Effects of different gene segments of influenza virus on the growth of recombinants

Abstract:

Abstract:［Objective］We explored which internal genes of influenza virus that affect the titer of recombinant viruses and contribute to the high yield of Influenza A seed virus in ovo.［Methods］ Six internal genes or mutant or polymerase complex of A/Puerto Rico/8/1934 (H1N1) (PR8) virus genes were replaced individually by corresponding gene of A/chicken/ZJ/China/2013 (H5N1) virus，and the hemagglutination titers of recombinant viruses were compared by HA assay.［Results］PB2 gene had the greatest influence，its replace failed to generate recombinant virus． When PB1，PA，or M gene was replaced，the titers of recombinant viruses dropped by 3.7，3.4，3.0 (log2)，respectively．NS gene had little influence upon HA titer． When polymerase complex genes were replaced，virus titer dropped slightly to 7.6 log2，and it did not confer the same growth characteristics (8.4 log2) found when a complete polymerase complex was of PR8 origin．When amino acids of position 627 of PR8 PB2 gene were mutated to glutamic acid，virus titer rose from 8.4 log2 to 8.7 log2.［Conclusion］ The optimal gene combinations may facilitate replication through viral RNA and protein interaction with cellular components as well as interaction of viral RNA and protein or protein-protein interactions within the virus．These multi-factorial contributions resulted in selection of a high replication competent reassortant in embryonated chicken eggs in comparison to the respective low yield wild type viruses，and laid the foundation for high yield of influenza vaccine production.