Detection and genetic characterization of group A rotavirus strains circulating among children with acute gastroenteritis in Japan

Circulating rotavirus strains in children with acute gastroenteritis in Iran, 1986 to 2023 and their genetic/antigenic divergence compared to approved vaccines strains (Rotarix, RotaTeq, ROTAVAC, ROTASIIL) before mass vaccination: Clues for vaccination policy makers

In the present study, first, rotaviruses that caused acute gastroenteritis in children under five years of age during the time before the vaccine was introduced in Iran (1986 to 2023) are reviewed. Subsequently, the antigenic epitopes of the VP7 and VP4/VP8 proteins in circulating rotavirus strains in Iran and that of the vaccine strains were compared and their genetic differences in histo-blood group antigens (HBGAs) and the potential impact on rotavirus infection susceptibility and vaccine efficacy were discussed. Overall data indicate that rotavirus was estimated in about 38.1 % of samples tested. The most common genotypes or combinations were G1 and P[8], or G1P[8]. From 2015 to 2023, there was a decline in the prevalence of G1P[8], with intermittent peaks of genotypes G3P[8] and G9P[8]. The analyses suggested that the monovalent Rotarix vaccine or monovalent vaccines containing the G1P[8] component might be proper in areas with a similar rotavirus genotype pattern and genetic background as the Iranian population where the G1P[8] strain is the most predominant and has the ability to bind to HBGA secretors. While the same concept can be applied to RotaTeq and RotasIIL vaccines, their complex vaccine technology, which involves reassortment, makes them less of a priority. The ROTASIIL vaccine, despite not having the VP4 arm (P[5]) as a suitable protection option, has previously shown the ability to neutralize not only G9-lineage I strains but also other G9-lineages at high titers. Thus, vaccination with the ROTASIIL vaccine may be more effective in Iran compared to RotaTeq. However, considering the rotavirus genotypic pattern, ROTAVAC might not be a good choice for Iran. Overall, the findings of this study provide valuable insights into the prevalence of rotavirus strains and the potential effectiveness of different vaccines in the Iranian and similar populations.

Emergence of a novel pathogenic porcine G1P[7] rotavirus in China

Among group A rotaviruses (RVAs), the G1 genotype is the main genotype causing diarrhea in children, but it has rarely been reported in pigs. During our epidemiological investigation, we detected G1P[7] rotavirus infection in piglets across several provinces in China and then isolated a porcine G1P[7] rotavirus strain (CN1P7). Sequencing revealed that the virus constellation was G1-P[7]-I5-R1-C1-M1-A8-N1-T1-E1-H1. Phylogenetic analyses revealed that CN1P7 most likely emerged due to genetic reassortment among porcine, human, giant panda and dog rotavirus strains. In vivo experiments were conducted on two-day-old piglets, which revealed that the CN1P7 strain was pathogenic to piglets. The virus was shed through the digestive tract and respiratory tract. In addition to the intestine, the CN1P7 strain displayed extraintestinal tropisms in piglets. Histopathological analysis revealed that the lung and small intestine were the targets of CN1P7. This study is the first to explore the molecular and pathogenic characterization of a pig-origin G1P[7] rotavirus.

Identification of a novel intra-genotype reassortant G1P[8] rotavirus in Italy, 2021

OBJECTIVES

Rotaviruses G1P[8] are epidemiologically relevant and are targeted by vaccines. The introduction of vaccines has altered rotavirus epidemiology. Hospital-based surveillance conducted in Sicily, Italy, showed a progressive decline in rotavirus prevalence since 2014, along with an increasing vaccine coverage (63.8% in 2020), and a marked decrease in circulation of G1P[8] strains. Surprisingly in 2021, G1P[8] viruses accounted for 90.5% (19/21) of rotavirus infections. This study aimed to understand if the increased activity of G1P[8]'s was related to virus-related peculiarities.

DESIGN

In 2021, 266 patients <15 years of age were hospitalized with acute gastroenteritis (AGE) and included in rotavirus surveillance. Viral proteins (VP7 and VP4) genotyping and sequence data were generated from all rotavirus-positive samples. The genetic makeup of G1P[8] rotaviruses was investigated by full-genome sequencing.

RESULTS

Peculiar G1P[8] rotaviruses, with VP7 and VP4 belonging to novel sub-lineages, circulated in 2021, accounting for 76.2% (16/21) of all rotavirus infections. On full-genome analysis, the novel G1P[8] variant displayed an intra-genotype (Wa-like) reassortant constellation, involving G12 and G1 strains, into a unique arrangement never observed before. The novel G1P[8] variant showed peculiar amino acid substitutions in 8-1 and 8-3 epitopes of the VP4 with respect to the Rotarix strain.

CONCLUSIONS

Prompt identification of virus variants circulating in the human population is pivotal to understanding epidemiological trends and assessing vaccine efficacy.

Emergence and high prevalence of unusual rotavirus G8P[8] strains in outpatients with acute gastroenteritis in Shanghai, China

Group A rotavirus (RVA) is considered an important cause of acute gastroenteritis (AGE) in all age groups, especially in children. We investigated the epidemiology of RVA in outpatients aged ≤ 16 years at the Children's Hospital of Fudan University, Shanghai, China. In this study, 16.6% (246/1482) were infected with RVA. The detection rate of RVA was significantly higher in the year of 2021 (20.3%, 147/725) compared to the year of 2020 (14.5%, 77/531) and 2022 (9.7%, 22/226) (p = 0.000). RVA infection was prevalent in all seasons from 2020 to 2022, with a different monthly distribution observed in different years. Among 246 RVA-positive samples, 14 different RVA genotypes were detected with different frequencies. Overall, G9P[8] (45.5%, 112/246) was the most common RVA genotype, followed by G8P[8] (37.4%, 92/246) and G3P[8] (4.1%, 10/246). The prevalence of G/P combinations varied from 2020 to 2022. G9P[8] was the most prevalent circulating genotype in 2020 (68.2%, 15/22) and 2021 (57.8%, 85/147). However, G8P[8] (68.8%, 53/77) suddenly became the most prevalent genotype in 2022 after being first identified in 2020 and prevalent in 2021. The G8 strains detected in the study were all clustered to DS-1-like G8 strains with the closest genetic distance to strains circulating in Southeast Asia. Our study demonstrated the diversity of circulating RVA genotypes in Shanghai. The sudden emergence and high prevalence of unusual G8P[8] strains deserve more concern and indicate the need for continuous surveillance of RVA in children with AGE in the future to refine future vaccine strategy.

