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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.

Since 2013, there has been an increase in reports of the spread of a double intergroup reassortant strain of rotavirus type A (RVA) with the genotype G3P[8] and other genes belonging to the second genogroup I2-R2-C2-M2-A2-N2-T2-E2-H2. In our study, we provide a molecular genetic characterization of rotaviruses with genotype G3P[8]-I2 isolated in Nizhny Novgorod. In our study, we used RT-PCR, Sanger sequencing, RNA-PAGE methods. Phylogenetic and phylodynamic analysis were performed using the Bayesian approach. According to our study, there was a significant increase in the proportion of G3P[8] from 15% during the period of 2020-2021 to 53% during the period of 2021-2022 in Nizhny Novgorod, Russia. Phylogenetic analysis based on the VP4 gene revealed that DS-1-like RVAs isolated in Nizhny Novgorod belong to different clusters of the P[8]-3.1 lineage, with a level of variation ranging from 1.1% to 1.3%. Based on the VP6 gene, the equine-like RVAs identified by us carry genetic variants belonging to three distinct clusters of the lineage I2-V, with a variation level ranging from 2.0% to 4.5%. These data indicate the genotypic diversity of circulating DS-1-like G3 RVAs. Phylogenetic analysis of the VP7 gene allowed us to assign the isolates identified in our study to the G3-1 lineage. We estimated that the circulation of the most recent common ancestor of the spreading strains dates back to 2002. Additionally, we determined the typical level of mutations in the VP7 gene, which amounted to 2.14*10-3 substitutions/per site/per year., (© 2023. The Author(s) under exclusive licence to Sociedade Brasileira de Microbiologia.)

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., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The picobirnaviruses (Picobirnaviridae, Picobirnavirus, PBVs) are currently thought to be animal viruses, as they are usually found in animal stool samples. However, no animal model or cell culture for their propagation has yet been found. In 2018, a hypothetical assumption about PBVs belonging to prokaryotic viruses was put forward and experimentally substantiated. This hypothesis is based on the presence of Shine-Dalgarno sequences in the genome of all PBVs before three reading frames (ORF) at the ribosomal binding site, with which the prokaryotic genome is saturated, while in the eukaryotic genome such regions occur with low frequency. The genome saturation with the Shine-Dalgarno sequences, as well as the preservation of this saturation in the progeny, according to scientists, allows us to attribute PBVs to prokaryotic viruses. On the other hand, there is a possibility that PBVs belong to viruses of eukaryotic hosts - fungi or invertebrates, since PBV-like sequences similar to the genome of fungal viruses from the families of mitoviruses and partitiviruses have been identified. In this regard, the idea arose that, in terms of reproduction mode, PBVs resemble fungal viruses. The divergence of views on the true PBV host(s) has sparked discussions among scientists and required further research to elucidate their nature. The review highlights the results of the search for a PBV host. The reasons for the occurrence of atypical sequences among the PBV genome sequences that use an alternative mitochondrial code of lower eukaryotes (fungi and invertebrates) for the translation of viral RNA-dependent RNA polymerase (RdRp) instead of the standard genetic code are analyzed. The purpose of the review was to collect arguments in support of the hypothesis about the phage nature of PBVs and to find the most realistic explanation of the reasons for identifying non-standard genomic sequences for PBVs. Based on the hypothesis about the genealogical relationship of PBVs with RNA viruses from other families with similar segmented genomes, such as Reoviridae, Cystoviridae, Totiviridae and Partitiviridae, virologists support the assumption of a decisive role in the origin of atypical PBV-like reassortment strains between PBVs and viruses of the listed families. The collected arguments given in this review indicate a high probability of a phage nature of PBVs. The data presented in the review show that the belonging of PBV-like progeny to prokaryotic or eukaryotic viruses is determined not only by its genome saturation level with a prokaryotic motif, standard or mitochondrial genetic code. The primary structure of the gene encoding the viral capsid protein responsible for the presence or absence of specific proteolytic properties of the virus that determine its ability for independent horizontal transmission into new cells may also be a decisive factor., Competing Interests: The authors declare no conflict of interest., (Copyright © AUTHORS.)

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.

