scholarly journals Correlation between polymerase activity and pathogenicity in two duck H5N1 influenza viruses suggests that the polymerase contributes to pathogenicity

Virology ◽  
2010 ◽  
Vol 401 (1) ◽  
pp. 96-106 ◽  
Author(s):  
Bo Wah Leung ◽  
Hualan Chen ◽  
George G. Brownlee
Keyword(s):  
Polymerase Activity ◽  
Influenza Viruses ◽  
H5n1 Influenza

scholarly journals Mutations in the PA Protein of Avian H5N1 Influenza Viruses Affect Polymerase Activity and Mouse Virulence

2017 ◽  
pp. JVI.01557-17 ◽  
Author(s):  
Gongxun Zhong ◽  
Mai Quynh Le ◽  
Tiago J.S. Lopes ◽  
Peter Halfmann ◽  
Masato Hatta ◽  
...  
Keyword(s):  
Amino Acid ◽  
Case Fatality ◽  
Polymerase Activity ◽  
Influenza Viruses ◽  
Viral Polymerase ◽  
Highly Pathogenic ◽  
H5n1 Influenza ◽  
Increased Risk ◽  
Severe Infections ◽  
Viral Determinants

To study the influenza viral determinants of pathogenicity, we characterized two highly pathogenic avian H5N1 influenza viruses isolated in Vietnam in 2012 (A/duck/Vietnam/QT1480/2012; QT1480) and 2013 (A/duck/Vietnam/QT1728/2013; QT1728) and found that the activity of their polymerase complexes differed significantly, even though both viruses were highly pathogenic in mice. Further studies revealed that the PA-S343A/E347D mutations reduced viral polymerase activity and mouse virulence when tested in the genetic background of QT1728 virus. In contrast, the PA-343S/347E mutations increased the polymerase activity of QT1480 and the virulence of a low pathogenic H5N1 influenza virus. The PA-343S residue (which alone increased viral polymerase activity and mouse virulence significantly relative to viral replication complexes encoding PA-343A) is frequently found in H5N1 influenza viruses of several subclades; infection with a virus possessing this amino acid may pose an increased risk to humans.IMPORTANCEH5N1 influenza viruses cause severe infections in humans with a case fatality rate that exceeds 50%. The factors that determine the high virulence of these viruses in humans are not fully understood. Here, we identified two amino acid changes in the viral polymerase PA protein that affect the activity of the viral polymerase complex and virulence in mice. Infection with viruses possessing these amino acid changes may pose an increased risk to humans.

scholarly journals PB2 Residue 271 Plays a Key Role in Enhanced Polymerase Activity of Influenza A Viruses in Mammalian Host Cells

2010 ◽  
Vol 84 (9) ◽  
pp. 4395-4406 ◽  
Author(s):  
Kendra A. Bussey ◽  
Tatiana L. Bousse ◽  
Emily A. Desmet ◽  
Baek Kim ◽  
Toru Takimoto
Keyword(s):  
Mammalian Cells ◽  
Influenza A ◽  
Virus Titer ◽  
Polymerase Activity ◽  
Influenza Viruses ◽  
Host Cells ◽  
Mammalian Host ◽  
Influenza A Viruses ◽  
H5n1 Influenza ◽  
Avian Viruses