Distribution of group a Rotavirus circulating in Mashhad, Iran

Background and Objectives

Group A Rotavirus (RVA) is the most important causative agent of acute diarrheal disease in pediatrics 5 years and below. This study aimed to determine the distribution of circulating RVA in Mashhad, Iran to develop health improvement strategies and vaccine decision making.

Materials and Methods

A total of 106 fecal specimens were collected from children admitted to Akbar and Dr. Sheikh referral pediatric hospitals of Mashhad City during the December 2020 to March 2021 and December 2021 to March 2022. All specimens were tested for specific bacterial, parasitic, and amoebic infections. Negative samples were analyzed for RVA infections using the RT-PCR method.

Results

RVA was detected in 31.3% of the specimens, indicating no statistical significance in gender distribution or between fall and winter positivity rates. The number of RVA-positive specimens increased following age increasing in the range of 1 to 60 months.

Conclusion

Today, acute diarrheal disease (ADD) is still caused mostly by Rotavirus infections in pediatrics in Mashhad. Comprehensive studies are needed to determine the genetic diversity of circulating Rotavirus strains in this era.

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.

Rotavirus A in Domestic Pigs and Wild Boars: High Genetic Diversity and Interspecies Transmission

Rotavirus A (RVA) is an important pathogen for porcine health. In comparison to humans, RVA in domestic animals and especially in wildlife is under researched. Therefore, the aim of the present study was to investigate the prevalence, genetic diversity, molecular epidemiology and interspecies transmission of RVA in domestic pigs and wild boars. During the three consecutive RVA seasons (2018–2021) we collected 445 and 441 samples from domestic pigs and wild boars, respectively. Samples were tested by real-time RT-PCR, and RVA-positive samples were genotyped in VP7 and VP4 segments. Our results report an RVA prevalence of 49.9% in domestic pigs and 9.3% in wild boars. Outstanding RVA genetic diversity was observed in VP7 and VP4 segments, especially in domestic pigs exhibiting a striking 23 different RVA combinations (G5P[13] and G9P[23] prevailed). Interspecies transmission events were numerous between domestic pigs and wild boars, sharing G3, G5, G6, G9, G11 and P[13] genotypes. Furthermore, our data indicate that such transmission events involved even bovines (G6, P[11]) and, intriguingly, humans (G1P[8]). This study contributes to the basic knowledge that may be considered important for vaccine development and introduction, as a valuable and currently missing tool for efficient pig health management in the EU.

Whole genome sequence of an uncommon G9P[4] species A rotavirus containing DS-1-like (genotype 2) genes in Japan

Species A rotaviruses (RVAs) have been recognized as one of the leading causes of acute gastroenteritis in humans worldwide. Here, the complete coding sequences of 11 RNA segments of an uncommon G9P[4] RVA strain, which was detected in feces of a diarrheal child in Japan, were determined by next-generation sequencing technology. Its genomic constellation, VP7-VP4-VP6-VP1-VP2-VP3-NSP1-NSP2-NSP3-NSP4-NSP5, was determined as G9-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2. This work reports the complete coding sequences of a G9P[4] RVA strain containing DS-1-like (genotype 2) genes that was isolated in Japan in 2013.

Molecular detection and prevalence of Rotavirus with acute gastroenteritis among the children of rural and urban areas

Rotavirus is the main infective agent of acute gastroenteritis (AGE) in children under the age of five years and causing significant morbidity as well as mortality throughout the world. The study was carried out to detect the prevalence rate, genotypes strain and risk factors of Rotavirus among the children of rural and urban areas of district Bannu Khyber Pakhtunkhwa Pakistan. A total of 180 stool samples were collected from children under the age of 5 years from two major hospitals of Bannu from January to December (2015). The samples were analyzed by Reverse-transcriptase Polymerase Chain Reaction (RT-PCR) for the detection of Rotavirus, positive samples were further processed for genotyping (G and P type) through specific PCR. Of the total, 41 (23%) samples were positive for Rotavirus. The most prevalent G genotypes found were: G3, G8, G9 (each 29%), followed by G10 (15%), and G11 (10%). Whereas the prevalent P genotypes were: P-8 (25%), P-4 and P-10 (each 20%), P-9 (15%), followed by P-6 and P-11 (each 10%). Moreover, Rotavirus infection was more prevalent in summer (23.73%) and winter (22.7%) than spring (20%) and autumn (21.4%). Rotavirus infection exhibited high frequency in June (14%), October (8%) and November (6%). It is concluded that Rotavirus is more prevalent in children and various genotypes (G and P) of Rotavirus are present in the study area. Lack of studies, awareness and rarer testing of Rotavirus are the principal reasons of virus prevalence in district Bannu, Pakistan.

