Rotaviruses: is their surveillance needed?

Genomic characterization of the rotavirus G3P[8] strain in vaccinated children, reveals possible reassortment events between human and animal strains in Manhiça District, Mozambique

Mozambique introduced the rotavirus vaccine (Rotarix®; GlaxoSmithKline Biologicals, Rixensart, Belgium) in 2015, and since then, the Centro de Investigação em Saúde de Manhiça has been monitoring its impact on rotavirus-associated diarrhea and the trend of circulating strains, where G3P[8] was reported as the predominant strain after the vaccine introduction. Genotype G3 is among the most commonly detected Rotavirus strains in humans and animals, and herein, we report on the whole genome constellation of G3P[8] detected in two children (aged 18 months old) hospitalized with moderate-to-severe diarrhea at the Manhiça District Hospital. The two strains had a typical Wa-like genome constellation (I1-R1-C1-M1-A1-N1-T1-E1-H1) and shared 100% nucleotide (nt) and amino acid (aa) identities in 10 gene segments, except for VP6. Phylogenetic analysis demonstrated that genome segments encoding VP7, VP6, VP1, NSP3, and NSP4 of the two strains clustered most closely with porcine, bovine, and equine strains with identities ranging from 86.9-99.9% nt and 97.2-100% aa. Moreover, they consistently formed distinct clusters with some G1P[8], G3P[8], G9P[8], G12P[6], and G12P[8] strains circulating from 2012 to 2019 in Africa (Mozambique, Kenya, Rwanda, and Malawi) and Asia (Japan, China, and India) in genome segments encoding six proteins (VP2, VP3, NSP1-NSP2, NSP5/6). The identification of segments exhibiting the closest relationships with animal strains shows significant diversity of rotavirus and suggests the possible occurrence of reassortment events between human and animal strains. This demonstrates the importance of applying next-generation sequencing to monitor and understand the evolutionary changes of strains and evaluate the impact of vaccines on strain diversity.

Molecular Characterization of Avian Rotaviruses F and G Detected in Brazilian Poultry Flocks

Avian rotaviruses (RVs) are important etiologic agents of gastroenteritis in birds. In general, avian RVs are understudied; consequently, there is a paucity of information regarding these viruses. Therefore, the characterization of these viral species is highly relevant because more robust information on genetic, epidemiologic, and evolutionary characteristics can clarify the importance of these infections, and inform efficient prevention and control measures. In this study, we describe partial genome characterizations of two avian RV species, RVF and RVG, detected in asymptomatic poultry flocks in Brazil. Complete or partial sequences of at least one of the genomic segments encoding VP1, VP2, VP4, VP6, VP7, NSP1, NSP4, NSP4, or NSP5 of 23 RVF and 3 RVG strains were obtained, and demonstrated that multiple variants of both RVF and RVG circulate among Brazilian poultry. In this study, new and important information regarding the genomic characteristics of RVF and RVG is described. In addition, the circulation of these viruses in the study region and the genetic variability of the strains detected are demonstrated. Thus, the data generated in this work should help in understanding the genetics and ecology of these viruses. Nonetheless, the availability of a greater number of sequences is necessary to advance the understanding of the evolution and zoonotic potential of these viruses.

Complete genome analyses of G12P[8] rotavirus strains from hospitalized children in Surabaya, Indonesia, 2017-2018

Rotavirus A (RVA) is a major viral cause of acute gastroenteritis (AGE) worldwide. G12 RVA strains have emerged globally since 2007. There has been no report of the whole genome sequences of G12 RVAs in Indonesia. We performed the complete genome analysis by the next-generation sequencing of five G12 strains from hospitalized children with AGE in Surabaya from 2017 to 2018. All five G12 strains were Wa-like strains (G12-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1) and were clustered into lineage-III of VP7 gene phylogenetic tree. STM430 sample was observed as a mixed-infection between G12 and G1 strains: G12/G1-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1. A phylogenetic tree analysis revealed that all five Indonesian G12 strains (SOEP379, STM371, STM413, STM430, and STM433) were genetically close to each other in all 11 genome segments with 98.0%-100% nucleotide identities, except VP3 and NSP4 of STM430, suggesting that these strains have originated from a similar ancestral G12 RVA. The VP3 and NSP4 genome segments of STM430-G12P[8] were separated phylogenetically from those of the other four G12 strains, probably due to intra-genotype reassortment between the G12 and G1 Wa-like strains. The change from G12P[6] lineage-II in 2007 to G12P[8] lineage-III 2017-2018 suggests the evolution and diversity of G12 RVAs in Indonesia over the past approximately 10 years.

