Restored PB1-F2 in the 2009 Pandemic H1N1 Influenza Virus Has Minimal Effects in Swine

PubMed Central

Pena, Lindomar; Loving, Crystal L.; Henningson, Jamie N.; Lager, Kelly M.; Lorusso, Alessio

2012-01-01

PB1-F2 is an 87- to 90-amino-acid-long protein expressed by certain influenza A viruses. Previous studies have shown that PB1-F2 contributes to virulence in the mouse model; however, its role in natural hosts—pigs, humans, or birds—remains largely unknown. Outbreaks of domestic pigs infected with the 2009 pandemic H1N1 influenza virus (pH1N1) have been detected worldwide. Unlike previous pandemic strains, pH1N1 viruses do not encode a functional PB1-F2 due to the presence of three stop codons resulting in premature truncation after codon 11. However, pH1N1s have the potential to acquire the full-length form of PB1-F2 through mutation or reassortment. In this study, we assessed whether restoring the full-length PB1-F2 open reading frame (ORF) in the pH1N1 background would have an effect on virus replication and virulence in pigs. Restoring the PB1-F2 ORF resulted in upregulation of viral polymerase activity at early time points in vitro and enhanced virus yields in porcine respiratory explants and in the lungs of infected pigs. There was an increase in the severity of pneumonia in pigs infected with isogenic virus expressing PB1-F2 compared to the wild-type (WT) pH1N1. The extent of microscopic pneumonia correlated with increased pulmonary levels of alpha interferon and interleukin-1β in pigs infected with pH1N1 encoding a functional PB1-F2 but only early in the infection. Together, our results indicate that PB1-F2 in the context of pH1N1 moderately modulates viral replication, lung histopathology, and local cytokine response in pigs. PMID:22379102

A reassortant H9N2 influenza virus containing 2009 pandemic H1N1 internal-protein genes acquired enhanced pig-to-pig transmission after serial passages in swine.

PubMed

Mancera Gracia, José Carlos; Van den Hoecke, Silvie; Richt, Juergen A; Ma, Wenjun; Saelens, Xavier; Van Reeth, Kristien

2017-05-02

Avian H9N2 and 2009 pandemic H1N1 (pH1N1) influenza viruses can infect pigs and humans, raising the concern that H9N2:pH1N1 reassortant viruses could emerge. Such reassortants demonstrated increased replication and transmissibility in pig, but were still inefficient when compared to pH1N1. Here, we evaluated if a reassortant virus containing the hemagglutinin and neuraminidase of A/quail/Hong Kong/G1/1997 (H9N2) in the A/California/04/2009 (pH1N1) backbone could become better adapted to pigs by serial passaging. The tropism of the original H9N2:pH1N1 (P0) virus was restricted to the nasal mucosa, with no virus detected in the trachea or lungs. Nevertheless, after seven passages the H9N2:pH1N1 (P7) virus replicated in the entire respiratory tract. We also compared the transmissibility of H9N2:pH1N1 (P0), H9N2:pH1N1 (P7) and pH1N1. While only 2/6 direct-contact pigs showed nasal virus excretion of H9N2:pH1N1 (P0) ≥five days, 4/6 direct-contact animals shed the H9N2:pH1N1 (P7). Interestingly, those four animals shed virus with titers similar to those of the pH1N1, which readily transmitted to all six contact animals. The broader tissue tropism and the increased post-transmission replication after seven passages were associated with the HA-D225G substitution. Our data demonstrate that the pH1N1 internal-protein genes together with the serial passages favour H9N2 virus adaptation to pigs.

Sensitivity of influenza rapid diagnostic tests to H5N1 and 2009 pandemic H1N1 viruses.

PubMed

Sakai-Tagawa, Yuko; Ozawa, Makoto; Tamura, Daisuke; Le, Mai thi Quynh; Nidom, Chairul A; Sugaya, Norio; Kawaoka, Yoshihiro

2010-08-01

Simple and rapid diagnosis of influenza is useful for making treatment decisions in the clinical setting. Although many influenza rapid diagnostic tests (IRDTs) are available for the detection of seasonal influenza virus infections, their sensitivity for other viruses, such as H5N1 viruses and the recently emerged swine origin pandemic (H1N1) 2009 virus, remains largely unknown. Here, we examined the sensitivity of 20 IRDTs to various influenza virus strains, including H5N1 and 2009 pandemic H1N1 viruses. Our results indicate that the detection sensitivity to swine origin H1N1 viruses varies widely among IRDTs, with some tests lacking sufficient sensitivity to detect the early stages of infection when the virus load is low.

Antigenic variation of H1N1, H1N2 and H3N2 swine influenza viruses in Japan and Vietnam.

PubMed

Takemae, Nobuhiro; Nguyen, Tung; Ngo, Long Thanh; Hiromoto, Yasuaki; Uchida, Yuko; Pham, Vu Phong; Kageyama, Tsutomu; Kasuo, Shizuko; Shimada, Shinichi; Yamashita, Yasutaka; Goto, Kaoru; Kubo, Hideyuki; Le, Vu Tri; Van Vo, Hung; Do, Hoa Thi; Nguyen, Dang Hoang; Hayashi, Tsuyoshi; Matsuu, Aya; Saito, Takehiko

2013-04-01

The antigenicity of the influenza A virus hemagglutinin is responsible for vaccine efficacy in protecting pigs against swine influenza virus (SIV) infection. However, the antigenicity of SIV strains currently circulating in Japan and Vietnam has not been well characterized. We examined the antigenicity of classical H1 SIVs, pandemic A(H1N1)2009 (A(H1N1)pdm09) viruses, and seasonal human-lineage SIVs isolated in Japan and Vietnam. A hemagglutination inhibition (HI) assay was used to determine antigenic differences that differentiate the recent Japanese H1N2 and H3N2 SIVs from the H1N1 and H3N2 domestic vaccine strains. Minor antigenic variation between pig A(H1N1)pdm09 viruses was evident by HI assay using 13 mAbs raised against homologous virus. A Vietnamese H1N2 SIV, whose H1 gene originated from a human strain in the mid-2000s, reacted poorly with post-infection ferret serum against human vaccine strains from 2000-2010. These results provide useful information for selection of optimal strains for SIV vaccine production.

Antigenicity of the 2015-2016 seasonal H1N1 human influenza virus HA and NA proteins.

PubMed

Clark, Amelia M; DeDiego, Marta L; Anderson, Christopher S; Wang, Jiong; Yang, Hongmei; Nogales, Aitor; Martinez-Sobrido, Luis; Zand, Martin S; Sangster, Mark Y; Topham, David J

2017-01-01

Antigenic drift of the hemagglutinin (HA) and neuraminidase (NA) influenza virus proteins contributes to reduced vaccine efficacy. To analyze antigenic drift in human seasonal H1N1 viruses derived from the 2009 pandemic H1N1 virus (pH1N1-like viruses) accounts for the limited effectiveness (around 40%) of vaccination against pH1N1-like viruses during the 2015-2016 season, nasal washes/swabs collected from adult subjects in the Rochester, NY area, were used to sequence and isolate the circulating viruses. The HA and NA proteins from viruses circulating during the 2015-2016 season encoded eighteen and fourteen amino acid differences, respectively, when compared to A/California/04/2009, a strain circulating at the origin of the 2009 pandemic. The circulating strains belonged to subclade 6B.1, defined by HA amino acid substitutions S101N, S179N, and I233T. Hemagglutination-inhibiting (HAI) and HA-specific neutralizing serum antibody (Ab) titers from around 50% of pH1N1-like virus-infected subjects and immune ferrets were 2-4 fold lower for the 2015-2016 circulating strains compared to the vaccine strain. In addition, using a luminex-based mPlex HA assay, the binding of human sera from subjects infected with pH1N1-like viruses to the HA proteins from circulating and vaccine strains was not identical, strongly suggesting antigenic differences in the HA protein. Additionally, NA inhibition (NAI) Ab titers in human sera from pH1N1-like virus-infected subjects increased after the infection and there were measurable antigenic differences between the NA protein of circulating strains and the vaccine strain using both ferret and human antisera. Despite having been vaccinated, infected subjects exhibited low HAI Ab titers against the vaccine and circulating strains. This suggests that poor responses to the H1N1 component of the vaccine as well as antigenic differences in the HA and NA proteins of currently circulating pH1N1-like viruses could be contributing to risk of

Higher titers of some H5N1 and recent human H1N1 and H3N2 influenza viruses in Mv1 Lu vs. MDCK cells

PubMed Central

2011-01-01

Background The infectivity of influenza A viruses can differ among the various primary cells and continuous cell lines used for such measurements. Over many years, we observed that all things equal, the cytopathic effects caused by influenza A subtype H1N1, H3N2, and H5N1 viruses were often detected earlier in a mink lung epithelial cell line (Mv1 Lu) than in MDCK cells. We asked whether virus yields as measured by the 50% tissue culture infectious dose and plaque forming titer also differed in MDCK and Mv1 Lu cells infected by the same influenza virus subtypes. Results The 50% tissue culture infectious dose and plaque forming titer of many influenza A subtype H1N1, H3N2, and H5N1 viruses was higher in Mv1 Lu than in MDCK cells. Conclusions The yields of influenza subtype H1N1, H3N2, and H5N1 viruses can be higher in Mv1 Lu cells than in MDCK cells. PMID:21314955

Nosocomial Co-Transmission of Avian Influenza A(H7N9) and A(H1N1)pdm09 Viruses between 2 Patients with Hematologic Disorders

PubMed Central

Chen, Huazhong; Liu, Shelan; Liu, Jun; Chai, Chengliang; Mao, Haiyan; Yu, Zhao; Tang, Yuming; Zhu, Geqin; Chen, Haixiao X.; Zhu, Chengchu; Shao, Hui; Tan, Shuguang; Wang, Qianli; Bi, Yuhai; Zou, Zhen; Liu, Guang; Jin, Tao; Jiang, Chengyu; Gao, George F.; Peiris, Malik

2016-01-01

A nosocomial cluster induced by co-infections with avian influenza A(H7N9) and A(H1N1)pdm09 (pH1N1) viruses occurred in 2 patients at a hospital in Zhejiang Province, China, in January 2014. The index case-patient was a 57-year-old man with chronic lymphocytic leukemia who had been occupationally exposed to poultry. He had co-infection with H7N9 and pH1N1 viruses. A 71-year-old man with polycythemia vera who was in the same ward as the index case-patient for 6 days acquired infection with H7N9 and pH1N1 viruses. The incubation period for the second case-patient was estimated to be <4 days. Both case-patients died of multiple organ failure. Virus genetic sequences from the 2 case-patients were identical. Of 103 close contacts, none had acute respiratory symptoms; all were negative for H7N9 virus. Serum samples from both case-patients demonstrated strong proinflammatory cytokine secretion but incompetent protective immune responses. These findings strongly suggest limited nosocomial co-transmission of H7N9 and pH1N1 viruses from 1 immunocompromised patient to another. PMID:26982379

H7N9 Influenza Virus Is More Virulent in Ferrets than 2009 Pandemic H1N1 Influenza Virus.

PubMed

Yum, Jung; Ku, Keun Bon; Kim, Hyun Soo; Seo, Sang Heui

2015-12-01

The novel H7N9 influenza virus has been infecting humans in China since February 2013 and with a mortality rate of about 40%. This study compared the pathogenicity of the H7N9 and 2009 pandemic H1N1 influenza viruses in a ferret model, which shows similar symptoms to those of humans infected with influenza viruses. The H7N9 influenza virus caused a more severe disease than did the 2009 pandemic H1N1 influenza virus. All of the ferrets infected with the H7N9 influenza virus had died by 6 days after infection, while none of those infected with the 2009 pandemic H1N1 influenza virus died. Ferrets infected with the H7N9 influenza virus had higher viral titers in their lungs than did those infected with the 2009 pandemic H1N1 influenza virus. Histological findings indicated that hemorrhagic pneumonia was caused by infection with the H7N9 influenza virus, but not with the 2009 pandemic H1N1 influenza virus. In addition, the lung tissues of ferrets infected with the H7N9 influenza virus contained higher levels of chemokines than did those of ferrets infected with the 2009 pandemic H1N1 influenza virus. This study suggests that close monitoring is needed to prevent human infection by the lethal H7N9 influenza virus.

Genetic Characterization of H1N1 and H1N2 Influenza A Viruses Circulating in Ontario Pigs in 2012.

PubMed

Grgić, Helena; Costa, Marcio; Friendship, Robert M; Carman, Susy; Nagy, Éva; Poljak, Zvonimir

2015-01-01

The objective of this study was to characterize H1N1 and H1N2 influenza A virus isolates detected during outbreaks of respiratory disease in pig herds in Ontario (Canada) in 2012. Six influenza viruses were included in analysis using full genome sequencing based on the 454 platform. In five H1N1 isolates, all eight segments were genetically related to 2009 pandemic virus (A(H1N1)pdm09). One H1N2 isolate had hemagglutinin (HA), polymerase A (PA) and non-structural (NS) genes closely related to A(H1N1)pdm09, and neuraminidase (NA), matrix (M), polymerase B1 (PB1), polymerase B2 (PB2), and nucleoprotein (NP) genes originating from a triple-reassortant H3N2 virus (tr H3N2). The HA gene of five Ontario H1 isolates exhibited high identity of 99% with the human A(H1N1)pdm09 [A/Mexico/InDRE4487/09] from Mexico, while one Ontario H1N1 isolate had only 96.9% identity with this Mexican virus. Each of the five Ontario H1N1 viruses had between one and four amino acid (aa) changes within five antigenic sites, while one Ontario H1N2 virus had two aa changes within two antigenic sites. Such aa changes in antigenic sites could have an effect on antibody recognition and ultimately have implications for immunization practices. According to aa sequence analysis of the M2 protein, Ontario H1N1 and H1N2 viruses can be expected to offer resistance to adamantane derivatives, but not to neuraminidase inhibitors.

Genetic Characterization of H1N1 and H1N2 Influenza A Viruses Circulating in Ontario Pigs in 2012

PubMed Central

Grgić, Helena; Costa, Marcio; Friendship, Robert M.; Carman, Susy; Nagy, Éva; Poljak, Zvonimir

2015-01-01

The objective of this study was to characterize H1N1 and H1N2 influenza A virus isolates detected during outbreaks of respiratory disease in pig herds in Ontario (Canada) in 2012. Six influenza viruses were included in analysis using full genome sequencing based on the 454 platform. In five H1N1 isolates, all eight segments were genetically related to 2009 pandemic virus (A(H1N1)pdm09). One H1N2 isolate had hemagglutinin (HA), polymerase A (PA) and non-structural (NS) genes closely related to A(H1N1)pdm09, and neuraminidase (NA), matrix (M), polymerase B1 (PB1), polymerase B2 (PB2), and nucleoprotein (NP) genes originating from a triple-reassortant H3N2 virus (tr H3N2). The HA gene of five Ontario H1 isolates exhibited high identity of 99% with the human A(H1N1)pdm09 [A/Mexico/InDRE4487/09] from Mexico, while one Ontario H1N1 isolate had only 96.9% identity with this Mexican virus. Each of the five Ontario H1N1 viruses had between one and four amino acid (aa) changes within five antigenic sites, while one Ontario H1N2 virus had two aa changes within two antigenic sites. Such aa changes in antigenic sites could have an effect on antibody recognition and ultimately have implications for immunization practices. According to aa sequence analysis of the M2 protein, Ontario H1N1 and H1N2 viruses can be expected to offer resistance to adamantane derivatives, but not to neuraminidase inhibitors. PMID:26030614

Antigenicity of the 2015–2016 seasonal H1N1 human influenza virus HA and NA proteins

PubMed Central

Anderson, Christopher S.; Wang, Jiong; Yang, Hongmei; Nogales, Aitor; Martinez-Sobrido, Luis; Zand, Martin S.; Sangster, Mark Y.; Topham, David J.

2017-01-01

Antigenic drift of the hemagglutinin (HA) and neuraminidase (NA) influenza virus proteins contributes to reduced vaccine efficacy. To analyze antigenic drift in human seasonal H1N1 viruses derived from the 2009 pandemic H1N1 virus (pH1N1-like viruses) accounts for the limited effectiveness (around 40%) of vaccination against pH1N1-like viruses during the 2015–2016 season, nasal washes/swabs collected from adult subjects in the Rochester, NY area, were used to sequence and isolate the circulating viruses. The HA and NA proteins from viruses circulating during the 2015–2016 season encoded eighteen and fourteen amino acid differences, respectively, when compared to A/California/04/2009, a strain circulating at the origin of the 2009 pandemic. The circulating strains belonged to subclade 6B.1, defined by HA amino acid substitutions S101N, S179N, and I233T. Hemagglutination-inhibiting (HAI) and HA-specific neutralizing serum antibody (Ab) titers from around 50% of pH1N1-like virus-infected subjects and immune ferrets were 2–4 fold lower for the 2015–2016 circulating strains compared to the vaccine strain. In addition, using a luminex-based mPlex HA assay, the binding of human sera from subjects infected with pH1N1-like viruses to the HA proteins from circulating and vaccine strains was not identical, strongly suggesting antigenic differences in the HA protein. Additionally, NA inhibition (NAI) Ab titers in human sera from pH1N1-like virus-infected subjects increased after the infection and there were measurable antigenic differences between the NA protein of circulating strains and the vaccine strain using both ferret and human antisera. Despite having been vaccinated, infected subjects exhibited low HAI Ab titers against the vaccine and circulating strains. This suggests that poor responses to the H1N1 component of the vaccine as well as antigenic differences in the HA and NA proteins of currently circulating pH1N1-like viruses could be contributing to risk of

Comparative pathology of pigs infected with Korean H1N1, H1N2, or H3N2 swine influenza A viruses.

PubMed

Lyoo, Kwang-Soo; Kim, Jeong-Ki; Jung, Kwonil; Kang, Bo-Kyu; Song, Daesub

2014-09-24

The predominant subtypes of swine influenza A virus (SIV) in Korea swine population are H1N1, H1N2, and H3N2. The viruses are genetically close to the classical U.S. H1N1 and triple-reassortant H1N2 and H3N2 viruses, respectively. Comparative pathogenesis caused by Korean H1N1, H1N2, and H3N2 SIV was evaluated in this study. The H3N2 infected pigs had severe scores of gross and histopathological lesions at post-inoculation days (PID) 2, and this then progressively decreased. Both the H1N1 and H1N2 infected pigs lacked gross lesions at PID 2, but they showed moderate to severe pneumonia on PID 4, 7 and 14. The pigs infected with H1N1 had significant scores of gross and histopathological lesions when compared with the other pigs infected with H1N2, H3N2, and mock at PID 14. Mean SIV antigen-positive scores were rarely detected for pigs infected with H1N2 and H3N2 from PID 7, whereas a significantly increased amount of viral antigens were found in the bronchioles and alveolar epithelium of the H1N1infected pigs at PID 14. We demonstrated that Korean SIV subtypes had different pulmonary pathologic patterns. The Korean H3N2 rapidly induced acute lung lesions such as broncho-interstitial pneumonia, while the Korean H1N1 showed longer course of infection as compared to other strains.

Influenza virus A(H1N1)2009 antibody-dependent cellular cytotoxicity in young children prior to the H1N1 pandemic.

PubMed

Mesman, Annelies W; Westerhuis, Brenda M; Ten Hulscher, Hinke I; Jacobi, Ronald H; de Bruin, Erwin; van Beek, Josine; Buisman, Annemarie M; Koopmans, Marion P; van Binnendijk, Robert S

2016-09-01

Pre-existing immunity played a significant role in protection during the latest influenza A virus H1N1 pandemic, especially in older age groups. Structural similarities were found between A(H1N1)2009 and older H1N1 virus strains to which humans had already been exposed. Broadly cross-reactive antibodies capable of neutralizing the A(H1N1)2009 virus have been implicated in this immune protection in adults. We investigated the serological profile of a group of young children aged 9 years (n=55), from whom paired blood samples were available, just prior to the pandemic wave (March 2009) and shortly thereafter (March 2010). On the basis of A(H1N1)2009 seroconversion, 27 of the 55 children (49 %) were confirmed to be infected between these two time points. Within the non-infected group of 28 children (51 %), high levels of seasonal antibodies to H1 and H3 HA1 antigens were detected prior to pandemic exposure, reflecting past infection with H1N1 and H3N2, both of which had circulated in The Netherlands prior to the pandemic. In some children, this reactivity coincided with specific antibody reactivity against A(H1N1)2009. While these antibodies were not able to neutralize the A(H1N1)2009 virus, they were able to mediate antibody-dependent cellular cytotoxicity (ADCC) in vitro upon interaction with the A(H1N1)2009 virus. This finding suggests that cross-reactive antibodies could contribute to immune protection in children via ADCC.

Sensitization with vaccinia virus encoding H5N1 hemagglutinin restores immune potential against H5N1 influenza virus.

PubMed

Yasui, Fumihiko; Itoh, Yasushi; Ikejiri, Ai; Kitabatake, Masahiro; Sakaguchi, Nobuo; Munekata, Keisuke; Shichinohe, Shintaro; Hayashi, Yukiko; Ishigaki, Hirohito; Nakayama, Misako; Sakoda, Yoshihiro; Kida, Hiroshi; Ogasawara, Kazumasa; Kohara, Michinori

2016-11-28

H5N1 highly pathogenic avian influenza (H5N1 HPAI) virus causes elevated mortality compared with seasonal influenza viruses like H1N1 pandemic influenza (H1N1 pdm) virus. We identified a mechanism associated with the severe symptoms seen with H5N1 HPAI virus infection. H5N1 HPAI virus infection induced a decrease of dendritic cell number in the splenic extrafollicular T-cell zone and impaired formation of the outer layers of B-cell follicles, resulting in insufficient levels of antibody production after infection. However, in animals vaccinated with a live recombinant vaccinia virus expressing the H5 hemagglutinin, infection with H5N1 HPAI virus induced parafollicular dendritic cell accumulation and efficient antibody production. These results indicate that a recombinant vaccinia encoding H5 hemagglutinin gene does not impair dendritic cell recruitment and can be a useful vaccine candidate.