Evolutionary analysis of rotavirus G1P[8] strains from Chennai, South India

Rotaviruses by virtue of its segmented genome generate numerous genotypes. G1P[8] is the most common genotype reported globally. We intend to identify the evolutionary differences among G1P[8] strains from the study with vaccine strains. Stool samples collected from children <5 years were screened for rotavirus antigen by enzyme linked immunosorbent assay. The samples that tested positive for rotavirus were subjected to VP7 and VP4 semi-nested RT-PCR. Sanger sequencing was performed in randomly chosen VP7 and VP4 rotavirus strains. Phylogenetic analysis showed less homology between study strains and vaccine strains and they were placed in different lineages. The VP7 and VP4 proteins of rotavirus were analyzed by two different platforms to identify the amino acid substitutions in the epitope regions. Nine amino acid substitutions with respect to Rotarix®, RotaTeq® and Rotasiil®-V66A, A/T68S, Q72R, N94S, D100E, T113I, S123N, M217T, and I281T were observed in VP7. There were five amino acid substitutions-S145G, N/D195G, N113D, N/I78T, E150D in VP4 (VP8 portion) with respect to Rotarix® and RotaTeq® vaccine strains. M217T substitution in VP7 (epitope 7-2) and N113D, D195G substitution in VP4 (epitope 8-3, 8-1) confer changes in polarity/electrical charge with respect to vaccine strains, thus indicating the need for continued surveillance.

Molecular epidemiology and surveillance of circulating rotavirus among children with gastroenteritis in Bangladesh during 2014-2019

Acute gastroenteritis is one of the major health problems in children aged <5 years around the world. Rotavirus A (RVA) is an important pathogen of acute gastroenteritis. The burden of rotavirus disease in the pediatric population is still high in Bangladesh. This study investigated the prevalence of group A, B, and C rotavirus (RAV, RBV, RCV), norovirus, adenovirus (AdV) and human bocavirus (HBoV) infections in children with acute gastroenteritis in Bangladesh from February 2014 to January 2019. A total of 574 fecal specimens collected from children with diarrhea in Bangladesh during the period of February 2014-January 2019 were examined for RAV, RBV and RCV by reverse transcriptase- multiplex polymerase chain reaction (RT- multiplex PCR). RAV was further characterized to G-typing and P-typing by RT-multiplex PCR and sequencing method. It was found that 24.4% (140 of 574) fecal specimens were positive for RVA followed by AdV of 4.5%. RBV and RCV could not be detected in this study. Genotype G1P[8] was the most prevalent (43%), followed by G2P[4] (18%), and G9P[8] (3%). Among other genotypes, G9P[4] was most frequent (12%), followed by G1P[6] (11%), G9P[6] (3%), and G11P[25] (3%). We found that 7% RVA were nontypeable. Mutations at antigenic regions of the VP7 gene were detected in G1P[8] and G2P[4] strains. Incidence of rotavirus infection had the highest peak (58.6%) during November to February with diarrhea (90.7%) as the most common symptom. Children aged 4-11 months had the highest rotavirus infection percentage (37.9%). By providing baseline data, this study helps to assess efficacy of currently available RVA vaccine. This study revealed a high RVA detection rate, supporting health authorities in planning strategies such as introduction of RVA vaccine in national immunization program to reduce the disease burden.

Genotype constellations of the rotavirus A strains circulating in Nizhny Novgorod, Russia, 2017-2018

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.

Genetic Characterizations and Molecular Evolution of VP7 Gene in Human Group A Rotavirus G1

Rotavirus group A (RVA) G1 is one leading genotype circulating in humans worldwide, and related molecular information from a global perspective is still limited. Here, we present a comprehensive description of the genetic characterizations and molecular evolution of the RVA G1 VP7 gene. Our results show that RVA G1 can be divided into two lineages and multiple sub-lineages with a relatively high genetic diversity. Vaccine strains are phylogenetic, closer to lineage I. The evolutionary rate of the RVA G1 VP7 gene is 8.869 × 10^-4 substitutions/site/year, and its most recent common ancestor was in 1933. The RVA G1 VP7 gene shows a linear evolution at the nucleotide level and a linear accumulation of difference at the amino acid level. Sub-lineage replacement of G1 VP7 gene is also observed and the effective population size of the G1 VP7 gene has had great change in the past decades and has remained stable in recent years. Altogether, the RVA G1 VP7 gene constantly evolves and there is no clear evidence that the evolution of the RVA G1 VP7 gene was influenced by vaccines. Continuous surveillance is still indispensable to evaluate the molecular epidemiology of RVA, especially in the post-vaccination era.

Whole-gene analysis of inter-genogroup reassortant rotaviruses from the Dominican Republic: Emergence of equine-like G3 strains and evidence of their reassortment with locally-circulating strains

Inter-genogroup reassortant group A rotavirus (RVA) strains possessing a G3 VP7 gene of putative equine origin (EQL-G3) have been detected in humans since 2013. Here we report detection of EQL-G3P[8] RVA strains from the Dominican Republic collected in 2014-16. Whole-gene analysis of RVA in stool specimens revealed 16 EQL-G3P[8] strains, 3 of which appear to have acquired an N1 NSP1 gene from locally-circulating G9P[8] strains and a novel G2P[8] reassortant possessing 7 EQL-G3-associated genes and 3 genes from a locally-circulating G2P[4] strain. Phylogenetic/genetic analyses of VP7 gene sequences revealed nine G3 lineages (I-IX) with newly-assigned lineage IX encompassing all reported human EQL-G3 strains along with the ancestral equine strain. VP1 and NSP2 gene phylogenies suggest that EQL-G3P[8] strains were introduced into the Dominican Republic from Thailand. The emergence of EQL-G3P[8] strains in the Dominican Republic and their reassortment with locally-circulating RVA could have implications for current vaccination strategies.

Prevalence and genotypes of group A rotavirus among outpatient children under five years old with diarrhea in Beijing, China, 2011-2016

BACKGROUND

Rotavirus is a leading cause of severe diarrheal disease, and one of the common causes of death in children aged under five years old. The dominant epidemic strains may change in different years in the same area. In order to provide evidence for rotavirus epidemic control and inform vaccine development, we analyzed epidemiological patterns and genetic characteristics of rotavirus in Beijing during 2011-2016.

METHODS

Stool specimens of outpatient children under five years old were collected from three children's hospitals on a weekly basis. Group A rotavirus antigens were detected using enzyme-linked immunosorbent assay (ELISA) kit. The partial VP4 genes and VP7 genes of rotavirus were both amplified and sequenced. Genotyping and phylogenetic analyses were performed. Logistic regression and Chi-square tests were performed to determine differences across age groups, districts and years in rotavirus prevalence and genotype distribution.

