Aim: Establish genetic characteristics, carry out phylogenetic analysis and determination of molecular markers of resistance to etiotropic preparations against influenza A/H3N2 and B viruses that had circulated in Russia in 2013 - 2015.
Materials and methods: 80 biological samples containing influenza A/H3N2 virus RNA and 31 samples containing influenza B virus RNA were studied. Sequencing of PCR fragments was carried out inABI-3 100 PRIZMTM GeneticAnalyzer (AppliedBiosystems, USA) and using MiSeq (Illumina, USA). Data treatment and analysis was carried out using CLC v.3.6.5., DNASTAR and BioNumerics v.6.5. programs.
Results: In 2013 -2014 A/Texas/50/2012-like-clade 3C.3 influenza A/H3N2 viruses dominated, 10% belonged to subclade 3C.2a and 10% - to 3C.3b. Most of the viruses (8 1%) of 2014 - 2015 were of 3C.2a clade, the portion of viruses belonging to 3C.3b and 3C.3a was 9 and 10%. Yamagata-like viruses predominated among the studied influenza B viruses, only 1 virus of 2014 - 2015 belonged to Victoria lineage, 1 reassortant of Yamagata and Victoria lineages was detected. Rimantadine- resistance mutationS3 lN(M2 protein) was detected in all the influenza A/H3N2 viruses. Mutations determining resistance to oseltamivir (NA gene) were not detected in influenza A/H3N2 and B viruses.
Conclusion: Increase of influenza morbidity in 2014 - 2015 was determined by the emergence of influenza A/H3N2 and B viruses, antigenically distinct from those that had circulated previously and those included into the vaccine, thus resulting in the WHO decision to change A/ H3N2 and B components of the 2015 - 2016 vaccine: Simultaneous circulation of 2 lineages of influenza B virus and emergence of their reassortants gives evidence on the necessity of use of quadrivalent vaccines, containing both lineages.