Genomic reassortants of pandemic A (H1N1) 2009 virus and endemic porcine H1 and H3 viruses in swine in Japan.

PubMed

Kirisawa, Rikio; Ogasawara, Yoshitaka; Yoshitake, Hayato; Koda, Asuka; Furuya, Tokujiro

2014-11-01

From 2010 to 2013 in Japan, we isolated 11 swine influenza viruses (SIVs) from pigs showing respiratory symptoms. Sequence and phylogenetic analyses showed that 6 H1N1 viruses originated from the pandemic (H1N1) 2009 (pdm 09) virus and the other 5 viruses were reassortants between SIVs and pdm 09 viruses, representing 4 genotypes. Two H1N2 viruses contained H1 and N2 genes originated from Japanese H1N2 SIV together with internal genes of pdm 09 viruses. Additionally, 1 H1N2 virus contained a further NP gene originating from Japanese H1N2 SIV. One H1N1 virus contained only the H1 gene originating from Japanese H1 SIV in a pdm 09 virus background. One H3N2 virus contained H3 and N2 genes originating from Japanese H3N2 SIV together with internal genes of pdm 09 virus. The results indicate that pdm 09 viruses are distributed widely in the Japanese swine population and that several reassortments with Japanese SIVs have occurred.

Intense Co-Circulation of Non-Influenza Respiratory Viruses during the First Wave of Pandemic Influenza pH1N1/2009: A Cohort Study in Reunion Island

PubMed Central

Turpin, Magali; Rollot, Olivier; Flahault, Antoine; Carrat, Fabrice; de Lamballerie, Xavier; Gérardin, Patrick; Dellagi, Koussay

2012-01-01

Objective The aim of the present study was to weigh up, at the community level, the respective roles played by pandemic Influenza (pH1N1) virus and co-circulating human Non-Influenza Respiratory Viruses (NIRVs) during the first wave of the 2009 pH1N1 pandemic. Methods A population-based prospective cohort study was conducted in Reunion Island during the austral winter 2009 (weeks 30–44) that allowed identification of 125 households with at least one member who developed symptoms of Influenza-like illness (ILI). Three consecutive nasal swabs were collected from each household member (443 individuals) on day 0, 3 and 8 post-ILI report and tested for pH1N1 and 15 NIRVs by RT-PCR. Results Two successive waves of viral infections were identified: a first wave (W33–37) when pH1N1 was dominant and co-circulated with NIRVs, sharply interrupted by a second wave (W38–44), almost exclusively composed of NIRVs, mainly human Rhinoviruses (hRV) and Coronaviruses (hCoV). Data suggest that some interference may occur between NIRVs and pH1N1 when they co-circulate within the same household, where NIRVs were more likely to infect pH1N1 negative individuals than pH1N1 positive peers (relative risk: 3.13, 95% CI: 1.80–5.46, P<0.001). Viral shedding was significantly shorter (P = 0.035) in patients who were co-infected by pH1N1 and NIRV or by two different NIRVs compared to those who were infected with only one virus, whatever this virus was (pH1N1 or NIRVs). Although intense co-circulation of NIRVs (especially hRV) likely brought pH1N1 under the detection threshold, it did not prevent spread of the pandemic Influenza virus within the susceptible population nor induction of an extensive herd immunity to it. Conclusion Our results suggest that NIRV co-infections during Influenza epidemics may act as cofactors that contribute to shape an outbreak and modulate the attack rate. They further warrant broad spectrum studies to fully understand viral epidemics. PMID:22984554

H1N1 influenza viruses varying widely in hemagglutinin stability transmit efficiently from swine to swine and to ferrets.

PubMed

Russier, Marion; Yang, Guohua; Marinova-Petkova, Atanaska; Vogel, Peter; Kaplan, Bryan S; Webby, Richard J; Russell, Charles J

2017-03-01

A pandemic-capable influenza virus requires a hemagglutinin (HA) surface glycoprotein that is immunologically unseen by most people and is capable of supporting replication and transmission in humans. HA stabilization has been linked to 2009 pH1N1 pandemic potential in humans and H5N1 airborne transmissibility in the ferret model. Swine have served as an intermediate host for zoonotic influenza viruses, yet the evolutionary pressure exerted by this host on HA stability was unknown. For over 70 contemporary swine H1 and H3 isolates, we measured HA activation pH to range from pH 5.1 to 5.9 for H1 viruses and pH 5.3 to 5.8 for H3 viruses. Thus, contemporary swine isolates vary widely in HA stability, having values favored by both avian (pH >5.5) and human and ferret (pH ≤5.5) species. Using an early 2009 pandemic H1N1 (pH1N1) virus backbone, we generated three viruses differing by one HA residue that only altered HA stability: WT (pH 5.5), HA1-Y17H (pH 6.0), and HA2-R106K (pH 5.3). All three replicated in pigs and transmitted from pig-to-pig and pig-to-ferret. WT and R106 viruses maintained HA genotype and phenotype after transmission. Y17H (pH 6.0) acquired HA mutations that stabilized the HA protein to pH 5.8 after transmission to pigs and 5.5 after transmission to ferrets. Overall, we found swine support a broad range of HA activation pH for contact transmission and many recent swine H1N1 and H3N2 isolates have stabilized (human-like) HA proteins. This constitutes a heightened pandemic risk and underscores the importance of ongoing surveillance and control efforts for swine viruses.

H1N1 influenza viruses varying widely in hemagglutinin stability transmit efficiently from swine to swine and to ferrets

PubMed Central

Yang, Guohua; Marinova-Petkova, Atanaska; Kaplan, Bryan S.; Webby, Richard J.

2017-01-01

A pandemic-capable influenza virus requires a hemagglutinin (HA) surface glycoprotein that is immunologically unseen by most people and is capable of supporting replication and transmission in humans. HA stabilization has been linked to 2009 pH1N1 pandemic potential in humans and H5N1 airborne transmissibility in the ferret model. Swine have served as an intermediate host for zoonotic influenza viruses, yet the evolutionary pressure exerted by this host on HA stability was unknown. For over 70 contemporary swine H1 and H3 isolates, we measured HA activation pH to range from pH 5.1 to 5.9 for H1 viruses and pH 5.3 to 5.8 for H3 viruses. Thus, contemporary swine isolates vary widely in HA stability, having values favored by both avian (pH >5.5) and human and ferret (pH ≤5.5) species. Using an early 2009 pandemic H1N1 (pH1N1) virus backbone, we generated three viruses differing by one HA residue that only altered HA stability: WT (pH 5.5), HA1-Y17H (pH 6.0), and HA2-R106K (pH 5.3). All three replicated in pigs and transmitted from pig-to-pig and pig-to-ferret. WT and R106 viruses maintained HA genotype and phenotype after transmission. Y17H (pH 6.0) acquired HA mutations that stabilized the HA protein to pH 5.8 after transmission to pigs and 5.5 after transmission to ferrets. Overall, we found swine support a broad range of HA activation pH for contact transmission and many recent swine H1N1 and H3N2 isolates have stabilized (human-like) HA proteins. This constitutes a heightened pandemic risk and underscores the importance of ongoing surveillance and control efforts for swine viruses. PMID:28282440

Pandemic (H1N1) 2009 virus infection during pregnancy in South India.

PubMed

Pramanick, Angsumita; Rathore, Swati; Peter, John V; Moorthy, Mahesh; Lionel, Jessie

2011-04-01

To assess the clinical profile of pregnant/puerperal women from a semi-urban Indian population who were infected with pandemic (H1N1) 2009 virus (P[H1N1]2009v) and to evaluate their outcome. In a cross-sectional study, 566 women (79 pregnant/puerperal, 487 nonpregnant) who presented to a tertiary care hospital with influenza-like illness were tested for P(H1N1)2009v by real-time reverse transcriptase polymerase chain reaction. Outcomes measures were the maternal mortality and the perinatal mortality rate (PMR). Twenty (25%) pregnant/puerperal and 144 (30%) nonpregnant women tested positive for P(H1N1)2009v, with 5 pregnant and 3 postpartum women requiring admission to the intensive care unit (ICU). P(H1N1)2009v-related mortality was higher in pregnant than nonpregnant women (25% versus 8%; P=0.04). In the pregnant/puerperal cohort, factors associated with death included delayed presentation (median 6days versus 1.5days in survivors; P=0.007), need for ICU admission (P=0.004), need for ventilation (P=0.001), and renal failure (P=0.001). The PMR was 55.5/1000 births compared with 33.5/1000 births in the hospital overall during the study period. In a low-income country, P(H1N1)2009v infection in pregnancy is associated with considerable mortality. Delayed presentation to a tertiary care center, lack of awareness, and restricted access to treatment might have contributed to the high mortality. Copyright © 2011 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

Decreased Serologic Response in Vaccinated Military Recruits during 2011 Correspond to Genetic Drift in Concurrent Circulating Pandemic A/H1N1 Viruses

DTIC Science & Technology

2012-04-13

that gave 75% cytopathic effect (CPE) were utilized in the MN assays. The proportions of LAIV and TIV vaccinees for the range of post- vaccination ...titers were plotted for the vaccine strain H3N2 and 2009 pH1N1 viruses and the circulating 2011 pH1N1 virus (Figure 1). Overall, titers in TIV vaccinees ...seroresponse against H3N2 than the 2009 and 2011 pH1N1 viruses. Post- vaccine seroprotection among LAIV vaccinees for 2009 pH1N1, H3N2, and 2011 pH1N1

Glycosylation on Hemagglutinin Affects the Virulence and Pathogenicity of Pandemic H1N1/2009 Influenza A Virus in Mice

PubMed Central

Li, Yongtao; Bradley, Konrad C.; Cao, Jiyue; Chen, Huanchun; Jin, Meilin; Zhou, Hongbo

2013-01-01

The two glycosylation sites (Asn142 and Asn177) were observed in the HA of most human seasonal influenza A/H1N1 viruses, while none in pandemic H1N1/2009 influenza A (pH1N1) viruses. We investigated the effect of the two glycosylation sites on viral virulence and pathogenicity in mice using recombinant pH1N1. The H1N1/144 and H1N1/177 mutants which gained potential glycosylation sites Asn142 and Asn177 on HA respectively were generated from A/Mexico/4486/2009(H1N1) by site-directed mutagenesis and reverse genetics, the same as the H1N1/144+177 gained both glycosylation sites Asn142 and Asn177. The biological characteristics and antigenicity of the mutants were compared with wild-type pH1N1. The virulence and pathogenicity of recombinants were also detected in mice. Our results showed that HA antigenicity and viral affinity for receptor may change with introduction of the glycosylation sites. Compared with wild-type pH1N1, the mutant H1N1/177 displayed an equivalent virus titer in chicken embryos and mice, and increased virulence and pathogenicity in mice. The H1N1/144 displayed the highest virus titer in mice lung. However, the H1N1/144+177 displayed the most serious alveolar inflammation and pathogenicity in infected mice. The introduction of the glycosylation sites Asn144 and Asn177 resulted in the enhancement on virulence and pathogenicity of pH1N1 in mice, and was also associated with the change of HA antigenicity and the viral affinity for receptor. PMID:23637827

Novel reassortant influenza A(H1N2) virus derived from A(H1N1)pdm09 virus isolated from swine, Japan, 2012.

PubMed

Kobayashi, Miho; Takayama, Ikuyo; Kageyama, Tsutomu; Tsukagoshi, Hiroyuki; Saitoh, Mika; Ishioka, Taisei; Yokota, Yoko; Kimura, Hirokazu; Tashiro, Masato; Kozawa, Kunihisa

2013-12-01

We isolated a novel influenza virus A(H1N2) strain from a pig on January 13, 2012, in Gunma Prefecture, Japan. Phylogenetic analysis showed that the strain was a novel type of double-reassortant virus derived from the swine influenza virus strains H1N1pdm09 and H1N2, which were prevalent in Gunma at that time.

Modified vaccinia virus Ankara expressing the hemagglutinin of pandemic (H1N1) 2009 virus induces cross-protective immunity against Eurasian 'avian-like' H1N1 swine viruses in mice.

PubMed

Castrucci, Maria R; Facchini, Marzia; Di Mario, Giuseppina; Garulli, Bruno; Sciaraffia, Ester; Meola, Monica; Fabiani, Concetta; De Marco, Maria A; Cordioli, Paolo; Siccardi, Antonio; Kawaoka, Yoshihiro; Donatelli, Isabella

2014-05-01

To examine cross-reactivity between hemagglutinin (HA) derived from A/California/7/09 (CA/09) virus and that derived from representative Eurasian "avian-like" (EA) H1N1 swine viruses isolated in Italy between 1999 and 2008 during virological surveillance in pigs. Modified vaccinia virus Ankara (MVA) expressing the HA gene of CA/09 virus (MVA-HA-CA/09) was used as a vaccine to investigate cross-protective immunity against H1N1 swine viruses in mice. Two classical swine H1N1 (CS) viruses and four representative EA-like H1N1 swine viruses previously isolated during outbreaks of respiratory disease in pigs on farms in Northern Italy were used in this study. Female C57BL/6 mice were vaccinated with MVA/HA/CA/09 and then challenged intranasally with H1N1 swine viruses. Cross-reactive antibody responses were determined by hemagglutination- inhibition (HI) and virus microneutralizing (MN) assays of sera from MVA-vaccinated mice. The extent of protective immunity against infection with H1N1 swine viruses was determined by measuring lung viral load on days 2 and 4 post-challenge. Systemic immunization of mice with CA/09-derived HA, vectored by MVA, elicited cross-protective immunity against recent EA-like swine viruses. This immune protection was related to the levels of cross-reactive HI antibodies in the sera of the immunized mice and was dependent on the similarity of the antigenic site Sa of H1 HAs. Our findings suggest that the herd immunity elicited in humans by the pandemic (H1N1) 2009 virus could limit the transmission of recent EA-like swine HA genes into the influenza A virus gene pool in humans. © 2013 The Authors Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.

H1N1 influenza (Swine flu)

MedlinePlus

Swine flu; H1N1 type A influenza ... The H1N1 virus is now considered a regular flu virus. It is one of the three viruses included in the regular (seasonal) flu vaccine . You cannot get H1N1 flu virus from ...

The pH of activation of the hemagglutinin protein regulates H5N1 influenza virus replication and pathogenesis in mice.

PubMed

Zaraket, Hassan; Bridges, Olga A; Russell, Charles J

2013-05-01

After receptor binding and internalization during influenza virus entry, the hemagglutinin (HA) protein is triggered by low pH to undergo irreversible conformational changes that mediate membrane fusion. To investigate how mutations that alter the activation pH of the HA protein influence the fitness of an avian H5N1 influenza virus in a mammalian model, we infected C57BL/6J or DBA/2J mice and compared the replication and virulence of recombinant A/chicken/Vietnam/C58/04 (H5N1) HA-Y231H mutant, wild-type, and HA-H241Q and HA-K582I mutant viruses that have HA activation pH values of 6.3, 5.9, 5.6, and 5.4, respectively. The HA-Y231H mutant virus was highly susceptible to acid inactivation in vitro and was attenuated for growth and virulence in mice, suggesting that an H5N1 HA protein triggered at pH 6.3 is too unstable for the virus to remain fit. Wild-type and HA-H241Q viruses were similar in pathogenicity and grew to similar levels in mice, ducks, and cell cultures derived from both avian and mammalian tissues, suggesting that H5N1 HA proteins triggered at pH values in the range of 5.9 to 5.6 broadly support replication. The HA-K582I mutant virus had greater growth and virulence in DBA/2J mice than the wild type did, although the mutant virus was highly attenuated in ducks. The data suggest that adaptation of avian H5N1 influenza virus for infection in mammals is supported by a decrease in the HA activation pH to 5.4. Identification of the HA activation pH as a host-specific infectivity factor is expected to aid in the surveillance and risk assessment of currently circulating H5N1 influenza viruses.

Possible Increased Pathogenicity of Pandemic (H1N1) 2009 Influenza Virus upon Reassortment

PubMed Central

Schrauwen, Eefje J.A.; Herfst, Sander; Chutinimitkul, Salin; Bestebroer, Theo M.; Rimmelzwaan, Guus F.; Osterhaus, Albert D.M.E.; Kuiken, Thijs

2011-01-01

Since emergence of the pandemic (H1N1) 2009 virus in April 2009, three influenza A viruses—seasonal (H3N2), seasonal (H1N1), and pandemic (H1N1) 2009—have circulated in humans. Genetic reassortment between these viruses could result in enhanced pathogenicity. We compared 4 reassortant viruses with favorable in vitro replication properties with the wild-type pandemic (H1N1) 2009 virus with respect to replication kinetics in vitro and pathogenicity and transmission in ferrets. Pandemic (H1N1) 2009 viruses containing basic polymerase 2 alone or in combination with acidic polymerase of seasonal (H1N1) virus were attenuated in ferrets. In contrast, pandemic (H1N1) 2009 with neuraminidase of seasonal (H3N2) virus resulted in increased virus replication and more severe pulmonary lesions. The data show that pandemic (H1N1) 2009 virus has the potential to reassort with seasonal influenza viruses, which may result in increased pathogenicity while it maintains the capacity of transmission through aerosols or respiratory droplets. PMID:21291589

Isolation and genetic characterization of avian-like H1N1 and novel ressortant H1N2 influenza viruses from pigs in China.

PubMed

Yu, Hai; Zhang, Peng-Chao; Zhou, Yan-Jun; Li, Guo-Xin; Pan, Jie; Yan, Li-Ping; Shi, Xiao-Xiao; Liu, Hui-Li; Tong, Guang-Zhi

2009-08-21

As pigs are susceptible to both human and avian influenza viruses, they have been proposed to be intermediate hosts or mixing vessels for the generation of pandemic influenza viruses through reassortment or adaptation to the mammalian host. In this study, we reported avian-like H1N1 and novel ressortant H1N2 influenza viruses from pigs in China. Homology and phylogenetic analyses showed that the H1N1 virus (A/swine/Zhejiang/1/07) was closely to avian-like H1N1 viruses and seemed to be derived from the European swine H1N1 viruses, which was for the first time reported in China; and the two H1N2 viruses (A/swine/Shanghai/1/07 and A/swine/Guangxi/13/06) were novel ressortant H1N2 influenza viruses containing genes from the classical swine (HA, NP, M and NS), human (NA and PB1) and avian (PB2 and PA) lineages, which indicted that the reassortment among human, avian, and swine influenza viruses had taken place in pigs in China and resulted in the generation of new viruses. The isolation of avian-like H1N1 influenza virus originated from the European swine H1N1 viruses, especially the emergence of two novel ressortant H1N2 influenza viruses provides further evidence that pigs serve as intermediate hosts or "mixing vessels", and swine influenza virus surveillance in China should be given a high priority.

Novel Reassortant Influenza A(H1N2) Virus Derived from A(H1N1)pdm09 Virus Isolated from Swine, Japan, 2012

PubMed Central

Kobayashi, Miho; Takayama, Ikuyo; Kageyama, Tsutomu; Tsukagoshi, Hiroyuki; Saitoh, Mika; Ishioka, Taisei; Yokota, Yoko; Kimura, Hirokazu; Tashiro, Masato

2013-01-01

We isolated a novel influenza virus A(H1N2) strain from a pig on January 13, 2012, in Gunma Prefecture, Japan. Phylogenetic analysis showed that the strain was a novel type of double-reassortant virus derived from the swine influenza virus strains H1N1pdm09 and H1N2, which were prevalent in Gunma at that time. PMID:24274745

A duplex real-time RT-PCR assay for detecting H5N1 avian influenza virus and pandemic H1N1 influenza virus.

PubMed

Kang, Xiao-ping; Jiang, Tao; Li, Yong-qiang; Lin, Fang; Liu, Hong; Chang, Guo-hui; Zhu, Qing-yu; Qin, E-de; Qin, Cheng-feng; Yang, Yin-hui

2010-06-02

A duplex real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay was improved for simultaneous detection of highly pathogenic H5N1 avian influenza virus and pandemic H1N1 (2009) influenza virus, which is suitable for early diagnosis of influenza-like patients and for epidemiological surveillance. The sensitivity of this duplex real-time RT-PCR assay was 0.02 TCID50 (50% tissue culture infective dose) for H5N1 and 0.2 TCID50 for the pandemic H1N1, which was the same as that of each single-target RT-PCR for pandemic H1N1 and even more sensitive for H5N1 with the same primers and probes. No cross reactivity of detecting other subtype influenza viruses or respiratory tract viruses was observed. Two hundred and thirty-six clinical specimens were tested by comparing with single real-time RT-PCR and result from the duplex assay was 100% consistent with the results of single real-time RT-PCR and sequence analysis.

Eurasian-Origin Gene Segments Contribute to the Transmissibility, Aerosol Release, and Morphology of the 2009 Pandemic H1N1 Influenza Virus

PubMed Central

Lakdawala, Seema S.; Lamirande, Elaine W.; Suguitan, Amorsolo L.; Wang, Weijia; Santos, Celia P.; Vogel, Leatrice; Matsuoka, Yumiko; Lindsley, William G.; Jin, Hong; Subbarao, Kanta

2011-01-01

The epidemiological success of pandemic and epidemic influenza A viruses relies on the ability to transmit efficiently from person-to-person via respiratory droplets. Respiratory droplet (RD) transmission of influenza viruses requires efficient replication and release of infectious influenza particles into the air. The 2009 pandemic H1N1 (pH1N1) virus originated by reassortment of a North American triple reassortant swine (TRS) virus with a Eurasian swine virus that contributed the neuraminidase (NA) and M gene segments. Both the TRS and Eurasian swine viruses caused sporadic infections in humans, but failed to spread from person-to-person, unlike the pH1N1 virus. We evaluated the pH1N1 and its precursor viruses in a ferret model to determine the contribution of different viral gene segments on the release of influenza virus particles into the air and on the transmissibility of the pH1N1 virus. We found that the Eurasian-origin gene segments contributed to efficient RD transmission of the pH1N1 virus likely by modulating the release of influenza viral RNA-containing particles into the air. All viruses replicated well in the upper respiratory tract of infected ferrets, suggesting that factors other than viral replication are important for the release of influenza virus particles and transmission. Our studies demonstrate that the release of influenza viral RNA-containing particles into the air correlates with increased NA activity. Additionally, the pleomorphic phenotype of the pH1N1 virus is dependent upon the Eurasian-origin gene segments, suggesting a link between transmission and virus morphology. We have demonstrated that the viruses are released into exhaled air to varying degrees and a constellation of genes influences the transmissibility of the pH1N1 virus. PMID:22241979

Identification of swine H1N2/pandemic H1N1 reassortant influenza virus in pigs, United States.

