Polymorphisms in OAS1 (2 ,5 -oligoadenylate synthetase 1; an interferon-induced antiviral protein) have also been associated with SARS susceptibility and progression [38, 40] and West Nile infection [41] . Consistent with the idea of increased H5N1 susceptibility and pathogenesis associated with poor IFN responses, the OAS1 SNP rs1077467 is correlated with reduced OAS-1 protein activity and associated with increased susceptibility to West Nile infection and in vitro viral replication [41] .