Polymerase activity of hybrid ribonucleoprotein complexes generated from reassortment between 2009 pandemic H1N1 and seasonal H3N2 influenza A viruses

Abstract

BackgroundA novel influenza virus (2009 pdmH1N1) was identified in early 2009 and progressed to a pandemic in mid-2009. This study compared the polymerase activity of recombinant viral ribonucleoprotein (vRNP) complexes derived from 2009 pdmH1N1 and the co-circulating seasonal H3N2, and their possible reassortants.ResultsThe 2009 pdmH1N1 vRNP showed a lower level of polymerase activity at 33°C compared to 37°C, a property remenisence of avian viruses. The 2009 pdmH1N1 vRNP was found to be more cold-sensitive than the WSN or H3N2 vRNP. Substituion of 2009 pdmH1N1 vRNP with H3N2-derived-subunits, and vice versa, still retained a substantial level of polymerase activity, which is probably compartable with survival. When the 2009 pdmH1N1 vRNP was substituted with H3N2 PA, a significant increase in activity was observed; whereas when H3N2 vRNP was substituted with 2009 pdmH1N1 PA, a significant decrease in activity occurred. Although, the polymerase basic protein 2 (PB2) of 2009 pdmH1N1 was originated from an avian virus, substitution of this subunit with H3N2 PB2 did not change its polymerase activity in human cells.ConclusionsIn conclusion, our data suggest that hybrid vRNPs resulted from reassortment between 2009 pdmH1N1 and H3N2 viruses could still retain a substantial level of polymerase activity. Substituion of the subunit PA confers the most prominent effect on polymerase activity. Further studies to explore the determinants for polymerase activity of influenza viruses in associate with other factors that limit host specificity are warrant.

Genomic Signatures for Avian H7N9 Viruses Adapting to Humans

“…Meanwhile, a reporter gene, such as luciferase, CAT, or GFP flanked by viral promoters was also transfected into cells to be driven by RNP complex [ 48 ]. RNP activity assay has not only been applied in H7N9 [ 26 , 27 , 49 ] but also in H5N1 avian influenza viruses [ 6 , 50 , 51 ], 2009 pandemic H1N1 influenza virus [ 52 – 55 ], and seasonal H3N2 influenza virus [ 51 , 54 ]. The RNP activity does not entirely correlate to the replication rate [ 56 ].…”

Replication and Transcription Activities of Ribonucleoprotein Complexes Reconstituted from Avian H5N1, H1N1pdm09 and H3N2 Influenza A Viruses

“…The protein expression plasmids for three polymerase subunits (PA, PB1 and PB2) and nucleoprotein (NP) of H1N1pdm09 and H3N2 had been described previously [20]. The expression plasmids of WSN H1N1, pPolI-vNP-Luc and pPolI-NA were kindly provided by Prof. George Brownlee [1], [21].…”

Biological characterization of RNA polymerase proteins from human 2009 pandemic H1N1 and low pathogenic avian H5N2 and H9N2 influenza viruses

“…Collectively, our findings were in line with previous reassortment studies on H1N1, 2009 pH1N1, H5N1 and H9N2 subtype viruses (Li et al, 2010;Hsieh et al, 2011;Lam et al, 2011;Octaviani et al, 2011;Liu et al, 2014), where PA and PB2 were found to be important host range determinants responsible for the increased polymerase activities. Not only PA and PB2 proteins, but also PB1 and NP proteins appeared to be involved in host range restriction and required for gene reassortment in influenza viruses.…”