showed recovery of tuberculin responses and both the first and second complement responses were observed. Nutritionally rehabilitated rats treated longer than 2 weeks, together with the well nourished control rats, showed positive tuberculin reactivity. The second complement response was also observed in such rats when bacterial infection was severe but not with mild infection. PMID:511223

  15. Complement--tapping into new sites and effector systems.

    PubMed

    Kolev, Martin; Le Friec, Gaelle; Kemper, Claudia

    2014-12-01

    Complement is traditionally known to be a system of serum proteins that provide protection against pathogens through direct cell lysis and the mobilization of innate and adaptive immunity. However, recent work indicates that the complement system has additional physiological roles beyond those in host defence. In this Opinion article, we describe the new modes and locations of complement activation that enable it to interact with other cell effector systems, such as growth factor receptors, inflammasomes and metabolic pathways. We propose that the location of complement activation dictates its function.

  16. Collective Infectious Units in Viruses.

    PubMed

    Sanjuán, Rafael

    2017-03-03

    Increasing evidence indicates that viruses do not simply propagate as independent virions among cells, organs, and hosts. Instead, viral spread is often mediated by structures that simultaneously transport groups of viral genomes, such as polyploid virions, aggregates of virions, virion-containing proteinaceous structures, secreted lipid vesicles, and virus-induced cell-cell contacts. These structures increase the multiplicity of infection, independently of viral population density and transmission bottlenecks. Collective infectious units may contribute to the maintenance of viral genetic diversity, and could have implications for the evolution of social-like virus-virus interactions. These may include various forms of cooperation such as immunity evasion, genetic complementation, division of labor, and relaxation of fitness trade-offs, but also noncooperative interactions such as negative dominance and interference, potentially leading to conflict.

  17. The role of complement inhibitors beyond controlling inflammation.

    PubMed

    Blom, A M

    2017-03-26

    The complement system is an arm of innate immunity that aids in the removal of pathogens and dying cells. Due to its harmful, pro-inflammatory potential, complement is controlled by several soluble and membrane-bound inhibitors. This family of complement regulators has been recently extended by the discovery of several new members, and it is becoming apparent that these proteins harbour additional functions. In this review, the current state of knowledge of the physiological functions of four complement regulators will be described: cartilage oligomeric matrix protein (COMP), CUB and sushi multiple domains 1 (CSMD1), sushi domain-containing protein 4 (SUSD4) and CD59. Complement activation is involved in both the development of and defence against cancer. COMP expression is pro-oncogenic, whereas CSMD1 and SUSD4 act as tumour suppressors. These effects may be related in part to the complex influence of complement on cancer but also depend on unrelated functions such as the protection of cells from endoplasmic reticulum stress conveyed by intracellular COMP. CD59 is the main inhibitor of the membrane attack complex, and its deficiency leads to complement attack on erythrocytes and severe haemolytic anaemia, which is now amenable to treatment with an inhibitor of C5 cleavage. Unexpectedly, the intracellular pool of CD59 is crucial for insulin secretion from pancreatic β-cells. This finding is one of several relating to the intracellular functions of complement proteins, which until recently were only considered to be present in the extracellular space. Understanding the alternative functions of complement inhibitors may unravel unexpected links between complement and other physiological systems, but is also important for better design of therapeutic complement inhibition.

  18. Minor Role of Plasminogen in Complement Activation on Cell Surfaces

    PubMed Central

    Hyvärinen, Satu; Jokiranta, T. Sakari

    2015-01-01

    Atypical hemolytic uremic syndrome (aHUS) is a rare, but severe thrombotic microangiopathy. In roughly two thirds of the patients, mutations in complement genes lead to uncontrolled activation of the complement system against self cells. Recently, aHUS patients were described with deficiency of the fibrinolytic protein plasminogen. This zymogen and its protease form plasmin have both been shown to interact with complement proteins in the fluid phase. In this work we studied the potential of plasminogen to restrict complement propagation. In hemolytic assays, plasminogen inhibited complement activation, but only when it had been exogenously activated to plasmin and when it was used at disproportionately high concentrations compared to serum. Addition of only the zymogen plasminogen into serum did not hinder complement-mediated lysis of erythrocytes. Plasminogen could not restrict deposition of complement activation products on endothelial cells either, as was shown with flow cytometry. With platelets, a very weak inhibitory effect on deposition of C3 fragments was observed, but it was considered too weak to be significant for disease pathogenesis. Thus it was concluded that plasminogen is not an important regulator of complement on self cells. Instead, addition of plasminogen was shown to clearly hinder platelet aggregation in serum. This was attributed to plasmin causing disintegration of formed platelet aggregates. We propose that reduced proteolytic activity of plasmin on structures of growing thrombi, rather than on complement activation fragments, explains the association of plasminogen deficiency with aHUS. This adds to the emerging view that factors unrelated to the complement system can also be central to aHUS pathogenesis and suggests that future research on the mechanism of the disease should expand beyond complement dysregulation. PMID:26637181

  19. ECHO virus

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/001340.htm ECHO virus To use the sharing features on this page, please enable JavaScript. Enteric cytopathic human orphan (ECHO) viruses are a group of viruses that lead to ...

  20. Variola virus immune evasion proteins.

    PubMed

    Dunlop, Lance R; Oehlberg, Katherine A; Reid, Jeremy J; Avci, Dilek; Rosengard, Ariella M

    2003-09-01

    Variola virus, the causative agent of smallpox, encodes approximately 200 proteins. Over 80 of these proteins are located in the terminal regions of the genome, where proteins associated with host immune evasion are encoded. To date, only two variola proteins have been characterized. Both are located in the terminal regions and demonstrate immunoregulatory functions. One protein, the smallpox inhibitor of complement enzymes (SPICE), is homologous to a vaccinia virus virulence factor, the vaccinia virus complement-control protein (VCP), which has been found experimentally to be expressed early in the course of vaccinia infection. Both SPICE and VCP are similar in structure and function to the family of mammalian complement regulatory proteins, which function to prevent inadvertent injury to adjacent cells and tissues during complement activation. The second variola protein is the variola virus high-affinity secreted chemokine-binding protein type II (CKBP-II, CBP-II, vCCI), which binds CC-chemokine receptors. The vaccinia homologue of CKBP-II is secreted both early and late in infection. CKBP-II proteins are highly conserved among orthopoxviruses, sharing approximately 85% homology, but are absent in eukaryotes. This characteristic sets it apart from other known virulence factors in orthopoxviruses, which share sequence homology with known mammalian immune regulatory gene products. Future studies of additional variola proteins may help illuminate factors associated with its virulence, pathogenesis and strict human tropism. In addition, these studies may also assist in the development of targeted therapies for the treatment of both smallpox and human immune-related diseases.

  1. Assessing reprogramming by chimera formation and tetraploid complementation.

    PubMed

    Li, Xin; Xia, Bao-long; Li, Wei; Zhou, Qi

    2015-01-01

    Pluripotent stem cells can be evaluated by pluripotent markers expression, embryoid body aggregation, teratoma formation, chimera contribution and even more, tetraploid complementation. Whether iPS cells in general are functionally equivalent to normal ESCs is difficult to establish. Here, we present the detailed procedure for chimera formation and tetraploid complementation, the most stringent criterion, to assessing pluripotency.

  2. Complement inhibitors to treat IgM-mediated autoimmune hemolysis

    PubMed Central

    Wouters, Diana; Zeerleder, Sacha

    2015-01-01

    Complement activation in autoimmune hemolytic anemia may exacerbate extravascular hemolysis and may occasionally result in intravascular hemolysis. IgM autoantibodies as characteristically found in cold autoantibody autoimmune hemolytic anemia, in cold agglutinin disease but also in a considerable percentage of patients with warm autoantibodies are very likely to activate complement in vivo. Therapy of IgM-mediated autoimmune hemolytic anemia mainly aims to decrease autoantibody production. However, most of these treatments require time to become effective and will not stop immediate ongoing complement-mediated hemolysis nor prevent hemolysis of transfused red blood cells. Therefore pharmacological inhibition of the complement system might be a suitable approach to halt or at least attenuate ongoing hemolysis and improve the recovery of red blood cell transfusion in autoimmune hemolytic anemia. In recent years, several complement inhibitors have become available in the clinic, some of them with proven efficacy in autoimmune hemolytic anemia. In the present review, we give a short introduction on the pathogenesis of autoimmune hemolytic anemia, followed by an overview on the complement system with a special focus on its regulation. Finally, we will discuss complement inhibitors with regard to their potential efficacy to halt or attenuate hemolysis in complement-mediated autoimmune hemolytic anemia. PMID:26521297

  3. How antibodies use complement to regulate antibody responses.

    PubMed

    Sörman, Anna; Zhang, Lu; Ding, Zhoujie; Heyman, Birgitta

    2014-10-01

    Antibodies, forming immune complexes with their specific antigen, can cause complete suppression or several 100-fold enhancement of the antibody response. Immune complexes containing IgG and IgM may activate complement and in such situations also complement components will be part of the immune complex. Here, we review experimental data on how antibodies via the complement system upregulate specific antibody responses. Current data suggest that murine IgG1, IgG2a, and IgG2b upregulate antibody responses primarily via Fc-receptors and not via complement. In contrast, IgM and IgG3 act via complement and require the presence of complement receptors 1 and 2 (CR1/2) expressed on both B cells and follicular dendritic cells. Complement plays a crucial role for antibody responses not only to antigen complexed to antibodies, but also to antigen administered alone. Lack of C1q, but not of Factor B or MBL, severely impairs antibody responses suggesting involvement of the classical pathway. In spite of this, normal antibody responses are found in mice lacking several activators of the classical pathway (complement activating natural IgM, serum amyloid P component (SAP), specific intracellular adhesion molecule-grabbing non-integrin R1 (SIGN-R1) or C-reactive protein. Possible explanations to these observations will be discussed.

  4. Inactivation of complement by Loxosceles reclusa spider venom.

    PubMed

    Gebel, H M; Finke, J H; Elgert, K D; Cambell, B J; Barrett, J T

    1979-07-01

    Zymosan depletion of serum complement in guinea pigs rendered them highly resistant to lesion by Loxosceles reclusa spider venom. Guinea pigs deficient in C4 of the complement system are as sensitive to the venom as normal guinea pigs. The injection of 35 micrograms of whole recluse venom intradermally into guinea pigs lowered their complement level by 35.7%. Brown recluse spider venom in concentrations as slight as 0.02 micrograms protein/ml can totally inactivate one CH50 of guinea pig complement in vitro. Bee, scorpion, and other spider venoms had no influence on the hemolytic titer of complement. Fractionation of recluse spider venom by Sephadex G-200 filtration separated the complement-inactivating property of the venom into three major regions which could be distinguished on the basis of heat stability as well as size. None was neutralized by antivenom. Polyacrylamide gel electrophoresis of venom resolved the complement inactivators into five fractions. Complement inactivated by whole venom or the Sephadex fractions could be restored to hemolytic activity by supplements of fresh serum but not by heat-inactivated serum, pure C3, pure C5, or C3 and C5 in combination.

  5. Complement Attack against Aspergillus and Corresponding Evasion Mechanisms.

    PubMed

    Speth, Cornelia; Rambach, Günter

    2012-01-01

    Invasive aspergillosis shows a high mortality rate particularly in immunocompromised patients. Perpetually increasing numbers of affected patients highlight the importance of a clearer understanding of interactions between innate immunity and fungi. Innate immunity is considered to be the most significant host defence against invasive fungal infections. Complement represents a crucial part of this first line defence and comprises direct effects against invading pathogens as well as bridging functions to other parts of the immune network. However, despite the potency of complement to attack foreign pathogens, the prevalence of invasive fungal infections is increasing. Two possible reasons may explain that phenomenon: First, complement activation might be insufficient for an effective antifungal defence in risk patients (due to, e.g., low complement levels, poor recognition of fungal surface, or missing interplay with other immune elements in immunocompromised patients). On the other hand, fungi may have developed evasion strategies to avoid recognition and/or eradication by complement. In this review, we summarize the most important interactions between Aspergillus and the complement system. We describe the various ways of complement activation by Aspergillus and the antifungal effects of the system, and also show proven and probable mechanisms of Aspergillus for complement evasion.

  6. The complement system in ischemia-reperfusion injuries.

    PubMed

    Gorsuch, William B; Chrysanthou, Elvina; Schwaeble, Wilhelm J; Stahl, Gregory L

    2012-11-01

    Tissue injury and inflammation following ischemia and reperfusion of various organs have been recognized for many years. Many reviews have been written over the last several decades outlining the role of complement in ischemia/reperfusion injury. This short review provides a current state of the art knowledge on the complement pathways activated, complement components involved and a review of the clinical biologics/inhibitors used in the clinical setting of ischemia/reperfusion. This is not a complete review of the complement system in ischemia and reperfusion injury but will give the reader an updated view point of the field, potential clinical use of complement inhibitors, and the future studies needed to advance the field.

  7. The Complement System in Ischemia-Reperfusion Injuries

    PubMed Central

    Gorsuch, William B.; Chrysanthou, Elvina; Schwaeble, Wilhelm J.; Stahl, Gregory L.

    2012-01-01

    Tissue injury and inflammation following ischemia and reperfusion of various organs has been recognized for many years. Many reviews have been written over the last several decades outlining the role of complement in ischemia/reperfusion injury. This short review provides a current state of the art knowledge on the complement pathways activated, complement components involved and a review of the clinical biologics/inhibitors used in the clinical setting of ischemia/reperfusion. This is not a complete review of the complement system in ischemia and reperfusion injury but will give the reader an updated view point of the field, potential clinical use of complement inhibitors, and the future studies needed to advance the field. PMID:22964228

  8. Systemic complement activation in age-related macular degeneration.

    PubMed

    Scholl, Hendrik P N; Charbel Issa, Peter; Walier, Maja; Janzer, Stefanie; Pollok-Kopp, Beatrix; Börncke, Florian; Fritsche, Lars G; Chong, Ngaihang V; Fimmers, Rolf; Wienker, Thomas; Holz, Frank G; Weber, Bernhard H F; Oppermann, Martin

    2008-07-02

    Dysregulation of the alternative pathway (AP) of complement cascade has been implicated in the pathogenesis of age-related macular degeneration (AMD), the leading cause of blindness in the elderly. To further test the hypothesis that defective control of complement activation underlies AMD, parameters of complement activation in blood plasma were determined together with disease-associated genetic markers in AMD patients. Plasma concentrations of activation products C3d, Ba, C3a, C5a, SC5b-9, substrate proteins C3, C4, factor B and regulators factor H and factor D were quantified in patients (n = 112) and controls (n = 67). Subjects were analyzed for single nucleotide polymorphisms in factor H (CFH), factor B-C2 (BF-C2) and complement C3 (C3) genes which were previously found to be associated with AMD. All activation products, especially markers of chronic complement activation Ba and C3d (p<0.001), were significantly elevated in AMD patients compared to controls. Similar alterations were observed in factor D, but not in C3, C4 or factor H. Logistic regression analysis revealed better discriminative accuracy of a model that is based only on complement activation markers Ba, C3d and factor D compared to a model based on genetic markers of the complement system within our study population. In both the controls' and AMD patients' group, the protein markers of complement activation were correlated with CFH haplotypes.This study is the first to show systemic complement activation in AMD patients. This suggests that AMD is a systemic disease with local disease manifestation at the ageing macula. Furthermore, the data provide evidence for an association of systemic activation of the alternative complement pathway with genetic variants of CFH that were previously linked to AMD susceptibility.

  9. A Viral Noncoding RNA Complements a Weakened Viral RNA Silencing Suppressor and Promotes Efficient Systemic Host Infection

    PubMed Central

    Flobinus, Alyssa; Hleibieh, Kamal; Klein, Elodie; Ratti, Claudio; Bouzoubaa, Salah; Gilmer, David

    2016-01-01

    Systemic movement of beet necrotic yellow vein virus (BNYVV) in Beta macrocarpa depends on viral RNA3, whereas in Nicotiana benthamiana this RNA is dispensable. RNA3 contains a coremin motif of 20 nucleotides essential for the stabilization of noncoding RNA3 (ncRNA3) and for long-distance movement in Beta species. Coremin mutants that are unable to accumulate ncRNA3 also do not achieve systemic movement in Beta species. A mutant virus carrying a mutation in the p14 viral suppressor of RNA silencing (VSR), unable to move long distances, can be complemented with the ncRNA3 in the lesion phenotype, viral RNA accumulation, and systemic spread. Analyses of the BNYVV VSR mechanism of action led to the identification of the RNA-dependent RNA polymerase 6 (RDR6) pathway as a target of the virus VSR and the assignment of a VSR function to the ncRNA3. PMID:27782046

  10. Extracellular stimulation of VSIG4/complement receptor Ig suppresses intracellular bacterial infection by inducing autophagy.

    PubMed

    Kim, Kwang H; Choi, Beom K; Kim, Young H; Han, Chungyong; Oh, Ho S; Lee, Don G; Kwon, Byoung S

    2016-09-01

    VSIG4/CRIg (V-set and immunoglobulin domain containing 4) is a transmembrane receptor of the immunoglobulin superfamily that is expressed specifically on macrophages and mature dendritic cells. VSIG4 signaling accelerates phagocytosis of C3-opsonized bacteria, thereby efficiently clearing pathogens within macrophages. We found that VSIG4 signaling triggered by C3-opsonized Listeria (opLM) or by agonistic anti-VSIG4 monoclonal antibody (mAb) induced macrophages to form autophagosomes. VSIG4-induced autophagosomes were selectively colocalized with the intracellular LM while starvation-induced autophagosomes were not. Consistent with these results, the frequency of autophagosomes induced by infection with opLM was lower in VSIG4-deficient bone marrow-derived macrophages (BMDMs) than in WT BMDMs. Furthermore, when VSIG4 molecules were overexpressed in HeLa cells, which are non-macrophage cells, VSIG4 triggering led to efficient uptake of LM, autophagosome formation, and killing of the infected LM. These findings suggest that VSIG4 signaling not only promotes rapid phagocytosis and killing of C3-opsonized intracellular bacteria, as previously reported, but also induces autophagosome formation, eliminating the LM that have escaped from phagosomes. We conclude that VSIG4 signaling provides an anti-immune evasion mechanism that prevents the outgrowth of intracellular bacteria in macrophages.

  11. Complement activation promotes muscle inflammation during modified muscle use

    NASA Technical Reports Server (NTRS)

    Frenette, J.; Cai, B.; Tidball, J. G.

    2000-01-01

    Modified muscle use can result in muscle inflammation that is triggered by unidentified events. In the present investigation, we tested whether the activation of the complement system is a component of muscle inflammation that results from changes in muscle loading. Modified rat hindlimb muscle loading was achieved by removing weight-bearing from the hindlimbs for 10 days followed by reloading through normal ambulation. Experimental animals were injected with the recombinant, soluble complement receptor sCR1 to inhibit complement activation. Assays for complement C4 or factor B in sera showed that sCR1 produced large reductions in the capacity for activation of the complement system through both the classical and alternative pathways. Analysis of complement C4 concentration in serum in untreated animals showed that the classical pathway was activated during the first 2 hours of reloading. Analysis of factor B concentration in untreated animals showed activation of the alternative pathway at 6 hours of reloading. Administration of sCR1 significantly attenuated the invasion of neutrophils (-49%) and ED1(+) macrophages (-52%) that occurred in nontreated animals after 6 hours of reloading. The presence of sCR1 also reduced significantly the degree of edema by 22% as compared to untreated animals. Together, these data show that increased muscle loading activated the complement system which then briefly contributes to the early recruitment of inflammatory cells during modified muscle loading.

  12. COMPLEMENT FIXATION TEST IN EXPERIMENTAL CLINICAL AND SUBCLINICAL MELIOIDOSIS

    PubMed Central

    Nigg, Clara; Johnston, Margaret M.

    1961-01-01

    Nigg, Clara (University of California, Berkeley), and Margaret M. Johnston. Complement fixation test in experimental clinical and subclinical melioidosis. J. Bacteriol. 82:159–168. 1961.—Soluble stable antigens prepared from Pseudomonas pseudomallei gave 4+ complement fixation reactions in a dilution of 1 to 8,000 when tested with specific rabbit antiserum diluted 1 to 10,000. The complement fixation reaction was positive in 100% of experimentally infected rabbits 9 to 11 days postinfection. Infected guinea pigs and monkeys showed similar results. Monkeys inoculated with very small infecting doses of P. pseudomallei developed positive complement fixation reactions in the absence of clinical manifestation of infection. An anamnestic complement-fixing antibody response could be induced in such monkeys, after the titer had dropped to approximately the preinfection level, by inoculating very small doses of viable P. pseudomallei or larger doses of killed melioidosis vaccine. The complement fixation test described appeared to be both sensitive and specific, and should be of value in human melioidosis which cannot be diagnosed on the basis of clinical manifestations alone. It is suggested that subclinical infections may play a role in the epidemiology of human meliodosis. The potential application of the complement fixation test to serological surveys in areas where melioidosis occurs endemically is discussed. PMID:13729013

  13. Complement factor B expression profile in a spontaneous uveitis model.

    PubMed

    Zipplies, Johanna K; Kirschfink, Michael; Amann, Barbara; Hauck, Stefanie M; Stangassinger, Manfred; Deeg, Cornelia A

    2010-12-01

    Equine recurrent uveitis serves as a spontaneous model for human autoimmune uveitis. Unpredictable relapses and ongoing inflammation in the eyes of diseased horses as well as in humans lead to destruction of the retina and finally result in blindness. However, the molecular mechanisms leading to inflammation and retinal degeneration are not well understood. An initial screening for differentially regulated proteins in sera of uveitic cases compared to healthy controls revealed an increase of the alternative pathway complement component factor B in ERU cases. To determine the activation status of the complement system, sera were subsequently examined for complement split products. We could demonstrate a significant higher concentration of the activation products B/Ba, B/Bb, Bb neoantigen, iC3b and C3d in uveitic condition compared to healthy controls, whereas for C5b-9 no differences were detected. Additionally, we investigated complement activation directly in the retina by immunohistochemistry, since it is the main target organ of this autoimmune disease. Interestingly, infiltrating cells co-expressed activated factor Bb neoantigen, complement split product C3d as well as CD68, a macrophage marker. In this study, we could demonstrate activation of the complement system both systemically as well as in the eye, the target organ of spontaneous recurrent uveitis. Based on these novel findings, we postulate a novel role for macrophages in connection with complement synthesis at the site of inflammation.

  14. Bullous pemphigoid autoantibodies directly induce blister formation without complement activation.

    PubMed

    Ujiie, Hideyuki; Sasaoka, Tetsumasa; Izumi, Kentaro; Nishie, Wataru; Shinkuma, Satoru; Natsuga, Ken; Nakamura, Hideki; Shibaki, Akihiko; Shimizu, Hiroshi

    2014-11-01

    Complement activation and subsequent recruitment of inflammatory cells at the dermal/epidermal junction are thought to be essential for blister formation in bullous pemphigoid (BP), an autoimmune blistering disease induced by autoantibodies against type XVII collagen (COL17); however, this theory does not fully explain the pathological features of BP. Recently, the involvement of complement-independent pathways has been proposed. To directly address the question of the necessity of the complement activation in blister formation, we generated C3-deficient COL17-humanized mice. First, we show that passive transfer of autoantibodies from BP patients induced blister formation in neonatal C3-deficient COL17-humanized mice without complement activation. By using newly generated human and murine mAbs against the pathogenic noncollagenous 16A domain of COL17 with high (human IgG1, murine IgG2), low (murine IgG1), or no (human IgG4) complement activation abilities, we demonstrate that the deposition of Abs, and not complements, is relevant to the induction of blister formation in neonatal and adult mice. Notably, passive transfer of BP autoantibodies reduced the amount of COL17 in lesional mice skin, as observed in cultured normal human keratinocytes treated with the same Abs. Moreover, the COL17 depletion was associated with a ubiquitin/proteasome pathway. In conclusion, the COL17 depletion induced by BP autoantibodies, and not complement activation, is essential for the blister formation under our experimental system.

  15. Complement in Pancreatic Disease—Perpetrator or Savior?

    PubMed Central

    Bettac, Lucas; Denk, Stephanie; Seufferlein, Thomas; Huber-Lang, Markus

    2017-01-01

    The complement system is a major pillar of the humoral innate immune system. As a first line of defense against pathogens, it mediates early inflammatory response and links different branches of humoral and cellular immunity. Disorders affecting the exocrine pancreas, such as acute pancreatitis, potentially lead to a life-threatening systemic inflammatory response with aberrant activation of complement and coagulation cascades. Pancreatic proteases can activate key effectors of the complement system, which in turn drive local and systemic inflammation. Beyond that, the extent of pancreas–complement interaction covers complex pro- and anti-inflammatory mechanisms, which to this day remain to be fully elucidated. This review provides a comprehensive overview of the pathophysiological role of complement in diseases of the exocrine pancreas, based on existing experimental and clinical data. Participation of complement in acute and chronic pancreatitis is addressed, as well as its role in tumor immunology. Therapeutic strategies targeting complement in these diseases have long been proposed but have not yet arrived in the clinical setting. PMID:28144242

  16. Foodborne viruses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Testing for human pathogenic viruses in foods represents a formidable task requiring the extraction, concentration, and assay of a host of viruses from a wide range of food matrices. The enteric viruses, particularly genogroup I and II (GI and GII) noroviruses and hepatitis A virus, are the princip...

  17. Complement activity and pharmacological inhibition in cardiovascular disease

    PubMed Central

    Théroux, Pierre; Martel, Catherine

    2006-01-01

    While complement is the most important component of humoral autoimmunity, and inflammation plays a key role in atherosclerosis, relatively few studies have looked at complement implications in atherosclerosis and its complications. C-reactive protein is a marker of inflammation and is also involved in atherosclerosis; it activates complement and colocalizes with activated complement proteins within the infarcting myocardium and the active atherosclerotic plaques. As new agents capable of modulating complement activity are being developed, new targets for the management of atherosclerosis are emerging that are related to autoimmunity and inflammation. The present paper reviews the putative roles of the various complement activation pathways in the development of atherosclerosis, in ST segment elevation and non-ST segment elevation acute coronary syndromes, and in coronary artery bypass graft surgery. It also provides a perspective on new therapeutic interventions being developed to modulate complement activity. These interventions include the C1 esterase inhibitor, which may be consumed in some inflammatory states resulting in the loss of one of the mechanisms inhibiting activation of the classical and lectin pathways; TP10, a recombinant protein of the soluble complement receptor type 1 (sCR1) which inhibits the C3 and C5 convertases of the common pathway by binding C3b and C4b; a truncated version of the soluble complement receptor type 1 CRI lacking the C4b binding site which selectively inhibits the alternative pathway; and pexelizumab, a monoclonal antibody selectively blocking C5 to prevent the activation of the terminal pathway that is involved in excessive inflammation and autoimmune responses. PMID:16498508

  18. Ohio strains of a virus pathogenic for infant mice, Coxsackie group; simultaneous occurrence with poliomyelitis virus in patients with summer grippe.