Effectiveness of self-financed rotavirus vaccination in Ise City, Japan

In Japan, the herd immunity effect of rotavirus vaccine has not yet been proven. Here, we conducted active surveillance for hospitalization due to rotavirus acute gastroenteritis (AGE) among children under 5 years of age in pre-rotavirus vaccination years and self-financed rotavirus vaccination years to clarify the rotavirus vaccine effectiveness (VE) in reducing hospitalization rates. A time-series analysis showed that the monthly hospitalization rates observed after vaccine introduction were significantly lower than the forecasted hospitalization rates (p < .001, Mann-Whitney U test). In the third year after vaccine introduction, the hospitalization rate declined despite the low vaccination rate of 27-50% for the two preceding years. We estimated four types of VE, namely direct, indirect, total, and overall. The direct VE was calculated from the relative risk ratio of hospitalizations between vaccinated and unvaccinated children. The indirect VE was defined as the population-level effects of vaccination on children not receiving the vaccine. The total VE was defined as the combination of the direct and indirect VE on children receiving the vaccine. The overall VE was determined by the weighted average of indirect VE on the children not receiving the vaccine and the total VE on the children receiving the vaccine. The direct, indirect, total, and overall VE values were calculated as 82% (95% confidence interval, 52-93), 70% (51-82), 95% (87-98), and 86% (77-91), respectively. The high values of indirect, total, and overall VE indicate that the rotavirus vaccine produces a herd immunity effect.

Serological Humoral Immunity Following Natural Infection of Children with High Burden Gastrointestinal Viruses

Acute gastroenteritis (AGE) is a major cause of morbidity and mortality worldwide, resulting in an estimated 440,571 deaths of children under age 5 annually. Rotavirus, norovirus, and sapovirus are leading causes of childhood AGE. A successful rotavirus vaccine has reduced rotavirus hospitalizations by more than 50%. Using rotavirus as a guide, elucidating the determinants, breath, and duration of serological antibody immunity to AGE viruses, as well as host genetic factors that define susceptibility is essential for informing development of future vaccines and improving current vaccine candidates. Here, we summarize the current knowledge of disease burden and serological antibody immunity following natural infection to inform further vaccine development for these three high-burden viruses.

Genotype Diversity before and after the Introduction of a Rotavirus Vaccine into the National Immunisation Program in Fiji

The introduction of the rotavirus vaccine, Rotarix, into the Fiji National Immunisation Program in 2012 has reduced the burden of rotavirus disease and hospitalisations in children less than 5 years of age. The aim of this study was to describe the pattern of rotavirus genotype diversity from 2005 to 2018; to investigate changes following the introduction of the rotavirus vaccine in Fiji. Faecal samples from children less than 5 years with acute diarrhoea between 2005 to 2018 were analysed at the WHO Rotavirus Regional Reference Laboratory at the Murdoch Children's Research Institute, Melbourne, Australia, and positive samples were serotyped by EIA (2005-2006) or genotyped by heminested RT-PCR (2007 onwards). We observed a transient increase in the zoonotic strain equine-like G3P[8] in the initial period following vaccine introduction. G1P[8] and G2P[4], dominant genotypes prior to vaccine introduction, have not been detected since 2015 and 2014, respectively. A decrease in rotavirus genotypes G2P[8], G3P[6], G8P[8] and G9P[8] was also observed following vaccine introduction. Monitoring the rotavirus genotypes that cause diarrhoeal disease in children in Fiji is important to ensure that the rotavirus vaccine will continue to be protective and to enable early detection of new vaccine escape strains if this occurs.

