[Variability of genes encoding nonstructural proteins of rotavirus А (Reoviridae: Rotavirus: Rotavirus A) genotype G9P[8] during the period of dominance in the territory of Nizhny Novgorod (central part of Russia) (2011-2020)]

INTRODUCTION

In Russia, rotavirus A is the main cause of severe viral gastroenteritis in young children. The molecular features that allow a rotavirus of a particular genotype to gain an evolutionary advantage remain unclear, therefore, the study of the genetic diversity of rotaviruses based on genes encoding nonstructural proteins (NSPs) responsible for the reproduction of the virus in the cell is an urgent task.

OBJECTIVE

To study the genetic diversity of rotaviruses of genotype G9P[8], which dominated Nizhny Novgorod in 20112020, based on genes encoding nonstructural proteins.

MATERIALS AND METHODS

Rotavirus-positive samples were subjected to PCR-genotyping and sequencing of NSP1 NSP5 genes. Phylogenetic analysis was carried out in the MEGA X program.

RESULTS

In the period 20112020, G9P[8] rotaviruses with four variants of the NSP2 gene were co-circulating in Nizhny Novgorod. New alleles were noted in 2012 (N1-a-III), 2016 (N1-a-IV) and in 2019 (N1-a-II). The appearance of new variants of other genes occurred in 2014 (E1-3, NSP4), 2018 (T1-a3-III, NSP3) and in 2019 (A1-b-II, NSP1). NSP2 gene had the most variable amino acid sequence (16 substitutions), 2 to 7 substitutions were observed in NSP1, NSP3 and NSP4, NSP5 was conservative.

DISCUSSION

The results obtained are consistent with the literature data and indicate the participation of NSP genes in maintaining the heterogeneity of the rotavirus population.

CONCLUSION

Until 2018, the genetic diversity of rotaviruses in Nizhny Novgorod was determined by the circulation of strains carrying several alleles of the NSP2 gene and conservative genes NSP1, NSP3NSP5. By the end of the study period, new variants of the genotype G9P[8] were formed in the population, carrying previously unknown combinations of alleles of nonstructural genes.

[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.

MANIFESTATIONS OF EPIDEMIC PROCESS OF ROTAVIRUS INFECTION IN NIZHNY NOVGOROD IN PRE-VACCINATION PERIOD

Aim. Study the manifestations of epidemic process of rotavirus infection in Nizhny Novgorod in pre-vaccination period to evaluate the possible effect on morbidity for the rotavirus vaccine application introduction. Materials and methods. Rotavirus morbidity data were analyzed for the 12-year period (2005 - 2016), as well as its age and season distribution. Rotavirus genotyping was carried out using multiplex PCR and partial sequencing of VP4 and VP7 genes. Results. RVI morbidity in Nizhny Novgorod was shown to be at a moderate level when specific prophylaxis was not applied, multi-year dynamics for morbidity reflects the all-Russian state. 2015 - 2016 were characterized by intensification of the epidemic process in age groups of organized children (3 - 6 and 7 - 14) and adults. Season increase included December-May. seasonal morbidity maximums in different age groups took place during different months. Genetic structure of Nizhny Novgorod population PV-A during this time was presented by 10 types with G9P[8] (44,4%) dominating. Conclusion. Growth of RVI morbidity in Nizhny Novgorod in 2015 - 2016 and changes in age and season manifestations of the infection took place under the condition of change of the dominating genotype PV-A (G4P[8] to G9P[8]).

Burden of Childhood Rotavirus Disease in the Outpatient Setting of the Russian Federation

BACKGROUND

This is a prospective, multicentered study conducted in 9 large urban areas in Russia, in order to determine the burden of rotavirus gastroenteritis in children <5 years of age and the genotypes circulating during 1 rotavirus season.

METHODS

From November 2012 to May 2013, surveillance was conducted in Moscow, Saint-Petersburg, Vologda, Krasnodar, Krasnoyarsk, Novosibirsk, Yaroslavl, Khanty-Mansiysk and Vladivostok. Children <5 years of age presenting at outpatient clinics with acute gastroenteritis (AGE) of less than 72 hours duration were enrolled in the study. Stool samples were tested for rotavirus and positive samples were P- and G-typed. Clinical symptoms were captured by physicians and parents on Day 1. Symptom severity was analyzed by Vesikari scoring system. The direct expenses of parents caused by AGE were obtained from questionnaires provided to parents by phone.

RESULTS

A total of 501 were children enrolled. Stool samples were analyzed for 487 (97%) children, and 151 (31%) of those were rotavirus positive. Rotavirus gastroenteritis was associated with more severe clinical course (Vesikari score 11.4 ± 2.2) versus non-rotavirus gastroenteritis (Vesikari score 9 ± 3). The identified serotypes were G4P[8] 38.9%, G1P[8] 34.2%, G3P[8] 6%, G9P[8] 6%, G2P[4] 2% and G4P[4] 0.7%. The mean overall expenses of parents caused by rotavirus and non-rotavirus gastroenteritis were 143.7 USD and 128.8 USD, respectively.

CONCLUSIONS

Rotavirus accounted for 31% of all AGE-related outpatient visits. The major rotavirus genotypes were G1P[8] and G4P[8]. Rotavirus gastroenteritis was associated with significantly more severe clinical symptoms than non-rotavirus gastroenteritis. The average costs of rotavirus cases for parents of children were elevated against the same indications for non-rotavirus. These findings underscore the need for a safe and effective rotavirus vaccine in Russia.

Predominance of new G9P[8] rotaviruses closely related to Turkish strains in Nizhny Novgorod (Russia)

Genotype G9P[8] rotaviruses are rare in the territory of Russia. They were found in Nizhny Novgorod only in 2011-2012 for the first time, when their proportion was 25.9%. During the next two seasons, G9P[8] strains were detected in only 1.8% of cases. Their proportion substantially increased again in 2014, and they became predominant in the city by 2016. Phylogenetic analysis on the basis of gene VP7 nucleotide sequences showed that this increase was accompanied by the emergence of new strains in the population. These isolates were related to Turkish strains, but not to Russian ones detected earlier.