    PubMed

    MELNICK, J L; LEDINKO, N

    1950-02-01

    Further evidence for the widespread occurrence of Coxsackie or C virus is presented in this paper. This virus is characterized by paralysis and myositis produced in infant mice. An epidemic of mild illnesses diagnosed as "non-paralytic poliomyelitis" and as "summer grippe" occurred during the summer of 1947 in Akron and Cincinnati, Ohio. From the pooled feces of such patients both poliomyelitis virus and C virus were obtained. From the samples of single patients, 3 immunologically related strains of C virus were isolated. One patient from whom virus was isolated had an illness which was diagnosed as non-paralytic poliomyelitis (with pleocytosis). Although poliomyelitis virus could not be isolated from this patient, previous tests (5) from similar non-paralytic patients in the same area revealed that 9 of 23 were infected with poliomyelitis virus. C virus could not be recovered from the stools of 3 of these poliomyelitis virus-infected patients. Four patients with an illness diagnosed as "summer grippe" were tested. Two harbored poliomyelitis virus of low virulence (4) as well as C virus, and two harbored poliomyelitis virus without any evidence of infection with C virus, either by virus isolation or by serological tests. The patients from whom C virus was isolated developed complement-fixing antibodies 4 weeks after onset. Neutralizing antibodies appeared within the first 5 days of disease (before complement-fixing antibodies) and increased in titer during the next 3 to 4 weeks. The patients from whom C virus could not be recovered failed to develop either neutralizing or complement-fixing antibodies. Other patients in the area were infected with C virus as indicated by their serological response to the agent.

  19. Mechanisms involved in antibody- and complement-mediated allograft rejection

    PubMed Central

    2010-01-01

    Antibody-mediated rejection has become critical clinically because this form of rejection is usually unresponsive to conventional anti-rejection therapy, and therefore, it has been recognized as a major cause of allograft loss. Our group developed experimental animal models of vascularized organ transplantation to study pathogenesis of antibody- and complement-mediated endothelial cell injury leading to graft rejection. In this review, we discuss mechanisms of antibody-mediated graft rejection resulting from activation of complement by C1q- and MBL (mannose-binding lectin)-dependent pathways and interactions with a variety of effector cells, including macrophages and monocytes through Fcγ receptors and complement receptors. PMID:20135240

  20. Inventing Viruses.

    PubMed

    Summers, William C

    2014-11-01

    In the nineteenth century, "virus" commonly meant an agent (usually unknown) that caused disease in inoculation experiments. By the 1890s, however, some disease-causing agents were found to pass through filters that retained the common bacteria. Such an agent was called "filterable virus," the best known being the virus that caused tobacco mosaic disease. By the 1920s there were many examples of filterable viruses, but no clear understanding of their nature. However, by the 1930s, the term "filterable virus" was being abandoned in favor of simply "virus," meaning an agent other than bacteria. Visualization of viruses by the electron microscope in the late 1930s finally settled their particulate nature. This article describes the ever-changing concept of "virus" and how virologists talked about viruses. These changes reflected their invention and reinvention of the concept of a virus as it was revised in light of new knowledge, new scientific values and interests, and new hegemonic technologies.

  1. Antigenic relationship between influenza B viruses*

    PubMed Central

    Chakraverty, Pratima

    1971-01-01

    The object of this study was to determine whether antigenic groupings exist among influenza B viruses. Altogether, 22 influenza type B strains isolated during the years 1940-68 were examined by reciprocal haemagglutination-inhibition, strain-specific complement-fixation, and serum neutralization tests with sera produced in ferrets and guinea-pigs. It was found that the strain-specific complement-fixation test was superior for separating influenza B viruses into groups whereas the haemagglutination-inhibition and serum neutralization tests were better for demonstrating similarities. The results obtained with these three immunological techniques confirmed that antigenic variation exists among influenza B viruses, although it is not as clearcut as among influenza A viruses. The results were subjected to numerical taxonomic analysis. Dendrograms and minimum-spanning trees were constructed, using methods based on cluster analysis of similarity coefficients. Four main groups of influenza B viruses were established, although they were all interlinked. The results of this study do not justify the separation of influenza B viruses into subtypes similar to those of influenza A viruses. PMID:5317011

  2. Peptide Inhibitor of Complement C1 (PIC1) Rapidly Inhibits Complement Activation after Intravascular Injection in Rats

    PubMed Central

    Sharp, Julia A.; Hair, Pamela S.; Pallera, Haree K.; Kumar, Parvathi S.; Mauriello, Clifford T.; Nyalwidhe, Julius O.; Phelps, Cody A.; Park, Dalnam; Thielens, Nicole M.; Pascal, Stephen M.; Chen, Waldon; Duffy, Diane M.; Lattanzio, Frank A.; Cunnion, Kenji M.; Krishna, Neel K.

    2015-01-01

    The complement system has been increasingly recognized to play a pivotal role in a variety of inflammatory and autoimmune diseases. Consequently, therapeutic modulators of the classical, lectin and alternative pathways of the complement system are currently in pre-clinical and clinical development. Our laboratory has identified a peptide that specifically inhibits the classical and lectin pathways of complement and is referred to as Peptide Inhibitor of Complement C1 (PIC1). In this study, we determined that the lead PIC1 variant demonstrates a salt-dependent binding to C1q, the initiator molecule of the classical pathway. Additionally, this peptide bound to the lectin pathway initiator molecule MBL as well as the ficolins H, M and L, suggesting a common mechanism of PIC1 inhibitory activity occurs via binding to the collagen-like tails of these collectin molecules. We further analyzed the effect of arginine and glutamic acid residue substitution on the complement inhibitory activity of our lead derivative in a hemolytic assay and found that the original sequence demonstrated superior inhibitory activity. To improve upon the solubility of the lead derivative, a pegylated, water soluble variant was developed, structurally characterized and demonstrated to inhibit complement activation in mouse plasma, as well as rat, non-human primate and human serum in vitro. After intravenous injection in rats, the pegylated derivative inhibited complement activation in the blood by 90% after 30 seconds, demonstrating extremely rapid function. Additionally, no adverse toxicological effects were observed in limited testing. Together these results show that PIC1 rapidly inhibits classical complement activation in vitro and in vivo and is functional for a variety of animal species, suggesting its utility in animal models of classical complement-mediated diseases. PMID:26196285

  3. Complement: a key system for immune surveillance and homeostasis.

    PubMed

    Ricklin, Daniel; Hajishengallis, George; Yang, Kun; Lambris, John D

    2010-09-01

    Nearly a century after the significance of the human complement system was recognized, we have come to realize that its functions extend far beyond the elimination of microbes. Complement acts as a rapid and efficient immune surveillance system that has distinct effects on healthy and altered host cells and foreign intruders. By eliminating cellular debris and infectious microbes, orchestrating immune responses and sending 'danger' signals, complement contributes substantially to homeostasis, but it can also take action against healthy cells if not properly controlled. This review describes our updated view of the function, structure and dynamics of the complement network, highlights its interconnection with immunity at large and with other endogenous pathways, and illustrates its multiple roles in homeostasis and disease.

  4. The Complement-Fixation Test in Hepatic Coccidiosis of Rabbits

    PubMed Central

    Rose, M. Elaine

    1961-01-01

    Antibodies to Eimeria stiedae were measured in rabbit serum by complement fixation. The titre rose to a maximum at about the 22nd day after infection, remained at this level for about 20 days and then declined. Antibodies were still detectable up to 160 days after infection. Evidence of past or present slight E. stiedae infection was found in clinically normal rabbits whose sera fixed complement with E. stiedae antigens. Challenge of rabbits which had recovered from a near-fatal infection had no effect upon the complement fixation titres of their sera. The serum of a rabbit which had been injected with alum-precipitated antigen fixed complement with E. stiedae antigens. However, the animal was still susceptible to a superimposed oral infection which had the effect of further increasing the serum titre. PMID:14493840

  5. Complement in immune and inflammatory disorders: therapeutic interventions

    PubMed Central

    Ricklin, Daniel; Lambris, John D.

    2013-01-01

    With the awareness that immune-inflammatory crosstalk is at the heart of many disorders, the desire for novel immunomodulatory strategies in the therapy of such diseases has grown dramatically. As a prime initiator and important modulator of immunological and inflammatory processes, the complement system has emerged as an attractive target for early and upstream intervention in inflammatory diseases and has moved into the spotlight of drug discovery. While prevalent conditions such as age-related macular degeneration have attracted the most attention, the diverse array of complement-mediated pathologies, with distinct underlying mechanisms, demands a multifaceted arsenal of therapeutic strategies. Fortunately, efforts in recent years have not only introduced the first complement inhibitors to the clinic but also filled the pipelines with promising candidates. With a focus on immunomodulatory strategies, this review discusses complement-directed therapeutic concepts and highlights promising candidate molecules. PMID:23564578

  6. Immobilization of soluble complement receptor 1 on islets.

    PubMed

    Luan, Nguyen M; Teramura, Yuji; Iwata, Hiroo

    2011-07-01

    Transplantation of pancreatic islets of Langerhans (islets) is a promising method to treat insulin-dependent diabetes mellitus. Control of complement activation is necessary to improve graft survival in alloislet and xenoislet transplantation. In this study, human soluble complement receptor 1 (sCR1) was immobilized on the islet cell surface through poly(ethylene glycol)-conjugated phospholipid (PEG-lipid) without loss of islet cell viability or insulin secretion ability. sCR1 on islets effectively inhibits complement activation and protects islets against attack by xenoreactive antibodies and complement. This method will be an efficient means to control early islet loss in clinical islet transplantation and realize xenoislet transplantation in the future.

  7. Luciferase fragment complementation imaging in preclinical cancer studies

    PubMed Central

    Lake, Madryn C.; Aboagye, Eric O.

    2014-01-01

    The luciferase fragment complementation assay (LFCA) enables molecular events to be non-invasively imaged in live cells in vitro and in vivo in a comparatively cheap and safe manner. It is a development of previous enzyme complementation assays in which reporter genes are split into two, individually enzymatically inactive, fragments that are able to complement one another upon interaction. This complementation can be used to externally visualize cellular activities. In recent years, the number of studies which have used LFCAs to probe questions relevant to cancer have increased, and this review summarizes the most significant and interesting of these. In particular, it focuses on work conducted on the epidermal growth factor, nuclear and chemokine receptor families, and intracellular signaling pathways, including IP3, cAMP, Akt, cMyc, NRF2 and Rho GTPases. LFCAs which have been developed to image DNA methylation and detect RNA transcripts are also discussed. PMID:25594026

  8. Complementation of Myelodysplastic Syndrome Clones with Lentivirus Expression Libraries

    DTIC Science & Technology

    2012-07-01

    were validated; they induced myeloid colonies in vitro and engrafted in the marrow of SG3, but not NSG mice. Myelodysplastic syndrome , lentivirus...cDNA libraries, complementation The Cleveland Clinic Foundation Cleveland, OH 44195 Complementation of Myelodysplastic Syndrome Clones with...Martin-Padura, P. Mancuso, P. Marighetti, C. Rabascio, G. Pruneri, L. D. Shultz, and F. Bertolini. 2008. Human acute leukemia cells injected in NOD

  9. Complementation of Myelodysplastic Syndrome Clones with Lentivirus Expression Libraries

    DTIC Science & Technology

    2013-01-01

    Complementation of Myelodysplastic Syndrome Clones with Lentivirus Expression Libraries PRINCIPAL INVESTIGATOR: Daniel J. Lindner, M.D., Ph.D...YYYY) 2013 2. REPORT TYPE Final 3. DATES COVERED (From - To) 201 31 2012 4. TITLE AND SUBTITLE Complementation of Myelodysplastic Syndrome Clones...vitro and engrafted in the marrow of SG3, but not NSG mice. 15. SUBJECT TERMS Myelodysplastic syndrome , lentivirus, cDNA libraries

  10. Protective responses to sublytic complement in the retinal pigment epithelium

    PubMed Central

    Tan, Li Xuan; Toops, Kimberly A.; Lakkaraju, Aparna

    2016-01-01

    The retinal pigment epithelium (RPE) is a key site of injury in inherited and age-related macular degenerations. Abnormal activation of the complement system is a feature of these blinding diseases, yet how the RPE combats complement attack is poorly understood. The complement cascade terminates in the cell-surface assembly of membrane attack complexes (MACs), which promote inflammation by causing aberrant signal transduction. Here, we investigated mechanisms crucial for limiting MAC assembly and preserving cellular integrity in the RPE and asked how these are compromised in models of macular degeneration. Using polarized primary RPE and the pigmented Abca4−/− Stargardt disease mouse model, we provide evidence for two protective responses occurring within minutes of complement attack, which are essential for maintaining mitochondrial health in the RPE. First, accelerated recycling of the membrane-bound complement regulator CD59 to the RPE cell surface inhibits MAC formation. Second, fusion of lysosomes with the RPE plasma membrane immediately after complement attack limits sustained elevations in intracellular calcium and prevents mitochondrial injury. Cholesterol accumulation in the RPE, induced by vitamin A dimers or oxidized LDL, inhibits these defense mechanisms by activating acid sphingomyelinase (ASMase), which increases tubulin acetylation and derails organelle traffic. Defective CD59 recycling and lysosome exocytosis after complement attack lead to mitochondrial fragmentation and oxidative stress in the RPE. Drugs that stimulate cholesterol efflux or inhibit ASMase restore both these critical safeguards in the RPE and avert complement-induced mitochondrial injury in vitro and in Abca4−/− mice, indicating that they could be effective therapeutic approaches for macular degenerations. PMID:27432952

  11. Legionella pneumophila lipopolysaccharide activates the classical complement pathway.

    PubMed Central

    Mintz, C S; Schultz, D R; Arnold, P I; Johnson, W

    1992-01-01

    Legionella pneumophila is a gram-negative bacterium capable of entering and growing in alveolar macrophages and monocytes. Complement and complement receptors are important in the uptake of L. pneumophila by human mononuclear phagocytes. The surface molecules of L. pneumophila that activate the complement system are unknown. To identify these factors, we investigated the effects of L. pneumophila lipopolysaccharide (LPS) on the classical and alternative complement pathways of normal human serum by functional hemolytic assays. Although incubation of LPS in normal human serum at 37 degrees C resulted in the activation of both pathways, complement activation proceeded primarily through the classical pathway. Activation of the classical pathway by LPS was dependent on natural antibodies of the immunoglobulin M class that were present in various quantities in sera from different normal individuals but were absent in an immunoglobulin-deficient serum obtained from an agammaglobulinemic patient. Additional studies using sheep erythrocytes coated with LPS suggested that the antibodies recognized antigenic sites in the carbohydrate portion of LPS. The ability of LPS to interact with the complement system suggests a role for LPS in the uptake of L. pneumophila by mononuclear phagocytes. PMID:1612744

  12. Complement involvement in kidney diseases: From physiopathology to therapeutical targeting.

    PubMed

    Salvadori, Maurizio; Rosso, Giuseppina; Bertoni, Elisabetta

    2015-05-06

    Complement cascade is involved in several renal diseases and in renal transplantation. The different components of the complement cascade might represent an optimal target for innovative therapies. In the first section of the paper the authors review the physiopathology of complement involvement in renal diseases and transplantation. In some cases this led to a reclassification of renal diseases moving from a histopathological to a physiopathological classification. The principal issues afforded are: renal diseases with complement over activation, renal diseases with complement dysregulation, progression of renal diseases and renal transplantation. In the second section the authors discuss the several complement components that could represent a therapeutic target. Even if only the anti C5 monoclonal antibody is on the market, many targets as C1, C3, C5a and C5aR are the object of national or international trials. In addition, many molecules proved to be effective in vitro or in preclinical trials and are waiting to move to human trials in the future.

  13. Exploitation of complement regulatory proteins by Borrelia and Francisella.

    PubMed

    Madar, Marian; Bencurova, Elena; Mlynarcik, Patrik; Almeida, André M; Soares, Renata; Bhide, Katarina; Pulzova, Lucia; Kovac, Andrej; Coelho, Ana V; Bhide, Mangesh

    2015-06-01

    Pathogens have developed sophisticated mechanisms of complement evasion such as binding to the host complement regulatory proteins (CRPs) on their surface or expression of CRP mimicking molecules. The ability of pathogens to evade the complement system has been correlated with pathogenesis and host selectivity. Hitherto, little work has been undertaken to determine whether Borrelia and Francisella exploit various CRPs to block complement attack. Seventeen Borrelia (twelve species) and six Francisella (three subspecies) strains were used to assess their ability to bind human, sheep and cattle CRPs or mimic membrane associated complement regulators. A series of experiments including affinity ligand binding experiments, pull-down assays and mass spectrometry based protein identification, revealed an array of CRP binding proteins of Borrelia and Francisella. Unlike Francisella, Borrelia strains were able to bind multiple human CRPs. Three strains of Borrelia (SKT-4, SKT-2 and HO14) showed the presence of a human CD46-homologous motif, indicating their ability to possess putative human CD46 mimicking molecules. Similarly, five strains of Borrelia and two strains of Francisella may have surface proteins with human CD59-homologous motifs. Among ovine and bovine CRPs, the only CRP bound by Francisella (LVS, Tul4 strain) was vitronectin, while ovine C4BP, ovine factor H and bovine factor H were bound to Borrelia strains SKT-2, DN127 and Co53. This study presents an array of proteins of Borrelia and Francisella that bind CRPs or may mimic membrane-CRPs, thus enabling multiphasic complement evasion strategies of these pathogens.

  14. Jamestown Canyon virus (California serogroup) is the etiologic agent of widespread infection in Michigan humans.

    PubMed

    Grimstad, P R; Calisher, C H; Harroff, R N; Wentworth, B B

    1986-03-01

    In a sample population of 780 Michigan residents tested for neutralizing antibodies to California serogroup viruses, 216 (27.7%) had specific neutralizing antibody to Jamestown Canyon virus. An additional eight (1.0%) had specific neutralizing to trivittatus virus; none had specific neutralizing antibody to La Crosse virus. Significantly more male residents than female residents of the Lower Peninsula had antibody to Jamestown Canyon virus. The frequency of neutralizing antibody titers fits the Poisson distribution, suggesting that Jamestown Canyon virus infections occur endemically in residents of Michigan. Among 128 sera with specific neutralizing antibody to Jamestown Canyon virus, only two (1.6%) were found to have significant hemagglutination-inhibiting antibody titers with La Crosse virus, while 23 of 44 (52%) had significant titers with Jamestown Canyon virus; a single serum had significant antibody by complement fixation tests with both La Crosse and Jamestown Canyon viruses. This study confirms earlier speculation that complement fixation and hemagglutination-inhibition tests with La Crosse virus (the only tests for California serogroup virus infections performed by most state diagnostic laboratories) fail to detect antibody to Jamestown Canyon virus. ASPEX computer-drawn maps demonstrated that the distribution of persons with antibody to Jamestown Canyon virus and residing in Michigan's Lower Peninsula is closely correlated with the estimated distribution of white-tailed deer in that part of the state, further supporting the hypothesis that white-tailed deer are the primary vertebrate host for Jamestown Canyon virus.

  15. Derivatives of human complement component C3 for therapeutic complement depletion: a novel class of therapeutic agents.

    PubMed

    Fritzinger, David C; Hew, Brian E; Lee, June Q; Newhouse, James; Alam, Maqsudul; Ciallella, John R; Bowers, Mallory; Gorsuch, William B; Guikema, Benjamin J; Stahl, Gregory L; Vogel, Carl-Wilhelm

    2008-01-01

    To obtain proteins with the complement-depleting activity of Cobra Venom Factor (CVF), but with less immunogenicity, we have prepared human C3/CVF hybrid proteins, in which the C-terminus of the alpha-chain of human C3 is exchanged with homologous regions of the C-terminus of the beta-chain of CVF. We show that these hybrid proteins are able to deplete complement, both in vitro and in vivo. One hybrid protein, HC3-1496, is shown to be effective in reducing complement-mediated damage in two disease models in mice, collagen-induced arthritis and myocardial ischemia/reperfusion injury. Human C3/CVF hybrid proteins represent a novel class ofbiologicals as potential therapeutic agents in many diseases where complement is involved in the pathogenesis.

  16. Histopathological and immunohistochemical study of type 3 complement receptors (CD11b/CD18) in livers and spleens of asymptomatic and symptomatic dogs naturally infected with Leishmania (Leishmania) chagasi.

    PubMed

    Lima, W G; Oliveira, P S; Caliari, M V; Gonçalves, R; Michalick, M S M; Melo, M N; Tafuri, W L; Tafuri, W L

    2007-05-15

    Leishmania promastigotes interact with macrophages through the association of multiple membrane surface receptors. Macrophage complement receptor CR3 (CD11b/CD18 or Mac-1) has been implicated in the interaction of both human and murine macrophages with serum-opsonized promastigotes. The aim of this study was to determine CR3 expression in the livers and spleens of dogs naturally infected with Leishmania (Leishmania) chagasi. CR3 expression in liver was higher in asymptomatic than in symptomatic animals. Moreover, the hepatic parasitism load determined by immunocytochemical analysis was lower in parallel with higher numbers of granulomas. In contrast, in spleens, CR3 expression was higher in symptomatic animals than in asymptomatic ones. However, the tissue parasite load was greater in spleens of symptomatic dogs. There was a strict correlation between the parasite load and cellular CR3 expression in the spleens of dogs naturally infected with L. chagasi. CR3 macrophage integrins could be essential receptors for Leishmania survival. Considering that the symptomatic animals showed higher parasite loads and higher CD11b/CD18 expression in their spleens, we can conclude that these splenic cells (monocyte-macrophages) might serve to perpetuate intracellular infection.

  17. Disease-causing mutations in genes of the complement system.

    PubMed

    Degn, Søren E; Jensenius, Jens C; Thiel, Steffen

    2011-06-10

    Recent studies have revealed profound developmental consequences of mutations in genes encoding proteins of the lectin pathway of complement activation, a central component of the innate immune system. Apart from impairment of immunity against microorganisms, it is known that hereditary deficiencies of this system predispose one to autoimmune conditions. Polymorphisms in complement genes are linked to, for example, atypical hemolytic uremia and age-dependent macular degeneration. The complement system comprises three convergent pathways of activation: the classical, the alternative, and the lectin pathway. The recently discovered lectin pathway is less studied, but polymorphisms in the plasma pattern-recognition molecule mannan-binding lectin (MBL) are known to impact its level, and polymorphisms in the MBL-associated serine protease-2 (MASP-2) result in defects of complement activation. Recent studies have described roles outside complement and immunity of another MBL-associated serine protease, MASP-3, in the etiology of 3MC syndrome, an autosomal-recessive disorder involving a spectrum of developmental features, including characteristic facial dysmorphism. Syndrome-causing mutations were identified in MASP1, encoding MASP-3 and two additional proteins, MASP-1 and MAp44. Furthermore, an association was discovered between 3MC syndrome and mutations in COLEC11, encoding CL-K1, another molecule of the lectin pathway. The findings were confirmed in zebrafish, indicating that MASP-3 and CL-K1 underlie an evolutionarily conserved pathway of embryonic development. Along with the discovery of a role of C1q in pruning synapses in mice, these recent advances point toward a broader role of complement in development. Here, we compare the functional immunologic consequences of "conventional" complement deficiencies with these newly described developmental roles.

  18. Disease-Causing Mutations in Genes of the Complement System

    PubMed Central

    Degn, Søren E.; Jensenius, Jens C.; Thiel, Steffen

    2011-01-01

    Recent studies have revealed profound developmental consequences of mutations in genes encoding proteins of the lectin pathway of complement activation, a central component of the innate immune system. Apart from impairment of immunity against microorganisms, it is known that hereditary deficiencies of this system predispose one to autoimmune conditions. Polymorphisms in complement genes are linked to, for example, atypical hemolytic uremia and age-dependent macular degeneration. The complement system comprises three convergent pathways of activation: the classical, the alternative, and the lectin pathway. The recently discovered lectin pathway is less studied, but polymorphisms in the plasma pattern-recognition molecule mannan-binding lectin (MBL) are known to impact its level, and polymorphisms in the MBL-associated serine protease-2 (MASP-2) result in defects of complement activation. Recent studies have described roles outside complement and immunity of another MBL-associated serine protease, MASP-3, in the etiology of 3MC syndrome, an autosomal-recessive disorder involving a spectrum of developmental features, including characteristic facial dysmorphism. Syndrome-causing mutations were identified in MASP1, encoding MASP-3 and two additional proteins, MASP-1 and MAp44. Furthermore, an association was discovered between 3MC syndrome and mutations in COLEC11, encoding CL-K1, another molecule of the lectin pathway. The findings were confirmed in zebrafish, indicating that MASP-3 and CL-K1 underlie an evolutionarily conserved pathway of embryonic development. Along with the discovery of a role of C1q in pruning synapses in mice, these recent advances point toward a broader role of complement in development. Here, we compare the functional immunologic consequences of “conventional” complement deficiencies with these newly described developmental roles. PMID:21664996

  19. 21 CFR 866.5260 - Complement C3b inactivator immunological test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... immunochemical techniques the complement C3b inactivator (a plasma protein) in serum. Complement is a group of serum proteins that destroy infectious agents. Measurement of complement C3b inactivator aids in...

  20. 21 CFR 866.5260 - Complement C3b inactivator immunological test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... immunochemical techniques the complement C3b inactivator (a plasma protein) in serum. Complement is a group of serum proteins that destroy infectious agents. Measurement of complement C3b inactivator aids in...

  1. 21 CFR 866.5260 - Complement C3b inactivator immunological test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... immunochemical techniques the complement C3b inactivator (a plasma protein) in serum. Complement is a group of serum proteins that destroy infectious agents. Measurement of complement C3b inactivator aids in...

  2. 21 CFR 866.5260 - Complement C3b inactivator immunological test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... immunochemical techniques the complement C3b inactivator (a plasma protein) in serum. Complement is a group of serum proteins that destroy infectious agents. Measurement of complement C3b inactivator aids in...

  3. 21 CFR 866.5260 - Complement C3b inactivator immunological test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... immunochemical techniques the complement C3b inactivator (a plasma protein) in serum. Complement is a group of serum proteins that destroy infectious agents. Measurement of complement C3b inactivator aids in...

  4. Complementation for an essential ancillary nonstructural protein function across parvovirus genera

    PubMed Central

    Mihaylov, Ivailo S.; Cotmore, Susan F.; Tattersall, Peter

    2014-01-01

    Parvoviruses encode a small number of ancillary proteins that differ substantially between genera. Within the genus Protoparvovirus, minute virus of mice (MVM) encodes three isoforms of its ancillary protein NS2, while human bocavirus 1 (HBoV1), in the genus Bocaparvovirus, encodes an NP1 protein that is unrelated in primary sequence to MVM NS2. To search for functional overlap between NS2 and NP1, we generated murine A9 cell populations that inducibly express HBoV1 NP1. These were used to test whether NP1 expression could complement specific defects resulting from depletion of MVM NS2 isoforms. NP1 induction had little impact on cell viability or cell cycle progression in uninfected cells, and was unable to complement late defects in MVM virion production associated with low NS2 levels. However, NP1 did relocate to MVM replication centers, and supports both the normal expansion of these foci and overcomes the early paralysis of DNA replication in NS2-null infections. PMID:25194919

  5. Zika Virus

    MedlinePlus

    Zika is a virus that is spread mostly by mosquitoes. A pregnant mother can pass it to ... through blood transfusions. There have been outbreaks of Zika virus in the United States, Africa, Southeast Asia, ...

  6. Chikungunya virus

    MedlinePlus

    Chikungunya virus infection; Chikungunya ... Where Chikungunya is found Before 2013, the virus was found in Africa, Asia, Europe, and the Indian and Pacific oceans. In late 2013, outbreaks occurred for the first time in the ...

  7. Chikungunya Virus

    MedlinePlus

    ... is key! Prevent Infection. Use mosquito repellent. Chikungunya Virus Distribution Chikungunya in the U.S. What's New Surveillance ... Clinical Challenge For Travelers CDC Travelers' Health Chikungunya Virus Home Prevention Transmission Symptoms & Treatment Geographic Distribution Chikungunya ...