PubMed

Ali, Ahmed; Khatri, Mahesh; Wang, Leyi; Saif, Yehia M; Lee, Chang-Won

2012-07-06

In October and November 2010, novel H1N2 reassortant influenza viruses were identified from pigs showing mild respiratory signs that included cough and depression. Sequence and phylogenetic analysis showed that the novel H1N2 reassortants possesses HA and NA genes derived from recent H1N2 swine isolates similar to those isolated from Midwest. Compared to the majority of reported reassortants, both viruses preserved human-like host restrictive and putative antigenic sites in their HA and NA genes. The four internal genes, PB2, PB1, PA, and NS were similar to the contemporary swine triple reassortant viruses' internal genes (TRIG). Interestingly, NP and M genes of the novel reassortants were derived from the 2009 pandemic H1N1. The NP and M proteins of the two isolates demonstrated one (E16G) and four (G34A, D53E, I109T, and V313I) amino acid changes in the M2 and NP proteins, respectively. Similar amino acid changes were also noticed upon incorporation of the 2009 pandemic H1N1 NP in other reassortant viruses reported in the U.S. Thus the role of those amino acids in relation to host adaptation need to be further investigated. The reassortments of pandemic H1N1 with swine influenza viruses and the potential of interspecies transmission of these reassortants from swine to other species including human indicate the importance of systematic surveillance of swine population to determine the origin, the prevalence of similar reassortants in the U.S. and their impact on both swine production and public health. Copyright © 2012 Elsevier B.V. All rights reserved.

Inactivation of H1N1 viruses exposed to acidic ozone water

NASA Astrophysics Data System (ADS)

Uhm, Han S.; Lee, Kwang H.; Seong, Baik L.

2009-10-01

The inactivation of H1N1 viruses upon exposure to acidic ozone water was investigated using chicken allantoic fluids of different dilutions, pH values, and initial ozone concentrations. The inactivation effect of the acidic ozone water was found to be stronger than the inactivation effect of the ozone water combined with the degree of acidity, indicating a synergic effect of acidity on ozone decay in water. It is also shown that acidic ozone water with a pH value of 4 or less is very effective means of virus inactivation if provided in conjunction with an ozone concentration of 20 mg/l or higher.

H1N1 seasonal influenza virus evolutionary rate changed over time.

PubMed

Suptawiwat, Ornpreya; Kongchanagul, Alita; Boonarkart, Chompunuch; Auewarakul, Prasert

2018-05-02

It was previously shown that the seasonal H1N1 influenza virus antigenic drift occurred at a slower rate than the seasonal H3N2 virus during the first decade of the 21th century. It was hypothesized that the slower antigenic evolution led to a decrease in average ages of infection, which in turn resulted in lower level of global viral circulation. It is unclear what caused the difference between the two viruses, but a plausible explanation may be related to the fact that the H1N1 virus had been in human population for much longer than the H3N2 virus. This would suggest that H1N1 antigenic drift in an earlier period may have been different from a more recent period. To test this hypothesis, we analyzed seasonal H1N1 influenza sequences during various time periods. In comparison to more recent H1N1 virus, the older H1N1 virus during the first half of the 20th century showed evidences of higher nonsynnonymous/synonymous ration (dN/dS) in its hemagglutinin (HA) gene. We compared amino acid sequence changes in the HA epitopes for each outbreak season and found that there were less changes in later years. Amino acid sequence diversity in the epitopes as measured by sequence entropy became smaller for each passing decade. These suggest that there might be some limit to the antigenic drift. The longer an influenza virus has drifted in human population, the less flexibility it may become. With less flexibility to adapt and escape the host immunity, the virus may have to rely more on younger naïve population. Copyright © 2018 Elsevier B.V. All rights reserved.

Continual re-introduction of human pandemic H1N1 influenza A viruses into US swine, 2009-2014

USDA-ARS?s Scientific Manuscript database

Human-to-swine transmission of pandemic H1N1 influenza viruses (pH1N1) increased the genetic diversity of influenza A viruses in swine (swIAVs) globally and is linked to the emergence of new pandemic threats, including H3N2v variants. Through phylogenetic analysis of contemporary swIAVs in the Unit...

Influenza A(H1N1)pdm09 during air travel

PubMed Central

Neatherlin, John; Cramer, Elaine H.; Dubray, Christine; Marienau, Karen J.; Russell, Michelle; Sun, Hong; Whaley, Melissa; Hancock, Kathy; Duong, Krista K.; Kirking, Hannah L.; Schembri, Christopher; Katz, Jacqueline M.; Cohen, Nicole J.; Fishbein, Daniel B.

2015-01-01

Summary The global spread of the influenza A(H1N1)pdm09 virus (pH1N1) associated with travelers from North America during the onset of the 2009 pandemic demonstrates the central role of international air travel in virus migration. To characterize risk factors for pH1N1 transmission during air travel, we investigated travelers and airline employees from four North American flights carrying ill travelers with confirmed pH1N1 infection. Of 392 passengers and crew identified, information was available for 290 (74%) passengers were interviewed. Overall attack rates for acute respiratory infection and influenza-like illness 1–7 days after travel were 5.2% and 2.4% respectively. Of 43 individuals that provided sera, 4 (9.3%) tested positive for pH1N1 antibodies, including 3 with serologic evidence of asymptomatic infection. Investigation of novel influenza aboard aircraft may be instructive. However, beyond the initial outbreak phase, it may compete with community-based mitigation activities, and interpretation of findings will be difficult in the context of established community transmission. PMID:23523241

Putative amino acid determinants of the emergence of the 2009 influenza A (H1N1) virus in the human population.

PubMed

Meroz, Daphna; Yoon, Sun-Woo; Ducatez, Mariette F; Fabrizio, Thomas P; Webby, Richard J; Hertz, Tomer; Ben-Tal, Nir

2011-08-16

The emergence of the unique H1N1 influenza A virus in 2009 resulted in a pandemic that has spread to over 200 countries. The constellation of molecular factors leading to the emergence of this strain is still unclear. Using a computational approach, we identified molecular determinants that may discriminate the hemagglutinin protein of the 2009 human pandemic H1N1 (pH1N1) strain from that of other H1N1 strains. As expected, positions discriminating the pH1N1 from seasonal human strains were located in or near known H1N1 antigenic sites, thus camouflaging the pH1N1 strain from immune recognition. For example, the alteration S145K (an antigenic position) was found as a characteristic of the pH1N1 strain. We also detected positions in the hemagglutinin protein differentiating classical swine viruses from pH1N1. These positions were mostly located in and around the receptor-binding pocket, possibly influencing binding affinity to the human cell. Such alterations may be liable in part for the virus's efficient infection and adaptation to humans. For instance, 133(A) and 149 were identified as discriminative positions. Significantly, we showed that the substitutions R133(A)K and R149K, predicted to be pH1N1 characteristics, each altered virus binding to erythrocytes and conferred virulence to A/swine/NC/18161/02 in mice, reinforcing the computational findings. Our findings provide a structural explanation for the deficient immunity of humans to the pH1N1 strain. Moreover, our analysis points to unique molecular factors that may have facilitated the emergence of this swine variant in humans, in contrast to other swine variants that failed.

Elicitation of Protective Antibodies against a Broad Panel of H1N1 Viruses in Ferrets Preimmune to Historical H1N1 Influenza Viruses.

PubMed

Carter, Donald M; Darby, Christopher A; Johnson, Scott K; Carlock, Michael A; Kirchenbaum, Greg A; Allen, James D; Vogel, Thorsten U; Delagrave, Simon; DiNapoli, Joshua; Kleanthous, Harold; Ross, Ted M

2017-12-15

Most preclinical animal studies test influenza vaccines in immunologically naive animal models, even though the results of vaccination may not accurately reflect the effectiveness of vaccine candidates in humans that have preexisting immunity to influenza. In this study, novel, broadly reactive influenza vaccine candidates were assessed in preimmune ferrets. These animals were infected with different H1N1 isolates before being vaccinated or infected with another influenza virus. Previously, our group has described the design and characterization of computationally optimized broadly reactive hemagglutinin (HA) antigens (COBRA) for H1N1 isolates. Vaccinating ferrets with virus-like particle (VLP) vaccines expressing COBRA HA proteins elicited antibodies with hemagglutination inhibition (HAI) activity against more H1N1 viruses in the panel than VLP vaccines expressing wild-type HA proteins. Specifically, ferrets infected with the 1986 virus and vaccinated with a single dose of the COBRA HA VLP vaccines elicited antibodies with HAI activity against 11 to 14 of the 15 H1N1 viruses isolated between 1934 and 2013. A subset of ferrets was infected with influenza viruses expressing the COBRA HA antigens. These COBRA preimmune ferrets had superior breadth of HAI activity after vaccination with COBRA HA VLP vaccines than COBRA preimmune ferrets vaccinated with VLP vaccines expressing wild-type HA proteins. Overall, priming naive ferrets with COBRA HA based viruses or using COBRA HA based vaccines to boost preexisting antibodies induced by wild-type H1N1 viruses, COBRA HA antigens elicited sera with the broadest HAI reactivity against multiple antigenic H1N1 viral variants. This is the first report demonstrating the effectiveness of a broadly reactive or universal influenza vaccine in a preimmune ferret model. IMPORTANCE Currently, many groups are testing influenza vaccine candidates to meet the challenge of developing a vaccine that elicits broadly reactive and long

Elicitation of Protective Antibodies against a Broad Panel of H1N1 Viruses in Ferrets Preimmune to Historical H1N1 Influenza Viruses

PubMed Central

Carter, Donald M.; Darby, Christopher A.; Johnson, Scott K.; Carlock, Michael A.; Kirchenbaum, Greg A.; Allen, James D.; Vogel, Thorsten U.; Delagrave, Simon; DiNapoli, Joshua; Kleanthous, Harold

2017-01-01

ABSTRACT Most preclinical animal studies test influenza vaccines in immunologically naive animal models, even though the results of vaccination may not accurately reflect the effectiveness of vaccine candidates in humans that have preexisting immunity to influenza. In this study, novel, broadly reactive influenza vaccine candidates were assessed in preimmune ferrets. These animals were infected with different H1N1 isolates before being vaccinated or infected with another influenza virus. Previously, our group has described the design and characterization of computationally optimized broadly reactive hemagglutinin (HA) antigens (COBRA) for H1N1 isolates. Vaccinating ferrets with virus-like particle (VLP) vaccines expressing COBRA HA proteins elicited antibodies with hemagglutination inhibition (HAI) activity against more H1N1 viruses in the panel than VLP vaccines expressing wild-type HA proteins. Specifically, ferrets infected with the 1986 virus and vaccinated with a single dose of the COBRA HA VLP vaccines elicited antibodies with HAI activity against 11 to 14 of the 15 H1N1 viruses isolated between 1934 and 2013. A subset of ferrets was infected with influenza viruses expressing the COBRA HA antigens. These COBRA preimmune ferrets had superior breadth of HAI activity after vaccination with COBRA HA VLP vaccines than COBRA preimmune ferrets vaccinated with VLP vaccines expressing wild-type HA proteins. Overall, priming naive ferrets with COBRA HA based viruses or using COBRA HA based vaccines to boost preexisting antibodies induced by wild-type H1N1 viruses, COBRA HA antigens elicited sera with the broadest HAI reactivity against multiple antigenic H1N1 viral variants. This is the first report demonstrating the effectiveness of a broadly reactive or universal influenza vaccine in a preimmune ferret model. IMPORTANCE Currently, many groups are testing influenza vaccine candidates to meet the challenge of developing a vaccine that elicits broadly reactive and long

Canine susceptibility to human influenza viruses (A/pdm 09H1N1, A/H3N2 and B).

PubMed

Song, Daesub; Kim, Hyekwon; Na, Woonsung; Hong, Minki; Park, Seong-Jun; Moon, Hyoungjoon; Kang, Bokyu; Lyoo, Kwang-Soo; Yeom, Minjoo; Jeong, Dae Gwin; An, Dong-Jun; Kim, Jeong-Ki

2015-02-01

We investigated the infectivity and transmissibility of the human seasonal H3N2, pandemic (pdm) H1N1 (2009) and B influenza viruses in dogs. Dogs inoculated with human seasonal H3N2 and pdm H1N1 influenza viruses exhibited nasal shedding and were seroconverted against the viruses; this did not occur in the influenza B virus-inoculated dogs. Transmission of human H3N2 virus between dogs was demonstrated by observing nasal shedding and seroconversion in naïve dogs after contact with inoculated dogs. The seroprevalence study offered evidence of human H3N2 infection occurring in dogs since 2008. Furthermore, serological evidence of pdm H1N1 influenza virus infection alone and in combination with canine H3N2 virus was found in the serum samples collected from field dogs during 2010 and 2011. Our results suggest that dogs may be hosts for human seasonal H3N2 and pdm H1N1 influenza viruses. © 2015 The Authors.

Strategy for assessment of the colloidal and biological stability of H1N1 influenza A viruses.

PubMed

Hämmerling, Frank; Lorenz-Cristea, Oliver; Baumann, Pascal; Hubbuch, Jürgen

2017-01-30

Current influenza vaccines are mostly formulated as liquids which requires a continuous cold chain to maintain the stability of the antigen. For development of vaccines with an increased stability at ambient temperatures, manifold parameters and their influences on the colloidal stability and activity of the antigen have to be understood. This work presents a strategy to examine both, the colloidal stability and the remaining biological activity of H1N1 influenza viruses under various conditions after an incubation of 40 days. H1N1 phase diagrams were generated for several pH values and different initial H1N1 and NaCl concentrations. It was shown that the highest H1N1 recoveries were obtained for pH 6 and that moderate amounts of NaCl are favorable for increased recoveries. In contrast to colloidal stability, the highest remaining HA activity was observed at pH 9. The electrostatic and hydrophobic surface properties of H1N1 were investigated to reveal the mechanisms accounting for the decrease in stability. Secondly, the capability of virus precipitation by polyethylene glycol in combination with determination of surface hydrophobicity was proven to be useful as a predictive tool to rank stability under different conditions. This methodology enables the rapid assessment of aggregation propensity of H1N1 formulations and the influence on the activity of the virus particles and might become a standard tool during the development of vaccine formulations. Copyright © 2016 Elsevier B.V. All rights reserved.

Pre-Existing Cross-Reactive Antibodies to Avian Influenza H5N1 and 2009 Pandemic H1N1 in US Military Personnel

PubMed Central

Pichyangkul, Sathit; Krasaesub, Somporn; Jongkaewwattana, Anan; Thitithanyanont, Arunee; Wiboon-ut, Suwimon; Yongvanitchit, Kosol; Limsalakpetch, Amporn; Kum-Arb, Utaiwan; Mongkolsirichaikul, Duangrat; Khemnu, Nuanpan; Mahanonda, Rangsini; Garcia, Jean-Michel; Mason, Carl J.; Walsh, Douglas S.; Saunders, David L.

2014-01-01

We studied cross-reactive antibodies against avian influenza H5N1 and 2009 pandemic (p) H1N1 in 200 serum samples from US military personnel collected before the H1N1 pandemic. Assays used to measure antibodies against viral proteins involved in protection included a hemagglutination inhibition (HI) assay and a neuraminidase inhibition (NI) assay. Viral neutralization by antibodies against avian influenza H5N1 and 2009 pH1N1 was assessed by influenza (H5) pseudotyped lentiviral particle-based and H1N1 microneutralization assays. Some US military personnel had cross-neutralizing antibodies against H5N1 (14%) and 2009 pH1N1 (16.5%). The odds of having cross-neutralizing antibodies against 2009 pH1N1 were 4.4 times higher in subjects receiving more than five inactivated whole influenza virus vaccinations than those subjects with no record of vaccination. Although unclear if the result of prior vaccination or disease exposure, these pre-existing antibodies may prevent or reduce disease severity. PMID:24277784

Continual Reintroduction of Human Pandemic H1N1 Influenza A Viruses into Swine in the United States, 2009 to 2014

PubMed Central

Stratton, Jered; Killian, Mary Lea; Janas-Martindale, Alicia; Vincent, Amy L.

2015-01-01

ABSTRACT The diversity of influenza A viruses in swine (swIAVs) presents an important pandemic threat. Knowledge of the human-swine interface is particularly important for understanding how viruses with pandemic potential evolve in swine hosts. Through phylogenetic analysis of contemporary swIAVs in the United States, we demonstrate that human-to-swine transmission of pandemic H1N1 (pH1N1) viruses has occurred continuously in the years following the 2009 H1N1 pandemic and has been an important contributor to the genetic diversity of U.S. swIAVs. Although pandemic H1 and N1 segments had been largely removed from the U.S. swine population by 2013 via reassortment with other swIAVs, these antigens reemerged following multiple human-to-swine transmission events during the 2013-2014 seasonal epidemic. These findings indicate that the six internal gene segments from pH1N1 viruses are likely to be sustained long term in the U.S. swine population, with periodic reemergence of pandemic hemagglutinin (HA) and neuraminidase (NA) segments in association with seasonal pH1N1 epidemics in humans. Vaccinating U.S. swine workers may reduce infection of both humans and swine and in turn limit the role of humans as sources of influenza virus diversity in pigs. IMPORTANCE Swine are important hosts in the evolution of influenza A viruses with pandemic potential. Here, we analyze influenza virus sequence data generated by the U.S. Department of Agriculture's national surveillance system to identify the central role of humans in the reemergence of pandemic H1N1 (pH1N1) influenza viruses in U.S. swine herds in 2014. These findings emphasize the important role of humans as continuous sources of influenza virus diversity in swine and indicate that influenza viruses with pandemic HA and NA segments are likely to continue to reemerge in U.S. swine in association with seasonal pH1N1 epidemics in humans. PMID:25833052

Continual Reintroduction of Human Pandemic H1N1 Influenza A Viruses into Swine in the United States, 2009 to 2014.

PubMed

Nelson, Martha I; Stratton, Jered; Killian, Mary Lea; Janas-Martindale, Alicia; Vincent, Amy L

2015-06-01

The diversity of influenza A viruses in swine (swIAVs) presents an important pandemic threat. Knowledge of the human-swine interface is particularly important for understanding how viruses with pandemic potential evolve in swine hosts. Through phylogenetic analysis of contemporary swIAVs in the United States, we demonstrate that human-to-swine transmission of pandemic H1N1 (pH1N1) viruses has occurred continuously in the years following the 2009 H1N1 pandemic and has been an important contributor to the genetic diversity of U.S. swIAVs. Although pandemic H1 and N1 segments had been largely removed from the U.S. swine population by 2013 via reassortment with other swIAVs, these antigens reemerged following multiple human-to-swine transmission events during the 2013-2014 seasonal epidemic. These findings indicate that the six internal gene segments from pH1N1 viruses are likely to be sustained long term in the U.S. swine population, with periodic reemergence of pandemic hemagglutinin (HA) and neuraminidase (NA) segments in association with seasonal pH1N1 epidemics in humans. Vaccinating U.S. swine workers may reduce infection of both humans and swine and in turn limit the role of humans as sources of influenza virus diversity in pigs. Swine are important hosts in the evolution of influenza A viruses with pandemic potential. Here, we analyze influenza virus sequence data generated by the U.S. Department of Agriculture's national surveillance system to identify the central role of humans in the reemergence of pandemic H1N1 (pH1N1) influenza viruses in U.S. swine herds in 2014. These findings emphasize the important role of humans as continuous sources of influenza virus diversity in swine and indicate that influenza viruses with pandemic HA and NA segments are likely to continue to reemerge in U.S. swine in association with seasonal pH1N1 epidemics in humans. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Inactivation and removal of influenza A virus H1N1 during the manufacture of plasma derivatives.

PubMed

Jeong, Eun Kyo; Sung, Hark Mo; Kim, In Seop

2010-11-01

Although transmission of pandemic influenza A virus H1N1 2009 is still occurring globally, little has been reported about how this outbreak has affected the safety of plasma derivatives. To evaluate the safety of plasma derivatives, dedicated virus clearance processes used during their production were investigated for their effectiveness in eliminating this virus of recent concern. In this study, influenza A virus H1N1 strain A/NWS/33 (H1N1) was chosen as a surrogate. H1N1 was completely inactivated by fraction IV fractionation as well as pasteurization during the manufacture of albumin. H1N1 was also effectively removed into the precipitate by fraction III fractionation and completely inactivated by low pH incubation as well as pasteurization during the manufacture of intravenous immunoglobulin. H1N1 was completely inactivated within 1 min of solvent/detergent treatment using 0.3% tri (n-butyl) phosphate and 1.0% Triton X-100 and also completely inactivated within 10 min of dry-heat treatment at 98 °C during the manufacture of factor VIII. H1N1 was completely removed by virus filtration process using Viresolve NFP filter and also completely inactivated by pasteurization during the manufacture of anti-thrombin III. These results indicate that all the virus clearance processes commonly used have sufficient H1N1 reducing capacity to achieve a high margin of safety. Copyright © 2010 The International Association for Biologicals. Published by Elsevier Ltd. All rights reserved.