RESULTS

A total of 3668 stool specimens from children with acute diarrhea identified through hospital-based surveillance were collected from 2011 to 2016 in Beijing. A total of 762 (20.8%) specimens tested positive for rotavirus. The rotavirus-positive rate was highest among the 1-2 years old age group (29.0%, 310/1070). November, December and January were the highest rotavirus-positive rate months each year. G9 was the most common G genotype (64.4%, 461/716), and P [8] was the most common P genotype (87.0%, 623/716) among the 716 rotavirus-positive specimens. G9P [8], G3P [8] and G2P [4] were the most common strains. The rotavirus-positive rates of samples in 2012 and 2013 were higher than that in 2011, and the dominant genotype changed from G3P [8] to G9P [8] in 2012 and 2013. VP7 gene sequences of G9 strains in this study clustered into two main lineages. Most of the G9 strains exhibited the highest nucleotide similarity (99.1%~ 100.0%) to the strain found in Japan (MI1128). VP4 gene sequences of P [8] strains were almost P[8]b.

CONCLUSIONS

Rotavirus accounted for more than one fifth of childhood diarrhea in Beijing during the study period. Targeted measures such as immunization with effective rotavirus vaccines should be carried out to reduce the morbidity and mortality due to rotavirus.

Prevalence and genotypes of Rotavirus among children under 5 years presenting with diarrhoea in Moshi, Tanzania: a hospital based cross sectional study

Background

Diarrhoea is a main cause of morbidity and mortality in children under 5 responsible for approximately four billion cases and 1.1 million deaths annually. In developing countries, it causes two million deaths each year. The major causative organism responsible is Rotavirus which is responsible for one-third of hospitalizations with approximately 40% mortality.

Results

The prevalence of Rotavirus infection was 26.4% (73/277). The predominant strain of Rotavirus found was G1 21/73 (53.8%), followed by G8 9/73 (23.1%), G12 5/73 (12.8%), G9 3/73(7.7%) and G4 1/73 (2.6%). All serotypes identified were in children who had completed Rotavirus vaccination except for one who had G8 in whom the vaccine was introduced after they had completed immunizations.

Conclusion

The overall prevalence of rotavirus has reduced from 33.2% in 2009 to 26.4% in 2016. We have found G1 to be the predominant serotype as well as other circulating serotypes namely G4, G8, G9 and G12. Despite a reduction in prevalence, there is a need for further rotavirus surveillance in the region.

Electronic supplementary material

The online version of this article (10.1186/s13104-017-2883-3) contains supplementary material, which is available to authorized users.

Prevalence and diversity of rotavirus A genotypes cirulating in Turkey during a 2-year sentinel surveillance period, 2014-2016

Human rotavirus A (RVA) is the main etiological agent of watery diarrhea among children under 5 years of age worldwide. The aims of this study were to investigate the prevalence and diversity of RVA genotypes circulating in Turkey during a 2-year sentinel surveillance study. A total of 1639 rotavirus antigen-positive stool samples were obtained from children younger than 5 years of age hospitalized with acute gastroenteritis. Rotavirus G and P genotypes were determined by reverse transcription polymerase chain reaction (RT-PCR) with consensus primers for the VP7 and VP4 genes, followed by semi-nested type-specific multiplex PCR. Rotavirus RNA was detected in 1396 (85.3%) of the samples tested. The highest detection rate (38.2%) was obtained among children in the 0-12 months age group, followed by children in the 13-24 months age group (36.2%). The most prevalent genotype was G1P[8] (24.6%) followed by G3P[8] (19.6%), G9P[8] (12.2%), G2P[4] (9.5%), G2P[8] (6.5%), and G4P[8] (4.8%). The proportions of uncommon and mixed genotypes were 21.5% and 1.14%, respectively. The large number of genotypes observed, including common, uncommon, and mixed types, indicates a high heterogeneity of RVA strains circulating in Turkey. The current study also exhibited dramatic fluctuations on the prevalences of the common genotypes, with increases in G3 and G1 and decreases in G9 and G2 from 2014-2016.

Rotavirus vaccine and health-care utilization for rotavirus gastroenteritis in Tsu City, Japan

Background

Rotavirus vaccines were introduced in Japan in November 2011. We evaluated the subsequent reduction of the health-care burden of rotavirus gastroenteritis.

Methods

We conducted active surveillance for rotavirus gastroenteritis among children under 5 years old before and after the vaccine introduction. We surveyed hospitalization rates for rotavirus gastroenteritis in children in Tsu City, Mie Prefecture, Japan, from 2007 to 2015 and surveyed the number of outpatient visits at a Tsu City clinic from 2010 to 2015. Stool samples were obtained for rotavirus testing and genotype investigation. We assessed rotavirus vaccine coverage for infants living in Tsu City.

Results

In the pre-vaccine years (2007–2011), hospitalization rates for rotavirus gastroenteritis in children under 5 years old were 5.5, 4.3, 3.1 and 3.9 cases per 1000 person-years, respectively. In the post-vaccine years (2011–2015), the rates were 3.0, 3.5, 0.8 and 0.6 cases per 1000 person-years, respectively. The hospitalization rate decreased significantly in the 2013–2014 and 2014–2015 seasons compared to the average of the seasons before vaccine introduction (P < 0.0001). In one pre-vaccine year (2010–2011), the number of outpatient visits due to the rotavirus infection was 66. In the post-vaccine years (2011–2015), the numbers for each season was 23, 23, 7 and 5, respectively. The most dominant rotavirus genotype shifted from G3P[8] to G1P[8] and to G2P[4]. The coverage of one dose of rotavirus vaccine in Tsu City was 56.5% in 2014.

Conclusion

After the vaccine introduction, the hospitalization rates and outpatient visits for rotavirus gastroenteritis greatly decreased.