  8. Role of Fc fragments in antibody-mediated recovery from ocular and subcutaneous herpes simplex virus infections.

    PubMed Central

    Oakes, J E; Lausch, R N

    1981-01-01

    The contributions of the Fc fragment of virus-specific antibody in the resistance of mice to peripheral herpes simplex virus infection were investigated. Rabbit anti-herpes simplex virus-specific F(ab')2 fragments prepared by pepsin digestion of immune immunoglobulin G (IgG) were found to be inactive in complement-mediated cytolysis while retaining their capacity to neutralize virus infectivity in vitro. When F(ab')2 fragments were passively transferred either before or simultaneously with virus inoculation, they were as efficient as intact IgG was in protecting animals from virus challenge. However, if passive transfer was delayed until 8 h after herpes simplex virus infection, only IgG antibody was protective. The loss of protective activity could not be attributed to a rapid disappearance of F(ab')2 fragments, because comparable levels of F(ab')2 fragments and IgG antibody were maintained in the blood of recipients during the time that antibody mediated its protective effects. The inability of F(ab')2 subunits to activate complement was also not a factor, because complement-deficient A/J mice and complement-sufficient SJL/J mice recovered from herpes simplex virus infection after the passive transfer of IgG. We concluded that the Fc component of the antibody molecule is needed to resolve intracellular infection and that the mechanism by which antibody mediates recovery remains undefined but does not appear to involve virus neutralization or complement activation. PMID:6266961

  9. Hepadna viruses

    SciTech Connect

    Robinson, W.; Koike, K.; Will, H.

    1987-01-01

    This book examines the molecular biology, disease pathogenesis, epidemiology, and clinical features of hepadna and other viruses with hepatic tropism and outlines future directions and approaches for their management. The volume's six sections provide a review of the various features, mechanisms, and functions of these viruses, ranging from hepadna virus replication and regulation of gene expression to the structure and function of hepadna-virus gene products.

  10. Complement activation by antibodies to Sm in systemic lupus erythematosus.

    PubMed

    Sabharwal, U K; Fong, S; Hoch, S; Cook, R D; Vaughan, J H; Curd, J G

    1983-02-01

    An enzyme linked immunosorbent assay was developed to quantitate antibodies to Sm (anti-Sm) and to measure complement activation by anti-Sm in vitro. Anti-Sm in plasma of patients with systemic lupus erythematosus (SLE) were bound to purified Sm bound to polyvinyl chloride microtitre plates and assayed for bound IgG or IgM using enzyme linked anti-gamma or anti-mu. The activation of C4 by anti-Sm was measured by adding diluted normal human serum (complement) to the wells and quantitating the amount of C4 bound to the well surface using (Fab')2 goat anti-C4 followed by enzyme linked rabbit anti-goat IgG. The plasmas of 12 of 36 patients with SLE contained anti-Sm and all 12 activated complement (complement activating anti-Sm). Twenty-eight plasmas containing anti-Sm from 12 patients with SLE were studied. Ten of the 12 patients had anti-Sm of the IgG class whereas two had anti-Sm of both IgG and IgM classes. The amount of C4 activating anti-Sm correlated significantly with the in vivo activation of C4 measured by rocket immunoelectrophoresis for C4d and C4, suggesting that complement activation by anti-Sm is important in vivo.

  11. Complement activation by Coccidioides immitis: in vitro and clinical studies.

    PubMed Central

    Galgiani, J N; Yam, P; Petz, L D; Williams, P L; Stevens, D A

    1980-01-01

    Mycelial- or spherule-phase derivatives of Coccidioides immitis caused a decrease in vitro of total hemolytic complement in serum from a nonsensitized person. Activation involved both classic and alternative pathways as shown by deprssion of hemolytic C4 and by generation of products of activation of components C3, C4, and factor B. In addition, functional complement activity or immunoreactive levels of complement components or both were measured in 23 patients with self-limited or disseminated coccidioidomycosis. Low total hemolytic complement was found in nine, usually during the early phase of primary illness, and was transient. Hemolytic C4 was low, and the effect of inulin to decrease complement levels was blunted, suggested both classic and alternative pathways may be deficient. However, associated depression of immunoreactive levels of components assayed (C3, C4, C5, factor B, and properdin) was not consistently found. This disparity raises the possibility of enhanced in vitro inactivation analogous to activation by immune complexes. Images Fig. 2 PMID:6901703

  12. Physicochemical signatures of nanoparticle-dependent complement activation

    SciTech Connect

    Thomas, Dennis G.; Chikkagoudar, Satish; Heredia-Langner, Alejandro; Tardiff, Mark F.; Xu, Zhixiang; Hourcade, Dennis; Pham, Christine; Lanza, Gregory M.; Weinberger, Kilian Q.; Baker, Nathan A.

    2014-03-21

    Nanoparticles are potentially powerful therapeutic tools that have the capacity to target drug payloads and imaging agents. However, some nanoparticles can activate complement, a branch of the innate immune system, and cause adverse side-effects. Recently, we developed an in vitro hemolytic assay protocol for measuring the nanoparticle-dependent complement activity of serum samples and applied this protocol to several nanoparticle formulations that differed in size, surface charge, and surface chemistry; quantifying the nanoparticle-dependent complement activity using a metric called Residual Hemolytic Activity (RHA). In the present work, we have used a decision tree learning algorithm to derive the rules for estimating nanoparticle-dependent complement response based on the data generated from the hemolytic assay studies. Our results indicate that physicochemical properties of nanoparticles, namely, size, polydispersity index, zeta potential, and mole percentage of the active surface ligand of a nanoparticle, can serve as good descriptors for prediction of nanoparticle-dependent complement activation in the decision tree modeling framework. The robustness and predictability of the model can be improved by training the model with additional data points that are uniformly distributed in the RHA/physicochemical descriptor space and by incorporating instability effects on nanoparticle physicochemical properties into the model.

  13. Complement factor H in host defense and immune evasion.

    PubMed

    Parente, Raffaella; Clark, Simon J; Inforzato, Antonio; Day, Anthony J

    2016-12-10

    Complement is the major humoral component of the innate immune system. It recognizes pathogen- and damage-associated molecular patterns, and initiates the immune response in coordination with innate and adaptive immunity. When activated, the complement system unleashes powerful cytotoxic and inflammatory mechanisms, and thus its tight control is crucial to prevent damage to host tissues and allow restoration of immune homeostasis. Factor H is the major soluble inhibitor of complement, where its binding to self markers (i.e., particular glycan structures) prevents complement activation and amplification on host surfaces. Not surprisingly, mutations and polymorphisms that affect recognition of self by factor H are associated with diseases of complement dysregulation, such as age-related macular degeneration and atypical haemolytic uremic syndrome. In addition, pathogens (i.e., non-self) and cancer cells (i.e., altered-self) can hijack factor H to evade the immune response. Here we review recent (and not so recent) literature on the structure and function of factor H, including the emerging roles of this protein in the pathophysiology of infectious diseases and cancer.

  14. Chick embryo lethal orphan virus can be polymer-coated and retargeted to infect mammalian cells.

    PubMed

    Stevenson, M; Boos, E; Herbert, C; Hale, A; Green, N; Lyons, M; Chandler, L; Ulbrich, K; van Rooijen, N; Mautner, V; Fisher, K; Seymour, L

    2006-02-01

    Non-human adenovirus vectors have attractive immunological properties for gene therapy but are frequently restricted by inefficient transduction of human target cells. Using chicken embryo lethal orphan (CELO) virus, we employed a nongenetic mechanism of polymer coating and retargeting with basic fibroblast growth factor (bFGF-pc-CELOluc), a strategy that permits efficient tropism modification of human adenovirus. bFGF-pc-CELOluc showed efficient uptake and transgene expression in chick embryo fibroblasts (CEF), and increased levels of binding and internalization in a variety of human cell lines. Transgene expression was also greater than unmodified CELOluc in PC-3 human prostate cells, although the specific activity (RLU per internalized viral genome) was decreased. In CEF, the specific activity of bFGF-pc-CELOluc was considerably higher than in the human prostate cell line PC-3. Retargeted virus was fully resistant to inhibition by human serum with known adenovirus-neutralizing activity in vitro, while in mice CELOluc was cleared less rapidly from the blood than Adluc following i.v. administration in the presence of adenovirus neutralizing serum. Polymer coating and retargeting with bFGF further reduced rates of clearance for both viruses, suggesting protection against both neutralizing and opsonizing factors. The data indicate that CELO virus may be retargeted to infect human cells via alternative, potentially disease-specific, receptors and resist the effects of pre-existing humoral immunity.

  15. Complement Evasion Mediated by Enhancement of Captured Factor H: Implications for Protection of Self-Surfaces from Complement

    PubMed Central

    Herbert, Andrew P.; Makou, Elisavet; Chen, Zhuo A.; Kerr, Heather; Richards, Anna; Rappsilber, Juri

    2015-01-01

    In an attempt to evade annihilation by the vertebrate complement system, many microbes capture factor H (FH), the key soluble complement-regulating protein in human plasma. However, FH is normally an active complement suppressor exclusively on self-surfaces and this selective action of FH is pivotal to self versus non-self discrimination by the complement system. We investigated whether the bacterially captured FH becomes functionally enhanced and, if so, how this is achieved at a structural level. We found, using site-directed and truncation mutagenesis, surface plasmon resonance, nuclear magnetic resonance spectroscopy, and cross-linking and mass spectrometry, that the N-terminal domain of Streptococcus pneumoniae protein PspC (PspCN) not only binds FH extraordinarily tightly but also holds it in a previously uncharacterized conformation. Functional enhancement arises from exposure of a C-terminal cryptic second binding site in FH for C3b, the activation-specific fragment of the pivotal complement component, C3. This conformational change of FH doubles its affinity for C3b and increases 5-fold its ability to accelerate decay of the binary enzyme (C3bBb) responsible for converting C3 to C3b in an amplification loop. Despite not sharing critical FH-binding residues, PspCNs from D39 and Tigr4 S. pneumoniae exhibit similar FH-anchoring and enhancing properties. We propose that these bacterial proteins mimic molecular markers of self-surfaces, providing a compelling hypothesis for how FH prevents complement-mediated injury to host tissue while lacking efficacy on virtually all other surfaces. In hemolysis assays with 2-aminoethylisothiouronium bromide–treated erythrocytes that recapitulate paroxysmal nocturnal hemoglobinuria, PspCN enhanced protection of cells by FH, suggesting a new paradigm for therapeutic complement suppression. PMID:26459349

  16. COMPLEMENT-FIXATION TITERS IN EXPERIMENTAL COCCIDIOIDOMYCOSIS IN RABBITS1

    PubMed Central

    Brosbe, Edwin A.; Kietzman, Jewell N.; Kurnick, Nathaniel B.

    1964-01-01

    Brosbe, Edwin A. (Veterans Administration Hospital, Long Beach, Calif.), Jewell N. Kietzman, and Nathaniel B. Kurnick. Complement-fixation titers in experimental coccidioidomycosis. J. Bacteriol. 88:233–241. 1964.—The course of experimental coccicioidomycosis in rabbits was followed with complement-fixation (CF) tests. Uniformity of complement-fixing antibody response to large infective doses was observed, and levels as high as 1:4,096 in the New Zealand albino and 1:16,384 in the Dutch rabbit were attained. Mortality reflected the size of the inoculum rather than the level of CF titer. Animals receiving additional challenges displayed no marked elevation in titer, although high titers persisted. Nitrogen mustard, for the most part, did not influence the CF titer. Images PMID:14197893

  17. Cockayne syndrome complementation group B associated with xeroderma pigmentosum phenotype.

    PubMed

    Itoh, T; Cleaver, J E; Yamaizumi, M

    1996-02-01

    Two siblings have been reported whose clinical manifestations (cutaneous photosensitivity and central nervous system dysfunction) are strongly reminiscent of the DeSanctis-Cacchione syndrome (DCS) variant of xeroderma pigmentosum (XP), a severe form of XP. Fibroblasts from the siblings showed UV sensitivity, a failure of recovery of RNA synthesis (RRS) after UV-irradiation, and a normal level of unscheduled DNA synthesis (UDS), which were, unexpectedly, the biochemical characteristics usually associated with Cockayne syndrome (CS). However, no complementation group assignment in these cells has yet been performed. We here report that these patients can be assigned to CS complementation group B (CSB) by cell fusion complementation analysis. To our knowledge, these are the first patients with defects in the CSB gene to be associated with an XP phenotype. The results imply that the gene product from the CSB gene must interact with the gene products involved in excision repair and associated with XP.

  18. Serum immunoglobulins and complement (C'3) in oral lichen planus.

    PubMed

    Sklavounou, A D; Laskaris, G; Angelopoulos, A P

    1983-01-01

    Serum immunoglobulins and complement (C'3) were determined by single radial immunodiffusion according to the method of Mancini and co-workers in fifty patients with oral lichen planus and twenty persons with clinically normal oral mucosa. Significantly increased levels of serum IgG (p less than 0.05) and a significant reduction of serum IgA concentration (p less than 0.05) in the experimental group as compared with normal controls were observed. Mean serum IgM and complement (C'3) levels were similar in patients and controls. No correlation between disease variety or extensiveness and immunoglobulin or complement levels was noticed. These results suggest that patients with oral lichen planus may have a generalized immunologic disorder in which humoral immunity is disturbed. Whether humoral immunity is of etiologic significance, contributes to the disease process, or, finally, represents an event secondary to the pathologic changes seen in the disease remains to be determined.

  19. The Complement System in Neuropathic and Postoperative Pain

    PubMed Central

    Fritzinger, David C.; Benjamin, Daniel E.

    2017-01-01

    Certain types of pain are major unmet medical needs that affect more than 8 percent of the population. Neuropathic pain can be caused by many pathogenic processes including injury, autoimmune disease, neurological disease, endocrine dysfunction, infection, toxin exposure, and substance abuse and is frequently resistant to available pain therapies. The same can be said of postsurgical pain, which can arise from uncontrolled inflammation around the wound site. The complement system is part of the innate immune system and can both initiate and sustain acute and chronic inflammatory pain. Here we review the complement system and original investigations that identify potential drug targets within this system. Drugs that act to inhibit the complement system could fill major gaps in our current standard of care for neuropathic pain states. PMID:28154610

  20. Variants in Complement Factor H and Complement Factor H-Related Protein Genes, CFHR3 and CFHR1, Affect Complement Activation in IgA Nephropathy

    PubMed Central

    Zhu, Li; Zhai, Ya-Ling; Wang, Feng-Mei; Hou, Ping; Lv, Ji-Cheng; Xu, Da-Min; Shi, Su-Fang; Liu, Li-Jun; Yu, Feng; Zhao, Ming-Hui; Novak, Jan; Gharavi, Ali G.

    2015-01-01

    Complement activation is common in patients with IgA nephropathy (IgAN) and associated with disease severity. Our recent genome-wide association study of IgAN identified susceptibility loci on 1q32 containing the complement regulatory protein-encoding genes CFH and CFHR1–5, with rs6677604 in CFH as the top single-nucleotide polymorphism and CFHR3–1 deletion (CFHR3–1∆) as the top signal for copy number variation. In this study, to explore the clinical effects of variation in CFH, CFHR3, and CFHR1 on IgAN susceptibility and progression, we enrolled two populations. Group 1 included 1178 subjects with IgAN and available genome-wide association study data. Group 2 included 365 subjects with IgAN and available clinical follow-up data. In group 1, rs6677604 was associated with mesangial C3 deposition by genotype–phenotype correlation analysis. In group 2, we detected a linkage between the rs6677604-A allele and CFHR3–1∆ and found that the rs6677604-A allele was associated with higher serum levels of CFH and lower levels of the complement activation split product C3a. Furthermore, CFH levels were positively associated with circulating C3 levels and negatively associated with mesangial C3 deposition. Moreover, serum levels of the pathogenic galactose-deficient glycoform of IgA1 were also associated with the degree of mesangial C3 deposition in patients with IgAN. Our findings suggest that genetic variants in CFH, CFHR3, and CFHR1 affect complement activation and thereby, predispose patients to develop IgAN. PMID:25205734

  1. Quantitative Modeling of the Alternative Pathway of the Complement System

    PubMed Central

    Dorado, Angel; Morikis, Dimitrios

    2016-01-01

    The complement system is an integral part of innate immunity that detects and eliminates invading pathogens through a cascade of reactions. The destructive effects of the complement activation on host cells are inhibited through versatile regulators that are present in plasma and bound to membranes. Impairment in the capacity of these regulators to function in the proper manner results in autoimmune diseases. To better understand the delicate balance between complement activation and regulation, we have developed a comprehensive quantitative model of the alternative pathway. Our model incorporates a system of ordinary differential equations that describes the dynamics of the four steps of the alternative pathway under physiological conditions: (i) initiation (fluid phase), (ii) amplification (surfaces), (iii) termination (pathogen), and (iv) regulation (host cell and fluid phase). We have examined complement activation and regulation on different surfaces, using the cellular dimensions of a characteristic bacterium (E. coli) and host cell (human erythrocyte). In addition, we have incorporated neutrophil-secreted properdin into the model highlighting the cross talk of neutrophils with the alternative pathway in coordinating innate immunity. Our study yields a series of time-dependent response data for all alternative pathway proteins, fragments, and complexes. We demonstrate the robustness of alternative pathway on the surface of pathogens in which complement components were able to saturate the entire region in about 54 minutes, while occupying less than one percent on host cells at the same time period. Our model reveals that tight regulation of complement starts in fluid phase in which propagation of the alternative pathway was inhibited through the dismantlement of fluid phase convertases. Our model also depicts the intricate role that properdin released from neutrophils plays in initiating and propagating the alternative pathway during bacterial infection. PMID

  2. 670-nm light treatment reduces complement propagation following retinal degeneration

    PubMed Central

    2012-01-01

    Aim Complement activation is associated with the pathogenesis of age-related macular degeneration (AMD). We aimed to investigate whether 670-nm light treatment reduces the propagation of complement in a light-induced model of atrophic AMD. Methods Sprague–Dawley (SD) rats were pretreated with 9 J/cm2 670-nm light for 3 minutes daily over 5 days; other animals were sham treated. Animals were exposed to white light (1,000 lux) for 24 h, after which animals were kept in dim light (5 lux) for 7 days. Expression of complement genes was assessed by quantitative polymerase chain reaction (qPCR), and immunohistochemistry. Counts were made of C3-expressing monocytes/microglia using in situ hybridization. Photoreceptor death was also assessed using outer nuclear layer (ONL) thickness measurements, and oxidative stress using immunohistochemistry for 4-hydroxynonenal (4-HNE). Results Following light damage, retinas pretreated with 670-nm light had reduced immunoreactivity for the oxidative damage maker 4-HNE in the ONL and outer segments, compared to controls. In conjunction, there was significant reduction in retinal expression of complement genes C1s, C2, C3, C4b, C3aR1, and C5r1 following 670 nm treatment. In situ hybridization, coupled with immunoreactivity for the marker ionized calcium binding adaptor molecule 1 (IBA1), revealed that C3 is expressed by infiltrating microglia/monocytes in subretinal space following light damage, which were significantly reduced in number after 670 nm treatment. Additionally, immunohistochemistry for C3 revealed a decrease in C3 deposition in the ONL following 670 nm treatment. Conclusions Our data indicate that 670-nm light pretreatment reduces lipid peroxidation and complement propagation in the degenerating retina. These findings have relevance to the cellular events of complement activation underling the pathogenesis of AMD, and highlight the potential of 670-nm light as a non-invasive anti-inflammatory therapy. PMID:23181358

  3. Gene for ataxia-telangiectasia complementation group D (ATDC)

    DOEpatents

    Murnane, J.P.; Painter, R.B.; Kapp, L.N.; Yu, L.C.

    1995-03-07

    Disclosed herein is a new gene, an AT gene for complementation group D, the ATDC gene and fragments thereof. Nucleic acid probes for the gene are provided as well as proteins encoded by the gene, cDNA therefrom, preferably a 3 kilobase (kb) cDNA, and recombinant nucleic acid molecules for expression of the proteins. Further disclosed are methods to detect mutations in the gene, preferably methods employing the polymerase chain reaction (PCR). Also disclosed are methods to detect AT genes from other AT complementation groups. 30 figs.

  4. Animal venoms/toxins and the complement system.

    PubMed

    Tambourgi, Denise V; van den Berg, Carmen W

    2014-10-01

    Nature is a wealthy source of agents that have been shown to be beneficial to human health, but nature is also a rich source of potential dangerous health damaging compounds. This review will summarise and discuss the agents from the animal kingdom that have been shown to interact with the human complement (C) system. Most of these agents are toxins found in animal venoms and animal secretions. In addition to the mechanism of action of these toxins, their contribution to the field of complement, their role in human pathology and the potential benefit to the venomous animal itself will be discussed. Potential therapeutic applications will also be discussed.

  5. Gene for ataxia-telangiectasia complementation group D (ATDC)

    DOEpatents

    Murnane, John P.; Painter, Robert B.; Kapp, Leon N.; Yu, Loh-Chung

    1995-03-07

    Disclosed herein is a new gene, an AT gene for complementation group D, the ATDC gene and fragments thereof. Nucleic acid probes for said gene are provided as well as proteins encoded by said gene, cDNA therefrom, preferably a 3 kilobase (kb) cDNA, and recombinant nucleic acid molecules for expression of said proteins. Further disclosed are methods to detect mutations in said gene, preferably methods employing the polymerase chain reaction (PCR). Also disclosed are methods to detect AT genes from other AT complementation groups.

  6. Restricted Quadratic Forms, Inertia Theorems and the Schur Complement,

    DTIC Science & Technology

    1985-01-01

    subspace S , the usual orthogonal complement of S. Definition 3.1. For an mxn matrix C, the generalized , or Moore - Penrose , inverse is the unique nym...References D. Carlson, E. Haynsworth and T. Markham (1974); A generalization of the Schur complement by means of the Moore - Penrose Inverse , SIAM 3...A The results of §2 are direct in the sense that they do not Involve any inversion of the matrix A. It will here be shown that when the Moore - Penrose

  7. Reincarnation of ancient links between coagulation and complement.

    PubMed

    Conway, E M

    2015-06-01

    Throughout evolution, organisms have developed means to contain wounds by simultaneously limiting bleeding and eliminating pathogens and damaged host cells via the recruitment of innate defense mechanisms. Disease emerges when there is unchecked activation of innate immune and/or coagulation responses. A key component of innate immunity is the complement system. Concurrent excess activation of coagulation and complement - two major blood-borne proteolytic pathways - is evident in numerous diseases, including atherosclerosis, diabetes, venous thromboembolic disease, thrombotic microangiopathies, arthritis, cancer, and infectious diseases. Delineating the cross-talk between these two cascades will uncover novel therapeutic insights.

  8. Decay-accelerating factor (CD55), a glycosylphosphatidylinositol-anchored complement regulatory protein, is a receptor for several echoviruses.

    PubMed Central

    Bergelson, J M; Chan, M; Solomon, K R; St John, N F; Lin, H; Finberg, R W

    1994-01-01

    Echoviruses are human pathogens belonging to the picornavirus family. Decay-accelerating factor (DAF) is a glycosylphosphatidylinositol (GPI)-anchored surface protein that protects cells from lysis by autologous complement. Anti-DAF monoclonal antibodies prevented echovirus 7 attachment to susceptible cells and protected cells from infection. HeLa cells specifically lost the capacity to bind echovirus 7 when treated with phosphatidylinositol-specific phospholipase C, an enzyme that releases GPI-anchored proteins from the cell surface, indicating that the virus receptor, like DAF, is a GPI-anchored protein. Although Chinese hamster ovary cells do not bind echovirus 7, transfectants expressing human DAF bound virus efficiently, and binding was prevented by pretreatment with an anti-DAF monoclonal antibody. Anti-DAF antibodies prevented infection by at least six echovirus serotypes. These results indicate that DAF is the receptor mediating attachment and infection by several echoviruses. Images PMID:7517044

  9. Antibody-Dependent Enhancement of Dengue Virus Infection in Primary Human Macrophages; Balancing Higher Fusion against Antiviral Responses

    PubMed Central

    Flipse, Jacky; Diosa-Toro, Mayra A.; Hoornweg, Tabitha E.; van de Pol, Denise P. I.; Urcuqui-Inchima, Silvio; Smit, Jolanda M.

    2016-01-01

    The dogma is that the human immune system protects us against pathogens. Yet, several viruses, like dengue virus, antagonize the hosts’ antibodies to enhance their viral load and disease severity; a phenomenon called antibody-dependent enhancement of infection. This study offers novel insights in the molecular mechanism of antibody-mediated enhancement (ADE) of dengue virus infection in primary human macrophages. No differences were observed in the number of bound and internalized DENV particles following infection in the absence and presence of enhancing concentrations of antibodies. Yet, we did find an increase in membrane fusion activity during ADE of DENV infection. The higher fusion activity is coupled to a low antiviral response early in infection and subsequently a higher infection efficiency. Apparently, subtle enhancements early in the viral life cycle cascades into strong effects on infection, virus production and immune response. Importantly, and in contrast to other studies, the antibody-opsonized virus particles do not trigger immune suppression and remain sensitive to interferon. Additionally, this study gives insight in how human macrophages interact and respond to viral infections and the tight regulation thereof under various conditions of infection. PMID:27380892

  10. Cigarette smoke can activate the alternative pathway of complement in vitro by modifying the third component of complement.

    PubMed Central

    Kew, R R; Ghebrehiwet, B; Janoff, A

    1985-01-01

    Cigarette smoking is associated with significant increases in the number of pulmonary mononuclear phagocytes and neutrophils. A potent chemoattractant for these cells is C5a, a peptide generated during complement (C) activation. We, therefore, investigated the possibility that cigarette smoke could activate the complement system in vitro. Our results show that factor(s) (mol wt less than 1,000) present in an aqueous solution of whole, unfiltered cigarette smoke can deplete the hemolytic capacity of whole human serum in a dose-dependent manner. The particle-free, filtered gas phase of cigarette smoke is inactive. The smoke factor(s) do not activate serum C1, but do deplete serum C4 activity. Treatment of purified human C3 with whole smoke solution modifies the molecule such that its subsequent addition to serum (containing Mg/EGTA to block the classical pathway) results in consumption of hemolytic complement by activation of the alternative pathway. Smoke-modified C3 shows increased anodal migration in agarose electrophoresis, but this is not due to proteolytic cleavage of the molecule as evidenced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In contrast to methylamine-treated C3, C3 treated with smoke is only partially susceptible to the action of the complement regulatory proteins Factors H and I. In addition, smoke-modified C3 has diminished binding to Factor H as compared with methylamine-treated C3. Finally, smoke-modified C3 incorporates [14C]methylamine which suggests that the thiolester bond may be intact. These data indicate that aqueous whole cigarette smoke solution can modify C3 and activate the alternative pathway of complement, perhaps by a previously unrecognized mechanism. Should this occur in vivo, complement activation might partly account for the extensive pulmonary leukocyte recruitment observed in smokers. Images PMID:3156879

  11. Optimization of the virus concentration method using polyethyleneimine-conjugated magnetic beads and its application to the detection of human hepatitis A, B and C viruses.