Characterization In Vitro and In Vivo of a Pandemic H1N1 Influenza Virus from a Fatal Case

PubMed Central

Cuevas, Maria Teresa; Pozo, Francisco; Guerra, Susana; García-Barreno, Blanca; Martinez-Orellana, Pamela; Pérez-Breña, Pilar; Montoya, Maria; Melero, Jose Antonio; Pizarro, Manuel; Ortin, Juan; Casas, Inmaculada; Nieto, Amelia

2013-01-01

Pandemic 2009 H1N1 (pH1N1) influenza viruses caused mild symptoms in most infected patients. However, a greater rate of severe disease was observed in healthy young adults and children without co-morbid conditions. Here we tested whether influenza strains displaying differential virulence could be present among circulating pH1N1 viruses. The biological properties and the genotype of viruses isolated from a patient showing mild disease (M) or from a fatal case (F), both without known co-morbid conditions were compared in vitro and in vivo. The F virus presented faster growth kinetics and stronger induction of cytokines than M virus in human alveolar lung epithelial cells. In the murine model in vivo, the F virus showed a stronger morbidity and mortality than M virus. Remarkably, a higher proportion of mice presenting infectious virus in the hearts, was found in F virus-infected animals. Altogether, the data indicate that strains of pH1N1 virus with enhanced pathogenicity circulated during the 2009 pandemic. In addition, examination of chemokine receptor 5 (CCR5) genotype, recently reported as involved in severe influenza virus disease, revealed that the F virus-infected patient was homozygous for the deleted form of CCR5 receptor (CCR5Δ32). PMID:23326447

Identification of reassortant pandemic H1N1 influenza virus in Korean pigs.

PubMed

Han, Jae Yeon; Park, Sung Jun; Kim, Hye Kwon; Rho, Semi; Nguyen, Giap Van; Song, Daesub; Kang, Bo Kyu; Moon, Hyung Jun; Yeom, Min Joo; Park, Bong Kyun

2012-05-01

Since the 2009 pandemic human H1N1 influenza A virus emerged in April 2009, novel reassortant strains have been identified throughout the world. This paper describes the detection and isolation of reassortant strains associated with human pandemic influenza H1N1 and swine influenza H1N2 (SIV) viruses in swine populations in South Korea. Two influenza H1N2 reassortants were detected, and subtyped by PCR. The strains were isolated using Madin- Darby canine kidney (MDCK) cells, and genetically characterized by phylogenetic analysis for genetic diversity. They consisted of human, avian, and swine virus genes that were originated from the 2009 pandemic H1N1 virus and a neuraminidase (NA) gene from H1N2 SIV previously isolated in North America. This identification of reassortment events in swine farms raises concern that reassortant strains may continuously circulate within swine populations, calling for the further study and surveillance of pandemic H1N1 among swine.

Oseltamivir-resistant pandemic influenza a (H1N1) 2009 viruses in Spain.

PubMed

Ledesma, Juan; Vicente, Diego; Pozo, Francisco; Cilla, Gustavo; Castro, Sonia Pérez; Fernández, Jonathan Suárez; Ruiz, Mercedes Pérez; Navarro, José María; Galán, Juan Carlos; Fernández, Mirian; Reina, Jordi; Larrauri, Amparo; Cuevas, María Teresa; Casas, Inmaculada; Breña, Pilar Pérez

2011-07-01

Pandemic influenza A (H1N1) 2009 virus appeared in Spain on April 25, 2009 for the first time. This new virus was adamantane-resistant but it was sensitive to neuraminidase (NA) inhibitors oseltamivir and zanamivir. To detect oseltamivir-resistant pandemic influenza A (H1N1) 2009 viruses by the Spanish Influenza Surveillance System (SISS) and a possible spread of oseltamivir-resistant viruses in Spain since starting of the pandemic situation. A total of 1229 respiratory samples taken from 413 severe and 766 non-severe patients with confirmed viral detection of pandemic influenza A (H1N1) 2009 viruses from different Spanish regions were analyzed for the specific detection of the H275Y mutation in NA between April 2009 and May 2010. H275Y NA substitution was found in 8 patients infected with pandemic influenza A (H1N1) 2009 viruses collected in November and December 2009 and in January 2010. All oseltamivir-resistant viruses were detected in severe patients (8/413, 1.93%) who previously received treatment with oseltamivir. Six of these patients were immunocompromised. In Spain, the number of oseltamivir-resistant pandemic influenza A (H1N1) 2009 viruses is until now very low. No evidence for any spread of oseltamivir-resistant H1N1 viruses is achieved in our Country. Copyright © 2011 Elsevier B.V. All rights reserved.

Novel triple reassortant H1N2 influenza viruses bearing six internal genes of the pandemic 2009/H1N1 influenza virus were detected in pigs in China.

PubMed

Qiao, Chuanling; Liu, Liping; Yang, Huanliang; Chen, Yan; Xu, Huiyang; Chen, Hualan

2014-12-01

The pandemic A/H1N1 influenza viruses emerged in both Mexico and the United States in March 2009, and were transmitted efficiently in the human population. Transmissions of the pandemic 2009/H1N1 virus from humans to poultry and other species of mammals were reported from several continents during the course of the 2009 H1N1 pandemic. Reassortant H1N1, H1N2, and H3N2 viruses containing genes of the pandemic 2009/H1N1 viruses appeared in pigs in some countries. In winter of 2012, a total of 2600 nasal swabs were collected from healthy pigs in slaughterhouses located throughout 10 provinces in China. The isolated viruses were subjected to genetic and antigenic analysis. Two novel triple-reassortant H1N2 influenza viruses were isolated from swine in China in 2012, with the HA gene derived from Eurasian avian-like swine H1N1, the NA gene from North American swine H1N2, and the six internal genes from the pandemic 2009/H1N1 viruses. The two viruses had similar antigenic features and some significant changes in antigenic characteristics emerged when compared to the previously identified isolates. We inferred that the novel reassortant viruses in China may have arisen from the accumulation of the three types of influenza viruses, which further indicates that swine herds serve as "mixing vessels" for influenza viruses. Influenza virus reassortment is an ongoing process, and our findings highlight the urgent need for continued influenza surveillance among swine herds. Copyright © 2014 Elsevier B.V. All rights reserved.

Pathogenicity and Transmissibility of Novel Reassortant H3N2 Influenza Viruses with 2009 Pandemic H1N1 Genes in Pigs

PubMed Central

Ma, Jingjiao; Shen, Huigang; Liu, Qinfang; Bawa, Bhupinder; Qi, Wenbao; Duff, Michael; Lang, Yuekun; Lee, Jinhwa; Yu, Hai; Bai, Jianfa; Tong, Guangzhi; Hesse, Richard A.; Richt, Jürgen A.

2014-01-01

ABSTRACT At least 10 different genotypes of novel reassortant H3N2 influenza viruses with 2009 pandemic H1N1 [A(H1N1)pdm09] gene(s) have been identified in U.S. pigs, including the H3N2 variant with a single A(H1N1)pdm09 M gene, which has infected more than 300 people. To date, only three genotypes of these viruses have been evaluated in animal models, and the pathogenicity and transmissibility of the other seven genotype viruses remain unknown. Here, we show that three H3N2 reassortant viruses that contain 3 (NP, M, and NS) or 5 (PA, PB2, NP, M, and NS) genes from A(H1N1)pdm09 were pathogenic in pigs, similar to the endemic H3N2 swine virus. However, the reassortant H3N2 virus with 3 A(H1N1)pdm09 genes and a recent human influenza virus N2 gene was transmitted most efficiently among pigs, whereas the reassortant H3N2 virus with 5 A(H1N1)pdm09 genes was transmitted less efficiently than the endemic H3N2 virus. Interestingly, the polymerase complex of reassortant H3N2 virus with 5 A(H1N1)pdm09 genes showed significantly higher polymerase activity than those of endemic and reassortant H3N2 viruses with 3 A(H1N1)pdm09 genes. Further studies showed that an avian-like glycine at position 228 at the hemagglutinin (HA) receptor binding site is responsible for inefficient transmission of the reassortant H3N2 virus with 5 A(H1N1)pdm09 genes. Taken together, our results provide insights into the pathogenicity and transmissibility of novel reassortant H3N2 viruses in pigs and suggest that a mammalian-like serine at position 228 in the HA is critical for the transmissibility of these reassortant H3N2 viruses. IMPORTANCE Swine influenza is a highly contagious zoonotic disease that threatens animal and public health. Introduction of 2009 pandemic H1N1 virus [A(H1N1)pdm09] into swine herds has resulted in novel reassortant influenza viruses in swine, including H3N2 and H1N2 variants that have caused human infections in the United States. We showed that reassortant H3N2 influenza

Different neuraminidase inhibitor susceptibilities of human H1N1, H1N2, and H3N2 influenza A viruses isolated in Germany from 2001 to 2005/2006.

PubMed

Bauer, Katja; Richter, Martina; Wutzler, Peter; Schmidtke, Michaela

2009-04-01

In the flu season 2005/2006 amantadine-resistant human influenza A viruses (FLUAV) of subtype H3N2 circulated in Germany. This raises questions on the neuraminidase inhibitor (NAI) susceptibility of FLUAV. To get an answer, chemiluminescence-based neuraminidase inhibition assays were performed with 51 H1N1, H1N2, and H3N2 FLUAV isolated in Germany from 2001 to 2005/2006. According to the mean IC(50) values (0.38-0.91 nM for oseltamivir and 0.76-1.13 nM for zanamivir) most H1N1 and H3N2 FLUAV were NAI-susceptible. But, about four times higher zanamivir concentrations were necessary to inhibit neuraminidase activity of H1N2 viruses. Two H1N1 isolates were less susceptible to both drugs in NA inhibition as well as virus yield reduction assays. Results from sequence analysis of viral hemagglutinin and neuraminidase genes and evolutionary analysis of N2 gene revealed (i) different subclades for N2 in H1N2 and H3N2 FLUAV that could explain the differences in zanamivir susceptibility among these viruses and (ii) specific amino acid substitutions in the neuraminidase segment of the two less NAI-susceptible H1N1 isolates. One H3N2 was isolate proved to be a mixture of a NA deletion mutant and full-length NA viruses.

Multiplex RT-PCR assay for differentiating European swine influenza virus subtypes H1N1, H1N2 and H3N2.

PubMed

Chiapponi, Chiara; Moreno, Ana; Barbieri, Ilaria; Merenda, Marianna; Foni, Emanuela

2012-09-01

In Europe, three major swine influenza viral (SIV) subtypes (H1N1, H1N2 and H3N2) have been isolated in pigs. Developing a test that is able to detect and identify the subtype of the circulating strain rapidly during an outbreak of respiratory disease in the pig population is of essential importance. This study describes two multiplex RT-PCRs which distinguish the haemagglutinin (HA) gene and the neuraminidase (NA) gene of the three major subtypes of SIV circulating in Europe. The HA PCR was able to identify the lineage (avian or human) of the HA of H1 subtypes. The analytical sensitivity of the test, considered to be unique, was assessed using three reference viruses. The detection limit corresponded to 1×10(-1) TCID(50)/200μl for avian-like H1N1, 1×10(0) TCID(50)/200μl for human-like H1N2 and 1×10(1) TCID(50)/200μl for H3N2 SIV. The multiplex RT-PCR was first carried out on a collection of 70 isolated viruses showing 100% specificity and then on clinical samples, from which viruses had previously been isolated, resulting in an 89% positive specificity of the viral subtype. Finally, the test was able to identify the viral subtype correctly in 56% of influenza A positive samples, from which SIV had not been isolated previously. It was also possible to identify mixed viral infections and the circulation of a reassortant strain before performing genomic studies. Copyright © 2012 Elsevier B.V. All rights reserved.

Antigenic Patterns and Evolution of the Human Influenza A (H1N1) Virus.

PubMed

Liu, Mi; Zhao, Xiang; Hua, Sha; Du, Xiangjun; Peng, Yousong; Li, Xiyan; Lan, Yu; Wang, Dayan; Wu, Aiping; Shu, Yuelong; Jiang, Taijiao

2015-09-28

The influenza A (H1N1) virus causes seasonal epidemics that result in severe illnesses and deaths almost every year. A deep understanding of the antigenic patterns and evolution of human influenza A (H1N1) virus is extremely important for its effective surveillance and prevention. Through development of antigenicity inference method for human influenza A (H1N1), named PREDAC-H1, we systematically mapped the antigenic patterns and evolution of the human influenza A (H1N1) virus. Eight dominant antigenic clusters have been inferred for seasonal H1N1 viruses since 1977, which demonstrated sequential replacements over time with a similar pattern in Asia, Europe and North America. Among them, six clusters emerged first in Asia. As for China, three of the eight antigenic clusters were detected in South China earlier than in North China, indicating the leading role of South China in H1N1 transmission. The comprehensive view of the antigenic evolution of human influenza A (H1N1) virus can help formulate better strategy for its prevention and control.

Antibody Pressure by a Human Monoclonal Antibody Targeting the 2009 Pandemic H1N1 Virus Hemagglutinin Drives the Emergence of a Virus with Increased Virulence in Mice

PubMed Central

O’Donnell, Christopher D.; Vogel, Leatrice; Wright, Amber; Das, Suman R.; Wrammert, Jens; Li, Gui-Mei; McCausland, Megan; Zheng, Nai-Ying; Yewdell, Jonathan W.; Ahmed, Rafi; Wilson, Patrick C.; Subbarao, Kanta

2012-01-01

ABSTRACT In 2009, a novel H1N1 influenza A virus (2009 pH1N1) emerged and caused a pandemic. A human monoclonal antibody (hMAb; EM4C04), highly specific for the 2009 pH1N1 virus hemagglutinin (HA), was isolated from a severely ill 2009 pH1N1 virus-infected patient. We postulated that under immune pressure with EM4C04, the 2009 pH1N1 virus would undergo antigenic drift and mutate at sites that would identify the antibody binding site. To do so, we infected MDCK cells in the presence of EM4C04 and generated 11 escape mutants, displaying 7 distinct amino acid substitutions in the HA. Six substitutions greatly reduced MAb binding (K123N, D131E, K133T, G134S, K157N, and G158E). Residues 131, 133, and 134 are contiguous with residues 157 and 158 in the globular domain structure and contribute to a novel pH1N1 antibody epitope. One mutation near the receptor binding site, S186P, increased the binding affinity of the HA to the receptor. 186P and 131E are present in the highly virulent 1918 virus HA and were recently identified as virulence determinants in a mouse-passaged pH1N1 virus. We found that pH1N1 escape variants expressing these substitutions enhanced replication and lethality in mice compared to wild-type 2009 pH1N1 virus. The increased virulence of these viruses was associated with an increased affinity for α2,3 sialic acid receptors. Our study demonstrates that antibody pressure by an hMAb targeting a novel epitope in the Sa region of 2009 pH1N1 HA is able to inadvertently drive the development of a more virulent virus with altered receptor binding properties. This broadens our understanding of antigenic drift. PMID:22647789

Influenza A (H1N1) virus pneumonia in intensive care unit.

PubMed

Adıgüzel, Nalan; Karakurt, Zuhal; Kalamanoğlu Balcı, Merih; Acartürk, Eylem; Güngör, Gökay; Yazıcıoğlu Moçin, Ozlem; Batı Kutlu, Semra; Yılmaz, Adnan

2010-01-01

Patients with influenza A (H1N1) virus infection have been admitted to intensive care units (ICU) due to development of severe respiratory failure. We described the clinical and epidemiologic characteristics of the 19 patients admitted to ICU due to influenza A (H1N1) virus infection. Study design is a descriptive case series in a third level-20 bed respiratory ICU at training hospital in Istanbul/Turkey. Influenza A (H1N1) virus infection was laboratory confirmed in specimens using real-time reverse transcriptase-polymerase-chain-reaction (RT-PCR). We collected data concerning demographic, epidemiologic and clinical characteristics of the patients, treatment mortality and outcome. From November 10 to December 31 2009, a total of 19 patients; 7 laboratory confirmed, 12 with high clinical suspicion were treated at ICU. Among 12 patients with high clinical suspicion; 3 patients had negative RT-PCR testing for influenza A (H1N1) virus, 9 patients had no tests. Mean age was 41.6 ± 11.9 (range 21 to 61). Median number of lung zone involvement was 4 (IQR= 3-4). Median PaO2/FiO2 was 105 (IQR= 85-165). Mean severity (APACHE II) and organ failure score (SOFA) were 13 ± 4 and 4.0 ± 1.3 respectively. Non-invasive mechanical ventilation (68.4%, n= 13), invasive mechanical ventilation (21.1%, n= 4) and nasal cannula oxygen (31.5%, n= 6) were implicated. The median length of ICU stay was 6 (IQR= 4-8). Oseltamivir therapy was given as 75 mg bid to 12 patients and 150 mg bid to 7 obese patients. ICU mortality rate was 21.1%. Presenting patients with pneumonia and acute respiratory failure due to influenza A (H1N1) virus infection were treated predominantly and successfully with non invasive mechanical ventilation. Clinicians should be aware of pulmonary complications of influenza A (H1N1) virus infection and that patients can be treated with non invasive mechanical ventilation paying attention to protective measures for health care providers.

Partial heterologous protection by low pathogenic H9N2 virus against natural H9N2-PB1 gene reassortant highly pathogenic H5N1 virus in chickens.

PubMed

Dash, Sandeep Kumar; Kumar, Manoj; Kataria, Jag Mohan; Nagarajan, Shanmugasundaram; Tosh, Chakradhar; Murugkar, Harshad V; Kulkarni, Diwakar D

2016-06-01

Low pathogenic avian influenza H9N2 and highly pathogenic avian influenza H5N1 viruses continue to co-circulate in chickens. Prior infection with low pathogenic avian influenza can modulate the outcome of H5N1 infection. In India, low pathogenic H9N2 and highly pathogenic H5N1 avian influenza viruses are co-circulating in poultry. Herein, by using chickens with prior infection of A/chicken/India/04TI05/2012 (H9N2) virus we explored the outcome of infection with H5N1 virus A/turkey/India/10CA03/2012 natural PB1 gene reassortant from H9N2. Four groups (E1-E4) of SPF chickens (n = 6) prior inoculated with 10(6) EID50 of H9N2 virus were challenged with 10(6) EID50 of H5N1 natural reassortant (PB1-H9N2) virus at days 1 (group E1); 3 (group E2); 7 (group E3) and 14 (group E4) post H9N2 inoculation. The survival percentage in groups E1-E4 was 0, 100, 66.6 and 50%, respectively. Virus shedding periods for groups E1-E4 were 3, 4, 7 and 9 days, respectively post H5N1 challenge. Birds of group E1 and E2 were shedding both H9N2 and H5N1 viruses and mean viral RNA copy number was higher in oropharyngeal swabs than cloacal swabs. In group, E3 and E4 birds excreted only H5N1 virus and mean viral RNA copy number was higher in most cloacal swabs than oral swabs. These results indicate that prior infection with H9N2 virus could protect from lethal challenge of reassortant H5N1 virus as early as with three days prior H9N2 inoculation and protection decreased in groups E3 and E4 as time elapsed. However, prior infection with H9N2 did not prevent infection with H5N1 virus and birds continue to excrete virus in oropharyngeal and cloacal swabs. Amino acid substitution K368E was found in HA gene of excreted H5N1 virus of group E3. Hence, concurrent infection can also cause emergence of viruses with mutations leading to virus evolution. The results of this study are important for the surveillance and epidemiological data analysis where both H9N2 and H5N1 viruses are co

Molecular characterization of a novel reassortant H1N2 influenza virus containing genes from the 2009 pandemic human H1N1 virus in swine from eastern China.

PubMed

Peng, Xiuming; Wu, Haibo; Xu, Lihua; Peng, Xiaorong; Cheng, Linfang; Jin, Changzhong; Xie, Tiansheng; Lu, Xiangyun; Wu, Nanping

2016-06-01

Pandemic outbreaks of H1N1 swine influenza virus have been reported since 2009. Reassortant H1N2 viruses that contain genes from the pandemic H1N1 virus have been isolated in Italy and the United States. However, there is limited information regarding the molecular characteristics of reassortant H1N2 swine influenza viruses in eastern China. Active influenza surveillance programs in Zhejiang Province identified a novel H1N2 influenza virus isolated from pigs displaying clinical signs of influenza virus infection. Whole-genome sequencing was performed and this strain was compared with other influenza viruses available in GenBank. Phylogenetic analysis suggested that the novel strain contained genes from the 2009 pandemic human H1N1 and swine H3N2 viruses. BALB/c mice were infected with the isolated virus to assess its virulence in mice. While the novel H1N2 isolate replicated well in mice, it was found to be less virulent. These results provide additional evidence that swine serve as intermediate hosts or 'mixing vessels' for novel influenza viruses. They also emphasize the importance of surveillance in the swine population for use as an early warning system for influenza outbreaks in swine and human populations.

Inactivation of influenza A virus H1N1 by disinfection process.

PubMed

Jeong, Eun Kyo; Bae, Jung Eun; Kim, In Seop

2010-06-01

Because any patient, health care worker, or visitor is capable of transmitting influenza to susceptible persons within hospitals, hospital-acquired influenza has been a clinical concern. Disinfection and cleaning of medical equipment, surgical instruments, and hospital environment are important measures to prevent transmission of influenza virus from hospitals to individuals. This study was conducted to evaluate the efficacy of disinfection processes, which can be easily operated at hospitals, in inactivating influenza A virus H1N1 (H1N1). The effects of 0.1 mol/L NaOH, 70% ethanol, 70% 1-propanol, solvent/detergent (S/D) using 0.3% tri (n-butyl)-phosphate and 1.0% Triton X-100, heat, and ethylene oxide (EO) treatments in inactivating H1N1 were determined. Inactivation of H1N1 was kinetically determined by the treatment of disinfectants to virus solution. Also, a surface test method, which involved drying an amount of virus on a surface and then applying the inactivation methods for 1 minute of contact time, was used to determine the virucidal activity. H1N1 was completely inactivated to undetectable levels in 1 minute of 70% ethanol, 70% 1-propanol, and solvent/detergent treatments in the surface tests as well as in the suspension tests. H1N1 was completely inactivated in 1 minute of 0.1 mol/L NaOH treatment in the suspension tests and also effectively inactivated in the surface tests with the log reduction factor of 3.7. H1N1 was inactivated to undetectable levels within 5 minutes, 2.5 minutes, and 1 minute of heat treatment at 70, 80, and 90 degrees C, respectively in the suspension tests. Also, H1N1 was completely inactivated by EO treatment in the surface tests. Common disinfectants, heat, and EO tested in this study were effective at inactivating H1N1. These results would be helpful in implementing effective disinfecting measures to prevent hospital-acquired infections. Copyright 2010 Association for Professionals in Infection Control and Epidemiology, Inc

Cold-Adapted Influenza and Recombinant Adenovirus Vaccines Induce Cross-Protective Immunity against pH1N1 Challenge in Mice

PubMed Central

Soboleski, Mark R.; Gabbard, Jon D.; Price, Graeme E.; Misplon, Julia A.; Lo, Chia-Yun; Perez, Daniel R.; Ye, Jianqiang; Tompkins, S. Mark; Epstein, Suzanne L.