Noroviruses are important etiological agents causing acute intestinal infection in humans. In the last decades, the most common norovirus genotype was GII.4 despite a significant genetic diversity among strains, while the active circulation of noroviruses with other genotypes was observed periodically. This study shows an increase in the detection rate of recombinant GII.3[P12] norovirus in Nizhny Novgorod, Russia, from 6.8% in 2018-2019 to 34.9% in 2020-2021. We performed a phylogenetic analysis based on the nucleotide sequences of noroviruses possessing this genotype obtained in this work, as well as presented in the GenBank database. It has been shown that the circulation of GII.3[P12] noroviruses in the study area was the result of several independent introductions, either directly from the Western Pacific region, or through the Asian part of Russia. The polyphyletic origin, the geographical expansion, and the growth of the epidemic significance of the recombinant GII.3[P12] noroviruses were noted., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Introduction: The novel coronavirus infection COVID-19 is a major public health problem worldwide. Several publications show the presence of gastrointestinal (GI) symptoms (nausea, vomiting, and diarrhea) in addition to respiratory disorders.The aim of this study was the monitoring of RNA of COVID-19 pathogen, coronavirus SARS-CoV-2 (Coronaviridae: Coronavirinae: Betacoronavirus; Sarbecovirus) in children hospitalized with acute intestinal infection (AII), with following molecular-genetic characterization of detected strains., Material and Methods: Fecal samples of children with AII hospitalized in infectious hospital of Nizhny Novgorod (Russia) in the period from 01.07.2020 to 31.10.2021 were used as material for the study. Viral RNA detection was performed by real-time polymerase chain reaction (RT-PCR). The nucleotide sequence of S-protein gene fragment was determined by Sanger sequencing., Results and Discussion: SARS-CoV-2 genetic material was detected in 45 out of 2476 fecal samples. The maximum number of samples containing RNA of the virus occurred in November 2020 (detection rate of 12.2%). In 20.0% of cases, SARS-CoV-2 RNA was detected in combination with rota-, noro-, and adenoviruses. 28 nucleotide sequences of S-protein gene fragment complementary DNA (cDNA) were determined. Phylogenetic analysis showed that the studied SARS-CoV-2 strains belonged to two variants. Analysis of the S-protein amino acid sequence of the strains studied showed the absence of the N501Y mutation in the 2020 samples, which is a marker for variants with a high epidemic potential, called variants of concern (VOC) according to the World Health Organization (WHO) definition (lines Alpha B.1.1.7, Beta B.1.351, Gamma P.1). Delta line variant B.1.617.2 was identified in two samples isolated in September 2021., Conclusion: The detection of SARS-CoV-2 RNA in the fecal samples of children with AII, suggesting that the fecal-oral mechanism of pathogen transmission may exist, determines the necessity to optimize its monitoring and to develop an algorithm of actions with patients with signs of AII under the conditions of a novel coronavirus infection pandemic.

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.

Currently, the full-genome-based classification is widely used to investigate rotavirus A (RVA) strains found in different countries around the world. However, the information on the full genotypes of rotaviruses circulating in Russia is limited. Using partial sequencing, this study determined the full genotype constellations of 15 RVA strains in total commonly detected in Nizhny Novgorod (European part of Russia) in 2017-2018, three from each of the following genotypes G1P[8], G4P[8], and G9P[8] and six from G2P[4]. There were two intergenogroup mono-reassortants possessing an identical genotype constellation of G4-P[8]-I1-R1-C1-M1-A1-N1-T1-E2-H1 with the DS-1-like NSP4 gene of probably local origin. A variety of subgenotype lineages and their combinations of Wa-like rotaviruses and genetic heterogeneity among G9P[8] and G1P[8] strains were shown on the basis of phylogenetic analysis of each gene. Moreover, two distinct co-circulating variants that differed in all 11 genome segments were found among DS-1-like rotaviruses., (Copyright © 2020 Elsevier B.V. All rights reserved.)

