[Contribution of neuraminidase of influenza viruses to the sensitivity to the serum inhibitors and reassortment efficiency].

The live attenuated influenza vaccine (LAIV) consists of reassortant viruses with hemagglutinin (HA) and neuraminidase (NA) gene segments inherited from the circulating wild-type (WT) parental and the 6 internal protein-encoding gene segments from the cold-adapted attenuated master donor viruses (genome composition 6:2). In this study, we describe the obstacles to developing LAIV vaccine strains depending on the phenotypic peculiarities of the WT viruses used for reassortment. The genomic composition analysis of 849 reassortants revealed that over 80% of the reassortants based on the inhibitor-resistant WT viruses inherited WT NA as compared to 26% of reassortants based on the inhibitor-sensitive WT viruses.