34. Murakami Y, Nerome K, Yoshioka Y, Mizuno S, Oya A (1988) Difference in growth behavior of human, swine, equine, and avian influenza viruses at a high temperature. Arch Virol 100: 231–244. 35. Goodman MF, Keener S, Guidotti S, Branscomb EW (1983) On the enzymatic basis for mutagenesis by manganese. J Biol Chem 258: 3469–3475. 36. Zhang S, Weng L, Geng L, Wang J, Zhou J, et al. Biochemical and kinetic analysis of the influenza virus RNA polymerase purified from insect cells. Biochem Biophys Res Commun 391: 570–574. 37. El-Deiry WS, Downey KM, So AG (1984) Molecular mechanisms of manganese mutagenesis. Proc Natl Acad Sci U S A 81: 7378–7382. 38. Portela A, Digard P (2002) The influenza virus nucleoprotein: a multifunctional RNA-binding protein pivotal to virus replication. J Gen Virol 83: 723–734. 39. Honda A, Ueda K, Nagata K, Ishihama A (1988) RNA polymerase of influenza virus: role of NP in RNA chain elongation. J Biochem 104: 1021–1026. 40. Perrino FW, Preston BD, Sandell LL, Loeb LA (1989) Extension of mismatched 39 termini of DNA is a major determinant of the infidelity of human Influenza Polymerase Fidelity immunodeficiency virus type 1 reverse transcriptase. Proc Natl Acad Sci U S A 86: 8343–8347. 41. Freistadt MS, Vaccaro JA, Eberle KE (2007) Biochemical characterization of the fidelity of poliovirus RNA-dependent RNA polymerase. Virol J 4: 44. 42. Donald HB, Isaacs A (1954) Counts of influenza virus particles. J Gen Microbiol 10: 457–464. 43. Severson WE, Schmaljohn CS, Javadian A, Jonsson CB (2003) Ribavirin causes error catastrophe during Hantaan virus replication. J Virol 77: 481–488. 44. Pillai SK, Wong JK, Barbour JD (2008) Turning up the volume on mutational pressure: is more of a good thing always better? (A case study of HIV-1 Vif and APOBEC3). Retrovirology 5: 26. 45. Pauli EK, Schmolke M, Hofmann H, Ehrhardt C, Flory E, et al. (2009) High level expression of the anti-retroviral protein APOBEC3G is induced by influenza A virus but does not confer antiviral activity. Retrovirology 6: 38. PLoS ONE | www.plosone.org 12 April 2010 | Volume 5 | Issue 4 | e10372