This article presents a general overview of the prevalence, genetic diversity and detection methods of picobirnaviruses (PBVs), which are small, non-enveloped icosahedral viruses with a segmented double-stranded RNA genome consisting of two segments taxonomically related to the genus Picobirnavirus of the family Picobirnaviridae. This review of scientific papers published in 1988-2019 provides data on the PBV distribution in the nature and a broad host range. PBV infection is characterized as opportunistic, the lack of understanding of the etiological role of PBVs in diarrhea is emphasized, since these viruses are detected both in symptomatic and asymptomatic cases. The concept of PBV infection as a chronic disease caused by a long-lasting persistence of the virus in the host is considered. Such factors as stress syndrome, physiological conditions, immune status and host age at the time of primary PBV infection influence the virus detection rate in humans and animals. The possible zoonotic nature of human PBV infection is noted due to the capacity for interspecies PBV transmission acquired during evolution as a result of the reassortment of the genome segments of different viruses infecting the same host. Data providing evidence that PBVs belong to eukaryotes and a challenging hypothesis stating that PBVs are bacterial viruses are presented. The need to intensify work on PBV detection because of their wide distribution, despite the complexity due to the lack of the cultivation system, is emphasized. Two strategies of RT-PCR as main PBV detection methods are considered. The genomes of individual representatives of the genus isolated from different hosts are characterized. Emphasis is placed on the feasibility of developing primers with broader specificity for expanding the range of identifiable representatives of the genus PBV due to a huge variety of their genotypes. The importance of effective monitoring of PBV prevalence for studying the zoonotic and anthroponotic potential using metagenomic analysis is highlighted, and so is the possibility of using PBV as a marker for environmental monitoring., (Copyright © AUTHORS.)

The G1P[8] genotype is one of the most common among rotaviruses circulating in the last 40 years. Therefore, this genotype is a component of rotavirus vaccines licensed throughout the world. This paper presents the results of a 35-year (1984-2019) observation of the circulation of G1P[8] rotaviruses among children under 14 in one region (Nizhny Novgorod, Russia) without vaccine pressure. Several complementary approaches were used: RNA electropherotyping by polyacrylamide gel electrophoresis, PCR genotyping, and cDNA sequencing of rotavirus VP4 and VP7 genes. A total of 8375 rotavirus-positive samples were examined, and the proportion of genotype G1P[8] rotaviruses was 39.9% (4.3-98.9%). Two cycles of high circulation activity (1984-1993 and 1993-2007) and one cycle of low activity (2007-2019) were noted. Phylogenetic analysis revealed the presence of rotaviruses of two VP4 gene lineages (P[8]-1 and P[8]-3) and two VP7 gene lineages (sublineages IA, IB, ID, II-B, II-C, and II- E). The prolonged circulation of rotaviruses of only one sublineage (G1-II-E) and then a change of the prevailing sublineage within the G1-II lineage (from E to C) during the active circulation were shown. Since 2011, when the circulation intensity of G1P[8] rotaviruses was low, the appearance of strains of the G1-I lineage and their co-circulation with strains of the G1-II lineage were observed in the population.

Introduction: In recent years the presence of reassortant rotavirus strains is increasingly mentioned in the world due to the application of the full-genome based classification system. Information on the circulation of such strains in the territory of Russia is limited. The aim of this work was the development of the approach for determination of genotypes of segments encoding VP6 (I) and NSP4 (E) to reveal reassortant strains., Material and Methods: Rotavirus-positive samples were studied by means of nucleotide sequencing and multiplex PCR. Phylogenetic analysis was conducted using the Bayesian approach., Results: Three alleles of the VP6 gene (I1-1, I2-IV, I2-VII) and seven alleles of the NSP4 gene (E1-I, E1-III, E2-VI, E2-VII, E2-X, E2-XII, E3) were detected on the base of nucleotide sequences of Nizhny Novgorod rotaviruses. Taking into account these results, the oligonucleotide primers specific to genotypes I1, I2, I3 and E1, E2, E3 were designed. Optimal conditions for multiplex PCR were chosen. The method was tested using the strains collected in Nizhny Novgorod in 2018. The diversity of I and E genotypes was determined and various combinations with G and P genotypes were identified., Discussion: G9-P[8]-I1-E1 rotaviruses were predominant (32.7 %) and G2-P[4]-I2-E2 rotaviruses were in second place (29.1 %). Strains with genotypes G4-P[8]-I1-E2, G3-P[8]-I2-E2 and G2-P[4]-I2-E1 were detected sporadically. They had genes of two rotavirus genogroups, so can be considered to be reassortant., Conclusion: The proposed approach is a useful tool for the characterization of rotaviruses in the conditions of the beginning of vaccination against rotavirus infection in Russia., Competing Interests: The authors declare no conflict of interest.

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.