    PubMed

    Uchida, Eriko; Kogi, Mieko; Oshizawa, Tadashi; Furuta, Birei; Satoh, Koei; Iwata, Akiko; Murata, Mitsuhiro; Hikata, Mikio; Yamaguchi, Teruhide

    2007-07-01

    To enhance the sensitivity of virus detection by polymerase chain reaction (PCR) and reverse transcription PCR (RT-PCR), a novel virus concentration method using polyethyleneimine (PEI)-conjugated magnetic beads was developed in our previous study. However, several viruses could not be concentrated by this method. In this paper, the conditions of virus concentration were optimized to concentrate a wide range of viruses more efficiently. The PEI beads adsorbed viruses more efficiently than other cationic polymers, and the optimum virus concentration was obtained under weak acidic conditions. Mass spectrometric analysis revealed that several serum proteins, such as complement type 3, complement type 4 and immunoglobulin M (IgM), were co-adsorbed by the PEI beads, suggesting that the beads may adsorb viruses not only by direct adsorption, but also via immune complex formation. This hypothesis was confirmed by the result that poliovirus, which PEI beads could not adsorb directly, could be concentrated by the beads via immune complex formation. On the other hand, hepatitis A (HAV) and hepatitis C (HCV) viruses were adsorbed directly by PEI beads almost completely. Like poliovirus, hepatitis B virus (HBV) was concentrated efficiently by the addition of anti-HBV IgM. In conclusion, virus concentration using PEI beads is a useful method to concentrate a wide range of viruses and can be used to enhance the sensitivity of detection of HAV, HBV and HCV.

  12. [Norwalk virus and Noro virus].

    PubMed

    Furuta, Itaru; Yamazumi, Toshiaki; Kitahashi, Toshiaki; Yagi, Kazurou; Takemura, Tukasa

    2003-01-01

    Norwalk virus and Noro virus are members of the Caliciviridae. These viruses are morphological similarity in each other and shows small round structure. These viruses also are well known as main pathogens of acute infectious gastroenteritis. Clinical features include an incubation period of 24 of 48 hours and illness period of 18 to 72 hours with vomiting and diarrhea in most patients and high secondary attack rates. Oral transmitted infection occurs contaminated water and foods. In our country, outbreak of Noro virus-related gastroenteritis are reported sometimes in hospital and nursing home from winter to early spring seasons. This article are described to the morphlogy, physical characteristics, epidemiology, and clinical manifestation relating to Norwalk virus and Noro virus.

  13. Cercarial glycocalyx of Schistosoma mansoni activates human complement.

    PubMed Central

    Samuelson, J C; Caulfield, J P

    1986-01-01

    Human complement activation by cercariae and schistosomula of the human parasite Schistosoma mansoni was studied in vitro. Cercariae are composed of tails which are shed after infection of the host and bodies which transform into the larvae or schistosomula after infection. After incubation in fresh normal human serum (NHS), cercarial tails bound more anti-C3 antibodies than did cercarial bodies (CB), and the tails were rapidly lysed, while the attached CB remained intact. Complement activation by cercariae was dependent on the alternative pathway but was independent of antibody, as shown by C3 deposition by hypogammaglobulinemic human sera. By transmission microscopy, the fibrillar glycocalyx on both CB and tails was stained by NHS but not by heat-inactivated serum (HI-NHS). The glycocalyx was labeled with periodate and tritiated borohydride, and parasites were incubated in NHS and HI-NHS. After solubilization, the labeled glycocalyx on organisms incubated in NHS but not HI-NHS bound anti-C3 antibodies. Of the CB incubated with eserine sulfate to prevent transformation, 78% +/- 10% were dead after culture for 24 h in NHS. In contrast, 21% +/- 12% of the CB were dead after culture in HI-NHS. Schistosomula incubated in NHS bound 37% of the amount of anti-C3 antibodies bound by cercariae but were not killed by NHS. In conclusion, the cercarial glycocalyx activated human complement, and schistosomula were less susceptible to killing than cercariae because they had less glycocalyx and activated less complement. Images PMID:3940995

  14. Children's Understanding of the Addition/Subtraction Complement Principle

    ERIC Educational Resources Information Center

    Torbeyns, Joke; Peters, Greet; De Smedt, Bert; Ghesquière, Pol; Verschaffel, Lieven

    2016-01-01

    Background: In the last decades, children's understanding of mathematical principles has become an important research topic. Different from the commutativity and inversion principles, only few studies have focused on children's understanding of the addition/subtraction complement principle (if a - b = c, then c + b = a), mainly relying on verbal…

  15. Loss of Infinitival Complementation in Romanian Diachronic Syntax

    ERIC Educational Resources Information Center

    Jordan, Maria

    2009-01-01

    For the most part, my study is a descriptive analysis of infinitival complement clauses and the corresponding subjunctive clauses in Romanian, that is, obligatory control (OC) structures. OC is a relation of obligatory coreferentiality between a matrix argument (controller) and the null subject of the subordinate (controlee) of the same sentence.…

  16. Complement activation of electrogenic ion transport in isolated rat colon.

    PubMed

    McCole, D F; Otti, B; Newsholme, P; Baird, A W

    1997-11-15

    The complement cascade is an important component in many immune and inflammatory reactions and may contribute to both the diarrhoea and inflammation associated with inflammatory bowel disease. Isolated rat colonic mucosae were voltage clamped in Ussing chambers. Basolateral addition of zymosan-activated whole human serum (ZAS) induced a rapid onset, transient inward short circuit current (SCC). This response was concentration dependent and was significantly attenuated by pre-heating ZAS at 60 degrees C for 30 min. Depletion of complement from normal human serum with cobra venom factor (CVF) significantly lowered SCC responses. Chloride was the primary charge carrying ion as responses to ZAS were abolished in the presence of the loop diuretic bumetanide. The complement component C3a stimulated ion transport but not to the same extent as whole serum. Exogenous C5 was without effect. The cyclooxygenase inhibitor piroxicam significantly attenuated the response to ZAS. These findings support the possibility that complement activation may contribute to the pathophysiology of secretory diarrhoea since activation of electrogenic chloride secretion converts intestinal epithelia to a state of net fluid secretion.

  17. Juvenile Justice and a Strengths Perspective: Complement or Clash?

    ERIC Educational Resources Information Center

    Clark, Michael D.

    2009-01-01

    Does the new realm of positive psychology and strength-based strategies complement or clash with the remedial discipline of social control traditionally practiced in juvenile justice programs? Many welcome the balance of positive psychology, the strengths perspective, and coping and resilience studies. Although emerging from different disciplines,…

  18. Detection of surface bound complement at increasing serum anticoagulant concentrations.

    PubMed

    Arvidsson, S; Askendal, A; Lindahl, T L; Tengvall, P

    2008-04-01

    Surface mediated immune complement activation can be detected by a variety of antibody utilizing methods such as ELISA, fluorescence- or radiolabelling techniques, QCM, and ellipsometry. In the present work we investigated how the common anticoagulants heparin, dalteparin, fondaparinux and sodium citrate affected the binding of anti-complement factor 3c (anti-C3c) on a model complement activator surface, immobilised IgG, after incubation in human blood serum. The results show, as expected, that different anticoagulants affect the antibody binding differently. Increasing amounts of heparin, dalteparin and sodium citrate in normal serum resulted in a decreasing anti-C3c binding. The antibody deposition was not sensitive for the fondaparinux concentration. Surprisingly high concentrations of anti-coagulantia were needed to completely eradicate the antibody binding. Experiments in EGTA-serum showed that anticoagulants interfered directly with both the classical and alternative pathways. Control C3a-des arg ELISA measurements show that the lowered antibody surface binding was not a result of complement depletion in serum. Kallikrein generation by hydrophilic glass surfaces was not affected by high anticoagulant concentrations.

  19. Complement and contact activation in term neonates after fetal acidosis

    PubMed Central

    Sonntag, J.; Wagner, M.; Strauss, E.; Obladen, M.

    1998-01-01

    AIMS—To evaluate complement and contact activation after fetal acidosis.
METHODS—Fifteen term neonates with hypoxic-ischaemic encephalopathy after umbilical arterial pH < 7.10 were compared with 15 healthy neonates with umbilical arterial pH > 7.20. Determinations of the complement function and C1-inhibitor activity were performed as kinetic tests 22-28 hours after birth. C1q, C1-inhibitor, and factor B concentrations were determined by radial immunodiffusion and those of C3a, C5a, and factor XIIa by enzyme immunoabsorbent assay.
RESULTS—Median complement function (46 vs 73 %), C1q (4.3 vs 9.1 mg/dl), and factor B (5.2 vs 7.7 mg/dl) decreased after fetal acidosis. The activated split products C3a (260 vs 185 µg/l), C5a (5.0 vs 0.6 µg/l), and factor XIIa (3.2 vs 1.3 µg/l) increased in the neonates after fetal acidosis. No differences were found in the concentration and activity of C1-inhibitor.
CONCLUSIONS—Complement and contact activation occurred in the newborns with hypoxic-ischaemic encephalopathy. Activation of these systems generates mediators which can trigger inflammation and tissue injury.

 PMID:9577283

  20. Heterogeneity of Lethals in a "Simple" Lethal Complementation Group

    PubMed Central

    Janca, Frank C.; Woloshyn, Effie P.; Nash, David

    1986-01-01

    Of 24 ethyl methanesulphonate-induced, recessive-lethal mutations in the region 9E1-9F13 of the X chromosome of Drosophila melanogaster , eight fall into a typically homogeneous lethal complementation group associated with the raspberry (ras) locus. Mutations in this group have previously been shown to be pleiotropic, affecting not only ras but also two other genetic entities, gua1 and pur1, which yield auxotrophic mutations.—The eight new mutations have been characterized phenotypically in double heterozygotes with gua1, pur1 and ras mutations. Despite their homogeneity in lethal complementation tests, the mutations prove quite diverse. For example, two mutations have little or no effect on eye color in double heterozygotes with ras2 . The differences between the lethals are allele-specific and cannot be explained as a trivial outcome of a hypomorphic series.—Taken alone, the lethal complementation studies mask the complexity of the locus and the diversity of its recessive lethal alleles. By extension, we argue that the general use of lethal saturation studies provides an unduly simplified image of genetic organization. We suggest that the reason why recessive lethal mutations rarely present complex complementation patterns is that complex loci tend to produce mutations that affect several subfunctions. PMID:3080355

  1. Activated Complement Factors as Disease Markers for Sepsis

    PubMed Central

    Charchaflieh, Jean; Rushbrook, Julie; Worah, Samrat; Zhang, Ming

    2015-01-01

    Sepsis is a leading cause of death in the United States and worldwide. Early recognition and effective management are essential for improved outcome. However, early recognition is impeded by lack of clinically utilized biomarkers. Complement factors play important roles in the mechanisms leading to sepsis and can potentially serve as early markers of sepsis and of sepsis severity and outcome. This review provides a synopsis of recent animal and clinical studies of the role of complement factors in sepsis development, together with their potential as disease markers. In addition, new results from our laboratory are presented regarding the involvement of the complement factor, mannose-binding lectin, in septic shock patients. Future clinical studies are needed to obtain the complete profiles of complement factors/their activated products during the course of sepsis development. We anticipate that the results of these studies will lead to a multipanel set of sepsis biomarkers which, along with currently used laboratory tests, will facilitate earlier diagnosis, timely treatment, and improved outcome. PMID:26420913

  2. The Importance of Being a Complement: CED Effects Revisited

    ERIC Educational Resources Information Center

    Jurka, Johannes

    2010-01-01

    This dissertation revisits subject island effects (Ross 1967, Chomsky 1973) cross-linguistically. Controlled acceptability judgment studies in German, English, Japanese and Serbian show that extraction out of specifiers is consistently degraded compared to extraction out of complements, indicating that the Condition on Extraction domains (CED,…

  3. Hair: A Diagnostic Tool to Complement Blood Serum and Urine.

    ERIC Educational Resources Information Center

    Maugh, Thomas H., II

    1978-01-01

    Trace elements and some drugs can be identified in hair and it seems likely that other organic chemicals will be identifiable in the future. Since hair is so easily collected, stored, and analyzed it promises to be an ideal complement to serum and urine analysis as a diagnostic tool. (BB)

  4. Complement activation and effect of eculizumab in scleroderma renal crisis

    PubMed Central

    Devresse, Arnaud; Aydin, Selda; Le Quintrec, Moglie; Demoulin, Nathalie; Stordeur, Patrick; Lambert, Catherine; Gastoldi, Sara; Pirson, Yves; Jadoul, Michel; Morelle, Johann

    2016-01-01

    Abstract Background: Scleroderma renal crisis (SRC) is a life-threatening complication of systemic sclerosis characterized by abrupt onset of hypertension, thrombotic microangiopathy, and kidney injury. The mechanisms of the disease remain ill-defined, but a growing body of evidence suggests that activation of the complement system may be involved. Methods: Here, we report the case of a patient presenting with severe SRC and strong evidence of complement activation, both in serum and in the kidney, in the absence of genetic defect of the complement system. Results: Immunofluorescence studies on kidney biopsy showed significant deposits of C1q and C4d in the endothelium of renal arterioles, pointing toward activation of the classical pathway. Because of the dramatic clinical and histological severity, and the lack of response to early treatment with angiotensin-converting enzyme inhibitors, calcium channel blockers and plasma exchange, the patient was treated with the specific C5 blocker eculizumab. Contrarily to conventional treatment, eculizumab efficiently blocked C5b-9 deposition ex vivo and maintained hematological remission. Unfortunately, the patient died from heart failure a few weeks later. Postmortem examination of the heart showed diffuse patchy interstitial fibrosis, the typical lesion of systemic sclerosis-related cardiomyopathy, but normal coronary arteries and myocardial microvasculature. Conclusion: SRC may lead to complement system activation through the classical pathway. Early administration of C5 inhibitor eculizumab may have therapeutic potential in patients with life-threatening SRC refractory to conventional treatment using angiotensin-converting enzyme inhibitors. PMID:27472742

  5. Complement modulates the cutaneous microbiome and inflammatory milieu

    PubMed Central

    Chehoud, Christel; Rafail, Stavros; Tyldsley, Amanda S.; Seykora, John T.; Lambris, John D.; Grice, Elizabeth A.

    2013-01-01

    The skin is colonized by a plethora of microbes that include commensals and potential pathogens, but it is currently unknown how cutaneous host immune mechanisms influence the composition, diversity, and quantity of the skin microbiota. Here we reveal an interactive role for complement in cutaneous host–microbiome interactions. Inhibiting signaling of the complement component C5a receptor (C5aR) altered the composition and diversity of the skin microbiota as revealed by deep sequencing of the bacterial 16S rRNA gene. In parallel, we demonstrate that C5aR inhibition results in down-regulation of genes encoding cutaneous antimicrobial peptides, pattern recognition receptors, and proinflammatory mediators. Immunohistochemistry of inflammatory cell infiltrates in the skin showed reduced numbers of macrophages and lymphocytes with C5aR inhibition. Further, comparing cutaneous gene expression in germ-free mice vs. conventionally raised mice suggests that the commensal microbiota regulates expression of complement genes in the skin. These findings demonstrate a component of host immunity that impacts colonization of the skin by the commensal microbiota and vice versa, a critical step toward understanding host–microbe immune mutualism of the skin and its implications for health and disease. Additionally, we reveal a role for complement in homeostatic host–microbiome interactions of the skin. PMID:23980152

  6. 21 CFR 866.5240 - Complement components immunological test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Complement components immunological test system. 866.5240 Section 866.5240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunological Test Systems §...

  7. 21 CFR 866.5240 - Complement components immunological test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Complement components immunological test system. 866.5240 Section 866.5240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunological Test Systems §...

  8. Complement and IL-22: partnering up for border patrol.

    PubMed

    Yamamoto, Hidekazu; Kemper, Claudia

    2014-10-16

    Intestinal pathobionts that escape into the periphery can cause serious morbidity and death. In this issue of Immunity, Hasegawa et al. (2014) show that the host's protective measures against such events include interleukin-22-driven systemic elimination of pathobionts via complement regulation.

  9. Complementation of multiple sulfatase deficiency in somatic cell hybrids.

    PubMed

    Fedde, K; Horwitz, A L

    1984-05-01

    Multiple sulfatase deficiency (MSD) is an inherited disorder characterized by deficient activity of seven different sulfatases. Genetic complementation for steroid sulfatase (STS), arylsulfatase A, and N-acetylgalactosamine 6-SO4 sulfatase was demonstrated in somatic cell hybrids between MSD fibroblasts and mouse cells ( LA9 ) or Chinese hamster cells ( CHW ). In an electrophoretic system that separates human and rodent STS isozymes, enzyme from hybrids migrated as human enzyme. We concluded that the rodent cell complemented the MSD deficiency and allowed normal expression of the STS structural gene. Some MSD- LA9 hybrids showed significant levels of human arylsulfatase A activity, as shown by the immunoprecipitation of active enzyme by human-specific antiserum. Complementation was also suggested for N-acetylgalactosamine 6- sulfatate sulfatase (GalNAc-6S sulfatase) in several MSD- LA9 hybrids by the demonstration of a significant increase in activity (10-fold) over that of the GalNAc-6S sulfatase-deficient parental mouse and MSD cells. Thus, it was possible to demonstrate complementation for more than one sulfatase in a single MSD-rodent hybrid. Normal levels of sulfatase activity in hybrids indicate that the sulfatase structural genes are intact in MSD cells.

  10. New high-cloning-efficiency vectors for complementation studies and recombinant protein overproduction in Escherichia coli and Salmonella enterica.

    PubMed

    VanDrisse, C M; Escalante-Semerena, J C

    2016-07-01

    Galloway et al. recently described a method to alter vectors to include Type IIS restriction enzymes for high efficiency cloning. Utilizing this method, the multiple cloning sites of complementation and overexpression vectors commonly used in our laboratory were altered to contain recognition sequences of the Type IIS restriction enzyme, BspQI. Use of this enzyme increased the rate of cloning success to >97% efficiency. L(+)-Arabinose-inducible complementation vectors and overexpression vectors encoding N-terminal recombinant tobacco etch virus protease (rTEV)-cleavable H6-tags were altered to contain BspQI sites that allowed for cloning into all vectors using identical primer overhangs. Additionally, a vector used for directing the synthesis of proteins with a C-terminal, rTEV-cleavable H6-tag was engineered to contain BspQI sites, albeit with different overhangs from that of the previously mentioned vectors. Here we apply a method used to engineer cloning vectors to contain BspQI sites and the use of each vector in either in vivo complementation studies or in vitro protein purifications.

  11. In planta protein interactions of three alphacryptoviruses and three betacryptoviruses from White Clover, Red Clover and Dill by bimolecular fluorescence complementation analysis.

    PubMed

    Lesker, Till; Maiss, Edgar

    2013-10-09

    Plant-infecting viruses of the genera Alpha- and Betacryptovirus within the family Partitiviridae cause no visible effects on their hosts and are only transmitted by cell division and through gametes. The bipartite dsRNA genome is encoding a RNA-dependent RNA polymerase (RdRp) and a coat protein (CP). Aside from sequence and structural analysis, the investigation of protein interactions is another step towards virus characterization. Therefore, ORFs of two type members White Clover Cryptic Virus 1 and 2 (WCCV-1 and WCCV-2), as well as the related viruses from Red Clover and Dill were introduced into a bimolecular fluorescence complementation assay. We showed CP-CP dimerization for all tested viruses with localization for alphacryptoviruses at the nuclear membrane and for betacryptoviruses close to cell walls within the cytoplasm. For CPs of WCCV-1 and WCCV-2, deletion mutants were created to determine internal interaction sites. Moreover, RdRp self-interaction was found for all viruses, whereas CP-RdRp interactions were only detectable for the alphacryptoviruses. An intra-genus test of CPs was successful in various virus combinations, whereas an inter-genus interaction of WCCV-1CP and WCCV-2CP was absent. This is the first report of in vivo protein interactions of members in the family Partitiviridae, indicating distinct features of the alpha- and betacryptoviruses.

  12. Pasteurella pneumotropica Evades the Human Complement System by Acquisition of the Complement Regulators Factor H and C4BP

    PubMed Central

    Sahagún-Ruiz, Alfredo; Granados Martinez, Adriana Patricia; Breda, Leandro Carvalho Dantas; Fraga, Tatiana Rodrigues; Castiblanco Valencia, Mónica Marcela; Barbosa, Angela Silva; Isaac, Lourdes

    2014-01-01

    Pasteurella pneumotropica is an opportunist Gram negative bacterium responsible for rodent pasteurellosis that affects upper respiratory, reproductive and digestive tracts of mammals. In animal care facilities the presence of P. pneumotropica causes severe to lethal infection in immunodeficient mice, being also a potential source for human contamination. Indeed, occupational exposure is one of the main causes of human infection by P. pneumotropica. The clinical presentation of the disease includes subcutaneous abscesses, respiratory tract colonization and systemic infections. Given the ability of P. pneumotropica to fully disseminate in the organism, it is quite relevant to study the role of the complement system to control the infection as well as the possible evasion mechanisms involved in bacterial survival. Here, we show for the first time that P. pneumotropica is able to survive the bactericidal activity of the human complement system. We observed that host regulatory complement C4BP and Factor H bind to the surface of P. pneumotropica, controlling the activation pathways regulating the formation and maintenance of C3-convertases. These results show that P. pneumotropica has evolved mechanisms to evade the human complement system that may increase the efficiency by which this pathogen is able to gain access to and colonize inner tissues where it may cause severe infections. PMID:25347183

  13. The role of complement in age-related macular degeneration: heparan sulphate, a ZIP code for complement factor H?

    PubMed

    Langford-Smith, Alex; Keenan, Tiarnan D L; Clark, Simon J; Bishop, Paul N; Day, Anthony J

    2014-01-01

    Age-related macular degeneration (AMD) is the leading cause of blindness in developed nations and has been associated with complement dysregulation in the central retina. The Y402H polymorphism in the complement regulatory protein factor H (CFH) can confer a >5-fold increased risk of developing AMD and is present in approximately 30% of people of European descent. CFH, in conjunction with other factors, regulates complement activation in host tissues, and the Y402H polymorphism has been found to alter the protein's specificity for heparan sulphate (HS) - a complex polysaccharide found ubiquitously in mammals. HS, which is present on the cell surface and also in the extracellular matrix, exhibits huge structural diversity due to variations in the level/pattern of sulphation, where particular structures may act as 'ZIP codes' for different tissue/cellular locations. Recent work has demonstrated that CFH contains two HS-binding domains that each recognize specific HS ZIP codes, allowing differential recognition of Bruch's membrane (in the eye) or the glomerular basement membrane (in the kidney). Importantly, the Y402H polymorphism impairs the binding of CFH to the HS in Bruch's membrane, which could result in increased complement activation and chronic local inflammation (in 402H individuals) and thereby contribute to AMD pathology.

  14. Plasma complement and vascular complement deposition in patients with coronary artery disease with and without inflammatory rheumatic diseases

    PubMed Central

    2017-01-01

    Purpose Inflammatory rheumatic diseases (IRD) are associated with accelerated coronary artery disease (CAD), which may result from both systemic and vascular wall inflammation. There are indications that complement may be involved in the pathogenesis of CAD in Systemic Lupus Erythematosus (SLE) and Rheumatoid Arthritis (RA). This study aimed to evaluate the associations between circulating complement and complement activation products with mononuclear cell infiltrates (MCI, surrogate marker of vascular inflammation) in the aortic media and adventitia in IRDCAD and non-IRDCAD patients undergoing coronary artery bypass grafting (CABG). Furthermore, we compared complement activation product deposition patterns in rare aorta adventitial and medial biopsies from SLE, RA and non-IRD patients. Methods We examined plasma C3 (p-C3) and terminal complement complexes (p-TCC) in 28 IRDCAD (SLE = 3; RA = 25), 52 non-IRDCAD patients, and 32 IRDNo CAD (RA = 32) from the Feiring Heart Biopsy Study. Aortic biopsies taken from the CAD only patients during CABG were previously evaluated for adventitial MCIs. The rare aortic biopsies from 3 SLE, 3 RA and 3 non-IRDCAD were assessed for the presence of C3 and C3d using immunohistochemistry. Results IRDCAD patients had higher p-TCC than non-IRDCAD or IRDNo CAD patients (p<0.0001), but a similar p-C3 level (p = 0.42). Circulating C3 was associated with IRD duration (ρ, p-value: 0.46, 0.03). In multiple logistic regression analysis, IRD remained significantly related to the presence and size of MCI (p<0.05). C3 was present in all tissue samples. C3d was detected in the media of all patients and only in the adventitia of IRD patients (diffuse in all SLE and focal in one RA). Conclusion The independent association of IRD status with MCI and the observed C3d deposition supports the unique relationship between rheumatic disease, and, in particular, SLE with the complement system. Exaggerated systemic and vascular complement activation may

  15. Development of Word Order in German Complement-Clause Constructions: Effects of Input Frequencies, Lexical Items, and Discourse Function

    ERIC Educational Resources Information Center

    Brandt, Silke; Lieven, Elena; Tomasello, Michael

    2010-01-01

    We investigate the development of word order in German children's spontaneous production of complement clauses. From soon after their second birthday, young German children use both verb final complements with complementizers and verb-second complements without complementizers. By their third birthday they use both kinds of complement clauses with…

  16. Complement Factor H Binds to Human Serum Apolipoprotein E and Mediates Complement Regulation on High Density Lipoprotein Particles.

    PubMed

    Haapasalo, Karita; van Kessel, Kok; Nissilä, Eija; Metso, Jari; Johansson, Tiira; Miettinen, Sini; Varjosalo, Markku; Kirveskari, Juha; Kuusela, Pentti; Chroni, Angelika; Jauhiainen, Matti; van Strijp, Jos; Jokiranta, T Sakari

    2015-11-27

    The alternative pathway of complement is an important part of the innate immunity response against foreign particles invading the human body. To avoid damage to host cells, it needs to be efficiently down-regulated by plasma factor H (FH) as exemplified by various diseases caused by mutations in its domains 19-20 (FH19-20) and 5-7 (FH5-7). These regions are also the main interaction sites for microbial pathogens that bind host FH to evade complement attack. We previously showed that inhibition of FH binding by a recombinant FH5-7 construct impairs survival of FH binding pathogens in human blood. In this study we found that upon exposure to full blood, the addition of FH5-7 reduces survival of, surprisingly, also those microbes that are not able to bind FH. This effect was mediated by inhibition of complement regulation and subsequently enhanced neutrophil phagocytosis by FH5-7. We found that although FH5-7 does not reduce complement regulation in the actual fluid phase of plasma, it reduces regulation on HDL particles in plasma. Using affinity chromatography and mass spectrometry we revealed that FH interacts with serum apolipoprotein E (apoE) via FH5-7 domains. Furthermore, binding of FH5-7 to HDL was dependent on the concentration of apoE on the HDL particles. These findings explain why the addition of FH5-7 to plasma leads to excessive complement activation and phagocytosis of microbes in full anticoagulated blood. In conclusion, our data show how FH interacts with apoE molecules via domains 5-7 and regulates alternative pathway activation on plasma HDL particles.

  17. Structure of the extracellular portion of CD46 provides insights into its interactions with complement proteins and pathogens.