Diversity of group A rotavirus genes detected in the Triângulo Mineiro region, Minas Gerais, Brazil

Group A rotaviruses are the main causative agent of infantile gastroenteritis. The segmented nature of the viral genome allows reassortment of genome segments, which can generate genetic variants. In this study, we characterized the diversity of the VP7, VP4 (VP8*), VP6, NSP4, and NSP5 genes of the rotaviruses that circulated from 2005 to 2011 in the Triângulo Mineiro (TM) region of Brazil. Samples with genotypes G2 (sublineages IVa-1 and IVa-3), G1 (sublineage I-A), G9 (lineage III), G12 (lineages II and III), G8 (lineage II), G3 (lineage III), P[4] (sublineages IVa and IVb), P[8] (sublineages P[8]-3.6, P[8]-3.3, and P[8]-3.1), I2 (lineage VII), E2 (lineages VI, XII, and X), and H2 (lineage III) were identified. The associations found in the samples were G1, G9, or G12 with P[8]-I1-E1-H1; G2 or G8 with P[4]-I2-E2-H2; G12 with I3-E3-H6; and G3 with P[4]-I2-E3-H3 (previously unreported combination). Reassortment events in G2P[4] strains and an apparent pattern of temporal segregation within the lineages were observed. Five TM samples contained genes that exhibited high nucleotide and amino acid identities with strains of animal origin. The present study includes a period of pre- and post-introduction of rotavirus vaccination in all Brazilian territories, thereby serving as a basis for monitoring changes in the genetic constitution of rotaviruses. The results also contribute to the understanding of the diversity and evolution of rotaviruses in a global context.

Evaluating the Impact of Breastfeeding on Rotavirus Antigenemia and Disease Severity in Indian Children

Objectives

To evaluate the contribution of breastfeeding to Rotavirus (RV)-induced antigenemia and/or RNAemia and disease severity in Indian children (<2 yrs age).

Methods

Paired stool and serum samples were collected from (a) hospitalized infants with diarrhea (n = 145) and (b) healthy control infants without diarrhea (n = 28). Stool RV-antigen was screened in both groups by commercial rapid-test and enzyme immunoassay. The disease severity was scored and real-time-PCR was used for viral-load estimation. Serum was evaluated for RV-antigenemia by EIA and RV-RNAemia by RT-PCR. Data was stratified by age-group and breastfeeding status and compared.

Results

Presence of RV-antigenemia and RV-RNAemia was positively related with presence of RV in stool. Disease severity and stool viral-load was significantly associated with RV-antigenemia[(r = 0.74; CI:0.66 to 0.84; P<0.0001,R² = 0.59) and (r = -0.55; CI:-0.68 to -0.39; P<0.0001,R² = 0.31) respectively], but not with RV-RNAemia. There was significant reduction in RV-antigenemiarate in the breast-fed group compared to non-breastfed infants, especially in 0–6 month age group (P<0.001). Non-breastfed infants were at risk for RV-antigenemia with severe disease manifestations in form of high Vesikari scores correlating with high fever, more vomiting episodes and dehydration.

Conclusion

RV-antigenemia was common in nonbreastfed children with severe RV-diarrhea and correlated with stool RV-load and disease severity.

Epidemiology of gastroenteritis viruses in Japan: Prevalence, seasonality, and outbreak

Acute gastroenteritis has been recognized as one of the most common diseases in humans and continues to be a major public health problem worldwide. Several groups of viruses have been reported as the causative agents of acute gastroenteritis, including rotavirus, norovirus, sapovirus, human astrovirus, adenovirus, and an increasing number of others which have been reported more recently. The epidemiology, prevalence, seasonality, and outbreaks of these viruses have been reviewed in a number of studies conducted in Japan over three decades. Rotavirus and norovirus were the two most common viruses detected almost equally in children under 5 years of age who were suffering from acute gastroenteritis. Like many other countries, the main rotavirus strains circulating in pediatric patients in Japan are G1P[8], G2P[4], G3P[8], and G9P[8]. Norovirus GII.4 was involved in most outbreaks in Japan and found to be associated with the emergence of new variants Sydney_2012. The classic human astrovirus, MLB, and VA clades astroviruses were also commonly found in pediatric patients with acute diarrhea. The sapovirus and adenovirus have been identified as the minor viral causative agents for acute gastroenteritis in Japan.

A food-borne outbreak of gastroenteritis due to genotype G1P[8] rotavirus among adolescents in Japan

Six high school students in Tochigi prefecture, Japan, developed gastroenteritis after eating at a pork cutlet shop. Molecular epidemiologic analyses showed that the causative agent was genotype G1P[8] rotavirus (RV), this being detected in stool samples from both the patients and the asymptomatic food handlers. The detected RV strains were closely related genetically. The only uncooked food that all victims had eaten was raw sliced cabbage. These findings results suggest that uncooked foods contaminated with RV may be sources of infectious gastroenteritis in adolescents.

Hospital based surveillance and genetic characterization of rotavirus strains in children (<5 years) with acute gastroenteritis in Kolkata, India, revealed resurgence of G9 and G2 genotypes during 2011-2013

INTRODUCTION

India accounts for an estimated 457,000-884,000 hospitalizations and 2 million outpatient visits for diarrhea. In spite of the huge burden of rotavirus (RV) disease, RV vaccines have not been introduced in national immunization programme of India. Therefore, continuous surveillance for prevalence and monitoring of the circulating genotypes is needed to assess the disease burden prior to introduction of vaccines in this region.

METHODS

During January 2011 through December 2013, 830 and 1000 stool samples were collected from hospitalized and out-patient department (OPD) patients, respectively, in two hospitals in Kolkata, Eastern India. After primary screening, the G-P typing was done by multiplex semi-nested PCR using type specific primers followed by sequencing. Phylogenetic analysis for the VP7 gene of 25 representative strains was done.