Background: Noroviruses--etiological agents of acute enteric infections, mainly related to the genotype GII.4. However, other genotypes of the noroviruses also play an important role in some epidemic seasons or in particular geographic regions. The norovirus genotype GII.6 has become the second most important etiologic agent of outbreaks of the norovirus infection after GII.4 in recent years., Objective: To characterize the norovirus genotype GII.6 genetic variants based on phylogenetic analysis of genome sequences submitted to the databases GenBank and NoroNet as well as identified in Nizhny Novgorod., Materials and Methods: Norovirus genotype GII.6 circulating with sporadic morbidity that had caused the outbreak of acute enteric infection in Nizhny Novgorod were identified by sequencing the region of the genome encoding the N/S-domain of capsid protein VP1. The comparative phylogenetic analysis of obtained sequences and sequences available in the international genetic databases was performed using the MEGA 5.2 software package., Results: The presence of three genetic variants of the noroviruses GII.6 genotype based on capsid protein gene, GII.6a (Seacroft_1990), GII.6b (Saitama_1997) and GII.6c (Shizuoka 2008), in combination with two genotypes of the polymerase gene, P6 and P7, was confirmed. It was shown that co-circulation of these variants from the 1970s reflected the differences in evolution between the minor genotypes of noroviruses and dominant genotype GII.4, whose new epidemic variants completely replaced the previous for several years. Noroviruses GII.6 circulating in Nizhny Novgorod and other cities of Russia belong to genovariants GII.6a and GII.6b., Conclusion: The recombinant noroviruses GII.P7_GII.6c became most widespread in Asia and Europe in recent years. Genetic variant GII.6c of the norovirus have not been identified in Russia, but we cannot exclude the possibility of their occurrence as a cause of the outbreaks of acute enteric infections in this country in the near future.

Aim: Genotyping of noroviruses that had circulated in the territory of Nizhny Novgorod during 6 epidemic seasons (2006 - 2012), detection of dominating genovariants and analysis of their change., Materials and Methods: Feces samples from children hospitalized in an intestinal infection department of one of the infectious disease hospitals of Nizhny Novgorod served as material for the study. Noroviruses were detected by reverse transcription polymerase chain reaction. Genotypes and gene variants were determined by analysis of nucleotide sequences of viral genome regions coding capsid protein and RNA-dependent RNA-polymerase., Results: During examination of 6589 children with an acute intestinal infection between July 2006 and June 2012 noroviruses were detected in 17.55% of cases. Nucleotide sequences of capsid and/or polymerase gene regions were determined for 114 norovirus isolates. Genotyping has shown that noroviruses of 8 various genotypes had circulated in the territory of Nizhny Novgorod--GII.1, GII.2, GII.3, GII.4, GII.6, GII.7, GII. 12, GII.13 with the domination of GII.4 noroviruses for the whole observation period. A dynamic of change of epidemic variants of genotype GII.4 noroviruses that had been accompanied by an increase of frequency of detection of norovirus in children hospitalized with acute intestinal infection similar to global was established. A short-term circulation of GII.4 2006b-NN 2008 norovirus subvariant in spring of 2008 and spread of genotype GII.12 norovirus during 2009, 2010 epidemic season were also shown., Conclusion: The data obtained give evidence to the necessity of norovirus circulation monitoring with the aim of early detection of novel virus variants that may determine an increase of norovirus infection morbidity.

A total of 5230 specimens from children with gastroenteritis collected in Nizhny Novgorod in 2006-2010 were screened for human parechoviruses (HPeV). HPeV were observed every year with mean frequency of 6.16%. The majority of HpeV (65.83%) was detected in children younger than 3 years. The typing of 71 detected HPeV with the use of partial sequencing of the VP3-VP1 region revealed the presence of HPeV1 (91.55%), HpeV6 (5.63%), HPeV3 (3.08%), HPeV4 (1.54%). HPeV1B was predominant among HPeV1, HPeV1A was identified rarely. Six stains of HPEV1 formed separate phylogenetic cluster, had sequence gomology with HPEV1A or HPeV1B not more than 88% and could be characterized as members of a separate genotype HPeV1.