ABSTRACT The direct infection of humans with highly pathogenic avian H5N1 influenza viruses has suggested viral mutation as one mechanism for the emergence of novel human influenza A viruses. Although the polymerase complex is known to be a key component in host adaptation, mutations that enhance the polymerase activity of avian viruses in mammalian hosts are not fully characterized. The genomic comparison of influenza A virus isolates has identified highly conserved residues in influenza proteins that are specific to either human or avian viruses, including 10 residues in PB2. We characterized the activity of avian polymerase complexes containing avian-to-human mutations at these conserved PB2 residues and found that, in addition to the E627K mutation, the PB2 mutation T271A enhances polymerase activity in human cells. We confirmed the effects of the T271A mutation using recombinant WSN viruses containing avian NP and polymerase genes with wild-type (WT) or mutant PB2. The 271A virus showed enhanced growth compared to that of the WT in mammalian cells in vitro. The 271A mutant did not increase viral pathogenicity significantly in mice compared to that of the 627K mutant, but it did enhance the lung virus titer. Also, cell infiltration was more evident in lungs of 271A-infected mice than in those of the WT. Interestingly, the avian-derived PB2 of the 2009 pandemic H1N1 influenza virus has 271A. The characterization of the polymerase activity of A/California/04/2009 (H1N1) and corresponding PB2 mutants indicates that the high polymerase activity of the pandemic strain in mammalian cells is, in part, dependent on 271A. Our results clearly indicate the contribution of PB2 amino acid 271 to enhanced polymerase activity and viral growth in mammalian hosts.

scholarly journals The polymerase complex genes contribute to the high virulence of the human H5N1 influenza virus isolate A/Vietnam/1203/04

2006 ◽  
Vol 203 (3) ◽  
pp. 689-697 ◽  
Author(s):  
Rachelle Salomon ◽  
John Franks ◽  
Elena A. Govorkova ◽  
Natalia A. Ilyushina ◽  
Hui-Ling Yen ◽  
...  
Keyword(s):  
Reverse Genetics ◽  
Mammalian Species ◽  
Polymerase Activity ◽  
Human Case ◽  
Influenza Viruses ◽  
Species Barrier ◽  
Ns Gene ◽  
H5n1 Influenza ◽  
High Virulence ◽  
Pandemic Threat

H5N1 influenza viruses transmitted from poultry to humans in Asia cause high mortality and pose a pandemic threat. Viral genes important for cell tropism and replication efficiency must be identified to elucidate and target virulence factors. We applied reverse genetics to generate H5N1 reassortants combining genes of lethal A/Vietnam/1203/04 (VN1203), a fatal human case isolate, and nonlethal A/chicken/Vietnam/C58/04 (CH58) and tested their pathogenicity in ferrets and mice. The viruses' hemagglutinins have six amino acids differences, identical cleavage sites, and avian-like α-(2,3)–linked receptor specificity. Surprisingly, exchanging hemagglutinin and neuraminidase genes did not alter pathogenicity, but substituting CH58 polymerase genes completely attenuated VN1203 virulence and reduced viral polymerase activity. CH58's NS gene partially attenuated VN1203 in ferrets but not in mice. Our findings suggest that for high virulence in mammalian species an avian H5N1 virus with a cleavable hemagglutinin requires adaptive changes in polymerase genes to overcome the species barrier. Thus, novel antivirals targeting polymerase proteins should be developed.

scholarly journals Glycine at Position 622 in PB1 Contributes to the Virulence of H5N1 Avian Influenza Virus in Mice

2015 ◽  
Vol 90 (4) ◽  
pp. 1872-1879 ◽  
Author(s):  
Xiaoxiao Feng ◽  
Zeng Wang ◽  
Jianzhong Shi ◽  
Guohua Deng ◽  
Huihui Kong ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Aspartic Acid ◽  
H5n1 Virus ◽  
Genetic Basis ◽  
Vaccine Development ◽  
Influenza Viruses ◽  
Avian Influenza Viruses ◽  
Live Attenuated Vaccine ◽  
H5n1 Influenza ◽  
H5n1 Avian Influenza