RESULTS

Among hospitalized and OPD patients, 53.4% and 47.5% cases were positive for rotaviruses, respectively. Unlike previous studies where G1 was predominant, in hospitalized cases G9 rotavirus strains were most prevalent (40%), followed by G2 (39.6%) whereas G1 and G12 occurred at 16.4% and 5.6% frequency. In OPD cases, the most prevalent strain was G2 (40.3%), followed by G1, G9 and G12 at 25.5%, 22.8%, 9.3%, respectively. Phylogenetically the G1, G2 and G9 strains from Kolkata did not cluster with corresponding genotypes of Rotarix, RotaTeq and Rotavac (116E) vaccine strains.

CONCLUSION

The study highlights the high prevalence of RV in children with gastroenteritis in Kolkata. The circulating genotypes have changed over the time with predominance of G9 and G2 strains during 2011-2013. The current G2, G9 and G1 Kolkata strains shared low amino acid homologies with current vaccine strains. Although there is substantial evidence for cross protection of vaccines against a variety of strains, still the strain variation should be monitored post vaccine introduction to determine if it has any impact on vaccine effectiveness.

Sequence analysis of VP7 and VP4 genes of G1P[8] rotaviruses circulating among diarrhoeic children in Pune, India: a comparison with Rotarix and RotaTeq vaccine strains

BACKGROUND

The G1P[8] rotaviruses are a common cause of rotavirus diarrhoea among children in India. Two rotavirus vaccines licensed in India, Rotarix and RotaTeq, contain strains with G1 and P[8] genotypes. A comparative analysis of these genotypes in the live rotavirus vaccines with circulating rotavirus strains is essential for assessment of rotavirus diversity.

METHODS

G1P[8] strains detected during rotavirus surveillance among diarrhoeic children hospitalized in Pune in 1992-1993 and 2006-2008, were included in the study. Amplification, sequencing and phylogenetic analysis of the VP7 and VP4 genes were carried out for identification of the G1 and P[8] lineages, respectively. Antigenic epitopes of VP7 and VP4 encoded proteins were compared to determine the differences between the G1P[8] strains from Pune and the vaccine strains.

RESULTS

G1-Lineage 1, P[8]-Lineage 3 strains were predominant in Pune during 1992-1993 and 2006-2008. Strains of G1-Lineage 2, P[8]-Lineage 3 and G1-Lineage 1, P[8]-Lineage 4 were detected at low levels during 2006-2008. The G1-Lineage 1, P[8]-Lineage 3 strains showed up to eight amino acid changes, each in the VP7 and VP4 epitopes, with respect to the Rotarix vaccine strain (G1-Lineage 2, P[8]-Lineage 1) and the G1 (Lineage-3) and P[8] (Lineage 2) components of the RotaTeq vaccine. The G1-Lineage 2 strains were closer to both vaccine strains with no or only two amino acid substitutions in the VP7 epitopes. The divergent P[8]-Lineage 4 (OP354-like) strains showed fourteen and fifteen amino acid differences, with Rotarix and RotaTeq vaccine strains, respectively, in the VP4 epitopes.

CONCLUSION

The differences between the G1P[8] strains in Pune and the G1 and P[8] components of the vaccine strains need to be described for appropriate evaluation of vaccine shedding. Continuous monitoring of the G1P[8] subgenotypic lineages would be necessary to study any long term impact of vaccine use on G1P[8] strain evolution.

Phylogenetic analysis of a G6P[5] bovine rotavirus strain isolated in a neonatal diarrhea outbreak in a beef cattle herd vaccinated with G6P[1] and G10P[11] genotypes

The aim of this study was to perform the molecular characterization of the eleven genes of a G6P[5] bovine group A rotavirus (RVA) strain detected in a diarrhea outbreak from a vaccinated beef cattle herd. The outbreak affected 80 % of calves between 15–30 days old. RVA was identified by RT-PCR in 12 (70.6 %) out of 17 diarrheic fecal samples evaluated. The rotavirus wild-type strain had the genotype constellation G6(IV)-P[5](IX)-I2c-R2-C2-M2-A3-N2-T6-E2e-H3a. This study confirms the importance of homotypic immunity against the bovine RVA P[5] genotype in neonatal diarrhea in cattle herds that are regularly vaccinated against rotaviruses.

Differences in lineage replacement dynamics of G1 and G2 rotavirus strains versus G9 strain over a period of 22 years in Bangladesh

Group A rotaviruses (RVAs) have been a major cause of severe gastroenteritis in Bangladesh, mainly in children below the age of five. At the icddr,b, RVA strains collection and characterization dates back for more than 20 years. This sample collection was used to study the molecular evolution of the VP7 gene of G1, G2 and G9 RVA strains, which have been circulating in Bangladesh for most of this study period. The evolutionary rates (95% HPD) for G1, G2 and G9 were calculated to be 0.93×10(-3) (0.68-1.18), 1.45×10(-3) (1.12-1.78) and 1.07×10(-3) (0.78-1.39), respectively, which is in line with previous data for the RVA VP7 outer capsid protein, which is under strong negative selective pressure. Bayesian analyses revealed that for the G1 and G2 genotypes, one or multiple lineages co-circulated for one or a few seasons, frequently followed by replacement with genetically different lineages. This can be explained by the existence of a large variety of G1 and G2 RVA lineages and the rapid dissemination of different lineages across the globe. In contrast, circulating G9 lineages were rather closely related to each other across the study period and they were usually derived from variants circulating in the previous season(s). This is consistent with the fact that G9 RVAs have circulated in the human population for less than 20 years, and therefore their genetic diversity is much smaller, not resulting in the replacement of circulating G9 strains by highly divergent G9 lineages from abroad. Such different evolutionary dynamics for different RVA genotypes may alter their response to the selective pressure that might be exerted by the introduction of RVA vaccines and therefore a continued close monitoring is warranted.