A collection of rotavirus samples collected over a 26-year period was examined to study the dynamics of change in RV strains of genotype P[8] in a geographically defined population (Nizhny Novgorod, Russia; children under 6 years) with no vaccine pressure. Phylogenetic analysis of gene VP4 (subunit VP8*) showed the presence of two lines of genotype P[8]: P[8]-1 and P[8]-3. Since 1997, the dominant population of rotavirus has been occupied by strains carrying the allele P[8]-3, which is associated with G1, G3 and G4. The complete replacement of the allele P[8]-1 to P[8]-3 took 19 epidemic years.

Aim: Genotyping ofastroviruses isolated from children with acute enteric infection (AEI) on the territory of Nizhny Novgorod in 2006 - 2011., Materials and Methods: Samples of feces from children hospitalized in intestine infection department of a Nizhny Novgorod infectious diseases hospitals served as study material. Astroviruses were detected by reverse transcription polymerase chain reaction method. Astrovirus genotypes were determined based on phylogenetic analysis of nucleotide sequence of genome fragment coding capsid protein., Results: During examination of 5759 children with AEI from July 2006 to June 2011 astroviruses were detected in 2.6% of cases, and in 2010 - 2011 the frequency of astrovirus detection (5.19%) was significantly higher than in the previous epidemic seasons and the average based on the whole observation period. Genotyping of the detected astroviruses showed that genotype 1, 2, 3, 4, 5 astroviruses circulated on the territory of Nizhny Novgorod with predomination ofgenotype 1. Genotype 1 astroviruses are presented by genetic lineages 1a, 1b, 1d with predomination of lineage la. From the start of 2010 all the detected isolates from genetic lineage la belonged to a single new sublineage - 1a-2010. The second by quantity of detected isolates were genotype 5 astroviruses identified for the first time in Nizhny Novgorod in July 2010. Genotype 2, 3 and 4 astroviruses were detected in isolated cases., Conclusion: Activation of astrovirus circulation in the population of Nizhny Novgorod that was shown by a significant increase of frequency of their detection in children with AEI in 2010 - 2011 epidemic season with the highest probability was caused by appearance of genotype 5 astroviruses, that had not previously been detected in this territory and other territories of Russian Federation.

In 2009 echovirus 9 caused a higher seasonal incidence of enterovirus infection (EVI) and its several outbreaks in a number of regions of Russia. Analysis of the partial VP1 coding region differentiated 4 phylogenetic lineages of echoviruses 9 variants identified in patients with aseptic meningitis and EVI in 2007-2009. One variant of echovirus 9 was most commonly encountered in 2009. Echoviruses 9 identified in different areas, which had a high (98.2-100%) homology of nucleotide sequences of the partial VP1 coding region, varied in the amino acid sequences within the B-C loop.

A total of 2312 children admitted to the Nizhni Novgorod infectious disease hospitals for diagnosed acute gastroenteritis were examined using the RT-PCR. The detection rate of human caliciviruses was found to be 6.5% (range 1.2 to 11.2%). The population of calicivuruses presented with noroviruses genogroups I (16%) and II (81%), and sapoviruses (3%). Noroviruses genogroup II included genotypes GII.2 and GII.4 with a preponderance of the variant CII.4-2006b. The detected sapoviruses were clustered with sapoviruses GI.1, GI.2, and GII.1 by phylogenetic analysis.

Aim: Analysis of manifestation of epidemic process of aseptic meningitis and causes of its activation using molecular genetic methods., Materials and Methods: Samples of feces and CSF, nasopharyngeal swabs from 296 patients with aseptic meningitis (AM), as well as 240 samples of drinking water and 6 samples of lake water were studied. Epidemiologic analysis, isolation of enteroviruses in Hep-2 and RD cell cultures, RT-PCR, partial sequencing of 5'NTR and genome region coding VP1 were performed., Results: Marked rise of AM caused by enteroviruses in Nizhny Novgorod during 2001 - 2007 was demonstrated. From August to October 2007, enteroviruses were detected in 93.8% of patients with AM (22.5 per thousand). Seasonal rise of incidence was determined by 9 serotypes of enteroviruses: E30 - 26 cases (53.1%), E7 - 7 (14.3%), E18 - 5 (10.3%), E13 - 3 (6.1%), E9 - 2 (4.0%), CB5 - 3 (6.1%),CA1 - 1 (2.0%), CA9 - 1 (2.0%), CA13 - 1 (2.0%). Serotype E30, represented by two subtypes, dominated. Dominating subtype E30-N1 was closely related with E30 strains isolated in 1994 - 2001 in Europe. Subtype E30-N2 was genetically related with Asian strains isolated in 2000 - 2006. RNA of E7, E9, E13, E18, CB5 viruses and dominating subtype E30-N1 were detected in nasopharyngeal swabs from patients with AM, which can explain rapid and wide spread of these viruses in susceptible population by aspiration route of transmission., Conclusion: Increased incidence of AM in Nizhny Novgorod in 2007 was caused by variant of E30 virus, which was genetically related with strains isolated in European countries in 1997.