    PubMed

    Persson, B David; Schmitz, Nikolaus B; Santiago, César; Zocher, Georg; Larvie, Mykol; Scheu, Ulrike; Casasnovas, José M; Stehle, Thilo

    2010-09-30

    The human membrane cofactor protein (MCP, CD46) is a central component of the innate immune system. CD46 protects autologous cells from complement attack by binding to complement proteins C3b and C4b and serving as a cofactor for their cleavage. Recent data show that CD46 also plays a role in mediating acquired immune responses, and in triggering autophagy. In addition to these physiologic functions, a significant number of pathogens, including select adenoviruses, measles virus, human herpes virus 6 (HHV-6), Streptococci, and Neisseria, use CD46 as a cell attachment receptor. We have determined the crystal structure of the extracellular region of CD46 in complex with the human adenovirus type 11 fiber knob. Extracellular CD46 comprises four short consensus repeats (SCR1-SCR4) that form an elongated structure resembling a hockey stick, with a long shaft and a short blade. Domains SCR1, SCR2 and SCR3 are arranged in a nearly linear fashion. Unexpectedly, however, the structure reveals a profound bend between domains SCR3 and SCR4, which has implications for the interactions with ligands as well as the orientation of the protein at the cell surface. This bend can be attributed to an insertion of five hydrophobic residues in a SCR3 surface loop. Residues in this loop have been implicated in interactions with complement, indicating that the bend participates in binding to C3b and C4b. The structure provides an accurate framework for mapping all known ligand binding sites onto the surface of CD46, thereby advancing an understanding of how CD46 acts as a receptor for pathogens and physiologic ligands of the immune system.

  18. The role of complement in C3 glomerulopathy.

    PubMed

    Zipfel, Peter F; Skerka, Christine; Chen, Qian; Wiech, Thorsten; Goodship, Tim; Johnson, Sally; Fremeaux-Bacchi, Veronique; Nester, Clara; de Córdoba, Santiago Rodríguez; Noris, Marina; Pickering, Matthew; Smith, Richard

    2015-09-01

    C3 glomerulopathy describes a spectrum of disorders with glomerular pathology associated with C3 cleavage product deposition and with defective complement action and regulation (Fakhouri et al., 2010; Sethi et al., 2012b). Kidney biopsies from these patients show glomerular accumulation or deposition of C3 cleavage fragments, but no or minor deposition of immunoglobulins (Appel et al., 2005; D'Agati and Bomback, 2012; Servais et al., 2007; Sethi and Fervenza, 2011). At present the current situation asks for a better definition of the underlining disease mechanisms, for precise biomarkers, and for a treatment for this disease. The complement system is a self activating and propelling enzymatic cascade type system in which inactive, soluble plasma components are activated spontaneously and lead into an amplification loop (Zipfel and Skerka, 2009). Activation of the alternative pathway is spontaneous, occurs by default, and cascade progression leads to amplification by complement activators. The system however is self-controlled by multiple regulators and inhibitors, like Factor H that control cascade progression in fluid phase and on surfaces. The activated complement system generates a series of potent effector components and activation products, which damage foreign-, as well as modified self cells, recruit innate immune cells to the site of action, coordinate inflammation and the response of the adaptive immune system in form of B cells and T lymphocytes (Kohl, 2006; Medzhitov and Janeway, 2002; Ogden and Elkon, 2006; Carroll, 2004; Kemper and Atkinson, 2007; Morgan, 1999; Muller-Eberhard, 1986; Ricklin et al., 2010). Complement controls homeostasis and multiple reactions in the vertebrate organism including defense against microbial infections (Diaz-Guillen et al., 1999; Mastellos and Lambris, 2002; Nordahl et al., 2004; Ricklin et al., 2010). In consequence defective control of the spontaneous self amplifying cascade or regulation is associated with numerous

  19. Complement activation in Ghanaian children with severe Plasmodium falciparum malaria

    PubMed Central

    Helegbe, Gideon K; Goka, Bamenla Q; Kurtzhals, Joergen AL; Addae, Michael M; Ollaga, Edwin; Tetteh, John KA; Dodoo, Daniel; Ofori, Michael F; Obeng-Adjei, George; Hirayama, Kenji; Awandare, Gordon A; Akanmori, Bartholomew D

    2007-01-01

    Background Severe anaemia (SA), intravascular haemolysis (IVH) and respiratory distress (RD) are severe forms of Plasmodium falciparum malaria, with RD reported to be of prognostic importance in African children with malarial anaemia. Complement factors have been implicated in the mechanism leading to excess anaemia in acute P. falciparum infection. Methods The direct Coombs test (DCT) and flow cytometry were used to investigate the mean levels of RBC-bound complement fragments (C3d and C3bαβ) and the regulatory proteins [complement receptor 1 (CD35) and decay accelerating factor (CD55)] in children with discrete clinical forms of P. falciparum malaria. The relationship between the findings and clinical parameters including coma, haemoglobin (Hb) levels and RD were investigated. Results Of the 484 samples tested, 131(27%) were positive in DCT, out of which 115/131 (87.8%) were positive for C3d alone while 16/131 (12.2%) were positive for either IgG alone or both. 67.4% of the study population were below 5 years of age and DCT positivity was more common in this age group relative to children who were 5 years or older (Odds ratio, OR = 3.8; 95%CI, 2.2–6.7, p < 0.001). DCT correlated significantly with RD (β = -304, p = 0.006), but multiple regression analysis revealed that, Hb (β = -0.341, p = 0.012) and coma (β = -0.256, p = 0.034) were stronger predictors of RD than DCT (β = 0.228, p = 0.061). DCT was also not associated with IVH, p = 0.19, while spleen size was inversely correlated with Hb (r = -402, p = 0.001). Flow cytometry showed similar mean fluorescent intensity (MFI) values of CD35, CD55 and C3bαβ levels on the surfaces of RBC in patients and asymptomatic controls (AC). However, binding of C3bαβ correlated significantly with CD35 or CD55 (p < 0.001). Conclusion These results suggest that complement activation contributed to anaemia in acute childhood P. falciparum malaria, possibly through induction of erythrophagocytosis and haemolysis. In

  20. Complement-dependent antibody cytotoxicity test of chicken antibody with duck complement used against cells of a Marek's disease lymphoma-derived cell line (MSB-1).

    PubMed

    Sugimoto, C; Kodama, H; Mikami, T

    1979-01-01

    Complement-dependent antibody cytotoxicity (CDAC) against cells of a lymphoblastoid cell line (MSB-1) derived from Marek's disease lymphoma was investigated in a chicken antibody system using complements from several animal species. Cytotoxicity was seldom observed when rabbit, guinea pig, or chicken complements were used in the presence of hyperimmune chicken serum against MSB-1. With duck complement, however, cytotoxicity was always observed. Therefore, duck complement appears to be suitable for assay of hyperimmune chicken serum against MSB-1 cells by the CDAC test.

  1. Phagocytic, Opsonic and Immunoglobulin Studies in Newborns

    PubMed Central

    Miller, Michael E.; Stiehm, E. Richard

    1973-01-01

    Despite improved diagnositc and therapeutic measures, neonatal septicemia continues to be a major clinical problem. Improvement in the management of the septic neonate should result from application of the increasing information being learned of the neonatal host defense mechanisms. The earlier concept that the neonate was “immunologically null” can now be discarded. Evidence summarized in this review has established that the neonate can marshal an immune response to most antigens and infectious agents. A further major advance in recent years has been in understanding of the inflammatory response in the neonate, which includes such activities as chemotaxis, phagocytosis and bactericidal killing of ingested bacteria by phagocytes. PMID:4580226

  2. Complements Spurned: Our Experience with Atypical Hemolytic Uremic Syndrome

    PubMed Central

    Nagar, Vidya S.; Chaterjee, Rudrarpan; Sood, Ankita; Sajjan, Basavaraj; Kaushik, Aniruddha; Vyahalkar, Sameer V.

    2017-01-01

    Atypical hemolytic uremic syndrome (aHUS) is a rare disorder resulting from a dysregulated activation of the alternative pathway of the complement system. It results in significant morbidity and mortality if not diagnosed and treated promptly. It lends itself to myriad renal and extrarenal manifestations, all potentially disabling. Eculizumab, a monoclonal antibody to complement C5 is now the widely accepted norm for treatment. However, in resource-limited settings, plasma exchange if instituted early may be as beneficial. We report a case of aHUS treated with extended plasma exchange with excellent results. Critical care monitoring is essential for the management of the disease in view of a tendency to develop multiple complications. Long-term immunosuppression may be successful in maintaining remission. PMID:28250608

  3. Schizophrenia risk from complex variation of complement component 4

    PubMed Central

    Sekar, Aswin; Bialas, Allison R.; de Rivera, Heather; Davis, Avery; Hammond, Timothy R.; Kamitaki, Nolan; Tooley, Katherine; Presumey, Jessy; Baum, Matthew; Van Doren, Vanessa; Genovese, Giulio; Rose, Samuel A.; Handsaker, Robert E.; Daly, Mark J.; Carroll, Michael C.; Stevens, Beth; McCarroll, Steven A.

    2016-01-01

    Schizophrenia is a heritable brain illness with unknown pathogenic mechanisms. Schizophrenia’s strongest genetic association at a population level involves variation in the Major Histocompatibility Complex (MHC) locus, but the genes and molecular mechanisms accounting for this have been challenging to recognize. We show here that schizophrenia’s association with the MHC locus arises in substantial part from many structurally diverse alleles of the complement component 4 (C4) genes. We found that these alleles promoted widely varying levels of C4A and C4B expression and associated with schizophrenia in proportion to their tendency to promote greater expression of C4A in the brain. Human C4 protein localized at neuronal synapses, dendrites, axons, and cell bodies. In mice, C4 mediated synapse elimination during postnatal development. These results implicate excessive complement activity in the development of schizophrenia and may help explain the reduced numbers of synapses in the brains of individuals affected with schizophrenia. PMID:26814963

  4. Schizophrenia risk from complex variation of complement component 4.

    PubMed

    Sekar, Aswin; Bialas, Allison R; de Rivera, Heather; Davis, Avery; Hammond, Timothy R; Kamitaki, Nolan; Tooley, Katherine; Presumey, Jessy; Baum, Matthew; Van Doren, Vanessa; Genovese, Giulio; Rose, Samuel A; Handsaker, Robert E; Daly, Mark J; Carroll, Michael C; Stevens, Beth; McCarroll, Steven A

    2016-02-11

    Schizophrenia is a heritable brain illness with unknown pathogenic mechanisms. Schizophrenia's strongest genetic association at a population level involves variation in the major histocompatibility complex (MHC) locus, but the genes and molecular mechanisms accounting for this have been challenging to identify. Here we show that this association arises in part from many structurally diverse alleles of the complement component 4 (C4) genes. We found that these alleles generated widely varying levels of C4A and C4B expression in the brain, with each common C4 allele associating with schizophrenia in proportion to its tendency to generate greater expression of C4A. Human C4 protein localized to neuronal synapses, dendrites, axons, and cell bodies. In mice, C4 mediated synapse elimination during postnatal development. These results implicate excessive complement activity in the development of schizophrenia and may help explain the reduced numbers of synapses in the brains of individuals with schizophrenia.

  5. Complement pathway biomarkers and age-related macular degeneration

    PubMed Central

    Gemenetzi, M; Lotery, A J

    2016-01-01

    In the age-related macular degeneration (AMD) ‘inflammation model', local inflammation plus complement activation contributes to the pathogenesis and progression of the disease. Multiple genetic associations have now been established correlating the risk of development or progression of AMD. Stratifying patients by their AMD genetic profile may facilitate future AMD therapeutic trials resulting in meaningful clinical trial end points with smaller sample sizes and study duration. PMID:26493033

  6. Complement depletion aggravates Staphylococcus aureus septicaemia and septic arthritis

    PubMed Central

    Sakiniene, E; Bremell, T; Tarkowski, A

    1999-01-01

    The aim of the study was to assess the role of the complement system in Staphylococcus aureus arthritis and septicaemia. The murine model of haematogenously acquired septic arthritis was used, injecting intravenously toxic shock syndrome toxin-1 (TSST-1), producing S. aureus LS-1. Complement was depleted using cobra venom factor (CVF). Evaluation of arthritis was performed clinically and histopathologically. In addition, the effect of complement depletion on the phagocytic activity of leucocytes was assessed in vivo and in vitro. Six days after inoculation of S. aureus the prevalence of arthritis in decomplemented mice was three-fold higher than that in controls (91% versus 25%). The clinical severity of arthritis at the end of the experiment, expressed as arthritic index, was 7.3 and 1.9, respectively. These findings were confirmed by histological index of synovitis as well as of cartilage and/or bone destruction being significantly higher in decomplemented mice than in controls (9.8 ± 1.7 versus 4.9 ± 1.2, P < 0.05; and 7.9 ± 1.7 versus 3.0 ± 0.9, P < 0.05, respectively). Also, the septicaemia-induced mortality was clearly higher in decomplemented mice compared with the controls. CVF treatment significantly reduced in vivo polymorphonuclear cell-dependent inflammation induced by subcutaneous injection of olive oil and mirroring the capacity of polymorphonuclear cells (PMNC) to migrate and/or extravasate. Besides, the decomplementation procedure significantly impaired phagocytic activity of peripheral blood leucocytes in vitro, since the number of phagocytes being able to ingest bacteria decreased by 50% when the cells were maintained in decomplemented serum compared with those in intact serum. The conclusion is that complement depletion aggravates the clinical course of S. aureus arthritis and septicaemia, possibly by a combination of decreased migration/extravasation of PMNC and an impairment of phagocytosis. PMID:9933426

  7. Complementation of Myelodysplastic Syndrome Clones with Lentivirus Expression Libraries

    DTIC Science & Technology

    2011-07-01

    Complementation of Myelodysplastic Syndrome Clones with Lentivirus Expression Libraries Daniel Lindner The Cleveland Clinic Cleveland, OH 44195 We have...MDS cell pools. This validation will ensure that the insert causes the desired phenotype. Myelodysplastic syndrome , lentivirus, cDNA libraries...A., I. Martin-Padura, P. Mancuso, P. Marighetti, C. Rabascio, G. Pruneri, L. D. Shultz, and F. Bertolini. 2008. Human acute leukemia cells injected

  8. Mycoplasma viruses.

    PubMed

    Maniloff, J

    1988-01-01

    Unlike bacterial viruses that infect cells bounded by a cell wall, mycoplasma viruses have evolved to enter and propagate in mycoplasma cells bounded only by a single lipid-protein cell membrane. In addition, mycoplasmas have the smallest amount of genetic information of any known cells, so their complexity is constrained by a limited genetic coding capacity. As a consequence of these host cell differences, mycoplasma viruses have been found to have a variety of structures and replication strategies which are different from those of the bacterial viruses. This article is a critical review of mycoplasma viruses infecting the genera Acholeplasma, Spiroplasma, and Mycoplasma; included are data on classification, morphology and structure, biological and physical properties, chemical composition, and productive and lysogenic replication cycles.

  9. Complement depletion with humanised cobra venom factor: efficacy in preclinical models of vascular diseases.

    PubMed

    Vogel, Carl-Wilhelm; Fritzinger, David C; Gorsuch, W Brian; Stahl, Gregory L

    2015-03-01

    The complement system is an intrinsic part of the immune system and has important functions in both innate and adaptive immunity. On the other hand, inadvertent or misdirected complement activation is also involved in the pathogenesis of many diseases, contributing solely or significantly to tissue injury and disease development. Multiple approaches to develop pharmacological agents to inhibit complement are currently being pursued. We have developed a conceptually different approach of not inhibiting but depleting complement, based on the complement-depleting activities of cobra venom factor (CVF), a non-toxic cobra venom component with structural and functional homology to complement component C3. We developed a humanised version of CVF by creating human complement component C3 derivatives with complement-depleting activities of CVF (humanised CVF) as a promising therapeutic agent for diseases with complement pathogenesis. Here we review the beneficial therapeutic effect of humanised CVF in several murine models of vascular diseases such as reperfusion injury.

  10. Killing of Gyrodactylus salaris (Platyhelminthes, Monogenea) mediated by host complement.

    PubMed

    Harris, P D; Soleng, A; Bakke, T A

    1998-08-01

    Gyrodactylus salaris, an important pathogen of Atlantic salmon Salmo salar, has been shown to be highly sensitive to factors in host serum and mucus, being killed rapidly (50% within 1 h) by serum at a dilution of 1:200. The time needed for killing was inversely proportional to serum concentration. Similar effects were noted using host mucus, which contained approximately 1/20th of the anti-Gyrodactylus activity of serum. Serum activity was abolished completely by heating at 45 degrees C for 30 min, and by addition of EDTA, but not by EGTA + 1 mM magnesium ions. Activity was not dependent on whether the serum was from infected or naive fishes, nor was it species specific. Attempts to pre-coat parasites in salmon anti-Gyrodactylus antibodies also failed to enhance the activity of fresh serum. These observations suggest that killing is due to the complement system of the host, acting via the alternate pathway. G. salaris appears to be exceptionally sensitive to complement, being killed at concentrations which could be experienced in vivo. The role of complement in the protection of fishes against gyrodactylid infection therefore deserves further investigation.

  11. Lamprey variable lymphocyte receptors mediate complement-dependent cytotoxicity.

    PubMed

    Wu, Fenfang; Chen, Liyong; Liu, Xin; Wang, Huaying; Su, Peng; Han, Yinglun; Feng, Bo; Qiao, Xu; Zhao, Jing; Ma, Ning; Liu, Huijie; Zheng, Zhen; Li, Qingwei

    2013-02-01

    An alternative adaptive-immune system is present in the most basal vertebrates--lampreys and hagfish--the only surviving jawless vertebrates. These eel-like fish use leucine-rich repeat-based receptors for Ag recognition instead of the Ig-based receptors used in jawed vertebrates. We report that in Japanese lamprey (Lampetra japonica), variable lymphocyte receptor (VLR)B interacts with C1q and C3 proteins to mediate complement-dependent cytotoxicity for bacteria and tumor cells. The immune-based lysis involves deposition of VLRB and C1q-like protein complex on the surface of target cells, activation of C3, and ultimate disruption of cell wall integrity. The demonstration of functional interaction between VLRB and complement components in lamprey provides evidence for the emergence of cooperative innate and adaptive-immune responses at a pivotal point in vertebrate evolution, before or in parallel with the evolution of Ig-based Abs and the classical complement-activation pathway.

  12. [The practical assessment of complement involvement in anaphylactoid reactions].

    PubMed

    Watkins, J

    1982-01-01

    While no single test is entirely satisfactory for the investigation of anaphylactoid response to intravenous anaesthetic drugs, changes in plasma chemistry are particularly easy to measure and may be carried out at centres remote from the clinical incident. Analysis should be carried out on a sequence of blood samples taken into EDTA over the 24 hours following such reaction. Few reactions are classical Type I, IgE antibody mediated, reactions and most involved the complement proteins in some specific manner. By measuring changes in the levels and activity of the complement proteins, particularly C3, C4 and C5, between samples, it is possible to deduce the likely mechanism of a reaction and thus to advise more wisely on future treatment of the patient. Although levels of any plasma protein may be readily measured by single radial immunodiffusion (Mancini technique) using appropriate specific antisera, one assessment of complement activity (degree of conversion) has until now largely been restricted to technically exacting Laurell immunoelectrophoresis. Two simple immunoelectrophoretic techniques are described here which do not require such expertise.

  13. Metabolic Complementation in Bacterial Communities: Necessary Conditions and Optimality

    PubMed Central

    Mori, Matteo; Ponce-de-León, Miguel; Peretó, Juli; Montero, Francisco

    2016-01-01

    Bacterial communities may display metabolic complementation, in which different members of the association partially contribute to the same biosynthetic pathway. In this way, the end product of the pathway is synthesized by the community as a whole. However, the emergence and the benefits of such complementation are poorly understood. Herein, we present a simple model to analyze the metabolic interactions among bacteria, including the host in the case of endosymbiotic bacteria. The model considers two cell populations, with both cell types encoding for the same linear biosynthetic pathway. We have found that, for metabolic complementation to emerge as an optimal strategy, both product inhibition and large permeabilities are needed. In the light of these results, we then consider the patterns found in the case of tryptophan biosynthesis in the endosymbiont consortium hosted by the aphid Cinara cedri. Using in-silico computed physicochemical properties of metabolites of this and other biosynthetic pathways, we verified that the splitting point of the pathway corresponds to the most permeable intermediate. PMID:27774085

  14. Therapeutic inhibition of the alternative complement pathway attenuates chronic EAE.

    PubMed

    Hu, Xianzhen; Holers, V Michael; Thurman, Joshua M; Schoeb, Trent R; Ramos, Theresa N; Barnum, Scott R

    2013-07-01

    Previous studies from our laboratory using complement-mutant mice demonstrated that the alternative pathway is the dominant activation pathway responsible for complement-mediated pathology in demyelinating disease. Using a well-characterized inhibitory monoclonal antibody (mAb 1379) directed against mouse factor B, we assessed the therapeutic value of inhibiting the alternative complement pathway in experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. Administration of anti-factor B antibody to mice prior to the onset of clinical signs of active EAE had no affect on the onset or acute phase of disease, but significantly attenuated the chronic phase of disease resulting in reduced cellular infiltration, inflammation and demyelination in antibody-treated mice. Attenuation of the chronic phase of disease was long lasting even though antibody administration was terminated shortly after disease onset. Chronic disease was also attenuated in transferred EAE when anti-factor B antibody was administered before or after disease onset. Similar levels of disease attenuation were observed in transferred EAE using MOG-specific encephalitogenic T cells. These studies demonstrate the therapeutic potential for inhibition of factor B in the chronic phase of demyelinating disease, where treatment options are limited.

  15. Therapeutic Inhibition of the Alternative Complement Pathway Attenuates Chronic EAE

    PubMed Central

    Hu, Xianzhen; Holers, V. Michael; Thurman, Joshua M.; Schoeb, Trent R.; Ramos, Theresa N; Barnum, Scott R.

    2013-01-01

    Previous studies from our laboratory using complement-mutant mice demonstrated that the alternative pathway is the dominant activation pathway responsible for complement-mediated pathology in demyelinating disease. Using a well-characterized inhibitory monoclonal antibody (mAb 1379) directed against mouse factor B, we assessed the therapeutic value of inhibiting the alternative complement pathway in experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. Administration of anti-factor B antibody to mice prior to the onset of clinical signs of active EAE had no affect on the onset or acute phase of disease, but significantly attenuated the chronic phase of disease resulting in reduced cellular infiltration, inflammation and demyelination in antibody-treated mice. Attenuation of the chronic phase of disease was long lasting even though antibody administration was terminated shortly after disease onset. Chronic disease was also attenuated in transferred EAE when anti-factor B antibody was administered before or after disease onset. Similar levels of disease attenuation were observed in transferred EAE using MOG-specific encephalitogenic T cells. These studies demonstrate the therapeutic potential for inhibition of factor B in the chronic phase of demyelinating disease, where treatment options are limited. PMID:23337717

  16. Complement C5 Activation during Influenza A Infection in Mice Contributes to Neutrophil Recruitment and Lung Injury

    PubMed Central

    Garcia, Cristiana C.; Weston-Davies, Wynne; Russo, Remo C.; Tavares, Luciana P.; Rachid, Milene A.; Alves-Filho, José C.; Machado, Alexandre V.; Ryffel, Bernhard; Nunn, Miles A.; Teixeira, Mauro M.

    2013-01-01

    Influenza virus A (IAV) causes annual epidemics and intermittent pandemics that affect millions of people worldwide. Potent inflammatory responses are commonly associated with severe cases of IAV infection. The complement system, an important mechanism of innate and humoral immune responses to infections, is activated during primary IAV infection and mediates, in association with natural IgM, viral neutralization by virion aggregation and coating of viral hemmagglutinin. Increased levels of the anaphylatoxin C5a were found in patients fatally infected with the most recent H1N1 pandemic virus. In this study, our aim was to evaluate whether targeting C5 activation alters inflammatory lung injury and viral load in a murine model of IAV infection. To address this question C57Bl/6j mice were infected intranasally with 104 PFU of the mouse adapted Influenza A virus A/WSN/33 (H1N1) or inoculated with PBS (Mock). We demonstrated that C5a is increased in bronchoalveolar lavage fluid (BALF) upon experimental IAV infection. To evaluate the role of C5, we used OmCI, a potent arthropod-derived inhibitor of C5 activation that binds to C5 and prevents release of C5a by complement. OmCI was given daily by intraperitoneal injection from the day of IAV infection until day 5. Treatment with OmCI only partially reduced C5a levels in BALF. However, there was significant inhibition of neutrophil and macrophage infiltration in the airways, Neutrophil Extracellular Traps (NETs) formation, death of leukocytes, lung epithelial injury and overall lung damage induced by the infection. There was no effect on viral load. Taken together, these data suggest that targeting C5 activation with OmCI during IAV infection could be a promising approach to reduce excessive inflammatory reactions associated with the severe forms of IAV infections. PMID:23696894

  17. Genome of Crocodilepox Virus

    PubMed Central

    Afonso, C. L.; Tulman, E. R.; Delhon, G.; Lu, Z.; Viljoen, G. J.; Wallace, D. B.; Kutish, G. F.; Rock, D. L.

    2006-01-01

    Here, we present the genome sequence, with analysis, of a poxvirus infecting Nile crocodiles (Crocodylus niloticus) (crocodilepox virus; CRV). The genome is 190,054 bp (62% G+C) and predicted to contain 173 genes encoding proteins of 53 to 1,941 amino acids. The central genomic region contains genes conserved and generally colinear with those of other chordopoxviruses (ChPVs). CRV is distinct, as the terminal 33-kbp (left) and 13-kbp (right) genomic regions are largely CRV specific, containing 48 unique genes which lack similarity to other poxvirus genes. Notably, CRV also contains 14 unique genes which disrupt ChPV gene colinearity within the central genomic region, including 7 genes encoding GyrB-like ATPase domains similar to those in cellular type IIA DNA topoisomerases, suggestive of novel ATP-dependent functions. The presence of 10 CRV proteins with similarity to components of cellular multisubunit E3 ubiquitin-protein ligase complexes, including 9 proteins containing F-box motifs and F-box-associated regions and a homologue of cellular anaphase-promoting complex subunit 11 (Apc11), suggests that modification of host ubiquitination pathways may be significant for CRV-host cell interaction. CRV encodes a novel complement of proteins potentially involved in DNA replication, including a NAD+-dependent DNA ligase and a protein with similarity to both vaccinia virus F16L and prokaryotic serine site-specific resolvase-invertases. CRV lacks genes encoding proteins for nucleotide metabolism. CRV shares notable genomic similarities with molluscum contagiosum virus, including genes found only in these two viruses. Phylogenetic analysis indicates that CRV is quite distinct from other ChPVs, representing a new genus within the subfamily Chordopoxvirinae, and it lacks recognizable homologues of most ChPV genes involved in virulence and host range, including those involving interferon response, intracellular signaling, and host immune response modulation. These data reveal

  18. Complement-triggered pathways orchestrate regenerative responses throughout phylogenesis

    PubMed Central

    Mastellos, Dimitrios C.; DeAngelis, Robert A.; Lambris, John D.

    2014-01-01

    Adult tissue plasticity, cell reprogramming, and organ regeneration are major challenges in the field of modern regenerative medicine. Devising strategies to increase the regenerative capacity of tissues holds great promise for dealing with donor organ shortages and low transplantation outcomes and also provides essential impetus to tissue bioengineering approaches for organ repair and replacement. The inherent ability of cells to reprogram their fate by switching into an embryonic-like, pluripotent progenitor state is an evolutionary vestige that in mammals has been retained mostly in fetal tissues and persists only in a few organs of the adult body. Tissue regeneration reflects the capacity of terminally differentiated cells to re-enter the cell cycle and proliferate in response to acute injury or environmental stress signals. In lower vertebrates, this regenerative capacity extends to several organs and remarkably culminates in precise tissue patterning, through cellular transdifferentiation and complex morphogenetic processes that can faithfully reconstruct entire body parts. Many lessons have been learned from robust regeneration models in amphibians such as the newt and axolotl. However, the dynamic interactions between the regenerating tissue, the surrounding stroma, and the host immune response, as it adapts to the actively proliferating tissue, remain ill-defined. The regenerating zone, through a sequence of distinct molecular events, adopts phenotypic plasticity and undergoes rigorous tissue remodeling that, in turn, evokes a significant inflammatory response. Complement is a primordial sentinel of the innate immune response that engages in multiple inflammatory cascades as it becomes activated during tissue injury and remodeling. In this respect, complement proteins have been implicated in tissue and organ regeneration in both urodeles and mammals. Distinct complement-triggered pathways have been shown to modulate critical responses that promote tissue

  19. Computer viruses

    NASA Technical Reports Server (NTRS)

    Denning, Peter J.

