[Molecular characterization of pandemic influenza viruses A/H1N1(sw2009) isolated in Russia in 2009-2010].

Aim: Assessment of genetic diversity of influenza virus A/H1N1 (sw2009) variants circulated in Russia, study of virus' pathogenicity in humans and potential resistance to antiviral drugs.

Materials And Methods: Sequencing of PCR-fragments of genome of influenza viruses isolated from clinical and autopsy samples of 436 patients. Four full genome sequences of influenza viruses A/H1N1 (sw2009) were obtained. Phylogenetic analysis was performed.

Results: High degree of homology (98.9-100%) was found among influenza A/H1N1(sw2009) viruses in HA and NA genes as well as in their aminoacid sequences (1.3 and 1.4% respectively). Differences in other proteins did not exceed 1.1%. Diversity was found in position 222 of receptor-binding locus of HA and single amino acid polymorphism--in several internal proteins. Known mutations determining resistance to Tamiflu and Arbidol were not detected. All viruses were resistant to remantadine. Molecular markers of high pathogenicity were not found.

Conclusion: High homology of influenza viruses determines low level of antigenic differences although in populations of viruses there are variants with different levels of adaptation to human organism and different affinity to receptors of upper and lower respiratory tract that can determine their different transmissibility.