Atypical characteristics of nucleoprotein of pandemic influenza virus H1N1 and their roles in reassortment restriction
- 182 Downloads
Sequence analysis of the nucleoprotein (NP) of swine-origin influenza virus H1N1 (S-OIV) reveals a number of atypical characteristics including an early start codon and a highly conserved, non-aromatic residue at position 313. Using an in vitro viral polymerase reconstitution assay, we found that the polymerase complex containing the NP of S-OIV (NPS-OIV) yielded substantially lower activity than those assayed with NP derived from other influenza virus strains. Moreover, alteration of the early start codon or introduction of an aromatic residue at position 313 (V313Y) did not increase but instead exacerbated the poor polymerase activity. Interestingly, when NPS-OIV was allowed to compete with that of a mouse-adapted influenza virus (A/PR/8/34) to form progeny virions, only progeny bearing NPS-OIV were produced, despite the low polymerase activity associated with NPS-OIV. Our results indicated that NPS-OIV requires both the early start codon and the V313 residue for its optimal function. These characteristics are required for a strong compatibility between the S-OIV polymerase subunits and its indigenous NP over that of other strains, which might explain why productive reassortment between S-OIV and seasonal influenza viruses has yet to occur in nature.
We are grateful to Drs. R.G. Webster and E. Hoffmann (St. Jude Children’s Research Hospital) for providing the plasmids for reverse genetics of the PR8 strain; and to Drs. Pathom Sawanpanyalert, Sathit Pichyangkul and Arunee Thititanyanont for providing viral samples. This work was supported in part by the National Science Development Agency (NSTDA) (CPMO-P-00-20386 grant).
- 3.Siston AM, Rasmussen SA, Honein MA, Fry AM, Seib K, Callaghan WM, Louie J, Doyle TJ, Crockett M, Lynfield R, Moore Z, Wiedeman C, Anand M, Tabony L, Nielsen CF, Waller K, Page S, Thompson JM, Avery C, Springs CB, Jones T, Williams JL, Newsome K, Finelli L, Jamieson DJ (2010) Pandemic 2009 influenza A(H1N1) virus illness among pregnant women in the United States. JAMA 303:1517–1525PubMedCrossRefGoogle Scholar
- 4.Herfst S, Chutinimitkul S, Ye J, de Wit E, Munster VJ, Schrauwen EJ, Bestebroer TM, Jonges M, Meijer A, Koopmans M, Rimmelzwaan GF, Osterhaus AD, Perez DR, Fouchier RA (2010) Introduction of virulence markers in PB2 of pandemic swine-origin influenza virus does not result in enhanced virulence or transmission. J Virol 84:3752–3758PubMedCrossRefGoogle Scholar
- 5.Jagger BW, Memoli MJ, Sheng ZM, Qi L, Hrabal RJ, Allen GL, Dugan VG, Wang R, Digard P, Kash JC, Taubenberger JK (2010) The PB2-E627K mutation attenuates viruses containing the 2009 H1N1 influenza pandemic polymerase. mBio 1:e00067-10Google Scholar
- 8.Yamada S, Hatta M, Staker BL, Watanabe S, Imai M, Shinya K, Sakai-Tagawa Y, Ito M, Ozawa M, Watanabe T, Sakabe S, Li C, Kim JH, Myler PJ, Phan I, Raymond A, Smith E, Stacy R, Nidom CA, Lank SM, Wiseman RW, Bimber BN, O’Connor DH, Neumann G, Stewart LJ, Kawaoka Y (2010) Biological and structural characterization of a host-adapting amino acid in influenza virus. PLoS Pathog 6:e1001034Google Scholar
- 11.Pan C, Cheung B, Tan S, Li C, Li L, Liu S, Jiang S Genomic signature and mutation trend analysis of pandemic (H1N1) 2009 influenza A virus. PLoS One 5:e9549Google Scholar