The performance of licensed rotavirus vaccines and the development of a new generation of rotavirus vaccines: a review

Rotavirus, which causes acute gastroenteritis and severe diarrhea, has posed a great threat to children worldwide over the last 30 y. Since no specific drugs and therapies against rotavirus are available, vaccination is considered the most effective method of decreasing the morbidity and mortality related to rotavirus-associated gastroenteritis. To date, six rotavirus vaccines have been developed and licensed by local governments. Notably, Rotarix™ and RotaTeq™ have been recommended as universal agents against rotavirus infection by the World Health Organization; however, lower efficacies were found in less-developed and developing regions with medium and high child mortality than well-developed ones with low child mortality. For now, two promising novel vaccines, Rotavac™ and RotaSiil™ were pre-qualified by the World Health Organization in 2018. Other rotavirus vaccines in the pipeline including neonatal strain (RV3-BB) and several non-replicating rotavirus vaccines with a parenteral delivery strategy are currently undergoing investigation, with the potential to improve the performance of, and eliminate the safety concerns associated with, previous live oral rotavirus vaccines. This paper reviews the important developments in rotavirus vaccines in the last 20 y and discusses problems and challenges that require investigation in the future.

Epidemiology and Genotype Distribution of Rotavirus Gastroenteritis in Under-Five Children of South Rajasthan, India

OBJECTIVE

To determine the epidemiology of rotavirus diarrhea and its genotypes distribution among under five children from Udaipur, Rajasthan.

METHODS

Hospital-based prospective study among children aged 0-59 mo of age hospitalized due to acute gastroenteritis and assess the clinical and epidemiological profile. Stool samples collected during 2017-2019 from 734 children, were tested by enzyme immune assay (EIA) to identify rotavirus and the samples that were positive were subjected to genotyping using published methods.

RESULTS

Rotavirus was detected in 12.94% (95/734) of the stool samples. Maximum positivity (38.9%) was seen in children aged 12-23 mo followed by 34.7% in 6-11 mo of age. Detection rates were higher (46.31%, 44/95) during winter months of December-February; 65% children with rotavirus diarrhea had severe dehydration followed by moderate dehydration in 32% of cases. G3P[8] (40, 43.01%) was the commonest genotype followed by G9P[4] (10, 10.75%).

CONCLUSION

Among under-five children hospitalized due to acute gastroenteritis in a tertiary care setting in Udaipur, Rajasthan, 12.9% of children were rotavirus positive with predominant (43.01%) circulation of G3P[8] strains.

Rotavirus Gastroenteritis Hospitalizations Among Under-5 Children in Northern India

OBJECTIVE

To study epidemiological profile, prevalence, and molecular epidemiology of RVGE in hospitalized under-5 children at a tertiary care teaching rural hospital located in sub-Himalayan belt of Northern India.

METHODS

This was a hospital-based surveillance study done over 4 y (2016-2019) including under-5 children hospitalized with acute gastroenteritis (AGE). Demographic and clinical parameters were recorded in a pre-designed performa. After consent, stool samples were collected and sent to Christian Medical College (CMC), Vellore for RV screening by enzyme immunoassay (EIA). Each EIA-positive sample was further subjected to G and P typing using published methods.

RESULTS

Out of total 851 included children, rotavirus gastroenteritis (RVGE) was detected in 23.03% (196/851) cases by EIA. The highest incidence for RVGE-positive cases (40.43%) was observed in 2016 with gradual decline over next 3 y. Maximum cases of diarrhea were observed in 12-23 mo age group along with highest rotavirus detection. G3P[8] was most common genotype (46.94%) found, followed by G1P[8] (13.78%), G2P[4] (4.59%), G1P[6] (8.16%) and G9P[4] (3.57%). Mixed genotype was seen in 13.78% of total cases.

CONCLUSION

This study summarizes the changing trends in the epidemiology of RVGE in Northern India along with the major circulating genotypes postvaccine introduction.

Rotavirus infection in children in Southeast Asia 2008-2018: disease burden, genotype distribution, seasonality, and vaccination

Background

Rotaviruses (RVs) are recognized as a major cause of acute gastroenteritis (AGE) in infants and young children worldwide. Here we summarize the virology, disease burden, prevalence, distribution of genotypes and seasonality of RVs, and the current status of RV vaccination in Southeast Asia (Cambodia, Indonesia, Lao People’s Democratic Republic, Malaysia, Myanmar, Philippines, Singapore, Thailand, and Vietnam) from 2008 to 2018.

Methods

Rotavirus infection in Children in Southeast Asia countries was assessed using data from Pubmed and Google Scholars. Most countries in Southeast Asia have not yet introduced national RV vaccination programs. We exclude Brunei Darussalam, and Timor Leste because there were no eligible studies identified during that time.

