Isolation of low pathogenic H5N2 influenza viruses in Western Siberia in 2007 – 2008
Session III – Shestopalova, Elena
Isolation of low pathogenic H5N2 influenza viruses in Western Siberia in 2007 – 2008.
Author(s):
Shestopalova E., Sysloparov I., Shestopalov A., Drozdov I.
FSRI SRC VB “VECTOR”, 630559 Koltsovo, Novosibirsk Region, Russian Federation
In 2005 for the first time in Russian Federation the epizooty caused by H5N1 influenza virus among wild and domestic birds was registered. The epizooty started in the south of Siberia and than spread in the south-western direction over the regions in Russian Federation and border countries. All the isolated influenza viruses that caused epizooty were referred to the Qinghai-like HPAI H5N1 viruses and were carried from China by wild birds.
After that the circulation of HPAI H5N1 viruses continued in the territory of Russian Federation also in 2006 - 2008. A number of viruses were isolated and characterized.
In 2007-2008 in the South of Western Siberia we have isolated two H5N2 viruses in wild ducks that corresponded the same strain. The phylogenetic analysis indicated that most probably this strain is a result of reassortation of avian low pathogenic H5N1 and H3N2 influenza viruses, circulating in 2005-2007 in the territory of Western China, Hong Kong and Japan. Reassortation must have happened in China as the first reassortant of H5N2 subtype with close to the virus (A/duck/Jiang Xi/1286/2005H5N2) homology were isolated there. And the fact that such reassortant was found in Altai Region during bird migration corroborates existence of avian influenza introduction channel from Western China to Western Siberia through the territory of Mongolia.
We did not find any neuraminidase inhibitor resistance for the studied strain. Analysis of nucleotide sequence of gene encoding M2 protein in studied strains showed that there is no amino acid substitution typical of resistance acquisition to that type of preparations.
The studied strain does not have any characteristic of highly pathogenic strains, like hemagglutinin cleavage site and deletion of 20 aminoacids in NA protein amino acid sequence.
Thus, H5N2 influenza virus isolated in the territory of south Siberia is nonpathogenic for humans, but presents a scientific interest as reassortative virus introduced from the territory of China.
The isolation of low pathogenic H5N2 viruses genetically similar to Chinese viruses in 2007 and 2008 in the South of Western Siberia indicate that the epizooty in 2005 was caused not by the sporadic accidental virus carrying to this territory from China. The systematic virus transmission exists between these regions. This makes possible the emerging and expansion of new epizooties caused by influenza viruses that circulate now in China and countries of South-Eastern Asia.