Molecular evolution of the VP7 gene of Japanese G2 rotaviruses before vaccine introduction

Changes in the prevalence of G2 rotavirus after vaccine introduction are an important issue. However, such changes in a given country should be interpreted in the global context over time. We determined 35 Japanese G2 sequences and compared them with 508 globally collected G2 sequences. The D96N substitution, a substitution known to be associated with an abrupt increase in G2 strains and antigenic changes, emerged in those strains that formed a nascent lineage outside of the currently predominant lineage (sublineage IVa). Further studies are warranted to monitor the potential of their global spread, since they also appeared in Europe and Australia.

Genetic diversity of G1P[8] rotavirus VP7 and VP8* antigens in Finland over a 20-year period: No evidence for selection pressure by universal mass vaccination with RotaTeq® vaccine

Two live-attenuated oral vaccines (Rotarix™ and Rotateq®) against rotavirus gastroenteritis were licensed in 2006 and have been introduced into National Immunization Programs (NIPs) of several countries. Large scale use of rotavirus vaccines might cause antigenic pressure on circulating rotavirus types or lead to selection of new rotaviruses thus decreasing vaccine efficacy. We examined the nucleotide and amino acid sequences of the surface proteins VP7 and VP4 (cleaved to VP8(*) and VP5(*)) of a total of 108 G1P[8] rotavirus strains collected over a 20-year period from 1992, including the years 2006-2009 when rotavirus vaccine (mainly Rotarix™) was available, and the years 2009-2012 after implementation of RotaTeq® vaccine into the NIP of Finland. In G1 VP7 no changes at amino acid level were observed. In VP8(*) periodical fluctuation of the sublineage over the study period was found with multiple changes both at nucleotide and amino acid levels. Most amino acid changes were in the dominant antigenic epitopes of VP8(*). A change in VP8(*) sublineage occurred between 2008 and 2009, with a temporal correlation to the use of Rotarix™ up to 30% coverage in the period. In contrast, no antigenic changes in the VP8(*) protein appeared to be correlated to the exclusive use of RotaTeq® vaccine after 2009. Nevertheless, long-term surveillance of antigenic changes in VP4 and also VP7 proteins in wild-type rotavirus strains is warranted in countries with large scale use of the currently licensed live oral rotavirus vaccines.

Epidemiology and genetic diversity of rotavirus strains in children with acute gastroenteritis in Lahore, Pakistan

Pakistan harbors high disease burden of gastro-enteric infections with majority of these caused by rotavirus. Unfortunately, lack of proper surveillance programs and laboratory facilities have resulted in scarcity of available data on rotavirus associated disease burden and epidemiological information in the country. We investigated 1306 stool samples collected over two years (2008–2009) from hospitalized children under 5 years of age for the presence of rotavirus strains and its genotypic diversity in Lahore. The prevalence rate during 2008 and 2009 was found to be 34% (n = 447 out of 1306). No significant difference was found between different age groups positive for rotavirus (p>0.05). A subset of EIA positive samples was further screened for rotavirus RNA through RT-PCR and 44 (49.43%) samples, out of total 89 EIA positive samples, were found positive. G and P type prevalence was found as follows: G1P [4] = 3(6.81%); G1P [6] = 9(20.45%); G1P [8] = 1(2.27%); G2P [4] = 21(47.72%); G2P [8] = 1(2.27%); G9P [4] = 1(2.27%); G9P [6] = 1(2.27%) and G9P [8] = 7(15.90%). Phylogenetic analysis revealed that the VP7 and VP4 sequences clustered closely with the previously detected strains in the country as well as Belgian rotaviruses. Antigenic characterization was performed by analyzing major epitopes in the immunodominant VP7 and VP4 gene segments. Although the neutralization conferring motifs were found variable between the Pakistani strains and the two recommended vaccines strains (Rotarix™ and RotaTeq™), we validate the use of rotavirus vaccine in Pakistan based on the proven and recognized vaccine efficacy across the globe. Our findings constitute the first report on rotavirus’ genotype diversity, their phylogenetic relatedness and epidemiology during the pre-vaccination era in Lahore, Pakistan and support the immediate introduction of rotavirus vaccine in the routine immunization program of the country.

Surveillance of human rotaviruses in 2007-2011, Hungary: exploring the genetic relatedness between vaccine and field strains

BACKGROUND

The availability of rotavirus vaccines has resulted in an intensification of post vaccine strain surveillance efforts worldwide to gain information on the impact of vaccines on prevalence of circulating rotavirus strains.

OBJECTIVES

In this study, the distribution of human rotavirus G and P types in Hungary is reported. In addition, the VP4 and VP7 genes of G1P[8] strains were sequenced to monitor if vaccine-derived strains were introduced and/or some strains/lineages were selected against.

STUDY DESIGN

The study was conducted in 8 geographic areas of Hungary between 2007 and 2011. Rotavirus positive stool samples were collected from diarrheic patients mostly <5 years of age. Viral RNA was amplified by multiplex genotyping RT-PCR assay, targeting the medically most important G and P types. When needed, sequencing of the VP7 and VP4 genes was performed.

RESULTS

In total, 2380 strains were genotyped. During the 5-year surveillance we observed the dominating prevalence of genotype G1P[8] (44.87%) strains, followed by G4P[8] (23.4%), G2P[4] (14.75%) and G9P[8] (6.81%) genotypes. Uncommon strains were identified in a low percentage of samples (4.12%). Phylogenetic analysis of 318 G1P[8] strains identified 55 strains similar to the Rotarix strain (nt sequence identities; VP7, up to 97.9%; VP4, up to 98.5%) although their vaccine origin was unlikely.

CONCLUSIONS

Current vaccines would have protected against the majority of identified rotavirus genotypes. A better understanding of the potential long-term effect of vaccine use on epidemiology and evolutionary dynamics of co-circulating wild type strains requires continuous strain surveillance.

