Abstract
The aim of the present study was identifying of molecular and genetic changes in hemaglutinin (HA), neuraminidase (NA) and non-structure protein (NS1) genes of pandemic influenza A(H1N1)pdm09 strains, that circulated in Ukraine during 2015-2016 epidemic season. Samples (nasopharyngeal swabs from patients) were analyzed using real-time polymerase chain reaction (RTPCR). Phylogenetic trees were constructed using MEGA 7 software. 3D structures were constructed in Chimera 1.11.2rc software. Viruses were collected in 2015-2016 season fell into genetic group 6B and in two emerging subgroups, 6B.1 and 6B.2 by gene of HA and NA. Subgroups 6B.1 and 6B.2 are defined by the following amino acid substitutions. In the NS1 protein were identified new amino acid substitutions D2E, N48S, and E125D in 2015-2016 epidemic season. Specific changes were observed in HA protein antigenic sites, but viruses saved similarity to vaccine strain. NS1 protein acquired substitution associated with increased virulence of the influenza virus.
Highlights
Influenza viruses are antigenicaly variable pathogens, capable of continuously evading immune response
Genetic analysis of influenza A(H1N1)pdm09 viruses circulating in Ukraine in the 2015/2016 epidemic season showed that all of them were similar to the vaccine strain recommended by WHO
Viruses had acquired amino acid substitutions in HA molecule antigenic sites, which can lead to antigenic changes at the epidemic seasons
Summary
Influenza viruses are antigenicaly variable pathogens, capable of continuously evading immune response. In circulating influenza viruses this antigenic drift is a major process, accumulating mutations at the antibody binding sites of receptor proteins, and enabling the virus to evade recognition by hosts' antibodies, which often translates into periodic epidemics of influenza. To tame the influenza spread a flexible vaccination WHO's program, based on periodic production of novel versions of vaccine, is adapted to the prevalent stain(s) For such programs the data on phylogenesis of circulating versions of pathogens, and genetic stability of their hemagglutinin (HA) sets data, could help to rationalize possible epidemiological measures [1]. This year's seasonal influenza risk assessment identifies type A viruses, in particular A(H1N1)pdm, as dominant far in EU/EEA countries. It causes yield losses ranging from 25 to 50 % depending on the pathogenicity of the virus strain [2]
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