Rotavirus infection in children of Nizhny Novgorod, Russia: the gradual change of the virus allele from P[8]-1 to P[8]-3 in the period 1984–2010

Detection and full-genotype determination of rare and reassortant rotavirus A strains in Nizhny Novgorod in the European part of Russia

Reassortant DS-1-like rotavirus A strains have been shown to circulate widely in many countries around the world. In Russia, the prevalence of such strains remains unclear due to the preferred use of the traditional binary classification system. In this work, we obtained partial sequence data from all 11 genome segments and determined the full-genotype constellations of rare and reassortant rotaviruses circulating in Nizhny Novgorod in 2016-2019. DS-1-like G3P[8] and G8P[8] strains were found, reflecting the global trend. Most likely, these strains were introduced into the territory of Russia from other countries but subsequently underwent further evolutionary changes locally. G3P[8], G9P[8], and G12P[8] Wa-like strains of subgenotypic lineages that are unusual for the territory of Russia were also identified. Reassortant G2P[8], G4P[4], and G9P[4] strains with one Wa-like gene (VP4 or VP7) on a DS-1-like backbone were found, and these apparently had a local origin. Feline-like G3P[9] and G6P[9] strains were found to be phylogenetically close to BA222 isolated from a cat in Italy but carried some traces of reassortment with human strains from Russia and other countries. Thus, full-genotype determination of rotavirus A strains in Nizhny Novgorod has clarified some questions related to their origin and evolution.

[Molecular monitoring of the rotavirus (Reoviridae: Sedoreovirinae: Rotavirus: Rotavirus A) strains circulating in Nizhny Novgorod (2012-2020): detection of the strains with the new genetic features]

INTRODUCTION

The pentavalent rotavirus vaccine has been registered in Russia, however, the vaccination coverage remains low, and an annual increase in the incidence of rotavirus infection is unavoidable. In this regard, molecular monitoring of rotaviruses in order to search for new variants possessing epidemic potential is an urgent task.

MATERIAL AND METHODS

PCR genotyping and VP4 and VP7 genes sequencing were used to characterize rotaviruses circulating in Nizhny Novgorod in 2012-2020. The phylogenetic analysis of the strains was carried out using the BEAST software package.

RESULTS

The spectrum included 17 genotypes with predominance of G9P[8] (37,4%). Detected in this study genotypes G1P[4], G1P[9], G2P[8], G4P[4], G4P[6], G8P[8], and G9P[4] were not previously identified in Nizhny Novgorod. The circulation of DS-1-like strains possessing genotypes G1P[8], G3P[8], G8P[8], or G9P[8] and a short RNA pattern had been shown. Rotaviruses of the common genotypes were genetically heterogeneous and belonged to different phylogenetic lineages and/or sublineages (P[4]-IV-a; P[4]-IV-b; P[8]-3.1; P[8]-3.3; P[8]-3.4 and P[8]-3.6; G1-I; G1-II; G2-IVa-1; G2-IVa-3; G3-1; G3-3; G4-I-c; G9-III; G9-VI).

DISCUSSION

These results extend the available data on the genotypic structure of rotavirus populations in Russia and show the genetic diversity of viral strains. G3P[8] DS-1-like viruses were representatives of the G3-1 lineage, new for the territory of Russia, and had the largest number of amino acid substitutions in the VP7 antigenic epitopes.

CONCLUSION

The emergence and spread of strains with new genetic features may allow rotavirus to overcome the immunological pressure formed by natural and vaccine-induced immunity, and maintain or increase the incidence of rotavirus infection.

Changing pattern of prevalence and genetic diversity of rotavirus, norovirus, astrovirus, and bocavirus associated with childhood diarrhea in Asian Russia, 2009-2012

This hospital-based surveillance study was carried out in Novosibirsk, Asian Russia from September 2009 to December 2012. Stool samples from 5486 children with diarrhea and from 339 healthy controls were screened for rotavirus, norovirus, astrovirus, and bocavirus by RT-PCR. At least one enteric virus was found in 2075 (37.8%) cases with diarrhea and 8 (2.4%) controls. In the diarrhea cases, rotavirus was the most commonly detected virus (24.9%), followed by norovirus (13.4%), astrovirus (2.8%) and bocavirus (1.1%). Mixed viral infections were identified in 4.3% cases. The prevalence of enteric viruses varied every season. Rotavirus infection was distributed in a typical seasonal pattern with a significant annual increase from November to May, while infections caused by other viruses showed no apparent seasonality. The most common rotavirus was G4P[8] (56%), followed by G1P[8] (20.1%), G3P[8] (5.5%), G9P[8], G2P[4] (each 1.3%), six unusual (1.2%), and five mixed strains (0.5%). Norovirus GII.3 (66.5%) was predominant, followed by GII.4 (27.3%), GII.6 (3.7%), GII.1 (1.6%), and four rare genotypes (totally, 0.9%). Re-infection with noroviruses of different genotypes was observed in four children. The classic human astrovirus belonged to HAstV-1 (82%), HAstV-5 (8%), HAstV-4 (4.7%), HAstV-3 (4%) and HAstV-2 (1.3%). Consecutive episodes of HAstV-1 and HAstV-4 infections were detected in one child with an 8-month interval. Bocavirus strains were genotyped as HBoV2 (56.5%), HBoV1 (38.7%), HBoV4 (3.2%) and HBoV3 (1.6%). In the controls, norovirus strains belonged to GII.4 (n = 4), GII.1, GII.3, and GII.6, and HBoV2 strain were detected. Most of the detected virus isolates were characterized by a partial sequencing of the genomes. The genotype distribution of most common enteric viruses found in the Asian part of Russia did not differ considerably from their distribution in European Russia in 2009-2012.