    1988-01-01

    The worm, Trojan horse, bacterium, and virus are destructive programs that attack information stored in a computer's memory. Virus programs, which propagate by incorporating copies of themselves into other programs, are a growing menace in the late-1980s world of unprotected, networked workstations and personal computers. Limited immunity is offered by memory protection hardware, digitally authenticated object programs,and antibody programs that kill specific viruses. Additional immunity can be gained from the practice of digital hygiene, primarily the refusal to use software from untrusted sources. Full immunity requires attention in a social dimension, the accountability of programmers.

  20. Genetic control of the alternative pathway of complement in humans and age-related macular degeneration.

    PubMed

    Hecker, Laura A; Edwards, Albert O; Ryu, Euijung; Tosakulwong, Nirubol; Baratz, Keith H; Brown, William L; Charbel Issa, Peter; Scholl, Hendrik P; Pollok-Kopp, Beatrix; Schmid-Kubista, Katharina E; Bailey, Kent R; Oppermann, Martin

    2010-01-01

    Activation of the alternative pathway of complement is implicated in common neurodegenerative diseases including age-related macular degeneration (AMD). We explored the impact of common variation in genes encoding proteins of the alternative pathway on complement activation in human blood and in AMD. Genetic variation across the genes encoding complement factor H (CFH), factor B (CFB) and component 3 (C3) was determined. The influence of common haplotypes defining transcriptional and translational units on complement activation in blood was determined in a quantitative genomic association study. Individual haplotypes in CFH and CFB were associated with distinct and novel effects on plasma levels of precursors, regulators and activation products of the alternative pathway of complement in human blood. Further, genetic variation in CFH thought to influence cell surface regulation of complement did not alter plasma complement levels in human blood. Plasma markers of chronic activation (split-products Ba and C3d) and an activating enzyme (factor D) were elevated in AMD subjects. Most of the elevation in AMD was accounted for by the genetic variation controlling complement activation in human blood. Activation of the alternative pathway of complement in blood is under genetic control and increases with age. The genetic variation associated with increased activation of complement in human blood also increased the risk of AMD. Our data are consistent with a disease model in which genetic variation in the complement system increases the risk of AMD by a combination of systemic complement activation and abnormal regulation of complement activation in local tissues.

  1. Clinical polyomavirus BK variants with agnogene deletion are non-functional but rescued by trans-complementation

    SciTech Connect

    Myhre, Marit Renee; Olsen, Gunn-Hege; Gosert, Rainer; Hirsch, Hans H.; Rinaldo, Christine Hanssen

    2010-03-01

    High-level replication of polyomavirus BK (BKV) in kidney transplant recipients is associated with the emergence of BKV variants with rearranged (rr) non-coding control region (NCCR) increasing viral early gene expression and cytopathology. Cloning and sequencing revealed the presence of a BKV quasispecies which included non-functional variants when assayed in a recombinant virus assay. Here we report that the rr-NCCR of BKV variants RH-3 and RH-12, both bearing a NCCR deletion including the 5' end of the agnoprotein coding sequence, mediated early and late viral reporter gene expression in kidney cells. However, in a recombinant virus they failed to produce infectious progeny despite large T-antigen and VP1 expression and the formation of nuclear virus-like particles. Infectious progeny was generated when the agnogene was reconstructed in cis or agnoprotein provided in trans from a co-existing BKV rr-NCCR variant. We conclude that complementation can rescue non-functional BKV variants in vitro and possibly in vivo.

  2. Oligomerization of Mumps Virus Phosphoprotein

    PubMed Central

    Pickar, Adrian; Elson, Andrew; Yang, Yang; Xu, Pei; Luo, Ming

    2015-01-01

    ABSTRACT The mumps virus (MuV) genome encodes a phosphoprotein (P) that is important for viral RNA synthesis. P forms the viral RNA-dependent RNA polymerase with the large protein (L). P also interacts with the viral nucleoprotein (NP) and self-associates to form a homotetramer. The P protein consists of three domains, the N-terminal domain (PN), the oligomerization domain (PO), and the C-terminal domain (PC). While PN is known to relax the NP-bound RNA genome, the roles of PO and PC are not clear. In this study, we investigated the roles of PO and PC in viral RNA synthesis using mutational analysis and a minigenome system. We found that PN and PC functions can be trans-complemented. However, this complementation requires PO, indicating that PO is essential for P function. Using this trans-complementation system, we found that P forms parallel dimers (PN to PN and PC to PC). Furthermore, we found that residues R231, K238, K253, and K260 in PO are critical for P's functions. We identified PC to be the domain that interacts with L. These results provide structure-function insights into the role of MuV P. IMPORTANCE MuV, a paramyxovirus, is an important human pathogen. The P protein of MuV is critical for viral RNA synthesis. In this work, we established a novel minigenome system that allows the domains of P to be complemented in trans. Using this system, we confirmed that MuV P forms parallel dimers. An understanding of viral RNA synthesis will allow the design of better vaccines and the development of antivirals. PMID:26311887

  3. 21 CFR 866.5250 - Complement C2 inhibitor (inactivator) immunological test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... the reagents used to measure by immunochemical techniques the complement C1 inhibitor (a plasma protein) in serum. Complement C1 inhibitor occurs normally in plasma and blocks the action of the...

  4. 21 CFR 866.5250 - Complement C2 inhibitor (inactivator) immunological test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... the reagents used to measure by immunochemical techniques the complement C1 inhibitor (a plasma protein) in serum. Complement C1 inhibitor occurs normally in plasma and blocks the action of the...

  5. 21 CFR 866.5250 - Complement C2 inhibitor (inactivator) immunological test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... the reagents used to measure by immunochemical techniques the complement C1 inhibitor (a plasma protein) in serum. Complement C1 inhibitor occurs normally in plasma and blocks the action of the...

  6. 21 CFR 866.5250 - Complement C 2 inhibitor (inactivator) immunological test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... the reagents used to measure by immunochemical techniques the complement C1 inhibitor (a plasma protein) in serum. Complement C1 inhibitor occurs normally in plasma and blocks the action of the...

  7. 21 CFR 866.5250 - Complement C 2 inhibitor (inactivator) immunological test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... the reagents used to measure by immunochemical techniques the complement C1 inhibitor (a plasma protein) in serum. Complement C1 inhibitor occurs normally in plasma and blocks the action of the...

  8. [Significance of the complement system for xenotransplantation: strategies for therapeutic intervention].

    PubMed

    Kirschfink, M; Haferkamp, A; Pomer, S; Chrupcala, M; Wosnik, A; Heckl-Ostreicher, B

    1998-01-01

    Hyperacute graft rejection triggered by the activation of the recipient's complement system represents the major obstacle to successful xenotransplantation. After the binding of preformed antibodies to vascular glycoproteins complement-induced activation and injury of endothelial cells with subsequent thrombosis leads to rapid destruction of foreign tissues. Inhibition of complement activation is therefore considered as a prerequisite for xenograft survival. Recent animal and cell culture experiments suggest that support of the physiological regulation of the complement system appears to be most promising. Besides the application of soluble complement inhibitors (e.g. soluble complement receptor 1, sCR1; C1 inhibitor) the genetic transfer of human membrane-bound complement regulatory proteins (e.g. DAF, CD59) offers new chances to protect the xenograft against the cytolytic complement attack. Results from the authors' experiments shall be included in a short overview to the issue.

  9. Zika Virus

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Zika Virus Note: Javascript is disabled or is not ... ol Português Recommend on Facebook Tweet Share Compartir Zika Cases in Texas Zika Cases in Florida Birth ...

  10. Lassa virus.

    PubMed

    Günther, Stephan; Lenz, Oliver

    2004-01-01

    Lassa virus is a RNA virus belonging to the family of Arenaviridae. It was discovered as the causative agent of a hemorrhagic fever--Lassa fever--about 30 years ago. Lassa fever is endemic in West Africa and is estimated to affect some 100,000 people annually. Great progress in the understanding of the life cycle of arenaviruses, including Lassa virus, has been made in recent years. New insights have been gained in the pathogenesis and molecular epidemiology of Lassa fever, and state-of the-art technologies for diagnosing this life-threatening disease have been developed. The intention of this review is to summarize in particular the recent literature on Lassa virus and Lassa fever. Several aspects ranging from basic research up to clinical practice and laboratory diagnosis are discussed and linked together.

  11. Xeroderma pigmentosum complementation group G associated with Cockayne syndrome

    SciTech Connect

    Vermeulen, W.; Jaspers, N.G.J.; Bootsma, D.; Hoeijmakers, J.H.J. ); Jaeken, J. )

    1993-07-01

    Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are two rare inherited disorders with a clinical and cellular hypersensitivity to the UV component of the sunlight spectrum. Although the two traits are generally considered as clinically and genetically distinct entities, on the biochemical level a defect in the nucleotide excision-repair (NER) pathway is involved in both. Classical CS patients are primarily deficient in the preferential repair of DNA damage in actively transcribed genes, whereas in most XP patients the genetic defect affects both [open quotes]preferential[close quotes] and [open quotes]overall[close quotes] NER modalities. Here the authors report a genetic study of two unrelated, severely affected patients with the clinical characteristics of CS but with a biochemical defect typical of XP. By complementation analysis, using somatic cell fusion and nuclear microinjection of cloned repair genes, they assign these two patients to XP complementation group G, which previously was not associated with CS. This observation extends the earlier identification of two patients with a rare combined XP/CS phenotype within XP complementation groups B and D, respectively. It indicates that some mutations in at least three of the seven genes known to be involved in XP also can result in a picture of partial or even full-blown CS. It is concluded that the syndromes XP and CS are biochemically closely related and may be part of a broader clinical disease spectrum. The authors suggest, as a possible molecular mechanism underlying this relation, that the XPGC repair gene has an additional vital function, as shown for some other NER genes. 33 refs., 5 tabs.

  12. Semisynthetic tRNA complement mediates in vitro protein synthesis.

    PubMed

    Cui, Zhenling; Stein, Viktor; Tnimov, Zakir; Mureev, Sergey; Alexandrov, Kirill

    2015-04-08

    Genetic code expansion is a key objective of synthetic biology and protein engineering. Most efforts in this direction are focused on reassigning termination or decoding quadruplet codons. While the redundancy of genetic code provides a large number of potentially reassignable codons, their utility is diminished by the inevitable interaction with cognate aminoacyl-tRNAs. To address this problem, we sought to establish an in vitro protein synthesis system with a simplified synthetic tRNA complement, thereby orthogonalizing some of the sense codons. This quantitative in vitro peptide synthesis assay allowed us to analyze the ability of synthetic tRNAs to decode all of 61 sense codons. We observed that, with the exception of isoacceptors for Asn, Glu, and Ile, the majority of 48 synthetic Escherichia coli tRNAs could support protein translation in the cell-free system. We purified to homogeneity functional Asn, Glu, and Ile tRNAs from the native E. coli tRNA mixture, and by combining them with synthetic tRNAs, we formulated a semisynthetic tRNA complement for all 20 amino acids. We further demonstrated that this tRNA complement could restore the protein translation activity of tRNA-depleted E. coli lysate to a level comparable to that of total native tRNA. To confirm that the developed system could efficiently synthesize long polypeptides, we expressed three different sequences coding for superfolder GFP. This novel semisynthetic translation system is a powerful tool for tRNA engineering and potentially enables the reassignment of at least 9 sense codons coding for Ser, Arg, Leu, Pro, Thr, and Gly.

  13. Functionality and Usability Assessment of the Complement Generation Tool (CGT): A Preliminary Review (Evaluation de la Fonctionnalite et de la Convivialite de Generation de Complements (CGT) - Examen Preliminaire)

    DTIC Science & Technology

    2011-04-01

    Functionality and Usability Assessment of the Complement Generation Tool (CGT) A preliminary review Wenbi Wang...Functionality and Usability Assessment of the Complement Generation Tool (CGT) A preliminary review Wenbi Wang Defence R&D...que représentée par le ministre de la Défense nationale, 2011 DRDC Toronto TM 2011-057 i Abstract …….. The Complement Generation Tool

  14. Eosinophil granule cationic proteins regulate the classical pathway of complement.

    PubMed Central

    Weiler, J M; Edens, R E; Bell, C S; Gleich, G J

    1995-01-01

    Major basic protein, the primary constituent of eosinophil granules, regulates the alternative and classical pathways of complement. Major basic protein and other eosinophil granule cationic proteins, which are important in mediating tissue damage in allergic disease, regulate the alternative pathway by interfering with C3b interaction with factor B to assemble an alternative pathway C3 convertase. In the present study, eosinophil peroxidase, eosinophil cationic protein and eosinophil-derived neurotoxin, as well as major basic protein, were examined for capacity to regulate the classical pathway. Eosinophil peroxidase, eosinophil cationic protein and major basic protein inhibited formation of cell-bound classical pathway C3 convertase (EAC1,4b,2a), causing 50% inhibition of complement-mediated lysis at about 0.19, 0.75 and 0.5 micrograms/10(7) cellular intermediates, respectively. Eosinophil-derived neurotoxin had no activity on this pathway of complement. The eosinophil granule proteins were examined for activity on the formation of the membrane attack complex. Major basic protein and eosinophil cationic protein had no activity on terminal lysis. In contrast, eosinophil peroxidase inhibited lysis of EAC1,4b,2a,3b,5b, but had only minimal activity on later events in complement lysis. These polycations were then examined to determine the site(s) at which they regulated the early classical pathway. Eosinophil granule polycationic proteins: (1) reduced the Zmax at all time points but had only minimal effect on the Tmax during the formation of the classical pathway C3 convertase (EAC1,4b,2a); (2) inhibited formation of EAC1,4b,2a proportional to C4 but independent of C2 concentration; (3) inhibited fluid phase formation of C1,4b,2a, as reflected by a decrease in C1-induced consumption of C2 over time; and (4) inhibited C1 activity over time without a direct effect on either C4 or C2. These observations suggest that polycations regulate the early classical pathway by

  15. Mouse embryos' fusion for the tetraploid complementation assay.

    PubMed

    Gertsenstein, Marina

    2015-01-01

    Production of the germline-competent chimeras using genetically modified ES cell lines is an essential step in the establishment of novel mouse models. In addition chimeras provide a powerful tool to study the cell lineage and to analyze complex phenotypes of mutant mice. Mouse chimeras with tetraploid embryos are used to rescue extraembryonic defects, to analyze an impact of gene function on specific lineage, to study the interaction between embryonic and extraembryonic tissues, and to produce mutant embryos and mice for the phenotype analysis. Tetraploid embryos are generated by the fusion of two blastomeres of the mouse embryo. The applications of tetraploid complementation assay and the protocol are described below.

  16. Approximate Schur complement preconditioning of the lowest order nodal discretizations

    SciTech Connect

    Moulton, J.D.; Ascher, U.M.; Morel, J.E.

    1996-12-31

    Particular classes of nodal methods and mixed hybrid finite element methods lead to equivalent, robust and accurate discretizations of 2nd order elliptic PDEs. However, widespread popularity of these discretizations has been hindered by the awkward linear systems which result. The present work exploits this awkwardness, which provides a natural partitioning of the linear system, by defining two optimal preconditioners based on approximate Schur complements. Central to the optimal performance of these preconditioners is their sparsity structure which is compatible with Dendy`s black box multigrid code.

  17. [Role of complement system in the pathogenesis of AMD].

    PubMed

    Machalińska, Anna; Karczewicz, Danuta

    2009-01-01

    Age related macular degeneration (AMD), is the leading cause of blindness in individuals over age 50 years old. The pathogenesis of AMD is still not well understood with both genetic and environmental factors known to influence susceptibility to this condition. Data accumulated in the last decade implicate the chronic inflammatory processes as playing an important role in the progression of AMD. According to the recent findings, complement system is suggested to be a triggering point of the initiation of pathologic inflammatory response in the development and clinical course of AMD.

  18. Quaternions, hexadecanions and the Schur complement in quantum mechanics

    NASA Astrophysics Data System (ADS)

    Mizrahi, Salomon S.; de Oliveira, Marcos C.

    2013-03-01

    We review the mathematical object invented by Sir William Rowan Hamilton, which he called quaternion, and we study its association with the matrix structure known as complement of Schur. We analyze the positivity of quaternions when represented by 2 × 2 matrices. We extend this very concept to the larger mathematical object, which generalizes the quaternion, the hexadecanion, which we shall define and use. We apply Schur's method to a quantum state that describes a beam of particles characterized by discrete degrees of freedom, the internal parity and the spin, as proposed by Lee and Yang (1956 Phys. Rev. 104 822).

  19. Highly individual patterns of virus-immune IgG effector responses in humans.

    PubMed

    Corrales-Aguilar, Eugenia; Trilling, Mirko; Reinhard, Henrike; Falcone, Valeria; Zimmermann, Albert; Adams, Ortwin; Santibanez, Sabine; Hengel, Hartmut

    2016-10-01

    IgG responses are fundamental to adaptive immunity and document immunological memory of previous pathogen encounter. While specific antigen recognition is mediated by the variable F(ab')2 domain of IgG, various effector functions become activated via the constant Fcγ part bridging IgG-opsonized targets to FcγR-expressing immune effector cells. Traditionally, neutralizing IgG is considered the most appropriate correlate of protective humoral immunity to viruses. However, evidence is increasing that antiviral IgG mediates protection to viruses via activation of FcγRs. Using a test system allowing quantitative detection of virus-immune IgG able to activate FcγRs, sera of healthy individuals and vaccinees were assessed with regard to two prototypical human pathogenic viruses: measles and human cytomegalovirus. Marked differences in the capacity of individuals to generate FcγRI-, FcγRII- and FcγRIII-activating responses were noted. Comparison of FcγR-activating IgG with neutralizing and ELISA IgG concentrations did not correlate for HCMV and only very poorly for MV. Since neither neutralizing IgG nor overall IgG responses faithfully predict the activation of FcγRs, only the simultaneous quantification of IgGs activating defined FcγRs will aid to delineate individual "immunograms" of virus IgG immunity. Such new multiparametric assessment of antiviral IgG qualities could be instrumental in defining correlates of protection and disease progression.

  20. Non-Finite Complements in Russian, Serbian/Croatian, and Macedonian

    ERIC Educational Resources Information Center

    Kim, Bo Ra

    2010-01-01

    This study investigates the coherence properties of non-finite complements in Russian, Serbian/Croatian, and Macedonian. I demonstrate that Slavic non-finite complements do not project a uniform syntactic structure. The maximal projection of non-finite complements is not fixed but depends on the selectional properties of the matrix verb. I present…

  1. The Object Complement in "Bahasa Malaysia." Colorado Research in Linguistics, No. 4.

    ERIC Educational Resources Information Center

    Devillers, Colette

    Together with a study of object complements, a succinct description of the Malay classifier construction is given. Object complementation is studied in a generative-transformational framework. For sentence object complements, four types of surface structure are proposed, but it is claimed that two types of deep structure trees underlie the…

  2. Powassan (POW) Virus Basics

    MedlinePlus

    ... Professionals Related Topics For International Travelers Powassan (POW) Virus Basics Download this fact sheet formatted for print: ... POW) Virus Fact Sheet (PDF) What is Powassan virus? Powassan (POW) virus is a flavivirus that is ...

  3. Virophages or satellite viruses?

    PubMed

    Krupovic, Mart; Cvirkaite-Krupovic, Virginija

    2011-11-01

    It has been argued that the smaller viruses associated with giant DNA viruses are a new biological entity. However, Mart Krupovic and Virginija Cvirkaite-Krupovic argue here that these smaller viruses should be classified with the satellite viruses.

  4. Ebola Virus and Marburg Virus

    MedlinePlus

    ... chimps and fruit bats in Africa. Transmission from animals to humans Experts suspect that both viruses are transmitted to humans through an infected animal's bodily fluids. Examples include: Blood. Butchering or eating ...

  5. Phenotypic complementation of genetic immunodeficiency by chronic herpesvirus infection.

    PubMed

    MacDuff, Donna A; Reese, Tiffany A; Kimmey, Jacqueline M; Weiss, Leslie A; Song, Christina; Zhang, Xin; Kambal, Amal; Duan, Erning; Carrero, Javier A; Boisson, Bertrand; Laplantine, Emmanuel; Israel, Alain; Picard, Capucine; Colonna, Marco; Edelson, Brian T; Sibley, L David; Stallings, Christina L; Casanova, Jean-Laurent; Iwai, Kazuhiro; Virgin, Herbert W

    2015-01-20

    Variation in the presentation of hereditary immunodeficiencies may be explained by genetic or environmental factors. Patients with mutations in HOIL1 (RBCK1) present with amylopectinosis-associated myopathy with or without hyper-inflammation and immunodeficiency. We report that barrier-raised HOIL-1-deficient mice exhibit amylopectin-like deposits in the myocardium but show minimal signs of hyper-inflammation. However, they show immunodeficiency upon acute infection with Listeria monocytogenes, Toxoplasma gondii or Citrobacter rodentium. Increased susceptibility to Listeria was due to HOIL-1 function in hematopoietic cells and macrophages in production of protective cytokines. In contrast, HOIL-1-deficient mice showed enhanced control of chronic Mycobacterium tuberculosis or murine γ-herpesvirus 68 (MHV68), and these infections conferred a hyper-inflammatory phenotype. Surprisingly, chronic infection with MHV68 complemented the immunodeficiency of HOIL-1, IL-6, Caspase-1 and Caspase-1;Caspase-11-deficient mice following Listeria infection. Thus chronic herpesvirus infection generates signs of auto-inflammation and complements genetic immunodeficiency in mutant mice, highlighting the importance of accounting for the virome in genotype-phenotype studies.

  6. Identification of the Fanconi anemia complementation group I gene, FANCI.

    PubMed

    Dorsman, Josephine C; Levitus, Marieke; Rockx, Davy; Rooimans, Martin A; Oostra, Anneke B; Haitjema, Anneke; Bakker, Sietske T; Steltenpool, Jûrgen; Schuler, Dezsö; Mohan, Sheila; Schindler, Detlev; Arwert, Fré; Pals, Gerard; Mathew, Christopher G; Waisfisz, Quinten; de Winter, Johan P; Joenje, Hans

    2007-01-01

    To identify the gene underlying Fanconi anemia (FA) complementation group I we studied informative FA-I families by a genome-wide linkage analysis, which resulted in 4 candidate regions together encompassing 351 genes. Candidates were selected via bioinformatics and data mining on the basis of their resemblance to other FA genes/proteins acting in the FA pathway, such as: degree of evolutionary conservation, presence of nuclear localization signals and pattern of tissue-dependent expression. We found a candidate, KIAA1794 on chromosome 15q25-26, to be mutated in 8 affected individuals previously assigned to complementation group I. Western blots of endogenous FANCI indicated that functionally active KIAA1794 protein is lacking in FA-I individuals. Knock-down of KIAA1794 expression by siRNA in HeLa cells caused excessive chromosomal breakage induced by mitomycin C, a hallmark of FA cells. Furthermore, phenotypic reversion of a patient-derived cell line was associated with a secondary genetic alteration at the KIAA1794 locus. These data add up to two conclusions. First, KIAA1794 is a FA gene. Second, this gene is identical to FANCI, since the patient cell lines found mutated in this study included the reference cell line for group I, EUFA592.

  7. Complement Coercion: Distinguishing Between Type-Shifting and Pragmatic Inferencing

    PubMed Central

    Katsika, Argyro; Braze, David; Deo, Ashwini; Piñango, Maria Mercedes

    2016-01-01

    Although Complement Coercion has been systematically associated with computational cost, there remains a serious confound in the experimental evidence built up in previous studies. The confound arises from the fact that lexico-semantic differences within the set of verbs assumed to involve coercion have not been taken into consideration. From among the set of verbs that have been reported to exhibit complement coercion effects we identified two clear semantic classes - aspectual verbs and psychological verbs. We hypothesize that the semantic difference between the two should result in differing processing profiles. Aspectual predicates (begin) trigger coercion and processing cost while psychological predicates (enjoy) do not. Evidence from an eye-tracking experiment supports our hypothesis. Coercion costs are restricted to aspectual predicates while no such effects are found with psychological predicates. These findings have implications for how these two kinds of predicates might be lexically encoded as well as for whether the observed interpolation of eventive meaning can be attributed to type-shifting (e.g. McElree et al., 2001) or to pragmatic-inferential processes (e.g. De Almeida, 2004). PMID:26925175

  8. Computer Viruses. Technology Update.

    ERIC Educational Resources Information Center

    Ponder, Tim, Comp.; Ropog, Marty, Comp.; Keating, Joseph, Comp.

    This document provides general information on computer viruses, how to help protect a computer network from them, measures to take if a computer becomes infected. Highlights include the origins of computer viruses; virus contraction; a description of some common virus types (File Virus, Boot Sector/Partition Table Viruses, Trojan Horses, and…

  9. Foodborne viruses.

    PubMed

    Koopmans, Marion; von Bonsdorff, Carl Henrik; Vinjé, Jan; de Medici, Dario; Monroe, Steve

    2002-06-01

    Foodborne and waterborne viral infections are increasingly recognized as causes of illness in humans. This increase is partly explained by changes in food processing and consumption patterns that lead to the worldwide availability of high-risk food. As a result, vast outbreaks may occur due to contamination of food by a single foodhandler or at a single source. Although there are numerous fecal-orally transmitted viruses, most reports of foodborne transmission describe infections with Norwalk-like caliciviruses (NLV) and hepatitis A virus (HAV), suggesting that these viruses are associated with the greatest risk of foodborne transmission. NLV and HAV can be transmitted from person to person, or indirectly via food, water, or fomites contaminated with virus-containing feces or vomit. People can be infected without showing symptoms. The high frequency of secondary cases of NLV illness and - to a lesser extent - of hepatitis A following a foodborne outbreak results in amplification of the problem. The burden of illness is highest in the elderly, and therefore is likely to increase due to the aging population. For HAV, the burden of illness may increase following hygienic control measures, due to a decreasing population of naturally immune individuals and a concurrent increase in the population at risk. Recent advances in the research of NLV and HAV have led to the development of molecular methods which can be used for molecular tracing of virus strains. These methods can be and have been used for the detection of common source outbreaks. While traditionally certain foods have been implicated in virus outbreaks, it is clear that almost any food item can be involved, provided it has been handled by an infected person. There are no established methods for detection of viruses in foods other than shellfish. Little information is available on disinfection and preventive measures specifically for these viruses. Studies addressing this issue are hampered by the lack of

  10. Combining complement fixation and luminol chemiluminescence for ultrasensitive detection of avian influenza A rH7N9.

    PubMed

    Li, Man; Shi, ZhuanZhuan; Li, ChangMing; Yu, Ling

    2016-03-21

    The complement fixation test (CFT) is a serological test that can be used to detect the presence of either a specific antibody or antigen to diagnose infections. In a conventional CFT, the assay result is determined by observing the clarity of the reaction solution or the sediment of red cells by the naked eye. Although the assay conditions are thereafter simplified, the sensitivity of the assay would be sacrificed due to the limitation of bulk observation. Inspired by the forensic scientists to examine blood at the scene of the crime, we rationally argued that the luminol chemiluminescence (CL) reaction could be applied in the CFT to sense physiological complement-mediated haemolytic phenomena for sensitive protein detection. The combination of the CFT and the luminol CL system was demonstrated in detection of rH7N9, a recombinant avian influenza virus protein. The testing can be accomplished within 2.5 h and the linear detection range covers 0.25 fg mL(-1) to 25 ng mL(-1). The feasibility of the CL based CFT in assaying a real biopsy was successfully demonstrated by specifically detecting rH7N9 and the carcinoembryonic antigen (CEA) in human serum. This new type of protein detection approach inherits the beauty of complement-mediated assay, such as being fast, and no protein immobilization, blocking and washing. In addition, the participation of luminol CL enables us to quantitatively analyse the intensity of a haemeolysis process, ameliorating the limitation of bulk observation in traditional CFT. It is anticipated that the luminol CL-CFT assay would be particularly suitable for investigation of small molecules, toxins, and short peptides.