2011-01-01

Background The rapid spread of the 2009 H1N1 pandemic influenza virus (pH1N1) highlighted problems associated with relying on strain-matched vaccines. A lengthy process of strain identification, manufacture, and testing is required for current strain-matched vaccines and delays vaccine availability. Vaccines inducing immunity to conserved viral proteins could be manufactured and tested in advance and provide cross-protection against novel influenza viruses until strain-matched vaccines became available. Here we test two prototype vaccines for cross-protection against the recent pandemic virus. Methodology/Principal Findings BALB/c and C57BL/6 mice were intranasally immunized with a single dose of cold-adapted (ca) influenza viruses from 1977 or recombinant adenoviruses (rAd) expressing 1934 nucleoprotein (NP) and consensus matrix 2 (M2) (NP+M2-rAd). Antibodies against the M2 ectodomain (M2e) were seen in NP+M2-rAd immunized BALB/c but not C57BL/6 mice, and cross-reacted with pH1N1 M2e. The ca-immunized mice did not develop antibodies against M2e. Despite sequence differences between vaccine and challenge virus NP and M2e epitopes, extensive cross-reactivity of lung T cells with pH1N1 peptides was detected following immunization. Both ca and NP+M2-rAd immunization protected BALB/c and C57BL/6 mice against challenge with a mouse-adapted pH1N1 virus. Conclusion/Significance Cross-protective vaccines such as NP+M2-rAd and ca virus are effective against pH1N1 challenge within 3 weeks of immunization. Protection was not dependent on recognition of the highly variable external viral proteins and could be achieved with a single vaccine dose. The rAd vaccine was superior to the ca vaccine by certain measures, justifying continued investigation of this experimental vaccine even though ca vaccine is already available. This study highlights the potential for cross-protective vaccines as a public health option early in an influenza pandemic. PMID:21789196

Antigenic Patterns and Evolution of the Human Influenza A (H1N1) Virus

PubMed Central

Liu, Mi; Zhao, Xiang; Hua, Sha; Du, Xiangjun; Peng, Yousong; Li, Xiyan; Lan, Yu; Wang, Dayan; Wu, Aiping; Shu, Yuelong; Jiang, Taijiao

2015-01-01

The influenza A (H1N1) virus causes seasonal epidemics that result in severe illnesses and deaths almost every year. A deep understanding of the antigenic patterns and evolution of human influenza A (H1N1) virus is extremely important for its effective surveillance and prevention. Through development of antigenicity inference method for human influenza A (H1N1), named PREDAC-H1, we systematically mapped the antigenic patterns and evolution of the human influenza A (H1N1) virus. Eight dominant antigenic clusters have been inferred for seasonal H1N1 viruses since 1977, which demonstrated sequential replacements over time with a similar pattern in Asia, Europe and North America. Among them, six clusters emerged first in Asia. As for China, three of the eight antigenic clusters were detected in South China earlier than in North China, indicating the leading role of South China in H1N1 transmission. The comprehensive view of the antigenic evolution of human influenza A (H1N1) virus can help formulate better strategy for its prevention and control. PMID:26412348

Glycosylations in the globular head of the hemagglutinin protein modulate the virulence and antigenic properties of the H1N1 influenza viruses

PubMed Central

Medina, Rafael A.; Stertz, Silke; Manicassamy, Balaji; Zimmermann, Petra; Sun, Xiangjie; Albrecht, Randy A.; Uusi-Kerttula, Hanni; Zagordi, Osvaldo; Belshe, Robert B.; Frey, Sharon E.; Eggink, Dirk; Tumpey, Terrence M.; García-Sastre, Adolfo

2014-01-01

The global spread of the 2009 pandemic H1N1 (pH1N1) virus in humans increases the likelihood that this influenza virus strain could undergo antigenic drift in the coming years. Previous seasonal H1N1 and H3N2 influenza strains acquired additional glycosylations in the globular head of their hemagglutinin (HA) proteins as they evolved over time; these are believed to shield antigenically relevant regions. We used influenza A/Netherlands/602/2009 recombinant (rpH1N1) viruses to which we added additional HA glycosylation sites reflecting their temporal appearance in previous seasonal H1N1 viruses. Additional glycosylations resulted in substantial attenuation in mice and ferrets, while deleting HA glycosylation sites from a pre-pandemic 1991 seasonal H1N1 influenza virus resulted in increased pathogenicity in mice. Sera from mice infected with wild type (WT) rpH1N1 virus showed a considerable loss of HA inhibitory (HI) activity against rpH1N1 viruses glycosylated at sites 144 or 144-172, indicating that the polyclonal antibody response elicited by WT rpH1N1 HA seems to be directed against an immunodominant region, likely site Sa, shielded by glycosylation at 144. Sera from humans vaccinated with the pH1N1 inactivated vaccine also showed reduced activity against the 144 and 144-172 mutant viruses. Remarkably, the HI activity of sera from virus-infected mice demonstrated that glycosylation at position 144 resulted in the induction of a broader polyclonal response able to cross-neutralize all WT and glycosylation mutant pH1N1 viruses. Mice infected with a recent seasonal virus in which glycosylation sites 71, 142 and 177 were removed, elicited antibodies that protected against challenge with the antigenically distant pH1N1 virus. Thus, acquisition of glycosylation sites in the HA of H1N1 human influenza viruses not only affects their pathogenicity and ability to escape from polyclonal antibodies elicited by previous influenza virus strains, but also their ability to

Experimental infection of clade 1.1.2 (H5N1), clade 2.3.2.1c (H5N1) and clade 2.3.4.4 (H5N6) highly pathogenic avian influenza viruses in dogs.

PubMed

Lyoo, K S; Na, W; Phan, L V; Yoon, S W; Yeom, M; Song, D; Jeong, D G

2017-12-01

Since the emergence of highly pathogenic avian influenza (HPAI) H5N1 in Asia, the haemagglutinin (HA) gene of this virus lineage has continued to evolve in avian populations, and H5N1 lineage viruses now circulate concurrently worldwide. Dogs may act as an intermediate host, increasing the potential for zoonotic transmission of influenza viruses. Virus transmission and pathologic changes in HPAI clade 1.1.2 (H5N1)-, 2.3.2.1c (H5N1)- and 2.3.4.4 (H5N6)-infected dogs were investigated. Mild respiratory signs and antibody response were shown in dogs intranasally infected with the viruses. Lung histopathology showed lesions that were associated with moderate interstitial pneumonia in the infected dogs. In this study, HPAI H5N6 virus replication in dogs was demonstrated for the first time. Dogs have been suspected as a "mixing vessel" for reassortments between avian and human influenza viruses to occur. The replication of these three subtypes of the H5 lineage of HPAI viruses in dogs suggests that dogs could serve as intermediate hosts for avian-human influenza virus reassortment if they are also co-infected with human influenza viruses. © 2017 Blackwell Verlag GmbH.

Signal Immune Reactions of Macrophages Differentiated from THP-1 Monocytes to Infection with Pandemic H1N1PDM09 Virus and H5N2 and H9N2 Avian Influenza A Virus.

PubMed

Sokolova, T M; Poloskov, V V; Shuvalov, A N; Rudneva, I A; Timofeeva, T A

2018-03-01

In culture of THP-1 cells differentiated into macrophages with PMA (THP-PMA macrophages) infected with influenza viruses of subtypes H1, H5 and H9, we measured the expression of TLR7 and RIG1 receptor genes, sensors of viral RNA and ribonucleoprotein, and the levels of production of inflammatory cytokines IL-1β, TNFα, IL-10, and IFNα. The sensitivity and inflammatory response of THP-PMA macrophages to pandemic influenza A virus H1N1pdm09 and avian influenza H5N2 and H9N2 viruses correlate with the intracellular level of their viral RNA and activation of the RIG1 gene. Abortive infection is accompanied by intensive macrophage secretion of TNFα, IL-1β, and toxic factors inducing cell death. Activity of endosomal TLR7 receptor gene changed insignificantly in 24 h after infection and significantly decreased in 48 and 72 h under the action of H5N2 and H9N2, which correlated with manifestation of the cytopathogenic effect of these viruses. H5N2 and H9N2 avian viruses in THP-PMA macrophages are strong activators of the expression of the gene of the cytoplasmic RIG1 receptor 24 and 48 h after infection, and the pandemic virus H1N1pdm09 is a weak stimulator of RIG1 gene. Avian influenza H5N2 and H9N2 viruses are released by rapid induction of the inflammatory response in macrophages. At the late stages of infection, we observed a minor increase in IL-10 secretion in macrophages and, probably, the polarization of a part of the population in type M2. The studied influenza A viruses are weak inductors of IFN in THP-PMA macrophages. In the culture medium of THP-PMA macrophages infected with H9N2 and H5N2 viruses, MTT test revealed high levels of toxic factors causing the death of Caco-2 cells. In contrast to avian viruses, pandemic virus H1N1pdm09 did not induce production of toxic factors.

Pathogenesis of pandemic influenza A (H1N1) and triple-reassortant swine influenza A (H1) viruses in mice

USDA-ARS?s Scientific Manuscript database

The pandemic H1N1 virus of 2009 (2009 H1N1) continues to cause illness worldwide, primarily in younger age groups. To better understand the pathogenesis of these viruses in mammals, we used a mouse model to evaluate the relative virulence of selected 2009 H1N1 viruses and compared them to a represe...

Seroprevalence of H1N1, H3N2 and H1N2 influenza viruses in pigs in seven European countries in 2002-2003.

PubMed

Van Reeth, Kristien; Brown, Ian H; Dürrwald, Ralf; Foni, Emanuela; Labarque, Geoffrey; Lenihan, Patrick; Maldonado, Jaime; Markowska-Daniel, Iwona; Pensaert, Maurice; Pospisil, Zdenek; Koch, Guus

2008-05-01

Avian-like H1N1 and human-like H3N2 swine influenza viruses (SIV) have been considered widespread among pigs in Western Europe since the 1980s, and a novel H1N2 reassortant with a human-like H1 emerged in the mid 1990s. This study, which was part of the EC-funded 'European Surveillance Network for Influenza in Pigs 1', aimed to determine the seroprevalence of the H1N2 virus in different European regions and to compare the relative prevalences of each SIV between regions. Laboratories from Belgium, the Czech Republic, Germany, Italy, Ireland, Poland and Spain participated in an international serosurvey. A total of 4190 sow sera from 651 farms were collected in 2002-2003 and examined in haemagglutination inhibition tests against H1N1, H3N2 and H1N2. In Belgium, Germany, Italy and Spain seroprevalence rates to each of the three SIV subtypes were high (> or =30% of the sows seropositive) to very high (> or =50%), except for a lower H1N2 seroprevalence rate in Italy (13.8%). Most sows in these countries with high pig populations had antibodies to two or three subtypes. In Ireland, the Czech Republic and Poland, where swine farming is less intensive, H1N1 was the dominant subtype (8.0-11.7% seropositives) and H1N2 and H3N2 antibodies were rare (0-4.2% seropositives). Thus, SIV of H1N1, H3N2 and H1N2 subtype are enzootic in swine producing regions of Western Europe. In Central Europe, SIV activity is low and the circulation of H3N2 and H1N2 remains to be confirmed. The evolution and epidemiology of SIV throughout Europe is being further monitored through a second 'European Surveillance Network for Influenza in Pigs'.

IL-1β and IL-6 Upregulation in Children with H1N1 Influenza Virus Infection

PubMed Central

Chiaretti, Antonio; Pulitanò, Silvia; Barone, Giovanni; Ferrara, Pietro; Capozzi, Domenico; Riccardi, Riccardo

2013-01-01

The role of cytokines in relation to clinical manifestations, disease severity, and outcome of children with H1N1 virus infection remains thus far unclear. The aim of this study was to evaluate interleukin IL-1β and IL-6 plasma expressions and their association with clinical findings, disease severity, and outcome of children with H1N1 infection. We prospectively evaluated 15 children with H1N1 virus infection and 15 controls with lower respiratory tract infections (LRTI). Interleukin plasma levels were measured using immunoenzymatic assays. Significantly higher levels of IL-1β and IL-6 were detected in all patients with H1N1 virus infection compared to controls. It is noteworthy to mention that in H1N1 patients with more severe clinical manifestations of disease IL-1β and IL-6 expressions were significantly upregulated compared to H1N1 patients with mild clinical manifestations. In particular, IL-6 was significantly correlated with specific clinical findings, such as severity of respiratory compromise and fever. No correlation was found between interleukin expression and final outcome. In conclusion, H1N1 virus infection induces an early and significant upregulation of both interleukins IL1β and IL-6 plasma expressions. The upregulation of these cytokines is likely to play a proinflammatory role in H1N1 virus infection and may contribute to airway inflammation and bronchial hyperreactivity in these patients. PMID:23737648

Prior infection of chickens with H1N1 or H1N2 avian influenza elicits partial heterologous protection against highly pathogenic H5N1.

PubMed

Nfon, Charles; Berhane, Yohannes; Pasick, John; Embury-Hyatt, Carissa; Kobinger, Gary; Kobasa, Darwyn; Babiuk, Shawn

2012-01-01

There is a critical need to have vaccines that can protect against emerging pandemic influenza viruses. Commonly used influenza vaccines are killed whole virus that protect against homologous and not heterologous virus. Using chickens we have explored the possibility of using live low pathogenic avian influenza (LPAI) A/goose/AB/223/2005 H1N1 or A/WBS/MB/325/2006 H1N2 to induce immunity against heterologous highly pathogenic avian influenza (HPAI) A/chicken/Vietnam/14/2005 H5N1. H1N1 and H1N2 replicated in chickens but did not cause clinical disease. Following infection, chickens developed nucleoprotein and H1 specific antibodies, and reduced H5N1 plaque size in vitro in the absence of H5 neutralizing antibodies at 21 days post infection (DPI). In addition, heterologous cell mediated immunity (CMI) was demonstrated by antigen-specific proliferation and IFN-γ secretion in PBMCs re-stimulated with H5N1 antigen. Following H5N1 challenge of both pre-infected and naïve controls chickens housed together, all naïve chickens developed acute disease and died while H1N1 or H1N2 pre-infected chickens had reduced clinical disease and 70-80% survived. H1N1 or H1N2 pre-infected chickens were also challenged with H5N1 and naïve chickens placed in the same room one day later. All pre-infected birds were protected from H5N1 challenge but shed infectious virus to naïve contact chickens. However, disease onset, severity and mortality was reduced and delayed in the naïve contacts compared to directly inoculated naïve controls. These results indicate that prior infection with LPAI virus can generate heterologous protection against HPAI H5N1 in the absence of specific H5 antibody.

Prior Infection of Chickens with H1N1 or H1N2 Avian Influenza Elicits Partial Heterologous Protection against Highly Pathogenic H5N1

PubMed Central

Nfon, Charles; Berhane, Yohannes; Pasick, John; Embury-Hyatt, Carissa; Kobinger, Gary; Kobasa, Darwyn; Babiuk, Shawn

2012-01-01

There is a critical need to have vaccines that can protect against emerging pandemic influenza viruses. Commonly used influenza vaccines are killed whole virus that protect against homologous and not heterologous virus. Using chickens we have explored the possibility of using live low pathogenic avian influenza (LPAI) A/goose/AB/223/2005 H1N1 or A/WBS/MB/325/2006 H1N2 to induce immunity against heterologous highly pathogenic avian influenza (HPAI) A/chicken/Vietnam/14/2005 H5N1. H1N1 and H1N2 replicated in chickens but did not cause clinical disease. Following infection, chickens developed nucleoprotein and H1 specific antibodies, and reduced H5N1 plaque size in vitro in the absence of H5 neutralizing antibodies at 21 days post infection (DPI). In addition, heterologous cell mediated immunity (CMI) was demonstrated by antigen-specific proliferation and IFN-γ secretion in PBMCs re-stimulated with H5N1 antigen. Following H5N1 challenge of both pre-infected and naïve controls chickens housed together, all naïve chickens developed acute disease and died while H1N1 or H1N2 pre-infected chickens had reduced clinical disease and 70–80% survived. H1N1 or H1N2 pre-infected chickens were also challenged with H5N1 and naïve chickens placed in the same room one day later. All pre-infected birds were protected from H5N1 challenge but shed infectious virus to naïve contact chickens. However, disease onset, severity and mortality was reduced and delayed in the naïve contacts compared to directly inoculated naïve controls. These results indicate that prior infection with LPAI virus can generate heterologous protection against HPAI H5N1 in the absence of specific H5 antibody. PMID:23240067

Hospitalized patients with 2009 pandemic influenza A (H1N1) virus infection in the United States--September-October 2009.

PubMed

Skarbinski, Jacek; Jain, Seema; Bramley, Anna; Lee, Esther J; Huang, Jean; Kirschke, David; Stone, Allison; Wedlake, Tiffany; Richards, Shawn M; Page, Shannon; Ragan, Patti; Bullion, Lesley; Neises, Daniel; Williams, Robin M; Petruccelli, Bruno P; Vandermeer, Meredith; Lofy, Kathryn H; Gindler, Jacqueline; Finelli, Lyn

2011-01-01

Given the potential worsening clinical severity of 2009 pandemic influenza A (H1N1) virus (pH1N1) infection from spring to fall 2009, we conducted a clinical case series among patients hospitalized with pH1N1 infection from September through October 2009. A case patient was defined as a hospitalized person who had test results positive for pH1N1 virus by real-time reverse-transcription polymerase chain reaction. Among 255 hospitalized patients, 34% were admitted to an intensive care unit and 8% died. Thirty-four percent of patients were children <18 years of age, 8% were adults ≥ 65 years of age, and 67% had an underlying medical condition. Chest radiographs obtained at hospital admission that had findings that were consistent with pneumonia were noted in 103 (46%) of 255 patients. Among 255 hospitalized patients, 208 (82%) received neuraminidase inhibitors, but only 47% had treatment started ≤ 2 days after illness onset. Overall, characteristics of hospitalized patients with pH1N1 infection in fall 2009 were similar to characteristics of patients hospitalized with pH1N1 infection in spring 2009, which suggests that clinical severity did not change substantially over this period.

Detection of influenza A(H1N1)v virus by real-time RT-PCR.

PubMed

Panning, M; Eickmann, M; Landt, O; Monazahian, M; Olschläger, S; Baumgarte, S; Reischl, U; Wenzel, J J; Niller, H H; Günther, S; Hollmann, B; Huzly, D; Drexler, J F; Helmer, A; Becker, S; Matz, B; Eis-Hübinger, Am; Drosten, C

2009-09-10

Influenza A(H1N1)v virus was first identified in April 2009. A novel real-time RT-PCR for influenza A(H1N1)v virus was set up ad hoc and validated following industry-standard criteria. The lower limit of detection of the assay was 384 copies of viral RNA per ml of viral transport medium (95% confidence interval: 273-876 RNA copies/ml). Specificity was 100% as assessed on a panel of reference samples including seasonal human influenza A virus H1N1 and H3N2, highly pathogenic avian influenza A virus H5N1 and porcine influenza A virus H1N1, H1N2 and H3N2 samples. The real-time RT-PCR assay for the influenza A matrix gene recommended in 2007 by the World Health Organization was modified to work under the same reaction conditions as the influenza A(H1N1)v virus-specific test. Both assays were equally sensitive. Clinical applicability of both assays was demonstrated by screening of almost 2,000 suspected influenza (H1N1)v specimens, which included samples from the first cases of pandemic H1N1 influenza imported to Germany. Measuring influenza A(H1N1)v virus concentrations in 144 laboratory-confirmed samples yielded a median of 4.6 log RNA copies/ml. The new methodology proved its principle and might assist public health laboratories in the upcoming influenza pandemic.

Genetic and biological characterisation of an avian-like H1N2 swine influenza virus generated by reassortment of circulating avian-like H1N1 and H3N2 subtypes in Denmark.

