Genetic characterization and phylogenetic analysis of human norovirus infection in individual municipalities of the Sverdlovsk region in 2022

Abstract

Introduction. Human Noroviruses (HuNoV) are highly contagious pathogens responsible of acute human norovirus infection (HuNoVI). GII.4 is the prevailing norovirus genotype in the incidence of gastroenteritis worldwide. Currently there are no studies on the molecular monitoring and phylogenetic analysis of HuNoV in the territory of the Sverdlovsk region, therefore it is not possible to objectively assess their genetic diversity. The aim of the study is to carry out genotyping and phylogenetic analysis of HNoVI in municipalities of the Sverdlovsk region: Ekaterinburg, Nizhny Tagil, Kamensk-Uralsky in 2022. Materials and methods. Fecal samples were collected from children suffering from HuNoVI in the municipalities of the Sverdlovsk region. Viral RNA was extracted from stool samples followed by reverse transcription polymerase chain reaction with degenerate primers flanking the ORF1/ORF2 junction. The amplified samples were genotyped by Sanger sequencing. Multiple sequence alignments were carried out and phylogenetic trees were constructed. Results. The total number of studied samples was 220. According to sequencing results, 73 positive sequences of HuNoV were typed, which represents 33% of the total volume of the studied samples. The largest share of genotypes is occupied by noroviruses GII (58%), noroviruses GI (42%). Noroviruses GII.17, GI.3 were the dominant genotypes. Phylogenetic analysis demonstrates that the identified sequences on the territory of the Sverdlovsk region have the smallest genetic distance, which gives grounds for their unification into a common cluster. Conclusion. For the first time, a genetic analysis of HuNoV was carried out in the territory of the Sverdlovsk region. The norovirus genotyping system based on the amplification of the ORF1/ORF2 region makes it possible to successfully identify various genotypes of noroviruses from the Sverdlovsk region. It has been confirmed that GII noroviruses remain the dominant genetic group. The results of phylogenetic analysis demonstrate the greatest homology in the formed clusters between isolates from Ekaterinburg, Nizhny Tagil, Kamensk-Uralsky.