Recombinant Norovirus Giip16 Polymerase Genotypes Were Predominant Etiologic Agents of Acute Gastroenteritis in Belarus in 2016 -2021

Abstract

Noroviruses are widespread causative agents of acute gastroenteritis (AGE). In recent years, recombinant genotypes of noroviruses, which include RNA-polymerase GII[16], have become globally widespread. The aim of the research was to analyze the genetic diversity of noroviruses circulating in 2016–2021 in the Republic of Belarus in order to establish the contribution of the identified genotypes to the formation of morbidity and to study the features of the circulation of their recombinant variants containing RNA polymerase GII [P16]. Sequencing and genetic analysis of a fragment of the ORF1 / ORF2 genome of 242 noroviruses from patients with AGE collected in 2016-2021 was carried out. It was found that 199 norovirus isolates (82.2% of all identified) were recombinant. During this period, genotypes containing GII.P16 polymerase and the VP1 gene of genotypes GII.2, GII.3, GII.4, GII.12, GII.13 prevailed (143 isolates, 71.9% of all recombinant genotypes). The proportion of individual recombinant genotypes was distributed as follows: GII.4 [P16] - 42.0%, GII.2 [P16] - 32.2%, GII.3 [P16] - 16.8%, GII.12 [P16] - 8.4%, GII.13 [P16] - 0.7%. The genotypes GII.4 [P16] and GII.2 [P16] circulated for the longest time - from 2016-2017 to 2021. Their circulation was accompanied by the emergence of outbreaks of AGE: genotype GII.2 [P16] caused outbreaks in 2016, 2018 and 2021, GII.4 [P16] - in 2017 and 2021. All investigated isolates of different recombinant genotypes contained the same variant of the GII.P16 RNA polymerase gene, which became globally distributed in the world in 2015-2017. Comparison of the nucleotide sequences of isolates within genotypes showed that, despite the long circulation period, there were no accumulation of mutations and no selection of genovariants within the genotype.