Full Factorial Analysis of Mammalian and Avian Influenza Polymerase Subunits Suggests a Role of an Efficient Polymerase for Virus Adaptation

• Published in: PloS one Vol. 4; no. 5; p. e5658
• Main Authors: Li, Olive T. W., Chan, Michael C. W., Leung, Cynthia S. W., Chan, Renee W. Y., Guan, Yi, Nicholls, John M., Poon, Leo L. M.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 21.05.2009; Public Library of Science (PLoS)
• Subjects: Adaptation, Biological; Addition polymerization; Amino acids; Animals; Avian flu; Avian influenza; Avian influenza viruses; Binding sites; Birds; Cell Line; Cells; Chemokines; Chickens; Cytokines; Cytokines - metabolism; Dogs; Factorial analysis; Genes; Genes, Viral; Humans; Incubation; Inducers; Infections; Infectious diseases; Inflammation; Inflammation Mediators - metabolism; Influenza; Influenza A virus - enzymology; Influenza A virus - genetics; Influenza in Birds - enzymology; Laboratories; Luciferases - metabolism; Macrophages; Mammals; Mammals - virology; Mutation; Mutation - genetics; Pandemics; Penicillin; Pneumocytes; Polymerase; Protein Subunits - metabolism; Proteins; Ribonucleoproteins; RNA Replicase - metabolism; Selection, Genetic; Serial Passage; Studies; Viral infections; Viral Proteins - metabolism; Virology; Virology/Effects of Virus Infection on Host Gene Expression; Virology/Viral and Gene Regulation; Virology/Virulence Factors and Mechanisms; Viruses
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0005658

Amongst all the internal gene segments (PB2. PB1, PA, NP, M and NS), the avian PB1 segment is the only one which was reassorted into the human H2N2 and H3N2 pandemic strains. This suggests that the reassortment of polymerase subunit genes between mammalian and avian influenza viruses might play roles for interspecies transmission. To test this hypothesis, we tested the compatibility between PB2, PB1, PA and NP derived from a H5N1 virus and a mammalian H1N1 virus. All 16 possible combinations of avian-mammalian chimeric viral ribonucleoproteins (vRNPs) were characterized. We showed that recombinant vRNPs with a mammalian PB2 and an avian PB1 had the strongest polymerase activities in human cells at all studied temperature. In addition, viruses with this specific PB2-PB1 combination could grow efficiently in cell cultures, especially at a high incubation temperature. These viruses were potent inducers of proinflammatory cytokines and chemokines in primary human macrophages and pneumocytes. Viruses with this specific PB2-PB1 combination were also found to be more capable to generate adaptive mutations under a new selection pressure. These results suggested that the viral polymerase activity might be relevant for the genesis of influenza viruses of human health concern.