Study of the biological properties of attenuated variants of the virulent A/WSN/33 strain of influenza virus, obtained by the site-specific mutagenesis of PB2-gene

Aim. Study of biological properties of attenuated variants of the virulent A/WSN/33 strain of influenza virus, obtained by the site-specific mutagenesis of PB2-gene. Materials and methods. Site-specific mutants of A/WSN/33 of influenza virus, having in PB2-gene ts-mutations from genome of cold-adapted (CA) master-strains: A/Ann Arbor/6/60 (H2N2); A/Leningrad/134/17/57 (H2N2); A/Krasnodar/101/35/59 (H2N2) were obtained with help of reverse genetics methods. The ts-phenotype, att-phenotype, immunogenicity and protective efficacy in homologous and heterologous control infections were studied in the obtained site-specific mutants. Results. It was shown that the inclusion in the PB2-gene of the virulent A/WSN/33 strain as single mutations and a combination of mutations from the genomes of CA donor-strains leads to a change in the ts-phenotype and att-phenotype of the mutants obtained. These mutants had high protective efficacy in homologous and heterologous control infection. Conclusion. The results obtained allow us to consider the site-specific mutants of influenza virus as possible candidates for live influenza vaccines.