Results

According to the 2008–2018 RV surveillance data for Southeast Asia, 40.78% of all diarrheal disease in children were caused by RV infection, which is still a major cause of morbidity and mortality in children under 5 years old in Southeast Asia. Mortality was inversely related to socioeconomic status. The most predominant genotype distribution of RV changed from G1P[8] and G2P[4] into the rare and unusual genotypes G3P[8], G8P[8], and G9P[8]. Although the predominat strain has changed, but the seasonality of RV infection remains unchanged. One of the best strategies for decreasing the global burden of the disease is the development and implementation of effective vaccines.

Conclusions

The most predominant genotype distribution of RV was changed time by time. Rotavirus vaccine is highly cost effective in Southeast Asian countries because the ratio between cost per disability-adjusted life years (DALY) averted and gross domestic product (GDP) per capita is less than one. These data are important for healthcare practitioners and officials to make appropriate policies and recommendations about RV vaccination.

Porcine rotavirus C strains carrying human-like NSP4 and NSP5

BACKGROUND

Rotavirus C (RVC) is an enteric pathogen that affects humans and animals around the world.

METHODS

In this study, we characterized the genetic diversity of RVC strains detected in asymptomatic Brazilian pigs by sequencing the NSP4, NSP5 and VP6 genes.

RESULTS

The results of reverse transcription polymerase chain reaction showed that 53 of 579 samples (9.2%) contained RVC. Positive samples were genotyped by sequencing gene segments NSP4, and NSP5. Most of the RCV strains encountered were classified into typically porcine genotypes: E1-H1. In two strains, BP182 and BP208, the NSP4 gene grouped with E2-RVC human strains with 94.2%-96.5% nucleotide identity, although the NSP5 gene was porcine-like (H1). In strain SD67, the NSP5 gene grouped with human H2-RVC with 92.5%-98.7% nucleotide identity and the NSP4 gene grouped with porcine strains (E1). Two strains (BP208 and SD67) were also genotyped by sequencing gene segment VP6. The VP6 gene grouped with porcine strains, I6 (89.3%-90.2% nucleotide identity) and I5 (88.7%-90.5% nucleotide identity), for strains BP208 and SD67, respectively.

CONCLUSIONS

These results are indicative of genomic reassortment between RVC strains of human and porcine origin. In recent years, the incidence of RVC infection among humans has increased significantly. It is important to measure the frequency of interspecies transmission in order to monitor the evolution of these viruses and to identify rearranged strains that may lead to an epidemic.

10-Year Rotavirus Infection Surveillance: Epidemiological Trends in the Pediatric Population of Perugia Province

Rotavirus (RV) infections are a leading cause of severe gastroenteritis in children, and vaccination is currently recommended in Italy, according to the National Immunization Plan 2017-2019. The objective of this study was to describe the epidemiological and molecular RV surveillance in the pediatric population of Perugia province, Umbria. Between September 2007 and August 2018, 663 RV-positive stool specimens were collected from children <15 years of age presenting with gastroenteritis to the emergency room of the Perugia province hospitals who were then hospitalized. Yearly hospitalization rates were expressed per 100,000 persons, and denominators were extrapolated from the National Institute of Statistics. During the 10-year surveillance, the epidemiological trend was fluctuating but slightly decreasing (Max: 89.7 per 100,000 in 2010/2011; Min: 34.8 per 100,000 in 2017/2018). The hospitalization rate was higher in males and in children under five years of age. Among common genotypes, G1P[8] was prevalent most of the years. The uncommon G12P [8] genotype emerged and was the most common in 2012/2013 (58.2%). Afterwards, its circulation remained high. As the Umbria Region started vaccinating from the 2018 birth cohort, our study reviewed pre-vaccination data and will help to assess the protection induced by vaccination and its effect on circulating strains.

The Impact of Rotavirus Vaccines on Genotype Diversity: A Comprehensive Analysis of 2 Decades of Australian Surveillance Data

Background

Introduction of rotavirus vaccines into national immunization programs (NIPs) could result in strain selection due to vaccine-induced selective pressure. This study describes the distribution and diversity of rotavirus genotypes before and after rotavirus vaccine introduction into the Australian NIP. State-based vaccine selection facilitated a unique comparison of diversity in RotaTeq and Rotarix vaccine states.