The complete nucleotide sequences of the NSP4 gene from Russian isolates of Group A rotaviruses with different G[P] types obtained in Nizhni Novgorod have been first ascertained. They belong to their affiliation to three NSP4 (A, B, and C) of the 5 known genotypes. Eleven strains had NSP4 genotype. Phylogenetic analysis based on the complete nucleotide sequences of the NSP4 gene revealed the sequence homology of G1P[8] viruses with the strains circulating in Scandinavia and that of the G3 type viruses with the strains from South-Eastern Asia. The rotavirus strains G1, G3, G4, and P[8] demonstrated the homology with porcine rotavirus strains, while the strains G3P[6], G3P[9], and G2P[4] did the homology with bovine rotavirus strains. There was an unusual strain of human rotaviruses G3P[9] genetically related to feline rotaviruses.

RT-PCR was used to determine G (VP7) and P (VP4) genotypes of group A rotavirus found in 2454 children with diarrhea in 1997-2005. Eight G[P] combinations, including G1-4 serotypes and P[4, 6, 8, 9] genotypes, were identified. The P[8] genotype was presented by the subtypes P[8]-1 and P[8]-2. In 1997-2005, the spectrum and distribution of G[P] types were as follows: G1P[8]-1 (10%), G1P[8]-2 (67%), G1P[6] (3%), G2P[4] (9%), G3P[8]-2 (5%), G3P[6] (1%), G3P[9] (1%), G4P[8]-2 (3%), G9 (0%), G?P[?] (1%). Five G[P] types of rotavirus were identified in the 2004-2005 season. The G2P[4] type was prevalent (37%), the GI P[8]-2 type was detected in 25% of cases; G3P[8]-2 in 22%; G4P[8]-2 in 12%; G3P in 2%), G[?]P[?] in 2%. The P[8]-1 subgemotype was not found. The spectrum of the G1P[8] types of rotavirus and their distribution should be taken into account while developing a vaccine prophylaxis program against rotavirus gastroenteritis in Russia.

A method is suggested for the detection of the human rotavirus VP4 gene by RT-PCR. The method is universal for all [P] types of group A rotavirus in clinical samples. As against RNA electrophoresis and ELISA, it provides for a more accurate detection of rotaviruses by 18.8 and 26.5%, respectively. It was established by RT-PCR in February, 2002, in Nizhny Novgorod, that rotaviruses were responsible for 67% of acute gastroenteritis in hospitalized children.

Double-segment profiles typical of picobirnavirus (PBV) were detected (during 1994-2001) in nucleic acids extracted from feces of children (3 cases) and calf (1 case) with diarrhea by using the method of electrophoresis. The human genomic PBV segments migrated in the polyacrylamide gel (PAAG) as dsRNA segments sized 1.7 and 2.4 kbp for small and large segments, respectively; the similar calf sizes were 1.5 and 2.6 kbp. PBVs were detected in various places of the Nizhny Novgorod Region and at different time periods. It was for the first time that the PBV circulation was proven to be present in Russia's territory. However, their association with diarrhea was not reliably established, and the pathogenic PBV potential needs further investigations.

1370 natural strains of human rotaviruses which circulated on the territory of Nizhny Novgorod during the period of 1984-1996 were differentiated with the use of electrophoretic typing of RNA. 58 electrophoretic types of RNA were detected; of these, 8 types dominated in the populations. The specific features of the circulation of strains with different electrophoretic types of RNA were characterized: co-circulation, time of domination, the change of the dominating genetic variant of the virus consecutively between seasons and during seasons. The change of domination during seasons, connected with the specific features of the circulation of rotaviruses having RNA of electrophoretic type 3, determined the winter-spring dynamics of the monthly detection rate of rotaviruses and was accompanied by an rise in the level of their detection. Such change was supposedly be caused by the biological properties of rotavirus with RNA of electrophoretic type 3, virulence constituting one of these properties. The study revealed that a change in the domination of the electrophoretic type of rotavirus, reflecting the change of the antigenic variant between seasons, occurred gradually during 5 seasons of the active circulation of strains.