PubMed

Trebbien, Ramona; Bragstad, Karoline; Larsen, Lars Erik; Nielsen, Jens; Bøtner, Anette; Heegaard, Peter M H; Fomsgaard, Anders; Viuff, Birgitte; Hjulsager, Charlotte Kristiane

2013-09-18

The influenza A virus subtypes H1N1, H1N2 and H3N2 are the most prevalent subtypes in swine. In 2003, a reassorted H1N2 swine influenza virus (SIV) subtype appeared and became prevalent in Denmark. In the present study, the reassortant H1N2 subtype was characterised genetically and the infection dynamics compared to an "avian-like" H1N1 virus by an experimental infection study. Sequence analyses were performed of the H1N2 virus. Two groups of pigs were inoculated with the reassortant H1N2 virus and an "avian-like" H1N1 virus, respectively, followed by inoculation with the opposite subtype four weeks later. Measurements of HI antibodies and acute phase proteins were performed. Nasal virus excretion and virus load in lungs were determined by real-time RT-PCR. The phylogenetic analysis revealed that the reassorted H1N2 virus contained a European "avian-like" H1-gene and a European "swine-like" N2-gene, thus being genetically distinct from most H1N2 viruses circulating in Europe, but similar to viruses reported in 2009/2010 in Sweden and Italy. Sequence analyses of the internal genes revealed that the reassortment probably arose between circulating Danish "avian-like" H1N1 and H3N2 SIVs. Infected pigs developed cross-reactive antibodies, and increased levels of acute phase proteins after inoculations. Pigs inoculated with H1N2 exhibited nasal virus excretion for seven days, peaking day 1 after inoculation two days earlier than H1N1 infected pigs and at a six times higher level. The difference, however, was not statistically significant. Pigs euthanized on day 4 after inoculation, had a high virus load in all lung lobes. After the second inoculation, the nasal virus excretion was minimal. There were no clinical sign except elevated body temperature under the experimental conditions. The "avian-like" H1N2 subtype, which has been established in the Danish pig population at least since 2003, is a reassortant between circulating swine "avian-like" H1N1 and H3N2. The Danish

Genetic and biological characterisation of an avian-like H1N2 swine influenza virus generated by reassortment of circulating avian-like H1N1 and H3N2 subtypes in Denmark

PubMed Central

2013-01-01

Background The influenza A virus subtypes H1N1, H1N2 and H3N2 are the most prevalent subtypes in swine. In 2003, a reassorted H1N2 swine influenza virus (SIV) subtype appeared and became prevalent in Denmark. In the present study, the reassortant H1N2 subtype was characterised genetically and the infection dynamics compared to an “avian-like” H1N1 virus by an experimental infection study. Methods Sequence analyses were performed of the H1N2 virus. Two groups of pigs were inoculated with the reassortant H1N2 virus and an “avian-like” H1N1 virus, respectively, followed by inoculation with the opposite subtype four weeks later. Measurements of HI antibodies and acute phase proteins were performed. Nasal virus excretion and virus load in lungs were determined by real-time RT-PCR. Results The phylogenetic analysis revealed that the reassorted H1N2 virus contained a European “avian-like” H1-gene and a European “swine-like” N2-gene, thus being genetically distinct from most H1N2 viruses circulating in Europe, but similar to viruses reported in 2009/2010 in Sweden and Italy. Sequence analyses of the internal genes revealed that the reassortment probably arose between circulating Danish “avian-like” H1N1 and H3N2 SIVs. Infected pigs developed cross-reactive antibodies, and increased levels of acute phase proteins after inoculations. Pigs inoculated with H1N2 exhibited nasal virus excretion for seven days, peaking day 1 after inoculation two days earlier than H1N1 infected pigs and at a six times higher level. The difference, however, was not statistically significant. Pigs euthanized on day 4 after inoculation, had a high virus load in all lung lobes. After the second inoculation, the nasal virus excretion was minimal. There were no clinical sign except elevated body temperature under the experimental conditions. Conclusions The “avian-like” H1N2 subtype, which has been established in the Danish pig population at least since 2003, is a reassortant

Fitness of Pandemic H1N1 and Seasonal influenza A viruses during Co-infection: Evidence of competitive advantage of pandemic H1N1 influenza versus seasonal influenza.

PubMed

Perez, Daniel Roberto; Sorrell, Erin; Angel, Matthew; Ye, Jianqiang; Hickman, Danielle; Pena, Lindomar; Ramirez-Nieto, Gloria; Kimble, Brian; Araya, Yonas

2009-08-24

On June 11, 2009 the World Health Organization (WHO) declared a new H1N1 influenza pandemic. This pandemic strain is as transmissible as seasonal H1N1 and H3N2 influenza A viruses. Major concerns facing this pandemic are whether the new virus will replace, co-circulate and/or reassort with seasonal H1N1 and/or H3N2 human strains. Using the ferret model, we investigated which of these three possibilities were most likely favored. Our studies showed that the current pandemic virus is more transmissible than, and has a biological advantage over, prototypical seasonal H1 or H3 strains.

Cross-protective immunity against influenza A/H1N1 virus challenge in mice immunized with recombinant vaccine expressing HA gene of influenza A/H5N1 virus

PubMed Central

2013-01-01

Background Influenza virus undergoes constant antigenic evolution, and therefore influenza vaccines must be reformulated each year. Time is necessary to produce a vaccine that is antigenically matched to a pandemic strain. A goal of many research works is to produce universal vaccines that can induce protective immunity to influenza A viruses of various subtypes. Despite intensive studies, the precise mechanisms of heterosubtypic immunity (HSI) remain ambiguous. Method In this study, mice were vaccinated with recombinant virus vaccine (rL H5), in which the hemagglutinin (HA) gene of influenza A/H5N1 virus was inserted into the LaSota Newcastle disease virus (NDV) vaccine strain. Following a challenge with influenza A/H1N1 virus, survival rates and lung index of mice were observed. The antibodies to influenza virus were detected using hemagglutination inhibition (HI). The lung viral loads, lung cytokine levels and the percentages of both IFN-γ+CD4+ and IFN-γ+CD8+ T cells in spleen were detected using real-time RT-PCR, ELISA and flow cytometry respectively. Results In comparison with the group of mice given phosphate-buffered saline (PBS), the mice vaccinated with rL H5 showed reductions in lung index and viral replication in the lungs after a challenge with influenza A/H1N1 virus. The antibody titer in group 3 (H1N1-H1N1) was significantly higher than that in other groups which only low levels of antibody were detected. IFN-γ levels increased in both group 1 (rL H5-H1N1) and group 2 (rL H5 + IL-2-H1N1). And the IFN-γ level of group 2 was significantly higher than that of group 1. The percentages of both IFN-γ+CD4+ and IFN-γ+CD8+ T cells in group 1 (rL H5-H1N1) and group 2 (rL H5 + IL-2-H1N1) increased significantly, as measured by flow cytometry. Conclusion After the mice were vaccinated with rL H5, cross-protective immune response was induced, which was against heterosubtypic influenza A/H1N1 virus. To some extent, cross-protective immune response can

Efficacy of a high-growth reassortant H1N1 influenza virus vaccine against the classical swine H1N1 subtype influenza virus in mice and pigs.

PubMed

Wen, Feng; Yu, Hai; Yang, Fu-Ru; Huang, Meng; Yang, Sheng; Zhou, Yan-Jun; Li, Ze-Jun; Tong, Guang-Zhi

2014-11-01

Swine influenza (SI) is an acute, highly contagious respiratory disease caused by swine influenza A viruses (SwIVs), and it poses a potential global threat to human health. Classical H1N1 (cH1N1) SwIVs are still circulating and remain the predominant subtype in the swine population in China. In this study, a high-growth reassortant virus (GD/PR8) harboring the hemagglutinin (HA) and neuraminidase (NA) genes from a novel cH1N1 isolate in China, A/Swine/Guangdong/1/2011 (GD/11) and six internal genes from the high-growth A/Puerto Rico/8/34(PR8) virus was generated by plasmid-based reverse genetics and tested as a candidate seed virus for the preparation of an inactivated vaccine. The protective efficacy of this vaccine was evaluated in mice and pigs challenged with GD/11 virus. Prime and boost inoculation of GD/PR8 vaccine yielded high-titer serum hemagglutination inhibiting (HI) antibodies and IgG antibodies for GD/11 in both mice and pigs. Complete protection of mice and pigs against cH1N1 SIV challenge was observed, with significantly fewer lung lesions and reduced viral shedding in vaccine-inoculated animals compared with unvaccinated control animals. Our data demonstrated that the GD/PR8 may serve as the seed virus for a promising SwIVs vaccine to protect the swine population.

Adaptation of Pandemic H1N1 Influenza Viruses in Mice▿

PubMed Central

Ilyushina, Natalia A.; Khalenkov, Alexey M.; Seiler, Jon P.; Forrest, Heather L.; Bovin, Nicolai V.; Marjuki, Henju; Barman, Subrata; Webster, Robert G.; Webby, Richard J.

2010-01-01

The molecular mechanism by which pandemic 2009 influenza A viruses were able to sufficiently adapt to humans is largely unknown. Subsequent human infections with novel H1N1 influenza viruses prompted an investigation of the molecular determinants of the host range and pathogenicity of pandemic influenza viruses in mammals. To address this problem, we assessed the genetic basis for increased virulence of A/CA/04/09 (H1N1) and A/TN/1-560/09 (H1N1) isolates, which are not lethal for mice, in a new mammalian host by promoting their mouse adaptation. The resulting mouse lung-adapted variants showed significantly enhanced growth characteristics in eggs, extended extrapulmonary tissue tropism, and pathogenicity in mice. All mouse-adapted viruses except A/TN/1-560/09-MA2 grew faster and to higher titers in cells than the original strains. We found that 10 amino acid changes in the ribonucleoprotein (RNP) complex (PB2 E158G/A, PA L295P, NP D101G, and NP H289Y) and hemagglutinin (HA) glycoprotein (K119N, G155E, S183P, R221K, and D222G) controlled enhanced mouse virulence of pandemic isolates. HA mutations acquired during adaptation affected viral receptor specificity by enhancing binding to α2,3 together with decreasing binding to α2,6 sialyl receptors. PB2 E158G/A and PA L295P amino acid substitutions were responsible for the significant enhancement of transcription and replication activity of the mouse-adapted H1N1 variants. Taken together, our findings suggest that changes optimizing receptor specificity and interaction of viral polymerase components with host cellular factors are the major mechanisms that contribute to the optimal competitive advantage of pandemic influenza viruses in mice. These modulators of virulence, therefore, may have been the driving components of early evolution, which paved the way for novel 2009 viruses in mammals. PMID:20592084

A novel H6N1 virus-like particle vaccine induces long-lasting cross-clade antibody immunity against human and avian H6N1 viruses.

PubMed

Yang, Ji-Rong; Chen, Chih-Yuan; Kuo, Chuan-Yi; Cheng, Chieh-Yu; Lee, Min-Shiuh; Cheng, Ming-Chu; Yang, Yu-Chih; Wu, Chia-Ying; Wu, Ho-Sheng; Liu, Ming-Tsan; Hsiao, Pei-Wen

2016-02-01

Avian influenza A(H6N1) virus is one of the most common viruses isolated from migrating birds and domestic poultry in many countries. The first and only known case of human infection by H6N1 virus in the world was reported in Taiwan in 2013. This led to concern that H6N1 virus may cause a threat to public health. In this study, we engineered a recombinant H6N1 virus-like particle (VLP) and investigated its vaccine effectiveness compared to the traditional egg-based whole inactivated virus (WIV) vaccine. The H6N1-VLPs exhibited similar morphology and functional characteristics to influenza viruses. Prime-boost intramuscular immunization in mice with unadjuvanted H6N1-VLPs were highly immunogenic and induced long-lasting antibody immunity. The functional activity of the VLP-elicited IgG antibodies was proved by in vitro seroprotective hemagglutination inhibition and microneutralization titers against the homologous human H6N1 virus, as well as in vivo viral challenge analyses which showed H6N1-VLP immunization significantly reduced viral load in the lung, and protected against human H6N1 virus infection. Of particular note, the H6N1-VLPs but not the H6N1-WIVs were able to confer cross-reactive humoral immunity; antibodies induced by H6N1-VLP vaccine robustly inhibited the hemagglutination activities and in vitro replication of distantly-related heterologous avian H6N1 viruses. Furthermore, the H6N1-VLPs were found to elicit significantly greater anti-HA2 antibody responses in immunized mice than H6N1-WIVs. Collectively, we demonstrated for the first time a novel H6N1-VLP vaccine that effectively provides broadly protective immunity against both human and avian H6N1 viruses. These results, which uncover the underlying mechanisms for induction of wide-range immunity against influenza viruses, may be useful for future influenza vaccine development. Copyright © 2015 Elsevier B.V. All rights reserved.

Epidemiology of pandemic influenza A/H1N1 virus during 2009-2010 in Taiwan.

PubMed

Lan, Yu-Ching; Su, Mei-Chi; Chen, Chao-Hsien; Huang, Su-Hua; Chen, Wan-Li; Tien, Ni; Lin, Cheng-Wen

2013-10-01

Outbreak of swine-origin influenza A/H1N1 virus (pdmH1N1) occurred in 2009. Taiwanese authorities implemented nationwide vaccinations with pdmH1N1-specific inactivated vaccine as of November 2009. This study evaluates prevalence, HA phylogenetic relationship, and transmission dynamic of influenza A and B viruses in Taiwan in 2009-2010. Respiratory tract specimens were analyzed for influenza A and B viruses. The pdmH1N1 peaked in November 2009, was predominant from August 2009 to January 2010, then sharply dropped in February 2010. Significant prevalence peaks of influenza B in April-June of 2010 and H3N2 virus in July and August were observed. Highest percentage of pdmH1N1- and H3N2-positive cases appeared among 11-15-year-olds; influenza B-positive cases were dominant among those 6-10 years old. Maximum likelihood phylogenetic trees showed 11 unique clusters of pdmH1N1, seasonal H3N2 influenza A and B viruses, as well as transmission clusters and mixed infections of influenza strains in Taiwan. The 2009 pdmH1N1 virus was predominant in Taiwan from August 2009 to January 2010; seasonal H3N2 influenza A and B viruses exhibited small prevalence peaks after nationwide vaccinations. Phylogenetic evidence indicated transmission clusters and multiple independent clades of co-circulating influenza A and B strains in Taiwan. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

Natural co-infection of influenza A/H3N2 and A/H1N1pdm09 viruses resulting in a reassortant A/H3N2 virus.

PubMed

Rith, Sareth; Chin, Savuth; Sar, Borann; Y, Phalla; Horm, Srey Viseth; Ly, Sovann; Buchy, Philippe; Dussart, Philippe; Horwood, Paul F

2015-12-01

Despite annual co-circulation of different subtypes of seasonal influenza, co-infections between different viruses are rarely detected. These co-infections can result in the emergence of reassortant progeny. We document the detection of an influenza co-infection, between influenza A/H3N2 with A/H1N1pdm09 viruses, which occurred in a 3 year old male in Cambodia during April 2014. Both viruses were detected in the patient at relatively high viral loads (as determined by real-time RT-PCR CT values), which is unusual for influenza co-infections. As reassortment can occur between co-infected influenza A strains we isolated plaque purified clonal viral populations from the clinical material of the patient infected with A/H3N2 and A/H1N1pdm09. Complete genome sequences were completed for 7 clonal viruses to determine if any reassorted viruses were generated during the influenza virus co-infection. Although most of the viral sequences were consistent with wild-type A/H3N2 or A/H1N1pdm09, one reassortant A/H3N2 virus was isolated which contained an A/H1N1pdm09 NS1 gene fragment. The reassortant virus was viable and able to infect cells, as judged by successful passage in MDCK cells, achieving a TCID50 of 10(4)/ml at passage number two. There is no evidence that the reassortant virus was transmitted further. The co-infection occurred during a period when co-circulation of A/H3N2 and A/H1N1pdm09 was detected in Cambodia. It is unclear how often influenza co-infections occur, but laboratories should consider influenza co-infections during routine surveillance activities. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

The hemagglutinin structure of an avian H1N1 influenza A virus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Tianwei; Wang, Gengyan; Li, Anzhang

2009-09-15

The interaction between hemagglutinin (HA) and receptors is a kernel in the study of evolution and host adaptation of H1N1 influenza A viruses. The notion that the avian HA is associated with preferential specificity for receptors with Sia{alpha}2,3Gal glycosidic linkage over those with Sia{alpha}2,6Gal linkage is not all consistent with the available data on H1N1 viruses. By x-ray crystallography, the HA structure of an avian H1N1 influenza A virus, as well as its complexes with the receptor analogs, was determined. The structures revealed no preferential binding of avian receptor analogs over that of the human analog, suggesting that the HA/receptormore » binding might not be as stringent as is commonly believed in determining the host receptor preference for some subtypes of influenza viruses, such as the H1N1 viruses. The structure also showed difference in glycosylation despite the preservation of related sequences, which may partly contribute to the difference between structures of human and avian origin.« less

B Cell Response and Hemagglutinin Stalk-Reactive Antibody Production in Different Age Cohorts following 2009 H1N1 Influenza Virus Vaccination

PubMed Central

Baer, Jane; Santiago, Felix W.; Fitzgerald, Theresa; Ilyushina, Natalia A.; Sundararajan, Aarthi; Henn, Alicia D.; Krammer, Florian; Yang, Hongmei; Luke, Catherine J.; Zand, Martin S.; Wright, Peter F.; Treanor, John J.; Topham, David J.

2013-01-01

The 2009 pandemic H1N1 (pH1N1) influenza virus carried a swine-origin hemagglutinin (HA) that was closely related to the HAs of pre-1947 H1N1 viruses but highly divergent from the HAs of recently circulating H1N1 strains. Consequently, prior exposure to pH1N1-like viruses was mostly limited to individuals over the age of about 60 years. We related age and associated differences in immune history to the B cell response to an inactivated monovalent pH1N1 vaccine given intramuscularly to subjects in three age cohorts: 18 to 32 years, 60 to 69 years, and ≥70 years. The day 0 pH1N1-specific hemagglutination inhibition (HAI) and microneutralization (MN) titers were generally higher in the older cohorts, consistent with greater prevaccination exposure to pH1N1-like viruses. Most subjects in each cohort responded well to vaccination, with early formation of circulating virus-specific antibody (Ab)-secreting cells and ≥4-fold increases in HAI and MN titers. However, the response was strongest in the 18- to 32-year cohort. Circulating levels of HA stalk-reactive Abs were increased after vaccination, especially in the 18- to 32-year cohort, raising the possibility of elevated levels of cross-reactive neutralizing Abs. In the young cohort, an increase in MN activity against the seasonal influenza virus A/Brisbane/59/07 after vaccination was generally associated with an increase in the anti-Brisbane/59/07 HAI titer, suggesting an effect mediated primarily by HA head-reactive rather than stalk-reactive Abs. Our findings support recent proposals that immunization with a relatively novel HA favors the induction of Abs against conserved epitopes. They also emphasize the need to clarify how the level of circulating stalk-reactive Abs relates to resistance to influenza. PMID:23576673

Intensive cytokine induction in pandemic H1N1 influenza virus infection accompanied by robust production of IL-10 and IL-6.

PubMed

Yu, Xuelian; Zhang, Xi; Zhao, Baihui; Wang, Jiayu; Zhu, Zhaokui; Teng, Zheng; Shao, Junjie; Shen, Jiaren; Gao, Ye; Yuan, Zhengan; Wu, Fan

2011-01-01

The innate immune system is the first line of defense against viruses by inducing expression of cytokines and chemokines. Many pandemic influenza H1N1 virus [P(H1N1)] infected severe cases occur in young adults under 18 years old who were rarely seriously affected by seasonal influenza. Results regarding host cytokine profiles of P(H1N1) are ambivalent. In the present study we investigated host cytokine profiles in P(H1N1) patients and identified cytokines related to disease severity. We retrieved 77, 59, 26 and 26 sera samples from P(H1N1) and non-flu influenza like illness (non-ILIs) cases with mild symptoms (mild patients), P(H1N1) vaccinees and healthy individuals, respectively. Nine and 16 sera were from hospitalized P(H1N1) and non-ILIs patients with severe symptoms (severe patients). Cytokines of IL-1, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IFN-γ and TNF-α were assayed by cytokine bead array, IL-17 and IL-23 measured with ELISA. Mild P(H1N1) patients produced significantly elevated IL-2, IL-12, IFN-γ, IL-6, TNF-α, IL-5, IL-10, IL-17 and IL-23 versus to healthy controls. While an overwhelming IL-6 and IL-10 production were observed in severe P(H1N1) patients. Higher IL-10 secretion in P(H1N1) vaccinees confirmed our observation that highly increased level of sera IL-6 and IL-10 in P(H1N1) patients may lead to disease progression. A comprehensive innate immune response was activated at the early stage of P(H1N1) infection with a combine Th1/Th2/Th3 cytokines production. As disease progression, a systemic production of IL-6 and IL-10 were observed in severe P(H1N1) patients. Further analysis found a strong correlation between IL-6 and IL-10 production in the severe P(H1N1) patients. IL-6 may be served as a mediator to induce IL-10 production. Highly elevated level of sera IL-6 and IL-10 in P(H1N1) patients may lead to disease progression, but the underlying mechanism awaits further detailed investigations.

Intensive Cytokine induction in Pandemic H1N1 Influenza Virus Infection Accompanied by Robust Production of IL-10 and IL-6

PubMed Central

Yu, Xuelian; Zhang, Xi; Zhao, Baihui; Wang, Jiayu; Zhu, Zhaokui; Teng, Zheng; Shao, Junjie; Shen, Jiaren; Gao, Ye; Yuan, Zhengan; Wu, Fan

2011-01-01

Background The innate immune system is the first line of defense against viruses by inducing expression of cytokines and chemokines. Many pandemic influenza H1N1 virus [P(H1N1)] infected severe cases occur in young adults under 18 years old who were rarely seriously affected by seasonal influenza. Results regarding host cytokine profiles of P(H1N1) are ambivalent. In the present study we investigated host cytokine profiles in P(H1N1) patients and identified cytokines related to disease severity. Methods and Principal Findings We retrieved 77, 59, 26 and 26 sera samples from P(H1N1) and non-flu influenza like illness (non-ILIs) cases with mild symptoms (mild patients), P(H1N1) vaccinees and healthy individuals, respectively. Nine and 16 sera were from hospitalized P(H1N1) and non-ILIs patients with severe symptoms (severe patients). Cytokines of IL-1, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IFN-γ and TNF-α were assayed by cytokine bead array, IL-17 and IL-23 measured with ELISA. Mild P(H1N1) patients produced significantly elevated IL-2, IL-12, IFN-γ, IL-6, TNF-α, IL-5, IL-10, IL-17 and IL-23 versus to healthy controls. While an overwhelming IL-6 and IL-10 production were observed in severe P(H1N1) patients. Higher IL-10 secretion in P(H1N1) vaccinees confirmed our observation that highly increased level of sera IL-6 and IL-10 in P(H1N1) patients may lead to disease progression. Conclusion and Significance A comprehensive innate immune response was activated at the early stage of P(H1N1) infection with a combine Th1/Th2/Th3 cytokines production. As disease progression, a systemic production of IL-6 and IL-10 were observed in severe P(H1N1) patients. Further analysis found a strong correlation between IL-6 and IL-10 production in the severe P(H1N1) patients. IL-6 may be served as a mediator to induce IL-10 production. Highly elevated level of sera IL-6 and IL-10 in P(H1N1) patients may lead to disease progression, but the underlying mechanism awaits further

Complex patterns of human antisera reactivity to novel 2009 H1N1 and historical H1N1 influenza strains.

