[Epidemic variants of norovirus genotype GII.4 in Nizhny Novgorod in 2006 - 2012].

Aim: Genotyping of noroviruses that had circulated in the territory of Nizhny Novgorod during 6 epidemic seasons (2006 - 2012), detection of dominating genovariants and analysis of their change.
Materials and Methods: Feces samples from children hospitalized in an intestinal infection department of one of the infectious disease hospitals of Nizhny Novgorod served as material for the study. Noroviruses were detected by reverse transcription polymerase chain reaction. Genotypes and gene variants were determined by analysis of nucleotide sequences of viral genome regions coding capsid protein and RNA-dependent RNA-polymerase.
Results: During examination of 6589 children with an acute intestinal infection between July 2006 and June 2012 noroviruses were detected in 17.55% of cases. Nucleotide sequences of capsid and/or polymerase gene regions were determined for 114 norovirus isolates. Genotyping has shown that noroviruses of 8 various genotypes had circulated in the territory of Nizhny Novgorod--GII.1, GII.2, GII.3, GII.4, GII.6, GII.7, GII. 12, GII.13 with the domination of GII.4 noroviruses for the whole observation period. A dynamic of change of epidemic variants of genotype GII.4 noroviruses that had been accompanied by an increase of frequency of detection of norovirus in children hospitalized with acute intestinal infection similar to global was established. A short-term circulation of GII.4 2006b-NN 2008 norovirus subvariant in spring of 2008 and spread of genotype GII.12 norovirus during 2009, 2010 epidemic season were also shown.
Conclusion: The data obtained give evidence to the necessity of norovirus circulation monitoring with the aim of early detection of novel virus variants that may determine an increase of norovirus infection morbidity.