ABSTRACTWe isolated two H5N1 viruses, A/duck/Hunan/S4020/2008 (DK/08) and A/chicken/Guangxi/S2039/2009 (CK/09), from live-bird markets during routine surveillance and found that these two viruses are genetically similar but differ in their replication and virulence in mice. The CK/09 virus is lethal for mice with a 50% mouse lethal dose (MLD50) of 1.6 log1050% egg infectious doses (EID50), whereas the DK/08 virus is nonpathogenic for mice with an MLD50value of 6.2 log10EID50. We explored the genetic basis of the virulence difference of these two viruses by generating a series of reassortant viruses and mutants in the lethal virus CK/09 background and evaluating their virulence in mice. We found that the PB1 gene of the DK/08 virus dramatically attenuated the virulence of the CK/09 virus and that the amino acid at position 622 in PB1 made an important contribution. We further demonstrated that the mutation of glycine (G) to aspartic acid (D) at position 622 in PB1 partially impaired the binding of PB1 to viral RNA, thereby dramatically decreasing the polymerase activity and attenuating H5N1 virus virulence in mice. Our results identify a novel virulence-related marker of H5N1 influenza viruses and provide a new target for live attenuated vaccine development.IMPORTANCEH5N1 avian influenza viruses have caused the deaths of nearly 60% of the humans that they have infected since 1997 and clearly represent a threat to public health. A thorough understanding of the genetic basis of virulence determinants will provide important insights for antiviral drug and live attenuated vaccine development. Several virulence-related markers in the PB2, PA, M1, and NS1 proteins of H5N1 viruses have been identified. In this study, we isolated two H5N1 avian influenza viruses that are genetically similar but differ in their virulence in mice, and we identified a new virulence-related marker in the PB1 gene. We found that the mutation of glycine (G) to aspartic acid (D) at position 622 in PB1 partially impairs the binding of PB1 to viral RNA, thereby attenuating H5N1 virus virulence in mice. This newly identified virulence-related marker could be applied to the development of live attenuated vaccines against H5N1 influenza.

scholarly journals H5N1 influenza viruses: outbreaks and biological properties

Cell Research ◽  
2009 ◽  
Vol 20 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Gabriele Neumann ◽  
Hualan Chen ◽  
George F Gao ◽  
Yuelong Shu ◽  
Yoshihiro Kawaoka
Keyword(s):  
Biological Properties ◽  
Influenza Viruses ◽  
H5n1 Influenza

scholarly journals A PB1-K577E Mutation in H9N2 Influenza Virus Increases Polymerase Activity and Pathogenicity in Mice

Viruses ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 653 ◽  
Author(s):  
Haruhiko Kamiki ◽  
Hiromichi Matsugo ◽  
Tomoya Kobayashi ◽  
Hiroho Ishida ◽  
Akiko Takenaka-Uema ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Novel Mutation ◽  
Polymerase Activity ◽  
Influenza Viruses ◽  
H9n2 Virus ◽  
Wild Type Virus ◽  
H9n2 Influenza Virus ◽  
Pathogenicity Determinant ◽  
Lower Temperature ◽  
Human Infections

H9N2 avian influenza viruses are present in poultry worldwide. These viruses are considered to have pandemic potential, because recent isolates can recognize human-type receptor and several sporadic human infections have been reported. In this study, we aimed to identify mutations related to mammalian adaptation of H9N2 influenza virus. We found that mouse-adapted viruses had several mutations in hemagglutinin (HA), PB2, PA, and PB1. Among the detected mutations, PB1-K577E was a novel mutation that had not been previously reported to involve mammalian adaptation. A recombinant H9N2 virus bearing only the PB1-K577E mutation showed enhanced pathogenicity in mice, with increased virus titers in nasal turbinates compared to that in mice infected with the wild-type virus. In addition, the PB1-K577E mutation increased virus polymerase activity in human cell culture at a lower temperature. These data suggest that the PB1-K577E mutation is a novel pathogenicity determinant of H9N2 virus in mice and could be a signature for mammalian adaptation.

scholarly journals Broadly Inhibiting Antineuraminidase Monoclonal Antibodies Induced by Trivalent Influenza Vaccine and H7N9 Infection in Humans

2019 ◽  
Vol 94 (4) ◽  
Author(s):  
Pramila Rijal ◽  
Bei Bei Wang ◽  
Tiong Kit Tan ◽  
Lisa Schimanski ◽  
Philipp Janesch ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Influenza Vaccine ◽  
Time Window ◽  
Wide Spectrum ◽  
Influenza Viruses ◽  
Human Mabs ◽  
Human Antibodies ◽  
Trivalent Influenza Vaccine ◽  
H5n1 Influenza ◽  
H7n9 Infection