Methods

From 1995 to 2015, the Australian Rotavirus Surveillance Program conducted genotypic analysis on 13051 rotavirus-positive samples from children <5 years of age, hospitalized with acute gastroenteritis. Rotavirus G and P genotypes were determined using serological and heminested multiplex reverse-transcription polymerase chain reaction assays.

Results

G1P[8] was the dominant genotype nationally in the prevaccine era (1995-2006). Following vaccine introduction (2007-2015), greater genotype diversity was observed with fluctuating genotype dominance. Genotype distribution varied based on the vaccine implemented, with G12P[8] dominant in states using RotaTeq, and equine-like G3P[8] and G2P[4] dominant in states and territories using Rotarix.

Conclusions

The increased diversity and differences in genotype dominance observed in states using RotaTeq (G12P[8]), and in states and territories using Rotarix (equine-like G3P[8] and G2P[4]), suggest that these vaccines exert different immunological pressures that influence the diversity of rotavirus strains circulating in Australia.

Distribution of rotavirus genotypes in the postvaccine introduction era in Ashaiman, Greater Accra Region, Ghana, 2014-2016

Group A Rotaviruses (RVAs) are the most important etiological agents of acute gastroenteritis (AGE) in children less than 5 years of age. Mortality resulting from RVA gastroenteritis is higher in developing countries than in developed ones, causing a huge public health burden in global regions like Africa and South-East Asia. This study reports RVA genotypes detected in Ashaiman, Greater Accra Region, Ghana, in the postvaccine introduction era for the period 2014-2016. Stool samples were collected from children less than 5 years of age who visited Ashaiman Polyclinic with AGE from November 2014 to May 2015 and from December 2015 to June 2016. The samples were tested by enzyme immunoassay (EIA), and one-step multiplex reverse transcription polymerase chain reaction was performed on the EIA positive samples for gel-based binomial genotyping. Of the 369 stool samples collected from children with AGE, 145 (39%) tested positive by EIA. Five VP7 (G1, G3, G9, G10, and G12) and three VP4 (P[4], P[6] and P[8]) genotypes were detected. Eight G/P combinations were identified of which, G3P[6], G12P[8], G1P[8], and G9P[4] were the most prevalent and responsible for 93 (68%) of the AGE cases, and seven mixed-types were detected which represented 8% of the RVA cases. High prevalence, diversity, and mixed-types of RVAs were detected from Ashaiman with the emergence of unusual genotypes.

Epidemiology and genetic diversity of group A rotavirus in acute diarrhea patients in pre-vaccination era in Himachal Pradesh, India

Acute gastroenteritis due to Group A rotaviruses remains the leading cause of mortality and morbidity in children in developing countries. India introduced its indigenous rotavirus vaccine Rotavac® in 2016 and Himachal Pradesh (HP) the first state to launch it. The present study aimed to evaluate rotavirus strain diversity associated with AGE prior to vaccine introduction in HP. A total of 331 fecal specimens collected from diarrheic children hospitalized at RPGMC Tanda, HP between July-2014 and June-2016 were screened for RVA by EIA. Rotavirus RNA was extracted by TRIZOL method and analyzed by RNA-PAGE. G/P typing was performed using semi-nested multiplex reverse transcriptase PCR. Rotavirus was detected in 45% (n = 149/331) of diarrheic children, with highest rate observed in the 6-11 months age group (47%). Vomiting was found more frequently associated with RV-infection. Among G-types, G12 was found most prevalent (33.1%) followed by G1 (28.4%), G9 (12.2%), G2 (9.5%), G3 (3.4%) and G10 (2.7%). G4 (0.7%) strains were rarely detected. Among P-types, P[6] was the most prevalent (40.5%) followed by P[8] (29.1%) and P[4] (14.2%). Of note, genotypes G3 and P[11] were detected for the first time in HP. Among G/P combinations, G12P[6] was most prevalent (30.4%) followed by G1P[8] (20.3%), G2P[4] (4.7%), G1P[6] (3.4%) and G3P[8] (2.7%). Interestingly, our study observed high percentage of unusual strains (14.2%) namely G9P[4], G2P[6], G2P[8], G12P[4] and G1P[11]. The regionally common strains G3P[6], G4P[6], G9P[6], G9P[8], G10P[6], G10P[8] and G12P[8] strains were very rarely detected. Of interest, RNA migration pattern of G1P[8] was DS-1 like and genomic heterogeneity was observed within G12P[4] strains with both long and short electropherotypes. Our study highlights rich genetic diversity with emergence of rare rotavirus strains circulating in HP and provides baseline data prior to Rotavac® introduction that will help to gauge the impact of the Rotavac® vaccine in HP.