Comparative studies of the yield of stable and unstable chromosome aberrations have been carried out in human lymphocytes gamma irradiated in vitro within the doze range 0.1--1.0 Gy. It was observed that the yield of unstable chromosome aberrations (dicentrics and centric rings) is satisfactorily described for discovered dose range with linear-quadratic approximation. For stable chromosome aberrations in G-banded chromosome the dose response dependence was less expressed. The studies revealed non-random involvement of different chromosomes in translocations, and the most frequently involved are 1 and 13 chromosomes.

The paper presents the data on cytogenetic studies of 663 children inhabited radionuclide contaminated territories of Bryansk Province. Statistically significant difference with control was observed only for the territory with the highest radioactive contamination level of 137Cs (1000 kBq/m2). For two other territories with lesser contamination (100 and 700 kBq/m2) the rate of chromosome aberrations is nearly the same and does not differ significantly from control one. No difference in the level of cytogenetic damage was discovered for children affected by radiation pre- or postnatally.

The electrophoretic typing of 1,370 rotavirus strains revealed the presence of group C rotaviruses in 1.3% of cases. In the Arkhangelsk region group C rotaviruses were detected in 34.4% of cases. The detected group C rotaviruses were shown to be no different in their morphology from typical ones; they were characterized by the variability of their genome and the absence of hybridization with RNA of group A rotaviruses. Group C rotaviruses were detected in children aged 3-6 years; in this age group they caused both sporadic morbidity and an outbreak of infection. The clinical manifestations of gastroenteritis caused by group C rotaviruses were no different from typical rotavirus gastroenteritis.

The electrophoretic study of the RNA of human rotavirus strains (1146 strains) circulating in 9 cities at the territory of the European part of the RSFSR was carried out. The electrophoretic (EP) types of rotavirus were established in each individual area. The study revealed that the most widespread rotaviruses responsible for the majority of gastroenteritis cases are those with the long EP type of RNA, characterized by the joint migration of segments 2, 3 and 7 (the 3rd EP type of RNA). Rotaviruses with the 3rd EP type of RNA much more often induce a severe course of rotavirus gastroenteritis in children aged 8 months to 3 years.

A procedure based on polymerase chain reaction was developed for the study of rotaviruses. A full-length cDNA copy of the gene coding for major neutralizing glycoprotein VP7 of a human rotavirus isolate 1407 with the "long" electrophoretype (classified as the first electrophoretype) was cloned and sequenced. The primary structure of glycoprotein VP7 of isolate 1407 in A and C antigenic regions was found to be similar to that of serotype 1 virus.

Rotavirus RNA was detected in nasopharyngeal washings, obtained from patients with rotavirus gastroenteritis (76.3% of cases) and gastroenteritis of unknown etiology (34.7% of cases), by the method of molecular hybridization with the use of RNA of monkey virus SA11, labeled with 32P in the process of T4-ligase reaction. In 100% of cases this detection correlated with the presence of lesions of the upper respiratory ways and was probably indicative of the rotavirus nature of the catarrhal syndrome in rotavirus gastroenteritis.

The schemes for profiles of migration of RNA segments from human rotaviruses isolated in Gorky city in 1981-1987 are presented. The groups of the "long", "short" and "wide" electrophoretypes were identified. The dominant rotaviral phoretypes are determined. The possibilities of electrophoretyping and prospects of the future research are discussed.

The findings of epidemiological study of rotavirus infections among children in Gorki over the period of 1981-1985 are analyzed. The age of the patients is specified, as are the disease seasonal patterns and the incidence rates of its manifest and asymptomatic forms, and of carriership cases among healthy children in different foci of this infection.

Rotaviruses were detected in 58 among 194 children with nonbacterial gastroenteritis whose feces were examined by direct electron microscopy and immune electron microscopy (IEM). Identification of Coxsackie B viruses isolated from patients with infectious-allergic myocarditis by IEM and the neutralization tests gave similar results (Coxsackie B6). Besides, IEM detected the accompanying virus types.