PubMed

Carter, Donald M; Lu, Hai-Rong; Bloom, Chalise E; Crevar, Corey J; Cherry, Joshua L; Lipman, David J; Ross, Ted M

2012-01-01

During the 2009 influenza pandemic, individuals over the age of 60 had the lowest incidence of infection with approximately 25% of these people having pre-existing, cross-reactive antibodies to novel 2009 H1N1 influenza isolates. It was proposed that older people had pre-existing antibodies induced by previous 1918-like virus infection(s) that cross-reacted to novel H1N1 strains. Using antisera collected from a cohort of individuals collected before the second wave of novel H1N1 infections, only a minority of individuals with 1918 influenza specific antibodies also demonstrated hemagglutination-inhibition activity against the novel H1N1 influenza. In this study, we examined human antisera collected from individuals that ranged between the ages of 1 month and 90 years to determine the profile of seropositive influenza immunity to viruses representing H1N1 antigenic eras over the past 100 years. Even though HAI titers to novel 2009 H1N1 and the 1918 H1N1 influenza viruses were positively associated, the association was far from perfect, particularly for the older and younger age groups. Therefore, there may be a complex set of immune responses that are retained in people infected with seasonal H1N1 that can contribute to the reduced rates of H1N1 influenza infection in older populations.

H1N1-associated acute retinitis.

PubMed

Rifkin, Lana; Schaal, Shlomit

2012-06-01

To present the first reported case of bilateral H(1)N(1)-associated acute retinitis and its successful treatment. Interventional case report. A 41-year-old HIV-positive male presented with acute vision loss, panuveitis, and retinitis. A diagnostic and therapeutic vitrectomy with intravitreal injection of vancomycin and ganciclovir and endolaser was performed. One month later, the patient returned with similar symptoms in the fellow eye and underwent the same procedure. ELISA immunoassay revealed H(1)N(1) antibodies in both the vitreous and serum. PCR for herpes viruses included HSV, CMV, and VZV. Bacterial and fungal cultures were negative. On 1-year follow-up, the vision remained 20/20 in both eyes without evidence of recurrent inflammation. H(1)N(1) should be included in the differential diagnosis of any patient with a history of recent influenza A (H(1)N(1)) infection and acute retinitis. H(1)N(1) may carry a better prognosis than other viruses causing acute retinitis.

Novel triple-reassortant H1N1 swine influenza viruses in pigs in Tianjin, Northern China.

PubMed

Sun, Ying-Feng; Wang, Xiu-Hui; Li, Xiu-Li; Zhang, Li; Li, Hai-Hua; Lu, Chao; Yang, Chun-Lei; Feng, Jing; Han, Wei; Ren, Wei-Ke; Tian, Xiang-Xue; Tong, Guang-Zhi; Wen, Feng; Li, Ze-Jun; Gong, Xiao-Qian; Liu, Xiao-Min; Ruan, Bao-Yang; Yan, Ming-Hua; Yu, Hai

2016-02-01

Pigs are susceptible to both human and avian influenza viruses and therefore have been proposed to be mixing vessels for the generation of pandemic influenza viruses through reassortment. In this study, for the first time, we report the isolation and genetic analyses of three novel triple-reassortant H1N1 swine influenza viruses from pigs in Tianjin, Northern China. Phylogenetic analysis showed that these novel viruses contained genes from the 2009 pandemic H1N1 (PB2, PB1, PA and NP), Eurasian swine (HA, NA and M) and triple-reassortant swine (NS) lineages. This indicated that the reassortment among the 2009 pandemic H1N1, Eurasian swine and triple-reassortant swine influenza viruses had taken place in pigs in Tianjin and resulted in the generation of new viruses. Furthermore, three human-like H1N1, two classical swine H1N1 and two Eurasian swine H1N1 viruses were also isolated during the swine influenza virus surveillance from 2009 to 2013, which indicated that multiple genetic lineages of swine H1N1 viruses were co-circulating in the swine population in Tianjin, China. The emergence of novel triple-reassortant H1N1 swine influenza viruses may be a potential threat to human health and emphasizes the importance of further continuous surveillance. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of a newly emerged genetic cluster of H1N1 and H1N2 swine influenza virus in the United States.

PubMed

Vincent, Amy L; Ma, Wenjun; Lager, Kelly M; Gramer, Marie R; Richt, Juergen A; Janke, Bruce H

2009-10-01

H1 influenza A viruses that were distinct from the classical swine H1 lineage were identified in pigs in Canada in 2003–2004; antigenic and genetic characterization identified the hemagglutinin (HA) as human H1 lineage. The viruses identified in Canadian pigs were human lineage in entirety or double (human–swine) reassortants. Here, we report the whole genome sequence analysis of four human-like H1 viruses isolated from U.S. swine in 2005 and 2007. All four isolates were characterized as triple reassortants with an internal gene constellation similar to contemporary U.S. swine influenza virus (SIV), with HA and neuraminidase (NA) most similar to human influenza virus lineages. A 2007 human-like H1N1 was evaluated in a pathogenesis and transmission model and compared to a 2004 reassortant H1N1 SIV isolate with swine lineage HA and NA. The 2007 isolate induced disease typical of influenza virus and was transmitted to contact pigs; however, the kinetics and magnitude differed from the 2004 H1N1 SIV. This study indicates that the human-like H1 SIV can efficiently replicate and transmit in the swine host and now co-circulates with contemporary SIVs as a distinct genetic cluster of H1 SIV.

2009 Pandemic H1N1 Influenza Virus Causes Disease and Upregulation of Genes Related to Inflammatory and Immune Responses, Cell Death, and Lipid Metabolism in Pigs▿

PubMed Central

Ma, Wenjun; Belisle, Sarah E.; Mosier, Derek; Li, Xi; Stigger-Rosser, Evelyn; Liu, Qinfang; Qiao, Chuanling; Elder, Jake; Webby, Richard; Katze, Michael G.; Richt, Juergen A.

2011-01-01

There exists limited information about whether adaptation is needed for cross-species transmission of the 2009 pandemic H1N1 influenza virus (pH1N1). Here, we compare the pathogenesis of two pH1N1 viruses, one derived from a human patient (A/CA/04/09 [CA09]) and the other from swine (A/swine/Alberta/25/2009 [Alb09]), with that of the 1918-like classical swine influenza virus (A/swine/Iowa/1930 [IA30]) in the pig model. Both pH1N1 isolates induced clinical symptoms such as coughing, sneezing, decreased activity, fever, and labored breathing in challenged pigs, but IA30 virus did not cause any clinical symptoms except fever. Although both the pH1N1 viruses and the IA30 virus caused lung lesions, the pH1N1 viruses were shed from the nasal cavities of challenged pigs whereas the IA30 virus was not. Global gene expression analysis indicated that transcriptional responses of the viruses were distinct. pH1N1-infected pigs had an upregulation of genes related to inflammatory and immune responses at day 3 postinfection that was not seen in the IA30 infection, and expression levels of genes related to cell death and lipid metabolism at day 5 postinfection were markedly different from those of IA30 infection. These results indicate that both pH1N1 isolates are more virulent due in part to differences in the host transcriptional response during acute infection. Our study also indicates that pH1N1 does not need prior adaptation to infect pigs, has a high potential to be maintained in naïve swine populations, and might reassort with currently circulating swine influenza viruses. PMID:21900171

A Historical Perspective of Influenza A(H1N2) Virus

PubMed Central

McVernon, Jodie; Hall, Robert; Leder, Karin

2014-01-01

The emergence and transition to pandemic status of the influenza A(H1N1)A(H1N1)pdm09) virus in 2009 illustrated the potential for previously circulating human viruses to re-emerge in humans and cause a pandemic after decades of circulating among animals. Within a short time of the initial emergence of A(H1N1)pdm09 virus, novel reassortants were isolated from swine. In late 2011, a variant (v) H3N2 subtype was isolated from humans, and by 2012, the number of persons infected began to increase with limited person-to-person transmission. During 2012 in the United States, an A(H1N2)v virus was transmitted to humans from swine. During the same year, Australia recorded its first H1N2 subtype infection among swine. The A(H3N2)v and A(H1N2)v viruses contained the matrix protein from the A(H1N1)pdm09 virus, raising the possibility of increased transmissibility among humans and underscoring the potential for influenza pandemics of novel swine-origin viruses. We report on the differing histories of A(H1N2) viruses among humans and animals. PMID:24377419

A historical perspective of influenza A(H1N2) virus.

PubMed

Komadina, Naomi; McVernon, Jodie; Hall, Robert; Leder, Karin

2014-01-01

The emergence and transition to pandemic status of the influenza A(H1N1)A(H1N1)pdm09) virus in 2009 illustrated the potential for previously circulating human viruses to re-emerge in humans and cause a pandemic after decades of circulating among animals. Within a short time of the initial emergence of A(H1N1)pdm09 virus, novel reassortants were isolated from swine. In late 2011, a variant (v) H3N2 subtype was isolated from humans, and by 2012, the number of persons infected began to increase with limited person-to-person transmission. During 2012 in the United States, an A(H1N2)v virus was transmitted to humans from swine. During the same year, Australia recorded its first H1N2 subtype infection among swine. The A(H3N2)v and A(H1N2)v viruses contained the matrix protein from the A(H1N1)pdm09 virus, raising the possibility of increased transmissibility among humans and underscoring the potential for influenza pandemics of novel swine-origin viruses. We report on the differing histories of A(H1N2) viruses among humans and animals.

Evaluation of the attenuation, immunogenicity, and efficacy of a live virus vaccine generated by codon-pair bias de-optimization of the 2009 pandemic H1N1 influenza virus, in ferrets

PubMed Central

Broadbent, Andrew J.; Santos, Celia P.; Anafu, Amanda; Wimmer, Eckard; Mueller, Steffen; Subbarao, Kanta

2015-01-01

Codon-pair bias de-optimization (CPBD) of viruses involves re-writing viral genes using statistically underrepresented codon pairs, without any changes to the amino acid sequence or codon usage. Previously, this technology has been used to attenuate the influenza A/Puerto Rico/8/34 (H1N1) virus. The de-optimized virus was immunogenic and protected inbred mice from challenge. In order to assess whether CPBD could be used to produce a live vaccine against a clinically relevant influenza virus, we generated an influenza A/California/07/2009 pandemic H1N1 (2009 pH1N1) virus with de-optimized HA and NA gene segments (2009 pH1N1-(HA+NA)Min), and evaluated viral replication and protein expression in MDCK cells, and attenuation, immunogenicity, and efficacy in outbred ferrets. The 2009 pH1N1-(HA+NA)Min virus grew to a similar titer as the 2009 pH1N1 wild type (wt) virus in MDCK cells (~106 TCID50/ml), despite reduced HA and NA protein expression on western blot. In ferrets, intranasal inoculation of 2009 pH1N1-(HA+NA)Min virus at doses ranging from 103 to 105 TCID50 led to seroconversion in all animals and protection from challenge with the 2009 pH1N1 wt virus 28 days later. The 2009 pH1N1-(HA+NA)Min virus did not cause clinical illness in ferrets, but replicated to a similar titer as the wt virus in the upper and lower respiratory tract, suggesting that de-optimization of additional gene segments may be warranted for improved attenuation. Taken together, our data demonstrate the potential of using CPBD technology for the development of a live influenza virus vaccine if the level of attenuation is optimized. PMID:26655630

Fitness of Pandemic H1N1 and Seasonal influenza A viruses during Co-infection

PubMed Central

Perez, Daniel Roberto; Sorrell, Erin; Angel, Matthew; Ye, Jianqiang; Hickman, Danielle; Pena, Lindomar; Ramirez-Nieto, Gloria; Kimble, Brian; Araya, Yonas

2009-01-01

On June 11, 2009 the World Health Organization (WHO) declared a new H1N1 influenza pandemic. This pandemic strain is as transmissible as seasonal H1N1 and H3N2 influenza A viruses. Major concerns facing this pandemic are whether the new virus will replace, co-circulate and/or reassort with seasonal H1N1 and/or H3N2 human strains. Using the ferret model, we investigated which of these three possibilities were most likely favored. Our studies showed that the current pandemic virus is more transmissible than, and has a biological advantage over, prototypical seasonal H1 or H3 strains. PMID:20029606

Protection of guinea pigs by vaccination with a recombinant swinepox virus co-expressing HA1 genes of swine H1N1 and H3N2 influenza viruses.

PubMed

Xu, Jiarong; Yang, Deji; Huang, Dongyan; Xu, Jiaping; Liu, Shichao; Lin, Huixing; Zhu, Haodan; Liu, Bao; Lu, Chengping

2013-03-01

Swine influenza (SI) is an acute respiratory infectious disease of swine caused by swine influenza virus (SIV). SIV is not only an important respiratory pathogen in pigs but also a potent threat to human health. Here, we report the construction of a recombinant swinepox virus (rSPV/H3-2A-H1) co-expressing hemagglutinin (HA1) of SIV subtypes H1N1 and H3N2. Immune responses and protection efficacy of the rSPV/H3-2A-H1 were evaluated in guinea pigs. Inoculation of rSPV/H3-2A-H1 yielded neutralizing antibodies against SIV H1N1 and H3N2. The IFN-γ and IL-4 concentrations in the supernatant of lymphocytes stimulated with purified SIV HA1 antigen were significantly higher (P < 0.01) than those of the control groups. Complete protection of guinea pigs against SIV H1N1 or H3N2 challenge was observed. No SIV shedding was detected from guinea pigs vaccinated with rSPV/H3-2A-H1 after challenge. Most importantly, the guinea pigs immunized with rSPV/H3-2A-H1 did not show gross and micrographic lung lesions. However, the control guinea pigs experienced distinct gross and micrographic lung lesions at 7 days post-challenge. Our data suggest that the recombinant swinepox virus encoding HA1 of SIV H1N1 and H3N2 might serve as a promising candidate vaccine for protection against SIV H1N1 and H3N2 infections.

Working safely with H5N1 viruses.

PubMed

García-Sastre, Adolfo

2012-01-01

Research on H5N1 influenza viruses has received much attention recently due to the possible dangers associated with newly developed avian H5N1 viruses that were derived from highly pathogenic avian viruses and are now transmissible among ferrets via respiratory droplets. An appropriate discussion, based on scientific facts about the risks that such viruses pose and on the biocontainment facilities and practices necessary for working safely with these viruses, is needed. Selecting the right level of biocontainment is critical for minimizing the risks associated with H5N1 research while simultaneously allowing an appropriately fast pace of discovery. Rational countermeasures for preventing the spread of influenza can be developed only by gaining a thorough knowledge of the molecular mechanisms at work in host specificity and transmission.

Prevention of influenza virus shedding and protection from lethal H1N1 challenge using a consensus 2009 H1N1 HA and NA adenovirus vector vaccine

PubMed Central

Jones, Frank R.; Gabitzsch, Elizabeth S.; Xu, Younong; Balint, Joseph P.; Borisevich, Viktoriya; Smith, Jennifer; Smith, Jeanon; Peng, Bi-Hung; Walker, Aida; Salazar, Magda; Paessler, Slobodan

2013-01-01

Vaccines against emerging pathogens such as the 2009 H1N1 pandemic virus can benefit from current technologies such as rapid genomic sequencing to construct the most biologically relevant vaccine. A novel platform (Ad5 [E1-, E2b-]) has been utilized to induce immune responses to various antigenic targets. We employed this vector platform to express hemagglutinin (HA) and neuraminidase (NA) genes from 2009 H1N1 pandemic viruses. Inserts were consensuses sequences designed from viral isolate sequences and the vaccine was rapidly constructed and produced. Vaccination induced H1N1 immune responses in mice, which afforded protection from lethal virus challenge. In ferrets, vaccination protected from disease development and significantly reduced viral titers in nasal washes. H1N1 cell mediated immunity as well as antibody induction correlated with the prevention of disease symptoms and reduction of virus replication. The Ad5 [E1-, E2b-] should be evaluated for the rapid development of effective vaccines against infectious diseases. PMID:21821082

In vitro and in vivo efficacy of fluorodeoxycytidine analogs against highly pathogenic avian influenza H5N1, seasonal, and pandemic H1N1 virus infections

PubMed Central

Kumaki, Yohichi; Day, Craig W.; Smee, Donald F.; Morrey, John D.; Barnard, Dale L.

2011-01-01

Various fluorodeoxyribonucleosides were evaluated for their antiviral activities against influenza virus infections in vitro and in vivo. Among the most potent inhibitors was 2'-deoxy-2'-fluorocytidine (2'-FdC). It inhibited various strains of low and highly pathogenic avian influenza H5N1 viruses, pandemic H1N1 viruses, an oseltamivir-resistant pandemic H1N1 virus, and seasonal influenza viruses (H3N2, H1N1, influenza B) in MDCK cells, with the 90% inhibitory concentrations ranging from 0.13 µM to 4.6 µM, as determined by a virus yield reduction assay. 2'-FdC was then tested for efficacy in BALB/c mice infected with a lethal dose of highly pathogenic influenza A/Vietnam/1203/2004 H5N1 virus. 2’FdC (60 mg/kg/d) administered intraperitoneally (i.p.) twice a day beginning 24 h after virus exposure significantly promoted survival (80% survival) of infected mice (p=0.0001). Equally efficacious were the treatment regimens in which mice were treated with 2'-FdC at 30 or 60 mg/kg/day (bid × 8) beginning 24 h before virus exposure. At these doses, 70–80% of the mice were protected from death due to virus infection (p=0.0005, p=0.0001; respectively). The lungs harvested from treated mice at day four of the infection displayed little surface pathology or histopathology, lung weights were lower, and the 60 mg/kg dose reduced lung virus titers, although not significantly compared to the placebo controls. All doses were well tolerated in uninfected mice. 2'-FdC could also be administered as late as 72 h post virus exposure and still significantly protect 60% mice from the lethal effects of the H5N1 virus infection (p=0.019). Other fluorodeoxyribonucleosides tested in the H5N1 mouse model, 2’-deoxy-5-fluorocytidine and 2'-deoxy-2', 2'-difluorocytidine, were very toxic at higher doses and not inhibitory at lower doses. Finally, 2'-FdC, which was active in the H5N1 mouse model, was also active in a pandemic H1N1 influenza A infection model in mice. When given at 30 mg

Protective Efficacy of an H5N1 Inactivated Vaccine Against Challenge with Lethal H5N1, H5N2, H5N6, and H5N8 Influenza Viruses in Chickens.

PubMed

Zeng, Xianying; Chen, Pucheng; Liu, Liling; Deng, Guohua; Li, Yanbing; Shi, Jianzhong; Kong, Huihui; Feng, Huapeng; Bai, Jie; Li, Xin; Shi, Wenjun; Tian, Guobin; Chen, Hualan

2016-05-01

The Goose/Guangdong-lineage H5 viruses have evolved into diverse clades and subclades based on their hemagglutinin (HA) gene during their circulation in wild birds and poultry. Since late 2013, the clade 2.3.4.4 viruses have become widespread in poultry and wild bird populations around the world. Different subtypes of the clade 2.3.4.4 H5 viruses, including H5N1, H5N2, H5N6, and H5N8, have caused vast disease outbreaks in poultry in Asia, Europe, and North America. In this study, we developed a new H5N1 inactivated vaccine by using a seed virus (designated as Re-8) that contains the HA and NA genes from a clade 2.3.4.4 virus, A/chicken/Guizhou/4/13(H5N1) (CK/GZ/4/13), and its six internal genes from the high-growth A/Puerto Rico/8/1934 (H1N1) virus. We evaluated the protective efficacy of this vaccine in chickens challenged with one H5N1 clade 2.3.2.1b virus and six different subtypes of clade 2.3.4.4 viruses, including H5N1, H5N2, H5N6, and H5N8 strains. In the clade 2.3.2.1b virus DK/GX/S1017/13-challenged groups, half of the vaccinated chickens shed virus through the oropharynx and two birds (20%) died during the observation period. All of the control chickens shed viruses and died within 6 days of infection with challenge virus. All of the vaccinated chickens remained healthy following challenge with the six clade 2.3.4.4 viruses, and virus shedding was not detected from any of these birds; however, all of the control birds shed viruses and died within 4 days of challenge with the clade 2.3.4.4 viruses. Our results indicate that the Re-8 vaccine provides protection against different subtypes of clade 2.3.4.4 H5 viruses.

Cross-protection against European swine influenza viruses in the context of infection immunity against the 2009 pandemic H1N1 virus: studies in the pig model of influenza.

PubMed

Qiu, Yu; De Hert, Karl; Van Reeth, Kristien

2015-09-24

Pigs are natural hosts for the same influenza virus subtypes as humans and are a valuable model for cross-protection studies with influenza. In this study, we have used the pig model to examine the extent of virological protection between a) the 2009 pandemic H1N1 (pH1N1) virus and three different European H1 swine influenza virus (SIV) lineages, and b) these H1 viruses and a European H3N2 SIV. Pigs were inoculated intranasally with representative strains of each virus lineage with 6- and 17-week intervals between H1 inoculations and between H1 and H3 inoculations, respectively. Virus titers in nasal swabs and/or tissues of the respiratory tract were determined after each inoculation. There was substantial though differing cross-protection between pH1N1 and other H1 viruses, which was directly correlated with the relatedness in the viral hemagglutinin (HA) and neuraminidase (NA) proteins. Cross-protection against H3N2 was almost complete in pigs with immunity against H1N2, but was weak in H1N1/pH1N1-immune pigs. In conclusion, infection with a live, wild type influenza virus may offer substantial cross-lineage protection against viruses of the same HA and/or NA subtype. True heterosubtypic protection, in contrast, appears to be minimal in natural influenza virus hosts. We discuss our findings in the light of the zoonotic and pandemic risks of SIVs.