ABSTRACT The majority of antibodies induced by influenza neuraminidase (NA), like those against hemagglutinin (HA), are relatively specific to viruses isolated within a limited time window, as seen in serological studies and the analysis of many murine monoclonal antibodies (MAbs). We report three broadly reactive human MAbs targeting N1 NA. Two were isolated from a young adult vaccinated with trivalent influenza vaccine (TIV), which inhibited N1 NA from viruses isolated from humans over a period of a hundred years. The third antibody, isolated from a child with acute mild H7N9 infection, inhibited both group 1 N1 and group 2 N9 NAs. In addition, the antibodies cross-inhibited the N1 NAs of highly pathogenic avian H5N1 influenza viruses. These antibodies are protective in prophylaxis against seasonal H1N1 viruses in mice. This study demonstrates that human antibodies to N1 NA with exceptional cross-reactivity can be recalled by vaccination and highlights the importance of standardizing the NA antigen in seasonal vaccines to offer optimal protection. IMPORTANCE Antibodies to the influenza virus NA can provide protection against influenza disease. Analysis of human antibodies to NA lags behind that of antibodies to HA. We show that human monoclonal antibodies against NA induced by vaccination and infection can be very broadly reactive, with the ability to inhibit a wide spectrum of N1 NAs on viruses isolated between 1918 and 2018. This suggests that antibodies to NA may be a useful therapy and that the efficacy of influenza vaccines could be enhanced by ensuring the appropriate content of NA antigen.

scholarly journals Cross-Reactive, Cell-Mediated Immunity and Protection of Chickens from Lethal H5N1 Influenza Virus Infection in Hong Kong Poultry Markets

2001 ◽  
Vol 75 (6) ◽  
pp. 2516-2525 ◽  
Author(s):  
Sang Heui Seo ◽  
Robert G. Webster
Keyword(s):  
T Cells ◽  
Influenza Virus ◽  
Hong Kong ◽  
Virus Infection ◽  
Cellular Immunity ◽  
Influenza Virus Infection ◽  
Influenza Viruses ◽  
H5n1 Influenza Virus ◽  
H9n2 Influenza Virus ◽  
H5n1 Influenza

ABSTRACT In 1997, avian H5N1 influenza virus transmitted from chickens to humans resulted in 18 confirmed infections. Despite harboring lethal H5N1 influenza viruses, most chickens in the Hong Kong poultry markets showed no disease signs. At this time, H9N2 influenza viruses were cocirculating in the markets. We investigated the role of H9N2 influenza viruses in protecting chickens from lethal H5N1 influenza virus infections. Sera from chickens infected with an H9N2 influenza virus did not cross-react with an H5N1 influenza virus in neutralization or hemagglutination inhibition assays. Most chickens primed with an H9N2 influenza virus 3 to 70 days earlier survived the lethal challenge of an H5N1 influenza virus, but infected birds shed H5N1 influenza virus in their feces. Adoptive transfer of T lymphocytes or CD8+ T cells from inbred chickens (B2/B2) infected with an H9N2 influenza virus to naive inbred chickens (B2/B2) protected them from lethal H5N1 influenza virus. In vitro cytotoxicity assays showed that T lymphocytes or CD8+ T cells from chickens infected with an H9N2 influenza virus recognized target cells infected with either an H5N1 or H9N2 influenza virus in a dose-dependent manner. Our findings indicate that cross-reactive cellular immunity induced by H9N2 influenza viruses protected chickens from lethal infection with H5N1 influenza viruses in the Hong Kong markets in 1997 but permitted virus shedding in the feces. Our findings are the first to suggest that cross-reactive cellular immunity can change the outcome of avian influenza virus infection in birds in live markets and create a situation for the perpetuation of H5N1 influenza viruses.

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