  11. Complementation Test of Rpe65 Knockout and Tvrm148

    PubMed Central

    Wright, Charles B.; Chrenek, Micah A.; Foster, Stephanie L.; Duncan, Todd; Redmond, T. Michael; Pardue, Machelle T.; Boatright, Jeffrey H.; Nickerson, John M.

    2013-01-01

    Purpose. A mouse mutation, tvrm148, was previously reported as resulting in retinal degeneration. Tvrm148 and Rpe65 map between markers D3Mit147 and D3Mit19 on a genetic map, but the physical map places RPE65 outside the markers. We asked if Rpe65 or perhaps another nearby gene is mutated and if the mutant reduced 11-cis-retinal levels. We studied the impact of the tvrm148 mutation on visual function, morphology, and retinoid levels. Methods. Normal phase HPLC was used to measure retinoid levels. Rpe65+/+, tvrm148/+ (T+/−), tvrm148/tvrm148 (T−/−), RPE65KO/KO (Rpe65−/−), and Rpe65T/− mice visual function was measured by optokinetic tracking (OKT) and electroretinography (ERG). Morphology was assessed by light microscopy and transmission electron microscopy (TEM). qRT-PCR was used to measure Rpe65 mRNA levels. Immunoblotting measured the size and amount of RPE65 protein. Results. The knockout and tvrm148 alleles did not complement. No 11-cis-retinal was detected in T−/− or Rpe65−/− mice. Visual acuity in Rpe65+/+ and T+/− mouse was ∼0.382 c/d, but 0.037 c/d in T−/− mice at postnatal day 210 (P210). ERG response in T−/− mice was undetectable except at bright flash intensities. Outer nuclear layer (ONL) thickness in T−/− mice was ∼70% of Rpe65+/+ by P210. Rpe65 mRNA levels in T−/− mice were unchanged, yet 14.5% of Rpe65+/+ protein levels was detected. Protein size was unchanged. Conclusions. A complementation test revealed the RPE65 knockout and tvrm148 alleles do not complement, proving that the tvrm148 mutation is in Rpe65. Behavioral, physiological, molecular, biochemical, and histological approaches indicate that tvrm148 is a null allele of Rpe65. PMID:23778877

  12. Anchoring tick salivary anti-complement proteins IRAC I and IRAC II to membrane increases their immunogenicity.

    PubMed

    Gillet, Laurent; Schroeder, Hélène; Mast, Jan; Thirion, Muriel; Renauld, Jean-Christophe; Dewals, Benjamin; Vanderplasschen, Alain

    2009-01-01

    Tick salivary proteins are promising targets for the development of anti-tick vaccines. Recently, we described two paralogous anti-complement proteins, called Ixodes ricinus anti-complement (IRAC) proteins I and II, that are co-expressed in tick I. ricinus salivary glands. However, our previous attempts to immunize rabbits against IRAC via infection with recombinant Bovine herpesvirus 4 (BoHV-4) vectors invariably failed although both recombinants expressed high levels of functional IRAC proteins in vitro. As IRAC are soluble monovalent antigens, one of the possible explanations is that monovalent ligation of the B-cell receptor induces receptor activation but fails to promote antigen presentation, a phenomenon that is thought to induce a state of B-cell tolerance. In the present study, we tried to increase IRAC immunogenicity by expressing them as oligovalent antigens. To this end, IRAC were fused to membrane anchors and BoHV-4 vectors expressing these recombinant forms were produced. The immunization potentials of recombinant viruses expressing either secreted or transmembrane IRAC proteins were then compared. While the former did not induce a detectable immune response against IRAC, the latter led to high titres of anti-IRAC antibodies that only marginally affected tick blood feeding. All together, the data presented in this study demonstrate that the immunogenicity of a soluble antigen can be greatly improved by anchoring it in membrane.

  13. [Pharmacological modulation of the complement system: an opportunity for successful xenotransplantation].

    PubMed

    Heckl-Ostreicher, B; Kirschfink, M

    1995-04-01

    Hyperacute graft rejection triggered by the activation of the recipient's complement system represents the major obstacle to a successful xenotransplantation. Inhibition of complement activation is, therefore, considered as a prerequisite for xenograft survival. Support of the physiological regulation of the complement system appears to be the most promising strategy as indicated by first results from animal xenograft experiments. The transfer of human membrane-bound complement regulatory proteins offers new chances to protect the xenograft against the cytolytic complement attack. Another approach aims at interfering with receptor/ligand interaction of the adhesion molecules CR3 and CR4 (CD11b,c/CD18). All strategies of complement intervention have to consider the important function of complement within the immunological defense.

  14. Design and generation of recombinant rabies virus vectors

    PubMed Central

    Osakada, Fumitaka; Callaway, Edward M.

    2014-01-01

    Rabies viruses, negative-strand RNA viruses, infect neurons through axon terminals and spread transsynaptically in a retrograde direction between neurons. Rabies viruses whose glycoprotein (G) gene is deleted from the genome cannot spread across synapses. Complementation of G in trans, however, enables transsynaptic spreading of G-deleted rabies viruses to directly-connected, presynaptic neurons. Recombinant rabies viruses can encode genes of interest for labeling cells, controlling gene expression, and monitoring or manipulating neural activity. Cre-dependent or bridge-protein-mediated transduction and single-cell electroporation via EnvA/TVA or EnvB/TVB system allow cell-type-specific or single-cell-specific targeting. These rabies virus-based approaches permit the linking of connectivity to cell morphology and circuit function for particular cell types or single cells. Here we describe methods for construction of rabies viral vectors, recovery of G-deleted rabies viruses from cDNA, amplification of the viruses, pseudotyping them with EnvA or EnvB, and concentration and titration of the viruses. The entire protocol takes 6–8 weeks. PMID:23887178

  15. Complementing ultrafast shape recognition with an optical isomerism descriptor.

    PubMed

    Zhou, Ting; Lafleur, Karine; Caflisch, Amedeo

    2010-11-01

    We introduce the mixed product of three vectors spanning four molecular locations as a descriptor of optical isomerism. This descriptor is very efficient as it does not require molecular superposition, and is very robust in discriminating between a given isomer and its mirror image. In particular, conformational isomers that are mirror images of each other, as well as optical isomers have opposite sign of the descriptor value. For efficient database searches, the optical isomerism descriptor can be used to complement an available ultrafast shape recognition (USR) method based solely on distances, which is not able to distinguish enantiomers. By an extensive comparison of the USR-based similarity score with an approach based on Gaussian molecular volume overlap, the accuracy and completeness of the former are discussed.

  16. Polymorphism of the complement receptor for C3bi.

    PubMed Central

    Russ, G R; Haddad, A P; Tait, B D; d'Apice, A J

    1985-01-01

    RM2.184, a mouse IgG2a monoclonal antibody, recognizes a polymorphic determinant on the complement receptor for C3bi which is present on granulocytes and monocytes. The RM2.184 epitope is distinct from the monomorphic determinant recognized by the monoclonal antibody OKM1. The RM2.184 epitope is probably on the alpha subunit and dependent on the association of the alpha and beta subunits for its configuration, as it can not be detected after the subunits have been dissociated. The phenotypic frequency of the RM2.184 antigen is approximately 14%, and its segregation in families is independent of HLA and consistent with an autosomal co-dominant mode of inheritance. Images PMID:2414326

  17. AMD and the alternative complement pathway: genetics and functional implications.

    PubMed

    Tan, Perciliz L; Bowes Rickman, Catherine; Katsanis, Nicholas

    2016-06-21

    Age-related macular degeneration (AMD) is an ocular neurodegenerative disorder and is the leading cause of legal blindness in Western societies, with a prevalence of up to 8 % over the age of 60, which continues to increase with age. AMD is characterized by the progressive breakdown of the macula (the central region of the retina), resulting in the loss of central vision including visual acuity. While its molecular etiology remains unclear, advances in genetics and genomics have illuminated the genetic architecture of the disease and have generated attractive pathomechanistic hypotheses. Here, we review the genetic architecture of AMD, considering the contribution of both common and rare alleles to susceptibility, and we explore the possible mechanistic links between photoreceptor degeneration and the alternative complement pathway, a cascade that has emerged as the most potent genetic driver of this disorder.

  18. Generation of human organs in pigs via interspecies blastocyst complementation.

    PubMed

    Wu, J; Platero Luengo, A; Gil, M A; Suzuki, K; Cuello, C; Morales Valencia, M; Parrilla, I; Martinez, C A; Nohalez, A; Roca, J; Martinez, E A; Izpisua Belmonte, J C

    2016-10-01

    More than eighteen years have passed since the first derivation of human embryonic stem cells (ESCs), but their clinical use is still met with several challenges, such as ethical concerns regarding the need of human embryos, tissue rejection after transplantation and tumour formation. The generation of human induced pluripotent stem cells (iPSCs) enables the access to patient-derived pluripotent stem cells (PSCs) and opens the door for personalized medicine as tissues/organs can potentially be generated from the same genetic background as the patient recipients, thus avoiding immune rejections or complication of immunosuppression strategies. In this regard, successful replacement, or augmentation, of the function of damaged tissue by patient-derived differentiated stem cells provides a promising cell replacement therapy for many devastating human diseases. Although human iPSCs can proliferate unlimitedly in culture and harbour the potential to generate all cell types in the adult body, currently, the functionality of differentiated cells is limited. An alternative strategy to realize the full potential of human iPSC for regenerative medicine is the in vivo tissue generation in large animal species via interspecies blastocyst complementation. As this technology is still in its infancy and there remains more questions than answers, thus in this review, we mainly focus the discussion on the conceptual framework, the emerging technologies and recent advances involved with interspecies blastocyst complementation, and will refer the readers to other more in-depth reviews on dynamic pluripotent stem cell states, genome editing and interspecies chimeras. Likewise, other emerging alternatives to combat the growing shortage of human organs, such as xenotransplantation or tissue engineering, topics that has been extensively reviewed, will not be covered here.

  19. Complement factor B activation in patients with preeclampsia.

    PubMed

    Velickovic, Ivan; Dalloul, Mudar; Wong, Karen A; Bakare, Olufunke; Schweis, Franz; Garala, Maya; Alam, Amit; Medranda, Giorgio; Lekovic, Jovana; Shuaib, Waqas; Tedjasukmana, Andreas; Little, Perry; Hanono, Daniel; Wijetilaka, Ruvini; Weedon, Jeremy; Lin, Jun; Toledano, Roulhac d'Arby; Zhang, Ming

    2015-06-01

    Preeclampsia is a leading cause of maternal and fetal morbidity and mortality. Bb, the active fragment of complement factor B (fB), has been reported to be a predictor of preeclampsia. However, conflicting results have been found by some investigators. We hypothesized that the disagreement in findings may be due to the racial/ethnic differences among various study groups, and that fB activation is significant in women of an ethnic minority with preeclampsia. We investigated the maternal and fetal levels of Bb (the activated fB fragment) in pregnant women of an ethnic minority with or without preeclampsia. We enrolled 291 pregnant women (96% of an ethnic minority, including 78% African-American). Thirteen percent of these were diagnosed with preeclampsia. Maternal venous blood was collected from all participants together with fetal umbilical cord blood samples from 154 deliveries in the 291 women. The results were analyzed using the Mann-Whitney U test and multivariate analyses. Maternal Bb levels were significantly higher in the preeclamptic group than in the nonpreeclamptic group. Levels of Bb in fetal cord blood were similar in both groups. Subgroup analyses of African-American patients' results confirmed the study hypothesis that there would be a significant increase in Bb in the maternal blood of the preeclamptic group and no increase in Bb in the fetal cord blood of this group. These results suggest that a maternal immune response through complement fB might play a role in the development of preeclampsia, particularly in African-American patients.

  20. Zika Virus.

    PubMed

    FitzSimmons, Jack; Shah, Shailen

    2016-06-29

    To the Editor: Petersen et al. (April 21 issue)(1) provide a detailed review of Zika virus. We have some concern regarding diagnostic criteria for microcephaly in fetuses and newborns exposed to the virus. According to the Centers for Disease Control and Prevention (CDC) recommendation that microcephaly should be defined as an occipitofrontal circumference below the third percentile, nearly 3% of newborns would be categorized as having microcephaly. In Brazil, where there are 3 million live births per year, the application of this definition would result in nearly 90,000 infants being labeled as having microcephaly - a far greater number than . . .

  1. Higher Throughput Quantification of Neutralizing Antibody to Herpes Simplex Viruses.

    PubMed

    Blevins, Tamara P; Mitchell, Michelle C; Korom, Maria; Wang, Hong; Yu, Yinyi; Morrison, Lynda A; Belshe, Robert B

    2015-01-01

    We report a rapid, higher throughput method for measuring neutralizing antibody to herpes simplex virus (HSV) in human sera. Clinical isolates and sera from the Herpevac Trial for Women were used in a colorimetric assay in which infection of tissue culture (lack of neutralization) was indicated by substrate metabolism by beta-galactosidase induced in the ELVIS cell line. The neutralization assay was optimized by addition of guinea pig complement, which particularly enhanced neutralizing antibody titers to HSV-2. Higher neutralizing antibody titers were also achieved using virus particles isolated from the supernatant of infected cells rather than lysate of infected cells as the source of virus. The effect of assay incubation time and incubation time with substrate were also optimized. We found that incubating with substrate until a standard optical density of 1.0 was reached permitted a better comparison among virus isolates, and achieved reliable measurement of neutralizing antibody activity. Interestingly, in contrast to results in the absence of complement, addition of complement allowed sera from HSV-2 gD-vaccinated subjects to neutralize HSV-1 and HSV-2 clinical and laboratory isolates with equal potency.

  2. Role of pseudorabies virus glycoprotein II in protection from lethal infection.

    PubMed

    Nakamura, T; Ihara, T; Nunoya, T; Kuwahara, H; Ishihama, A; Ueda, S

    1993-07-01

    A monoclonal antibody (mAb), named 1.21, with complement-dependent neutralizing activity was produced against glycoprotein II (gII) of pseudorabies virus (PRV). By immunoaffinity chromatography using a mAB 1.21 column, gII was purified from Nonidet P40-lysates of PRV infected BHK21/13 cells. When mice and pigs were immunized with purified gII, complement-dependent virus-neutralizing antibodies were produced. The immunized animals survived potentially lethal challenge with PRV. These results indicate that an immunological response against gII plays an important role in the protection from PRV infection.

  3. Recombinant Complement Receptor 2 Radiolabeled with [99mTc(CO)3]+ : A Potential New Radiopharmaceutical for Imaging Activated Complement

    PubMed Central

    McDonnell, James M.; Yahya, Norhakim; Thakor, David; Razavi, Reza; Smith, Richard; Sacks, Steven; Mullen, Gregory E. D.

    2011-01-01

    We describe the design and synthesis of a new Tc-99m labeled bioconjugate for imaging activated complement, based on Short Consensus Repeats 1 and 2 of Complement Receptor 2 (CR2), the binding domain for C3d. To avoid non specific modification of CR2 and the potential for modifying lysine residues critical to the CR2/C3d contact surface, we engineered a new protein, recombinant CR2 (rCR2), to include the C-terminal sequence VFPLECHHHHHH, a hexahistidine tag (for site-specific radiolabeling with [99mTc(CO)3(OH2)3]+). The protein was characterized by N-terminal sequencing, SDS-PAGE and size exclusion chromatography. To test the function of the recombinant CR2, binding to C3d was confirmed by enzyme-linked immunosorbent assay (ELISA). The function was further confirmed by binding of rCR2 to C3d+ red blood cells (RBC) which were generated by deposition of human or rat C3d and analyzed by fluorescence microscopy and flow cytometry. The affinity of rCR2 for C3d+, in presence of 150 mM NaCl, was measured using surface plasma resonance giving rise to a KD≈500 nM. Radiolabeling of rCR2 or an inactive mutant of rCR2 (K41E CR2) or an unrelated protein of a similar size (C2A) with [99mTc(CO)3(OH2)3]+ at gave radiochemical yields >95%. Site-specifically radiolabeled rCR2 bound to C3d to C3d+ RBC. Binding of radiolabeled rCR2 to C3d was inhibited by anti-C3d and the radiolabeled inactive mutant K41E CR2 and C2A did not bind to C3d+ RBCs. We conclude that rCR2-Tc99m has excellent radiolabeling, stability and C3d binding characteristics and warrants in vivo evaluation as an activated complement imaging agent. PMID:21494666

  4. A pathogenic role of complement in arterial hypertension and hypertensive end organ damage.

    PubMed

    Wenzel, Ulrich O; Bode, Marlies; Köhl, Jörg; Ehmke, Heimo

    2017-03-01

    The self-amplifying cascade of messenger and effector molecules of the complement system serves as a powerful danger-sensing system that protects the host from a hostile microbial environment, while maintaining proper tissue and organ function through effective clearance of altered or dying cells. As an important effector arm of innate immunity, it also plays important roles in the regulation of adaptive immunity. Innate and adaptive immune responses have been identified as crucial players in the pathogenesis of arterial hypertension and hypertensive end organ damage. In line with this view, complement activation may drive the pathology of hypertension and hypertensive injury through its impact on innate and adaptive immune responses. It is well known that complement activation can cause tissue inflammation and injury and complement-inhibitory drugs are effective treatments for several inflammatory diseases. In addition to these proinflammatory properties, complement cleavage fragments of C3 and C5 can exert anti-inflammatory effects that dampen the inflammatory response to injury. Recent experimental data strongly support a role for complement in arterial hypertension. The remarkably similar clinical and histopathological features of malignant nephrosclerosis and atypical hemolytic uremic syndrome, which is driven by complement activation, suggest a role for complement also in the development of malignant nephrosclerosis. Herein, we will review canonical and noncanonical pathways of complement activation as the framework to understand the multiple roles of complement in arterial hypertension and hypertensive end organ damage.

  5. The role of complement in CD4⁺ T cell homeostasis and effector functions.

    PubMed

    Kolev, Martin; Le Friec, Gaëlle; Kemper, Claudia

    2013-02-01

    The complement system is among the evolutionary oldest 'players' of the immune system. It was discovered in 1896 by Jules Bordet as a heat-labile fraction of the serum responsible for the opsonisation and subsequent killing of bacteria. The decades between the 1920s and 1990s then marked the discovery and biochemical characterization of the proteins comprising the complement system. Today, complement is defined as a complex system consisting of more than 30 membrane-bound and soluble plasma proteins, which are activated in a cascade-like manner, very similarly to the caspase proteases and blood coagulation systems. Complement is engrained in the immunologist's mind as a serum-effective, quintessential part of innate immunity, vitally required for the detection and removal of pathogens or other dangerous entities. Three decades ago, this rather confined definition was challenged and then refined when it was shown that complement participates vitally in the induction and regulation of B cell responses, thus adaptive immunity. Similarly, research work published in more recent years supports an equally important role for the complement system in shaping T cell responses. Today, we are again facing paradigm shifts in the field: complement is actively involved in the negative control of T cell effector immune responses, and thus, by definition in immune homeostasis. Further, while serum complement activity is without doubt fundamental in the defence against invading pathogens, local immune cell-derived production of complement emerges as key mediator of complement's impact on adaptive immune responses. And finally, the impact of complement on metabolic pathways and the crosstalk between complement and other immune effector systems is likely more extensive than previously anticipated and is fertile ground for future discoveries. In this review, we will discuss these emerging new roles of complement, with a focus on Th1 cell biology.

  6. Blood SC5b-9 complement levels increase at parturition during term and preterm labor.

    PubMed

    Segura-Cervantes, Enrique; Mancilla-Ramirez, Javier; Zurita, Luis; Paredes, Yuriria; Arredondo, José Luis; Galindo-Sevilla, Norma

    2015-06-01

    We explored the hypothesis that complement, an innate and adaptive immune effector, is active in the plasma of parturient women and is deposited on fetal membranes collected after delivery. A cross-sectional study was designed to evaluate complement activity at parturition. Pregnant women (n = 97) between 15 and 41 years of age were enrolled in a hospital protocol during the perinatal period to assess both SC5b-9 complement activity in blood and complement deposition on fetal membranes during parturition. Soluble SC5b-9 complement activity in plasma fractions was measured using a standard enzyme-linked immunosorbent assay (ELISA) that included specific anti-complement antibodies. Complement deposition on membranes was analyzed using immuno-dot blots and immunohistochemistry. Soluble SC5b-9 complement complex levels were increased in the plasma of women during term labor (TL; median 3361; range 1726-5670 ng/mL), preterm labor (PL; median 2958; range 1552-7092 ng/mL), and preterm premature rupture of membranes (PPROM; median 2272; range 167-6540 ng/mL) compared with pregnant women who were not in labor (P; median 1384; range 174-4570 ng/mL; P < 0.001, Kruskal-Wallis test). Active complement, as assessed by the C9 neo-antigen in C5b-9 complexes, was deposited on fetal membranes, with no difference between term and preterm delivery. The deposition of active complement on fetal membranes was confirmed by immunohistochemistry. Women who underwent non-labor-indicated Cesarean sections did not exhibit complement deposition. Soluble SC5b-9 complement complex levels increased in the plasma of women during parturition, and complement C5b-9 complexes were deposited on fetal membranes.

  7. [Influenza virus].

    PubMed

    Juozapaitis, Mindaugas; Antoniukas, Linas

    2007-01-01

    Every year, especially during the cold season, many people catch an acute respiratory disease, namely flu. It is easy to catch this disease; therefore, it spreads very rapidly and often becomes an epidemic or a global pandemic. Airway inflammation and other body ailments, which form in a very short period, torment the patient several weeks. After that, the symptoms of the disease usually disappear as quickly as they emerged. The great epidemics of flu have rather unique characteristics; therefore, it is possible to identify descriptions of such epidemics in historic sources. Already in the 4th century bc, Hippocrates himself wrote about one of them. It is known now that flu epidemics emerge rather frequently, but there are no regular intervals between those events. The epidemics can differ in their consequences, but usually they cause an increased mortality of elderly people. The great flu epidemics of the last century took millions of human lives. In 1918-19, during "The Spanish" pandemic of flu, there were around 40-50 millions of deaths all over the world; "Pandemic of Asia" in 1957 took up to one million lives, etc. Influenza virus can cause various disorders of the respiratory system: from mild inflammations of upper airways to acute pneumonia that finally results in the patient's death. Scientist Richard E. Shope, who investigated swine flu in 1920, had a suspicion that the cause of this disease might be a virus. Already in 1933, scientists from the National Institute for Medical Research in London - Wilson Smith, Sir Christopher Andrewes, and Sir Patrick Laidlaw - for the first time isolated the virus, which caused human flu. Then scientific community started the exhaustive research of influenza virus, and the great interest in this virus and its unique features is still active even today.

  8. Effects of complement inhibition with soluble complement receptor-1 on vascular injury and inflammation during renal allograft rejection in the rat.

    PubMed

    Pratt, J R; Hibbs, M J; Laver, A J; Smith, R A; Sacks, S H

    1996-12-01

    Complement is both an effector of the humoral immune response and a stimulator of leukocyte activation. To examine the influence of complement on the allograft response, we inhibited complement using recombinant human soluble complement receptor-1 (sCR1; TP10), in an unsensitized model of rat renal allograft rejection. Lewis to DA renal transplant recipients were treated daily with 25 mg/kg sCR1 or saline and sacrificed on days 1 to 5 after transplant. Transplanted organs were examined histologically and immunohistochemically for leukocyte subset markers and for the third component of complement, C3, and membrane attack complex deposition. A second set of recipients was followed from day 5 to day 9 to assess graft survival. sCR1-treated recipients displayed > 90% inhibition of plasma complement activity and a marked reduction in tissue C3 and membrane attack complex deposition. Inactivation of complement reduced the vascular injury such that there was almost complete sparing of vascular damage in day 5 sCR1-treated rats. There was a significant reduction in infiltrating leukocytes by day 5 after transplant, and complement inhibition delayed the time to reach a histologically defined end point of graft survival from 5 days in controls to 9 days in the sCR1-treated group. These results imply that the vascular and cell-mediated injury arises, in part, from complement activation. The partial inhibition of these injuries by sCR1 may have functional implications for strategies to inhibit allograft rejection.

  9. Study of the viral interference between infectious pancreatic necrosis virus (IPNV) and infectious haematopoietic necrosis virus (IHNV) in rainbow trout (Oncorhynchus mykiss).

    PubMed

    Byrne, N; Castric, J; Lamour, F; Cabon, J; Quentel, C

    2008-05-01

    The resistance of rainbow trout (Oncorhynchus mykiss) to an infectious haematopoietic necrosis virus (IHNV) challenge following a preceding non-lethal infection with infectious pancreatic necrosis virus (IPNV) was investigated through experimental dual infections. Trout initially infected with IPNV were inoculated 14 days later with IHNV. Single infections of trout with 1 of the 2 viruses or with cell culture supernatant were also carried out and constituted control groups. No mortality was noted in fish after a single infection with IPNV. This virus had no influence on the head kidney leucocyte phagocytic activity and plasma haemolytic complement activity. IHNV induced a high mortality (72%) and reduced the macrophage phagocytic activity and complement haemolytic activity. It also induced a late production of anti-IHNV antibodies which occurred after clearance of the virus in the fish. In trout co-infected with both viruses, a mortality rate of 2% occurred and the immune parameters were similar to those observed in the fish infected with IPNV only, demonstrating that in co-infected trout IPNV inhibits the effects of IHNV. The studied parameters did not allow us to define the mechanism of interference occurring between these 2 viruses, but some hypothesis are put forward to explain the interference between the 2 viruses.

  10. Visualizing double-stranded RNA distribution and dynamics in living cells by dsRNA binding-dependent fluorescence complementation

    SciTech Connect

    Cheng, Xiaofei; Deng, Ping; Cui, Hongguang; Wang, Aiming

    2015-11-15

    Double-stranded RNA (dsRNA) is an important type of RNA that plays essential roles in diverse cellular processes in eukaryotic organisms and a hallmark in infections by positive-sense RNA viruses. Currently, no in vivo technology has been developed for visualizing dsRNA in living cells. Here, we report a dsRNA binding-dependent fluorescence complementation (dRBFC) assay that can be used to efficiently monitor dsRNA distribution and dynamics in vivo. The system consists of two dsRNA-binding proteins, which are fused to the N- and C-terminal halves of the yellow fluorescent protein (YFP). Binding of the two fusion proteins to a common dsRNA brings the split YFP halves in close proximity, leading to the reconstitution of the fluorescence-competent structure and restoration of fluorescence. Using this technique, we were able to visualize the distribution and trafficking of the replicative RNA intermediates of positive-sense RNA viruses in living cells. - Highlights: • A live-cell imaging system was developed for visualizing dsRNA in vivo. • It uses dsRNA binding proteins fused with two halves of a fluorescent protein. • Binding to a common dsRNA enables the reporter to become fluorescent. • The system can efficiently monitor viral RNA replication in living cells.