Phylogenetic comparison of the VP7, VP4, VP6, and NSP4 genes of rotaviruses isolated from children in Nizhny Novgorod, Russia, 2015-2016, with cogent genes of the Rotarix and RotaTeq vaccine strains

Group A rotaviruses (RVA) are one of the leading causes of gastroenteritis in young children worldwide. The introduction of universal mass vaccination around the world has contributed to a reduction in hospitalizations and outpatient visits associated with rotavirus infection. Continued surveillance of RVA strains is needed to determine long-term effects of vaccine introduction. In the present work, we carried out the analysis of the genotypic diversity of RVA strains isolated in Nizhny Novgorod (Russia) during the 2015-2016 epidemic season. Also we conducted a comparative analysis of the amino acid sequences of T-cell epitopes of wild-type and vaccine (RotaTeq and Rotarix) strains. In total, 1461 samples were examined. RVAs were detected in 30.4% of cases. Rotaviruses with genotype G9P[8] (40.5%) dominated in the 2015-16 epidemic season. Additionally, RVAs with the following genotypes were detected: G4P[8] (25.4%), G1P[8] (13%), G2P[4] (3.2%). Rotaviruses with genotypes G3P[9], G6P[9], and G1P[9] totaled 3%. The number of partially typed and untyped RVA samples was 66 (14.9%). The findings of a RVA of G6P[9] genotype in Russia were an original observation. Our analysis of VP6 and NSP4 T-cell epitopes showed highly conserved amino acid sequences. The found differences seem not to be caused by the immune pressure but were rather related to the genotypic affiliations of the proteins. Vaccination against rotavirus infection is not included in the national vaccination schedule in Russia. Monitoring of the genotypic and antigenic diversity of contemporary RVA will allow providing a comparative analysis of wild-type strains in areas with and without vaccine campaign.

Detection and molecular characterization of reassortant DS-1-like G1P [8] strains of rotavirus A

Group A rotaviruses (RVA) are the main cause of viral gastroenteritis in children worldwide. In this study we provide the molecular characteristics of reassortant DS-1-like G1P[8] RVA strains detected in Russia for the first time. Previously, such reassortant strains were detected in Japan and Thailand. The G1P[8] RVAs with DS-1-like short electropherotype RNA-PAGE were isolated from children hospitalised with an acute gastroenteritis during the 2013-2014 period. The DS-1-like G1P[8] strains accounted for 2.6% of all RVA strains detected continuously throughout the season. A phylogenetic analysis was made on the basis of the established nucleotide sequences of genes VP7, VP8* (VP4), VP6 and NSP4. The Nizhny Novgorod strains belong to G1-I and G1-II alleles of VP7 gene and to P[8]-3 allele of VP4. According to their VP6 sequences, two Russian samples clustered with the reassortant strains isolated in Japan, Thailand and Australia and two other strains were phylogenetically close to the typical G2P[4] DS-1-like RVA. Nucleotide sequences of G1P[8] strains that belong to NSP4 gene form a separate cluster from G3P[8] DS-1-like rotaviruses detected in Thailand and Australia. The RVA alleles included in Rotarix and RotaTeq vaccine strains were clustered separately from the studied reassortant RVAs. On the grounds of phylogenetic analysis we assume a polyphyletic origin of reassortants between Wa- and DS-1-like strains. Mutation rates evaluated by Bayesian inference in clusters with reassortant RVA strains were 1.004Е-3 (VP7), 1.227E-3 (VP4), 3.909E-4 (VP6), and 4.014Е-4 (NSP4). Analysis of tMRCA showed relatively contemporary origin of alleles DS-1-like G1P[8] rotaviruses: VP7 - 1998 (G1-I) and 1981 (G1-II), VP4 - 1998, VP6 - 1994, NSP4 - 1979.