Structural Basis of Preexisting Immunity to the 2009 H1N1 Pandemic Influenza Virus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Rui; Ekiert, Damian C.; Krause, Jens C.

The 2009 H1N1 swine flu is the first influenza pandemic in decades. The crystal structure of the hemagglutinin from the A/California/04/2009 H1N1 virus shows that its antigenic structure, particularly within the Sa antigenic site, is extremely similar to those of human H1N1 viruses circulating early in the 20th century. The cocrystal structure of the 1918 hemagglutinin with 2D1, an antibody from a survivor of the 1918 Spanish flu that neutralizes both 1918 and 2009 H1N1 viruses, reveals an epitope that is conserved in both pandemic viruses. Thus, antigenic similarity between the 2009 and 1918-like viruses provides an explanation for themore » age-related immunity to the current influenza pandemic.« less

Live attenuated H5N1 vaccine with H9N2 internal genes protects chickens from infections by both Highly Pathogenic H5N1 and H9N2 Influenza Viruses

PubMed Central

Nang, Nguyen Tai; Song, Byung Min; Kang, Young Myong; Kim, Heui Man; Kim, Hyun Soo; Seo, Sang Heui

2012-01-01

Please cite this paper as: Nang et al. (2013) Live attenuated H5N1 vaccine with H9N2 internal genes protects chickens from infections by both Highly Pathogenic H5N1 and H9N2 Influenza Viruses. Influenza and Other Respiratory Viruses 7(2) 120–131. Background  The highly pathogenic H5N1 and H9N2 influenza viruses are endemic in many countries around the world and have caused considerable economic loss to the poultry industry. Objectives  We aimed to study whether a live attenuated H5N1 vaccine comprising internal genes from a cold‐adapted H9N2 influenza virus could protect chickens from infection by both H5N1 and H9N2 viruses. Methods  We developed a cold‐adapted H9N2 vaccine virus expressing hemagglutinin and neuraminidase derived from the highly pathogenic H5N1 influenza virus using reverse genetics. Results and Conclusions  Chickens immunized with the vaccine were protected from lethal infections with homologous and heterologous H5N1 or H9N2 influenza viruses. Specific antibody against H5N1 virus was detected up to 11 weeks after vaccination (the endpoint of this study). In vaccinated chickens, IgA and IgG antibody subtypes were induced in lung and intestinal tissue, and CD4+ and CD8+ T lymphocytes expressing interferon‐gamma were induced in the splenocytes. These data suggest that a live attenuated H5N1 vaccine with cold‐adapted H9N2 internal genes can protect chickens from infection with H5N1 and H9N2 influenza viruses by eliciting humoral and cellular immunity. PMID:22487301

Assessing Google Flu Trends Performance in the United States during the 2009 Influenza Virus A (H1N1) Pandemic

PubMed Central

Cook, Samantha; Conrad, Corrie; Fowlkes, Ashley L.; Mohebbi, Matthew H.

2011-01-01

Background Google Flu Trends (GFT) uses anonymized, aggregated internet search activity to provide near-real time estimates of influenza activity. GFT estimates have shown a strong correlation with official influenza surveillance data. The 2009 influenza virus A (H1N1) pandemic [pH1N1] provided the first opportunity to evaluate GFT during a non-seasonal influenza outbreak. In September 2009, an updated United States GFT model was developed using data from the beginning of pH1N1. Methodology/Principal Findings We evaluated the accuracy of each U.S. GFT model by comparing weekly estimates of ILI (influenza-like illness) activity with the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet). For each GFT model we calculated the correlation and RMSE (root mean square error) between model estimates and ILINet for four time periods: pre-H1N1, Summer H1N1, Winter H1N1, and H1N1 overall (Mar 2009–Dec 2009). We also compared the number of queries, query volume, and types of queries (e.g., influenza symptoms, influenza complications) in each model. Both models' estimates were highly correlated with ILINet pre-H1N1 and over the entire surveillance period, although the original model underestimated the magnitude of ILI activity during pH1N1. The updated model was more correlated with ILINet than the original model during Summer H1N1 (r = 0.95 and 0.29, respectively). The updated model included more search query terms than the original model, with more queries directly related to influenza infection, whereas the original model contained more queries related to influenza complications. Conclusions Internet search behavior changed during pH1N1, particularly in the categories “influenza complications” and “term for influenza.” The complications associated with pH1N1, the fact that pH1N1 began in the summer rather than winter, and changes in health-seeking behavior each may have played a part. Both GFT models performed well prior to and during pH1N1

Decreased Serologic Response in Vaccinated Military Recruits during 2011 Correspond to Genetic Drift in Concurrent Circulating Pandemic A/H1N1 Viruses

PubMed Central

Faix, Dennis J.; Hawksworth, Anthony W.; Myers, Christopher A.; Hansen, Christian J.; Ortiguerra, Ryan G.; Halpin, Rebecca; Wentworth, David; Pacha, Laura A.; Schwartz, Erica G.; Garcia, Shawn M. S.; Eick-Cost, Angelia A.; Clagett, Christopher D.; Khurana, Surender; Golding, Hana; Blair, Patrick J.

2012-01-01

Background Population-based febrile respiratory illness surveillance conducted by the Department of Defense contributes to an estimate of vaccine effectiveness. Between January and March 2011, 64 cases of 2009 A/H1N1 (pH1N1), including one fatality, were confirmed in immunized recruits at Fort Jackson, South Carolina, suggesting insufficient efficacy for the pH1N1 component of the live attenuated influenza vaccine (LAIV). Methodology/Principal Findings To test serologic protection, serum samples were collected at least 30 days post-vaccination from recruits at Fort Jackson (LAIV), Parris Island (LAIV and trivalent inactivated vaccine [TIV]) at Cape May, New Jersey (TIV) and responses measured against pre-vaccination sera. A subset of 78 LAIV and 64 TIV sera pairs from recruits who reported neither influenza vaccination in the prior year nor fever during training were tested by microneutralization (MN) and hemagglutination inhibition (HI) assays. MN results demonstrated that seroconversion in paired sera was greater in those who received TIV versus LAIV (74% and 37%). Additionally, the fold change associated with TIV vaccination was significantly different between circulating (2011) versus the vaccine strain (2009) of pH1N1 viruses (ANOVA p value = 0.0006). HI analyses revealed similar trends. Surface plasmon resonance (SPR) analysis revealed that the quantity, IgG/IgM ratios, and affinity of anti-HA antibodies were significantly greater in TIV vaccinees. Finally, sequence analysis of the HA1 gene in concurrent circulating 2011 pH1N1 isolates from Fort Jackson exhibited modest amino acid divergence from the vaccine strain. Conclusions/Significance Among military recruits in 2011, serum antibody response differed by vaccine type (LAIV vs. TIV) and pH1N1 virus year (2009 vs. 2011). We hypothesize that antigen drift in circulating pH1N1 viruses contributed to reduce vaccine effectiveness at Fort Jackson. Our findings have wider implications regarding vaccine

Reassortant Avian Influenza A(H5N1) Viruses with H9N2-PB1 Gene in Poultry, Bangladesh

PubMed Central

Yamage, Mat; Dauphin, Gwenaëlle; Claes, Filip; Ahmed, Garba; Giasuddin, Mohammed; Salviato, Annalisa; Ormelli, Silvia; Bonfante, Francesco; Schivo, Alessia; Cattoli, Giovanni

2013-01-01

Bangladesh has reported a high number of outbreaks of highly pathogenic avian influenza (HPAI) (H5N1) in poultry. We identified a natural reassortant HPAI (H5N1) virus containing a H9N2-PB1 gene in poultry in Bangladesh. Our findings highlight the risks for prolonged co-circulation of avian influenza viruses and the need to monitor their evolution. PMID:24047513

The Influenza Virus and the 2009 H1N1 Outbreak

DTIC Science & Technology

2016-04-08

Envelope L’ol • Sequencing Figure 1 Influenza Virus Anatomy -Neuramlnldase (Sialldase) ’ Hemagglutlnln 9 Key laboratory techniques...discover the 2009 H1 N1 influenza virus Phylogenetic Tree Out of the over 400 human H1 ’s USAFSAM sequenced this season no specimen has had less than a...surveillance/vaccine contents • Shot Versus Flu Mist • How does Tamiflu work • Sequencing HA - Culture, HAI, PCR, Serology ••• • t.tt

Novel reassortant of swine influenza H1N2 virus in Germany.

PubMed

Zell, Roland; Motzke, Susann; Krumbholz, Andi; Wutzler, Peter; Herwig, Volker; Dürrwald, Ralf

2008-01-01

European porcine H1N2 influenza viruses arose after multiple reassortment steps involving a porcine influenza virus with avian-influenza-like internal segments and human H1N1 and H3N2 viruses in 1994. In Germany, H1N2 swine influenza viruses first appeared in 2000. Two German H1N2 swine influenza virus strains isolated from pigs with clinical symptoms of influenza are described. They were characterized by the neutralization test, haemagglutination inhibition (HI) test and complete sequencing of the viral genomes. The data demonstrate that these viruses represent a novel H1N2 reassortant. The viruses showed limited neutralization by sera raised against heterologous A/sw/Bakum/1,832/00-like H1N2 viruses. Sera pools from recovered pigs showed a considerably lower HI reaction, indicative of diagnostic difficulties in using the HI test to detect these viruses with A/sw/Bakum/1,832/00-like H1N2 antigens. Genome sequencing revealed the novel combination of the human-like HAH1 gene of European porcine H1N2 influenza viruses and the NAN2 gene of European porcine H3N2 viruses.

Whole Genome Characterization, Phylogenetic and Genome Signature Analysis of Human Pandemic H1N1 Virus in Thailand, 2009–2012

PubMed Central

Makkoch, Jarika; Suwannakarn, Kamol; Payungporn, Sunchai; Prachayangprecha, Slinporn; Cheiocharnsin, Thaweesak; Linsuwanon, Piyada; Theamboonlers, Apiradee; Poovorawan, Yong

2012-01-01

Background Three waves of human pandemic influenza occurred in Thailand in 2009–2012. The genome signature features and evolution of pH1N1 need to be characterized to elucidate the aspects responsible for the multiple waves of pandemic. Methodology/Findings Forty whole genome sequences and 584 partial sequences of pH1N1 circulating in Thailand, divided into 1st, 2nd and 3rd wave and post-pandemic were characterized and 77 genome signatures were analyzed. Phylogenetic trees of concatenated whole genome and HA gene sequences were constructed calculating substitution rate and dN/dS of each gene. Phylogenetic analysis showed a distinct pattern of pH1N1 circulation in Thailand, with the first two isolates from May, 2009 belonging to clade 5 while clades 5, 6 and 7 co-circulated during the first wave of pH1N1 pandemic in Thailand. Clade 8 predominated during the second wave and different proportions of the pH1N1 viruses circulating during the third wave and post pandemic period belonged to clades 8, 11.1 and 11.2. The mutation analysis of pH1N1 revealed many adaptive mutations which have become the signature of each clade and may be responsible for the multiple pandemic waves in Thailand, especially with regard to clades 11.1 and 11.2 as evidenced with V731I, G154D of PB1 gene, PA I330V, HA A214T S160G and S202T. The substitution rate of pH1N1 in Thailand ranged from 2.53×10−3±0.02 (M2 genes) to 5.27×10−3±0.03 per site per year (NA gene). Conclusions All results suggested that this virus is still adaptive, maybe to evade the host's immune response and tends to remain in the human host although the dN/dS were under purifying selection in all 8 genes. Due to the gradual evolution of pH1N1 in Thailand, continuous monitoring is essential for evaluation and surveillance to be prepared for and able to control future influenza activities. PMID:23251479

Monitoring and Characterization of Oseltamivir-Resistant Pandemic (H1N1) 2009 Virus, Japan, 2009–2010

PubMed Central

Ujike, Makoto; Ejima, Miho; Anraku, Akane; Shimabukuro, Kozue; Obuchi, Masatsugu; Kishida, Noriko; Hong, Xu; Takashita, Emi; Fujisaki, Seiichiro; Yamashita, Kazuyo; Horikawa, Hiroshi; Kato, Yumiko; Oguchi, Akio; Fujita, Nobuyuki; Tashiro, Masato

2011-01-01

To monitor and characterize oseltamivir-resistant (OR) pandemic (H1N1) 2009 virus with the H275Y mutation, we analyzed 4,307 clinical specimens from Japan by neuraminidase (NA) sequencing or inhibition assay; 61 OR pandemic (H1N1) 2009 viruses were detected. NA inhibition assay and M2 sequencing indicated that OR pandemic (H1N1) 2009 virus was resistant to M2 inhibitors, but sensitive to zanamivir. Full-genome sequencing showed OR and oseltamivir-sensitive (OS) viruses had high sequence similarity, indicating that domestic OR virus was derived from OS pandemic (H1N1) 2009 virus. Hemagglutination inhibition test demonstrated that OR and OS pandemic (H1N1) 2009 viruses were antigenically similar to the A/California/7/2009 vaccine strain. Of 61 case-patients with OR viruses, 45 received oseltamivir as treatment, and 10 received it as prophylaxis, which suggests that most cases emerged sporadically from OS pandemic (H1N1) 2009, due to selective pressure. No evidence of sustained spread of OR pandemic (H1N1) 2009 was found in Japan; however, 2 suspected incidents of human-to-human transmission were reported. PMID:21392439

[Swine-origin influenza H1N1/California--passions and facts].

PubMed

Gendon, Iu Z

2010-01-01

Analysis of pandemic caused by swine influenza virus H1N1/California showed moderate virulence of this virus compared to pandemic viruses, which caused pandemics in 1918, 1957, and 1968. During seasonal influenza epidemic in countries of southern hemisphere (June-August 2009) despite on circulation of H1N1/California strain, epidemics was caused by human influenza viruses H3N2 and H1N1. It was concluded that strain H1N1/California could not be attributed to pandemic strains of influenza viruses.

Safety and Immunogenicity of 2009 pH1N1 Vaccination in HIV-Infected Pregnant Women

PubMed Central

Abzug, Mark J.; Nachman, Sharon A.; Muresan, Petronella; Handelsman, Edward; Watts, D. Heather; Fenton, Terence; Heckman, Barbara; Petzold, Elizabeth; Weinberg, Adriana; Levin, Myron J.; Siberry, George; Miller, Judi; Levy, Wende; Heckman, Barbara; Ebiasah, Ruth; Palumbo, Paul; Dragavon, Joan; Donelson, Lori; Jurgrau, Andrea; Garry, David; Bloom, Anthony

2013-01-01

Background. Pregnant women infected with human immunodeficiency virus (HIV) may have particular vulnerability to 2009 pandemic H1N1 influenza (pH1N1) infection. The safety and immunogenicity of pH1N1 vaccination in HIV-infected pregnant women are unknown. Methods. HIV-infected women 18–39 years of age and 14–34 weeks’ gestation on antiretroviral therapy received two 30-μg doses of unadjuvanted, inactivated pH1N1 vaccine 21 days apart. Hemagglutination inhibition titers were measured at entry, 21 days after dose 1, and 10 and 21 days after dose 2, and, in mothers and infants, at delivery and 3 and 6 months postdelivery. Results. No severe vaccine-related adverse events were observed among 127 subjects. At entry, 21% had seroprotective (≥1:40) titers. Seroprotection and seroresponse (≥4-fold rise) occurred in 73% and 66% after dose 1 and 80% and 72% after dose 2, respectively. Of women lacking seroprotection at entry, 66% attained seroprotection after dose 1 and 75% after dose 2. Seroprotective titers were present in 67% of mothers and 65% of infants at delivery (median 66 days after dose 2), 60% of mothers and 26% of infants at 3 months postdelivery, and 59% of mothers and 12% of infants at 6 months postdelivery. Conclusions. Two 30-μg doses were moderately immunogenic in HIV-infected pregnant women. No concerning vaccine-related safety signals were observed. Seroprotection persisted in most women postpartum. Efficient transplacental antibody transfer occurred, but seroprotection in infants waned rapidly. Vaccination to protect HIV-infected pregnant women and their newborns from new influenza strains is feasible, but more immunogenic platforms should be evaluated. Clinical Trials Registration. NCT00992017. PMID:23378284

Avian influenza virus (H5N1); effects of physico-chemical factors on its survival

PubMed Central

Shahid, Muhammad Akbar; Abubakar, Muhammad; Hameed, Sajid; Hassan, Shamsul

2009-01-01

Present study was performed to determine the effects of physical and chemical agents on infective potential of highly pathogenic avian influenza (HPAI) H5N1 (local strain) virus recently isolated in Pakistan during 2006 outbreak. H5N1 virus having titer 108.3 ELD50/ml was mixed with sterilized peptone water to get final dilution of 4HA units and then exposed to physical (temperature, pH and ultraviolet light) and chemical (formalin, phenol crystals, iodine crystals, CID 20, virkon®-S, zeptin 10%, KEPCIDE 300, KEPCIDE 400, lifebuoy, surf excel and caustic soda) agents. Harvested amnio-allantoic fluid (AAF) from embryonated chicken eggs inoculated with H5N1 treated virus (0.2 ml/egg) was subjected to haemagglutination (HA) and haemagglutination inhibition (HI) tests. H5N1 virus lost infectivity after 30 min at 56°C, after 1 day at 28°C but remained viable for more than 100 days at 4°C. Acidic pH (1, 3) and basic pH (11, 13) were virucidal after 6 h contact time; however virus retained infectivity at pH 5 (18 h), 7 and 9 (more than 24 h). UV light was proved ineffectual in inactivating virus completely even after 60 min. Soap (lifebuoy®), detergent (surf excel®) and alkali (caustic soda) destroyed infectivity after 5 min at 0.1, 0.2 and 0.3% dilution. All commercially available disinfectants inactivated virus at recommended concentrations. Results of present study would be helpful in implementing bio-security measures at farms/hatcheries levels in the wake of avian influenza virus (AIV) outbreak. PMID:19327163

Transmission dynamics of pandemic influenza A(H1N1)pdm09 virus in humans and swine in backyard farms in Tumbes, Peru.

PubMed

Tinoco, Yeny O; Montgomery, Joel M; Kasper, Mathew R; Nelson, Martha I; Razuri, Hugo; Guezala, Maria C; Azziz-Baumgartner, Eduardo; Widdowson, Marc-Alain; Barnes, John; Gilman, Robert H; Bausch, Daniel G; Gonzalez, Armando E

2016-01-01

We aimed to determine the frequency of pH1N1 transmission between humans and swine on backyard farms in Tumbes, Peru. Two-year serial cross-sectional study comprising four sampling periods: March 2009 (pre-pandemic), October 2009 (peak of the pandemic in Peru), April 2010 (1st post-pandemic period), and October 2011 (2nd post-pandemic period). Backyard swine serum, tracheal swabs, and lung sample were collected during each sampling period. We assessed current and past pH1N1 infection in swine through serological testing, virus culture, and RT-PCR and compared the results with human incidence data from a population-based active surveillance cohort study in Peru. Among 1303 swine sampled, the antibody prevalence to pH1N1 was 0% pre-pandemic, 8% at the peak of the human pandemic (October 2009), and 24% in April 2010 and 1% in October 2011 (post-pandemic sampling periods). Trends in swine seropositivity paralleled those seen in humans in Tumbes. The pH1N1 virus was isolated from three pigs during the peak of the pandemic. Phylogenetic analysis revealed that these viruses likely represent two separate human-to-swine transmission events in backyard farm settings. Our findings suggest that human-to-swine pH1N1 transmission occurred during the pandemic among backyard farms in Peru, emphasizing the importance of interspecies transmission in backyard pig populations. Continued surveillance for influenza viruses in backyard farms is warranted. © 2015 The Authors. Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.

Pre-infection of pigs with Mycoplasma hyopneumoniae modifies outcomes of infection with European swine influenza virus of H1N1, but not H1N2, subtype.

PubMed

Deblanc, C; Gorin, S; Quéguiner, S; Gautier-Bouchardon, A V; Ferré, S; Amenna, N; Cariolet, R; Simon, G

2012-05-25

Swine influenza virus (SIV) and Mycoplasma hyopneumoniae (Mhp) are widespread in farms and are major pathogens involved in the porcine respiratory disease complex (PRDC). The aim of this experiment was to compare the pathogenicity of European avian-like swine H1N1 and European human-like reassortant swine H1N2 viruses in naïve pigs and in pigs previously infected with Mhp. Six groups of SPF pigs were inoculated intra-tracheally with either Mhp, or H1N1, or H1N2 or Mhp+H1N1 or Mhp+H1N2, both pathogens being inoculated at 21 days intervals in these two last groups. A mock-infected group was included. Although both SIV strains induced clinical signs when singly inoculated, results indicated that the H1N2 SIV was more pathogenic than the H1N1 virus, with an earlier shedding and a greater spread in lungs. Initial infection with Mhp before SIV inoculation increased flu clinical signs and pathogenesis (hyperthermia, loss of appetite, pneumonia lesions) due to the H1N1 virus but did not modify significantly outcomes of H1N2 infection. Thus, Mhp and SIV H1N1 appeared to act synergistically, whereas Mhp and SIV H1N2 would compete, as H1N2 infection led to the elimination of Mhp in lung diaphragmatic lobes. In conclusion, SIV would be a risk factor for the severity of respiratory disorders when associated with Mhp, depending on the viral subtype involved. This experimental model of coinfection with Mhp and avian-like swine H1N1 is a relevant tool for studying the pathogenesis of SIV-associated PRDC and testing intervention strategies for the control of the disease. Copyright © 2012 Elsevier B.V. All rights reserved.