  11. Anti-microbial activity and anti-complement activity of extracts obtained from selected Hawaiian medicinal plants.

    PubMed

    Locher, C P; Burch, M T; Mower, H F; Berestecky, J; Davis, H; Van Poel, B; Lasure, A; Vanden Berghe, D A; Vlietinck, A J

    1995-11-17

    Selected plants having a history of use in Polynesian traditional medicine for the treatment of infectious disease were investigated for anti-viral, anti-fungal and anti-bacterial activity in vitro. Extracts from Scaevola sericea, Psychotria hawaiiensis, Pipturus albidus and Eugenia malaccensis showed selective anti-viral activity against Herpes Simplex Virus-1 and 2 and Vesicular Stomatitis Virus. Aleurites moluccana extracts showed anti-bacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, while Pipturus albidus and Eugenia malaccensis extracts showed growth inhibition of Staphylococcus aureus and Streptococcus pyogenes. Psychotria hawaiiensis and Solanum niger inhibited growth of the fungi Microsporum canis, Trichophyton rubrum and Epidermophyton floccosum, while Ipomoea sp., Pipturus albidus, Scaevola sericea, Eugenia malaccensis, Piper methysticum, Barringtonia asiatica and Adansonia digitata extracts showed anti-fungal activity to a lesser extent. Eugenia malaccensis was also found to inhibit the classical pathway of complement suggesting that an immunological basis for its in vivo activity was identified. This study has confirmed some of the ethnobotanical reports of Hawaiian medicinal plants having curative properties against infections using biological assays in vitro.

  12. Complement-activated oligodendroglia: a new pathogenic entity identified by immunostaining with antibodies to human complement proteins C3d and C4d.

    PubMed

    Yamada, T; Akiyama, H; McGeer, P L

    1990-05-04

    Clusters of oligodendroglial fibers were identified immunohistochemically in human brain tissue with antibodies to the complement proteins C3d and C4d in several neurological disorders. These included Pick's, Huntington's, Parkinson's and Alzheimer's disease, amyotrophic lateral sclerosis, progressive supranuclear palsy and Shy-Drager syndrome. These complement-activated oligodendroglia occurred in selected areas of gray and white matter. They were rarely observed in control tissue. Immunogold electron microscopy established that the C4d antibody was attached to degenerating myelin sheaths. These data indicate attachment of classical complement pathway proteins to selective oligodendroglia in several neurological disorders.

  13. The complement system and its role in the pathogenesis of periodontitis: current concepts.

    PubMed

    Damgaard, C; Holmstrup, P; Van Dyke, T E; Nielsen, C H

    2015-06-01

    Periodontitis is a highly prevalent inflammatory disease in tooth supporting tissues, induced by bacteria growing in a biofilm on tooth surfaces. Components of the complement system are present in the periodontal tissue and the system is activated in periodontitis. Continuous complement activation and modulation by bacteria within the biofilm in periodontal pockets, however, may enhance local tissue destruction, providing the biofilm with both essential nutrients and space to grow. A more profound understanding of the mechanisms involved in complement-derived tissue degradation may facilitate the development of new treatment concepts for periodontitis. Further studies on the role of complement in periodontitis pathogenesis may also contribute to the understanding of why some individuals fail to resolve periodontitis. Here, we review evidence that links complement to the pathogenesis of periodontitis with an emphasis on interaction of complement with bacteria from periodontitis-associated biofilm.

  14. The Geometry of Viruses.

    ERIC Educational Resources Information Center

    Case, Christine L.

    1991-01-01

    Presented is an activity in which students make models of viruses, which allows them to visualize the shape of these microorganisms. Included are some background on viruses, the biology and geometry of viruses, directions for building viruses, a comparison of cells and viruses, and questions for students. (KR)

  15. Analysis of the interaction between respiratory syncytial virus and lipid-rafts in Hep2 cells during infection

    SciTech Connect

    Brown, Gaie; Jeffree, Chris E.; McDonald, Terence; McL Rixon, Helen W.; Aitken, James D.; Sugrue, Richard J. . E-mail: r.sugrue@vir.gla.ac.uk

    2004-10-01

    The assembly of respiratory syncytial virus (RSV) in lipid-rafts was examined in Hep2 cells. Confocal and electron microscopy showed that during RSV assembly, the cellular distribution of the complement regulatory proteins, decay accelerating factor (CD55) and CD59, changes and high levels of these cellular proteins are incorporated into mature virus filaments. The detergent-solubility properties of CD55, CD59, and the RSV fusion (F) protein were found to be consistent with each protein being located predominantly within lipid-raft structures. The levels of these proteins in cell-released virus were examined by immunoelectronmicroscopy and found to account for between 5% and 15% of the virus attachment (G) glycoprotein levels. Collectively, our findings suggest that an intimate association exists between RSV and lipid-raft membranes and that significant levels of these host-derived raft proteins, such as those regulating complement activation, are subsequently incorporated into the envelope of mature virus particles.

  16. Comprehensive and comparative transcription analyses of the complement pathway in rainbow trout.

    PubMed

    Köbis, Judith M; Rebl, Alexander; Kühn, Carsten; Korytář, Tomáš; Köllner, Bernd; Goldammer, Tom

    2015-01-01

    The complement system is one of the most ancient and most essential innate immune cascades throughout the animal kingdom. Survival of aquatic animals, such as rainbow trout, depends on this early inducible, efficient immune cascade. Despite increasing research on genes coding for complement components in bony fish, some complement-related genes are still unknown in salmonid fish. In the present study, we characterize the genes encoding complement factor D (CFD), CD93 molecule (CD93), and C-type lectin domain family 4, member M (CLEC4M) from rainbow trout (Oncorhynchus mykiss). Subsequently, we performed comprehensive and comparative expression analyses of 36 complement genes including CFD, CD93, and CLEC4M and further putative complement-associated genes to obtain general information about the functional gene interaction within the complement pathway in fish. These quantification analyses were conducted in liver, spleen and gills of healthy fish of two rainbow trout strains, selected for survival (strain BORN) and growth (Import strain), respectively. The present expression study clearly confirms for rainbow trout that liver represents the primary site of complement expression. Spleen and gills also express most complement genes, although the mean transcript levels were generally lower than in liver. The transcription data suggest a contribution of spleen and gills to complement activity. The comparison of the two rainbow trout strains revealed a generally similar complement gene expression. However, a significantly lower expression of numerous genes especially in spleen seems characteristic for the BORN strain. This suggests a strain-specific complement pathway regulation under the selected rearing conditions.

  17. Complement in lupus nephritis: the good, the bad, and the unknown.

    PubMed

    Bao, Lihua; Quigg, Richard J

    2007-01-01

    The complement system consists of 3 pathways and more than 30 proteins, including those with biological activity that directly or indirectly mediate the effects of this system, plus a set of regulatory proteins necessary to prevent injudicious complement activation on host tissue. The role for complement in the pathogenesis of systemic lupus erythematosus (SLE) is paradoxic. On one hand, the complement system appears to have protective features in that hereditary homozygous deficiencies of classic pathway components are associated with an increased risk for SLE. On the other hand, immune complex-mediated activation of complement in affected tissues is clearly evident in both experimental and human SLE along with pathologic features that are logical consequences of complement activation. By using accurate mouse models of SLE, we have gained remarkable insights into pathogenic features likely relevant to the human disease, and the ability to test potential therapies, some of which have made it to standard clinical use. Studies in genetically altered mice and using recombinant protein inhibitors of complement have confirmed what was believed but unproven-early complement proteins C1q and C4 are protective whereas complement activation later in the pathways is proinflammatory and deleterious. Two complement inhibitors, soluble complement receptor 1 (TP10, Avant Immunotherapeutics, Needham, MA) and a monoclonal anti-C5 antibody (Eculizumab, Alexion Pharmaceuticals, Inc., Cheshire, CT) have been shown to inhibit complement safely and now are being investigated in a variety of clinical conditions. Although these and others earlier in their clinical development hold promise to be used therapeutically in lupus nephritis, this optimism must be tempered by the fact that the clinical trials to prove this remain fraught with obstacles.

  18. Versatility of the complement system in neuroinflammation, neurodegeneration and brain homeostasis

    PubMed Central

    Orsini, Franca; De Blasio, Daiana; Zangari, Rosalia; Zanier, Elisa R.; De Simoni, Maria-Grazia

    2014-01-01

    The immune response after brain injury is highly complex and involves both local and systemic events at the cellular and molecular level. It is associated to a dramatic over-activation of enzyme systems, the expression of proinflammatory genes and the activation/recruitment of immune cells. The complement system represents a powerful component of the innate immunity and is highly involved in the inflammatory response. Complement components are synthesized predominantly by the liver and circulate in the bloodstream primed for activation. Moreover, brain cells can produce complement proteins and receptors. After acute brain injury, the rapid and uncontrolled activation of the complement leads to massive release of inflammatory anaphylatoxins, recruitment of cells to the injury site, phagocytosis and induction of blood brain barrier (BBB) damage. Brain endothelial cells are particularly susceptible to complement-mediated effects, since they are exposed to both circulating and locally synthesized complement proteins. Conversely, during neurodegenerative disorders, complement factors play distinct roles depending on the stage and degree of neuropathology. In addition to the deleterious role of the complement, increasing evidence suggest that it may also play a role in normal nervous system development (wiring the brain) and adulthood (either maintaining brain homeostasis or supporting regeneration after brain injury). This article represents a compendium of the current knowledge on the complement role in the brain, prompting a novel view that complement activation can result in either protective or detrimental effects in brain conditions that depend exquisitely on the nature, the timing and the degree of the stimuli that induce its activation. A deeper understanding of the acute, subacute and chronic consequences of complement activation is needed and may lead to new therapeutic strategies, including the ability of targeting selective step in the complement cascade

  19. Generation of Viable Mice from Induced Pluripotent Stem Cells (iPSCs) Through Tetraploid Complementation.

    PubMed

    Kang, Lan; Gao, Shaorong

    2015-01-01

    Tetraploid complementation assay is the most rigorous criteria for pluripotency characterization of pluripotent stem cells including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Pluripotent stem cells could complement the developmental deficiency of tetraploid embryos and thus support the full-term mice development. Here we describe the protocol for tetraploid complementation using iPSCs to produce viable all-iPSC mice.

  20. Xeroderma pigmentosum complementation group f polymorphisms influence risk of glioma.

    PubMed

    Cheng, Hong-Bin; Xie, Chen; Zhang, Ru-You; Hu, Shao-Shan; Wang, Zhi; Yue, Wu

    2013-01-01

    We conducted an exploratory investigation of whether variation in six common SNPs of xeroderma pigmentosum complementation group F (XPF) is associated with risk of glioma in a Chinese population. Six single nucleotide polymorphisms (SNPs) were genotyped in 207 glioma cases and 236 cancer-free controls by a 384-well plate format on the Sequenom MassARRAY platform (Sequenom, San Diego, USA). The rs1800067 G and rs2276466 G allele frequencies were significantly higher in the glioma group than controls. Individuals with the rs1800067 GG genotype were at greater risk of glioma when compared with the A/A genotype in the codominant model, with an OR (95% CI) of 2.63 (1.04-7.25). The rs2276466 polymorphism was significantly associated with moderate increased risk of glioma in codominant and dominant models, with ORs (95% CI) of 1.90 (1.05-3.44) and 1.55 (1.07-2.47), respectively. The combination genotype of rs1800067 G and rs2276466 G alleles was associated with a reduced risk of glioma (OR=0.44, 95% CI=0.19-0.98). These findings indicate that genetic variants of the XPF gene have critical functions in the development of glioma.

  1. The sequence and topology of human complement component C9.

    PubMed Central

    Stanley, K K; Kocher, H P; Luzio, J P; Jackson, P; Tschopp, J

    1985-01-01

    A partial nucleotide sequence of human complement component C9 cDNA representing 94% of the coding region of the mature protein is presented. The amino acid sequence predicted from the open reading frame of this cDNA concurs with the amino acid sequence at the amino-terminal end of three proteolytic fragments of purified C9 protein. No long stretches of hydrophobic residues are present, even in the carboxy-terminal half of the molecule which reacts with lipid-soluble photoaffinity probes. Monoclonal antibody epitopes have been mapped by comparing overlapping fragments of C9 molecule to which the antibodies bind on Western blots. Several of these epitopes map to small regions containing other surface features (e.g., proteolytic cleavage sites and N-linked oligosaccharide). The amino-terminal half of C9 is rich in cysteine residues and contains a region with a high level of homology to the LDL receptor cysteine-rich domains. A model for C9 topology based on these findings is proposed. Images Fig. 5. Fig. 6. Fig. 7. Fig. 8. Fig. 9. PMID:4018030

  2. Sex chromosome complement involvement in angiotensin receptor sexual dimorphism.

    PubMed

    Dadam, Florencia M; Cisternas, Carla D; Macchione, Ana F; Godino, Andrea; Antunes-Rodrigues, José; Cambiasso, María J; Vivas, Laura M; Caeiro, Ximena E

    2017-02-27

    This study aimed to define whether sex chromosome complement (SCC) may differentially modulate sex differences in relative gene expression of basal Agtr1a, Agtr2, and Mas1 receptors at fore/hindbrain nuclei and at medulla/cortical kidney. Samples were collected from gonadectomized male (XX and XY) and female (XX and XY) mice of the "four core genotypes" model. At brain level, a SCC effect at the area postrema was demonstrated. An increase in mRNA level of Agtr1a and Agtr1a/Agtr2 ratio in XY-SCC mice was associated with a decrease in Mas1 compared to XX-SCC mice. In the renal cortex, a SCC effect for Agtr2 and Mas1 was observed. Regardless of sex (male or female), XX-SCC mice expressed higher levels of mRNA Agtr2 and Mas1 than XY-SCC mice {F(1,12) = 6,126,p < 0.05; F(1,21) = 5,143,p < 0.05}. Furthermore, XX-female mice showed a significant increase in Mas1 expression compared to XY-female mice. These results reveal a SCC modulatory effect at central and kidney level on angiotensin receptor expression, with an enhancement of the vasodilatory arm in XX-mice and an increase in the vasoconstriction arm in XY-mice, which may underlie sex differences in the regulation of arterial pressure.

  3. Large Covariance Estimation by Thresholding Principal Orthogonal Complements.

    PubMed

    Fan, Jianqing; Liao, Yuan; Mincheva, Martina

    2013-09-01

    This paper deals with the estimation of a high-dimensional covariance with a conditional sparsity structure and fast-diverging eigenvalues. By assuming sparse error covariance matrix in an approximate factor model, we allow for the presence of some cross-sectional correlation even after taking out common but unobservable factors. We introduce the Principal Orthogonal complEment Thresholding (POET) method to explore such an approximate factor structure with sparsity. The POET estimator includes the sample covariance matrix, the factor-based covariance matrix (Fan, Fan, and Lv, 2008), the thresholding estimator (Bickel and Levina, 2008) and the adaptive thresholding estimator (Cai and Liu, 2011) as specific examples. We provide mathematical insights when the factor analysis is approximately the same as the principal component analysis for high-dimensional data. The rates of convergence of the sparse residual covariance matrix and the conditional sparse covariance matrix are studied under various norms. It is shown that the impact of estimating the unknown factors vanishes as the dimensionality increases. The uniform rates of convergence for the unobserved factors and their factor loadings are derived. The asymptotic results are also verified by extensive simulation studies. Finally, a real data application on portfolio allocation is presented.

  4. Structural basis of complement membrane attack complex formation

    PubMed Central

    Serna, Marina; Giles, Joanna L.; Morgan, B. Paul; Bubeck, Doryen

    2016-01-01

    In response to complement activation, the membrane attack complex (MAC) assembles from fluid-phase proteins to form pores in lipid bilayers. MAC directly lyses pathogens by a ‘multi-hit' mechanism; however, sublytic MAC pores on host cells activate signalling pathways. Previous studies have described the structures of individual MAC components and subcomplexes; however, the molecular details of its assembly and mechanism of action remain unresolved. Here we report the electron cryo-microscopy structure of human MAC at subnanometre resolution. Structural analyses define the stoichiometry of the complete pore and identify a network of interaction interfaces that determine its assembly mechanism. MAC adopts a ‘split-washer' configuration, in contrast to the predicted closed ring observed for perforin and cholesterol-dependent cytolysins. Assembly precursors partially penetrate the lipid bilayer, resulting in an irregular β-barrel pore. Our results demonstrate how differences in symmetric and asymmetric components of the MAC underpin a molecular basis for pore formation and suggest a mechanism of action that extends beyond membrane penetration. PMID:26841837

  5. Structural basis of complement membrane attack complex formation.

    PubMed

    Serna, Marina; Giles, Joanna L; Morgan, B Paul; Bubeck, Doryen

    2016-02-04

    In response to complement activation, the membrane attack complex (MAC) assembles from fluid-phase proteins to form pores in lipid bilayers. MAC directly lyses pathogens by a 'multi-hit' mechanism; however, sublytic MAC pores on host cells activate signalling pathways. Previous studies have described the structures of individual MAC components and subcomplexes; however, the molecular details of its assembly and mechanism of action remain unresolved. Here we report the electron cryo-microscopy structure of human MAC at subnanometre resolution. Structural analyses define the stoichiometry of the complete pore and identify a network of interaction interfaces that determine its assembly mechanism. MAC adopts a 'split-washer' configuration, in contrast to the predicted closed ring observed for perforin and cholesterol-dependent cytolysins. Assembly precursors partially penetrate the lipid bilayer, resulting in an irregular β-barrel pore. Our results demonstrate how differences in symmetric and asymmetric components of the MAC underpin a molecular basis for pore formation and suggest a mechanism of action that extends beyond membrane penetration.

  6. Molecular genetics of the fourth component of human complement

    SciTech Connect

    Carroll, M.C.

    1987-05-15

    The fourth component of complement in humans is coded for by two closely linked loci, i.e., C4A and C4B, that have been positioned within the class III region of the human major histocompatibility complex along with the genes for C2, Bf, and steroid 21-OH. Both C4 loci are highly polymorphic and certain alleles, particularly the nulls, are associated with susceptibility to autoimmune disease. About one-half of the null alleles are due to a large deletion that includes both a C4 and flanking 21-OH gene. Despite the near identity of the products of the two loci, the proteins differ dramatically in their efficiency of covalent binding to antigen. The amino acid substitutions responsible for the functional differences have been identified and they are clustered relatively near the covalent binding site within the C4d region of the ..cap alpha.. chain. These observations support the hypothesis that the susceptibility to autoimmune disease is related to the structural variation of the C4 protein.

  7. Large Covariance Estimation by Thresholding Principal Orthogonal Complements

    PubMed Central

    Fan, Jianqing; Liao, Yuan; Mincheva, Martina

    2012-01-01

    This paper deals with the estimation of a high-dimensional covariance with a conditional sparsity structure and fast-diverging eigenvalues. By assuming sparse error covariance matrix in an approximate factor model, we allow for the presence of some cross-sectional correlation even after taking out common but unobservable factors. We introduce the Principal Orthogonal complEment Thresholding (POET) method to explore such an approximate factor structure with sparsity. The POET estimator includes the sample covariance matrix, the factor-based covariance matrix (Fan, Fan, and Lv, 2008), the thresholding estimator (Bickel and Levina, 2008) and the adaptive thresholding estimator (Cai and Liu, 2011) as specific examples. We provide mathematical insights when the factor analysis is approximately the same as the principal component analysis for high-dimensional data. The rates of convergence of the sparse residual covariance matrix and the conditional sparse covariance matrix are studied under various norms. It is shown that the impact of estimating the unknown factors vanishes as the dimensionality increases. The uniform rates of convergence for the unobserved factors and their factor loadings are derived. The asymptotic results are also verified by extensive simulation studies. Finally, a real data application on portfolio allocation is presented. PMID:24348088

  8. Complement C5a Generation by Staphylococcal Biofilms

    PubMed Central

    Satorius, Ashley E.; Szafranski, Jacob; Pyne, Derek; Ghanesan, Mahesh; Solomon, Michael J.; Newton, Duane W.; Bortz, David M.

    2013-01-01

    Biofilms production is a central feature of nosocomial infection of catheters and other medical devices used in resuscitation and critical care. However, the very effective biofilm forming pathogen Staphylococcus epidermidis often produces a modest host inflammatory response and few of the signs and symptoms associated with more virulent pathogens. To examine the impact of bacterial biofilm formation on provocation of an innate immune response, we studied the elaboration of the major complement anaphylatoxin C5a by human serum upon contact with S. epidermidis biofilms. Wildtype S. epidermidis and mutants of sarA (a regulatory protein that promotes synthesis of the biofilm-forming polysaccharide intercellular adhesin, PIA) and icaB (responsible for post-export processing of PIA) were studied. C5a release, as a function of exposed biofilm surface area, was on the order of 1 fmol cm−2 sec−1 and was dependent on the presence of PIA. Experimental results were used to inform a physiologically-based pharmacokinetic model of C5a release by an infected central venous catheter, one of S. epidermidis' primary means of causing human disease. These simulations revealed that the magnitude of C5a release on a superior vena cava catheter completely covered with S. epidermidis would be lower than necessary to alert circulating leukocytes. Combined, the experimental and computational results are highly consistent with clinical observations in which the clinical signs of central line associated bloodstream infection are often muted in association with this important pathogen. PMID:23459111

  9. A complementation method for functional analysis of mammalian genes

    PubMed Central

    Gonzalez-Santos, Juana Maria; Cao, Huibi; Wang, Anan; Koehler, David R.; Martin, Bernard; Navab, Roya; Hu, Jim

    2005-01-01

    Our progress in understanding mammalian gene function has lagged behind that of gene identification. New methods for mammalian gene functional analysis are needed to accelerate the process. In yeast, the powerful genetic shuffle system allows deletion of any chromosomal gene by homologous recombination and episomal expression of a mutant allele in the same cell. Here, we report a method for mammalian cells, which employs a helper-dependent adenoviral (HD-Ad) vector to synthesize small hairpin (sh) RNAs to knock-down the expression of an endogenous gene by targeting untranslated regions (UTRs). The vector simultaneously expresses an exogenous version of the same gene (wild-type or mutant allele) lacking the UTRs for functional analysis. We demonstrated the utility of the method by using PRPF3, which encodes the human RNA splicing factor Hprp3p. Recently, missense mutations in PRPF3 were found to cause autosomal-dominant Retinitis Pigmentosa, a form of genetic eye diseases affecting the retina. We knocked-down endogenous PRPF3 in multiple cell lines and rescued the phenotype (cell death) with exogenous PRPF3 cDNA, thereby creating a genetic complementation method. Because Ad vectors can efficiently transduce a wide variety of cell types, and many tissues in vivo, this method could have a wide application for gene function studies. PMID:15944448

  10. Elastase and metalloproteinase activities regulate soluble complement receptor 1 release.

    PubMed

    Sadallah, S; Hess, C; Miot, S; Spertini, O; Lutz, H; Schifferli, J A

    1999-11-01

    Complement receptor 1 (CR1) is cleaved from the surface of polymorphonuclear cells (PMN) in the membrane-proximal region to yield a soluble fragment (sCR1) that contains the functional domains. The enzymes involved in this cleavage are produced by the PMN itself, since in vitro stimulation of purified PMN is followed by sCR1 release. Purified human neutrophil elastase (HNE) cleaved CR1 from erythrocytes and urinary vesicles originating from podocytes and enhanced tenfold the cleavage of CR1 from activated PMN. The largest fragment released from PMN by HNE was identical in size to CR1 shed spontaneously. The CR1 fragments cleaved from erythrocytes were functional. The shedding of sCR1 by activated PMN was inhibited by phenylmethylsulfonyl fluoride (80 +/- 10%), alpha1-antiprotease (50 +/- 5%) and elafin (60 +/- 5%). Furthermore the cleavage was blocked by the metalloprotease inhibitor 1,10-phenanthroline (70 +/- 6 %) as well as by a monoclonal antibody against human neutrophil collagenase MMP8 (40 +/- 10%). Maximal inhibition of sCR1 shedding was obtained by a combination of 1,10-phenanthroline with elafin (86 +/- 6%). These inhibitors had no effect on L-selectin shedding, indicating that the cleavage of CR1 was specific. In conclusion, elastase or elastase-like activity may be responsible for the shedding of functional sCR1 in vivo, and this activity is controlled by the local release of PMN metalloproteases and alpha1antiprotease.

  11. Complement Factor H Inhibits CD47-Mediated Resolution of Inflammation.

    PubMed

    Calippe, Bertrand; Augustin, Sebastien; Beguier, Fanny; Charles-Messance, Hugo; Poupel, Lucie; Conart, Jean-Baptiste; Hu, Shulong J; Lavalette, Sophie; Fauvet, Alexandre; Rayes, Julie; Levy, Olivier; Raoul, William; Fitting, Catherine; Denèfle, Thomas; Pickering, Matthew C; Harris, Claire; Jorieux, Sylvie; Sullivan, Patrick M; Sahel, José-Alain; Karoyan, Philippe; Sapieha, Przemyslaw; Guillonneau, Xavier; Gautier, Emmanuel L; Sennlaub, Florian

    2017-02-21

    Variants of the CFH gene, encoding complement factor H (CFH), show strong association with age-related macular degeneration (AMD), a major cause of blindness. Here, we used murine models of AMD to examine the contribution of CFH to disease etiology. Cfh deletion protected the mice from the pathogenic subretinal accumulation of mononuclear phagocytes (MP) that characterize AMD and showed accelerated resolution of inflammation. MP persistence arose secondary to binding of CFH to CD11b, which obstructed the homeostatic elimination of MPs from the subretinal space mediated by thrombospsondin-1 (TSP-1) activation of CD47. The AMD-associated CFH(H402) variant markedly increased this inhibitory effect on microglial cells, supporting a causal link to disease etiology. This mechanism is not restricted to the eye, as similar results were observed in a model of acute sterile peritonitis. Pharmacological activation of CD47 accelerated resolution of both subretinal and peritoneal inflammation, with implications for the treatment of chronic inflammatory disease.

  12. Mapping biochemical networks with protein fragment complementation assays.

    PubMed

    Remy, Ingrid; Michnick, Stephen W

    2015-01-01

    Cellular biochemical machineries, what we call pathways, consist of dynamically assembling and disassembling macromolecular complexes. Although our models for the organization of biochemical machines are derived largely from in vitro experiments, do they reflect their organization in intact, living cells? We have developed a general experimental strategy that addresses this question by allowing the quantitative probing of molecular interactions in intact, living cells. The experimental strategy is based on Protein fragment Complementation Assays (PCA), a method whereby protein interactions are coupled to refolding of enzymes from cognate fragments where reconstitution of enzyme activity acts as the detector of a protein interaction. A biochemical machine or pathway is defined by grouping interacting proteins into those that are perturbed in the same way by common factors (hormones, metabolites, enzyme inhibitors, etc.). In this chapter we review some of the essential principles of PCA and provide details and protocols for applications of PCA, particularly in mammalian cells, based on three PCA reporters, dihydrofolate reducta