Phylogenetic and computational structural analysis of VP7 gene of group a human rotavirus G1P[8] strains obtained in Sapporo, Japan from 1987 to 2000

Many studies indicate that G1P[8] genotypes are the most prevalent rotavirus strains worldwide. Although two vaccines have been licensed and their value proven in many countries, continuous surveillance for genetic evolution of circulating rotavirus strains before and after the introduction of the vaccines is desirable. G and P typing were carried out on all field strains isolated during 1987-2000 in Sapporo, Japan. Phylogenetic analysis for the VP7 gene of rotavirus G1P[8] strains was performed. Amino acid substitutions were mapped on the predicted three-dimensional VP7 protein image. G1P[8] genotype predominated. One hundred thirteen strains with G1P[8] genotype were analyzed. Phylogenetic studies of the VP7 gene classified these strains into three lineages. The mean estimated substitution rate was 7.25 × 10(-4) nucleotide substitutions per site per year. One predominant lineage contained the mutant strains which had VP7 amino acid substitutions at residue 91 and 212 that is in the neutralization domains. They were estimated to locate in or near intersubunit boundary of VP7 trimer. It is suggested that the most prevalent G1P[8] lineage strains in Sapporo obtained some survival advantages by changing the neutralization domains of VP7.

Genetic variation in the VP7 gene of rotavirus G1P[8] strains isolated in Vietnam, 1998-2009

Group A rotavirus genotype G1P[8] is the most common strain affecting humans around the world over the past few decades. In this study, we examined genetic variation in the VP7 gene of rotavirus G1P[8] strains, detected in children of four major cities of Vietnam during three different rotavirus seasons: 1998-1999, 2007-2008 and 2008-2009 in order to assess the evolution of the virus over 11 years. Fecal samples (n=73) from children hospitalized for gastroenteritis caused by G1P[8] rotavirus were analyzed by DNA sequencing of gene 9 encoding the VP7 capsid protein. Phylogenetic analyses indicated that VP7 gene of the G1 strains from 1999 contained a lineage I, while rotaviruses from 2009 clustered in lineage II. Both of these lineages were found co-circulating in 2007-2008 season. While different sublineages of lineage I and II co-circulated in the 1998-1999 and 2007-2008 seasons, almost all strains in 2009 belonged to sub-lineage II-C. In the analysis using selected 10 strains, the VP4 genes of these 2 VP7-G1 lineages were all grouped in F45-like cluster. Deduced amino acid analyses indicated that there were thirteen amino acid substitutions between strains of two lineages. Of those, two were found in antigenic regions A and C, implying possible antigenic differences between these two lineages. The G1P[8] strains in Vietnam are very genetically diverse and dynamic, implying the frequent monitoring on evolution of rotavirus will be important to assess efficacy of rotavirus vaccine in Vietnam.

Burden of rotavirus gastroenteritis and distribution of rotavirus strains in Asia: a systematic review

BACKGROUND

Rotavirus is the leading cause of severe diarrhea in children worldwide. We systematically reviewed the burden of rotavirus gastroenteritis (RVGE) and distribution of rotavirus strains in Asia.

METHODS

We searched MEDLINE, EMBASE and the World Health Organization (WHO) website for the term "rotavirus" and the name of each country. We included studies that were conducted in children between 2000 and 2011 and that examined the epidemiology, health and/or economic burden of RVGE, and G and P-type distribution in Eastern, South East, Southern and Central Asia. Random effects models were used to pool the proportions of RVGE. We also estimated child mortality due to RVGE using the updated WHO and United Nations Children's Fund's mortality estimates in 2008.

RESULTS

The search identified 113 eligible articles. The incidence rates of rotavirus-related hospitalizations in children under 5 years of age ranged from 2.1 to 20.0 cases per 1000 children per year with the highest rates reported in Bangladesh, South Korea, Taiwan, Thailand, and Vietnam. Rotavirus accounted for 37.5% of year-round hospitalized gastroenteritis cases, with higher proportions reported in South East Asia. Rotavirus was associated with approximately 145,000 deaths every year in Asia, with the greatest numbers occurring in India, Pakistan, and Indonesia. The highest annual societal costs of treating RVGE were reported in China (US$365 million), followed by Japan (US$254 million) and India (US$41-72 million). A diversity of rotavirus G and P-types was observed across Asia and the distribution of strains differed by country and year. The most common strains were G1P[8] (23.6%), G2P[4] (11.8%), G3P[8] (18.9%), and G9P[8] (7.4%).

CONCLUSIONS

Rotavirus is associated with substantial hospitalizations and deaths among children and causes large healthcare expenditures throughout Asia. Safe and effective rotavirus vaccines could substantially reduce the burden of disease.

Antigenemia and cytokine expression in rotavirus gastroenteritis in children

BACKGROUND

Antigenemia is commonly found in children with rotavirus infection, although its clinical significance is undetermined. The aim of this study was to evaluate the association of antigenemia with clinical manifestations and cytokine profiles in children infected by rotavirus.

METHODS

In total, 68 children hospitalized with rotavirus gastroenteritis were enrolled. Serum samples were collected for detection of antigenemia and viremia. Clinical, laboratory and demographic data were analyzed. Proinflammatory, Th1 and Th2 cytokines were evaluated by bead-based flow cytometry.

RESULTS

Antigenemia and viremia were found in 45.6% (n = 31) and 5.9% (n = 4) of the 68 rotavirus-infected children, respectively. The mean age of the antigenemia group was significantly greater than that of the non-antigenemia group (43.5 vs. 27.3 months; p = 0.034). The antigenemia group had a significantly shorter length of hospitalization (4.8 vs. 5.8 days; p = 0.0354) in comparison with the non-antigenemia group, and antigenemia was inversely associated with the length of hospitalization (β = 0.31, p = 0.021). A significantly higher tumor necrosis factor (TNF)-β level was found in the patients with antigenemia than those without (236.7 vs. 29.2 pg/mL, p = 0.026). The severity of disease and the rate of extra-intestinal manifestations did not differ between the groups. Viremia was associated with a higher fever (p = 0.012).

CONCLUSIONS

Antigenemia was positively correlated with shorter hospital stay in children with rotavirus infection. Enhanced innate and T-cell-mediated immunity evidenced by up-regulation of TNF-β was found in patients with antigenemia.