Enhanced expression of secretable influenza virus neuraminidase in suspension mammalian cells by influenza virus nonstructural protein 1

► Secretable NA (sNA) head domain of influenza A/Vietnam/DT-036/05 (H5N1) virus was expressed in mammalian cells. ► Cotransfection of a plasmid encoding nonstructural protein 1 (NS1) of influenza A/Puerto Rico/8/34 virus with the sNA plasmid increased sNA expression by 7.4 fold. ► The sNA/NS1 cotransfection protocol was optimized for rapid transient gene expression system in serum-free mammalian cell culture. ► The resulting sNA displayed comparable MW, glycosylation, Km for MUNANA, and Ki for oseltamivir carboxylate to those of H5N1 NA on the virus surface. ► This strategy may be applied for rapid expression of sNA of other strains of influenza virus as well as other recombinant proteins.