Unusual BA222-like strains of <i>Rotavirus A</i> (Sedoreoviridae: <i>Rotavirus: Rotavirus A</i>): molecular and genetic analysis based on all genome segments

Abstract

Introduction. Rotavirus infection is the major cause of severe dehydrating diarrhea requiring hospitalization in young children worldwide. Due to their segmented genome, rotaviruses are capable of gene reassortment, which makes the emergence and spread of genetically novel strains possible. The purpose of this study was to search for unusual rotaviruses circulating in Nizhny Novgorod in 2021‒2023 and their molecular genetic characterization based on all genome segments. Materials and methods. Rotavirus-positive stool samples of children were examined by PCR genotyping and electrophoresis in PAAG. cDNA fragments of each of the 11 genes (VP1‒VP4, VP6, VP7, NSP1‒NSP5), 570 to 850 nucleotide pairs in length were sequenced for the selected strains. The phylogenetic analysis was performed in the MEGA X program. Results. In the study period 2021‒2023, 11 G[P] combinations with a predominance of G3P[8] (59.5%) were identified. Six atypical Rotavirus А (RVA) strains were identified: 2 strains of the G2P[4] genotype (G2-P[4]-I2-R2-C2-M2-A3-N2-T3-E2-H3, G2-P[4]-I2-R2-C2-M2-A3-N2-T3-E3-H2) and 4 G3P[9] strains (all strains had the genotype G3-P[9]-I2-R2-C2-M2-A3-N2-T3-E3-H3). Phylogenetic analysis based on all genes showed an evolutionary relationship between rotaviruses similar to rotaviruses of cats and dogs (BA222-like) and unusual strains of the G2P[4] genotype, for which a mixed combination of genotypes was identified and characterized for the first time. Discussion. The results obtained expand the understanding of the diversity of reassortant RVAs, as well as complement the data on the genotypic structure of the rotavirus population in Nizhny Novgorod. Conclusion. The wide genetic diversity of reassortant RVA can help rotaviruses overcome the immunological pressure provided by natural and vaccine-induced immunity. In this regard, to control the emergence of new variants and assess changes in the virulence of rotaviruses after reassortment processes, continuous molecular monitoring for circulating RVA is necessary.

Keywords

• rotavirus a
• genotyping
• full genotype
• phylogenetic analysis
• genetic variants
• genetic diversity
• reassortment