Molecular characterization of rotavirus group A strains circulating prior to vaccine introduction in rural coastal Kenya, 2002-2013

Background: Kenya introduced the monovalent Rotarix® rotavirus group A (RVA) vaccine nationally in mid-2014.  Long-term surveillance data is important prior to wide-scale vaccine use to assess the impact on disease and to investigate the occurrence of heterotypic strains arising through immune selection. This report presents baseline data on RVA genotype circulation patterns and intra-genotype genetic diversity over a 7-year period in the pre-vaccine era in Kilifi, Kenya, from 2002 to 2004 and from 2010 to 2013.

Methods: A total of 745 RVA strains identified in children admitted with acute gastroenteritis to a referral hospital in Coastal Kenya, were sequenced using the di-deoxy sequencing method in the VP4 and VP7 genomic segments (encoding P and G proteins, respectively). Sequencing successfully generated 569 (76%) and 572 (77%) consensus sequences for the VP4 and VP7 genes respectively. G and P genotypes were determined by use of BLAST and the online RotaC v2 RVA classification tool.

Results: The most common GP combination was G1P[8] (51%), similar to the Rotarix® strain, followed by G9P[8] (15%) , G8P[4] (14%) and G2P[4] (5%).  Unusual GP combinations—G1P[4], G2P[8], G3P[4,6], G8P[8,14], and G12P[4,6,8]—were observed at frequencies of <5%. Phylogenetic analysis showed that the infections were caused by both locally persistent strains as evidenced by divergence of local strains occurring over multiple seasons from the global ones, and newly introduced strains, which were closely related to global strains. The circulating RVA diversity showed temporal fluctuations both season by season and over the longer-term. None of the unusual strains increased in frequency over the observation period.  

Conclusions: The circulating RVA diversity showed temporal fluctuations with several unusual strains recorded, which rarely caused major outbreaks.  These data will be useful in interpreting genotype patterns observed in the region during the vaccine era.

First detection of a reassortant G3P[8] rotavirus A strain in Italy: a case report in an 8-year-old child

Background

Acute gastroenteritis (AGE) due to group A rotavirus (RVA) agent is one of the major causes of hospitalization in paediatric age. The G3P[8] RVA genotype has been usually considered as one of the major human genotypes, largely circulating in Asia, but showing low detection rates in the European countries. In recent years, the G3P[8] RVAs emerged also in Europe as a predominant genotype and the viral strains detected revealed high similarities with equine-like G3P[8] RVA strains, resulting in a new variant circulating in humans and able to cause AGE in the paediatric population.

Case presentation

An 8-year-old boy was admitted to the Emergency Room because he had suffered from severe diarrhoea, vomiting, and high fever over the previous two days. Severe dehydration was evident based on low serum concentrations of potassium and sodium, low glycaemia, and pre-renal failure (creatinine 2.48 mg/dL, urea 133 mg/dL). Immunological tests were within normal range. Enzyme immunoassay for the detection of RV was positive, and a sample of faeces was collected in order to perform the molecular characterization of the viral strain. The phylogenetic trees revealed relatedness between the VP7 and VP4 genes of the G3P[8] RVA Italian strain (namely PG2) and those belonging to recent G3P[8] RVAs detected worldwide. The G3 VP7 belonged to the G3-I lineage and shared the highest nucleotide sequence identity (99.8%) with the equine-like G3 previously identified in other countries. The P [8] VP4 revealed a similar clustering pattern to that observed for the VP7. In addition, the molecular characterization of the 11 gene segments of strain PG2 revealed a G3-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 genomic constellation.

Conclusions

This case shows the first detection in Italy of a reassortant G3P[8] RVA associated with a severe AGE, which is unusual in a school-age child without any known severe underlying problems. The findings reported in this paper highlight the importance of continuously monitoring the RVA strains circulating in paediatric age in order to detect novel viral variants able to spread in the general population.

High prevalence of enteric viruses associated with acute gastroenteritis in pediatric patients in a low-income area in Vitória, Southeastern Brazil

Acute gastroenteritis (AGE) is a significant cause of child mortality worldwide. In Brazil, despite the reduction in infant mortality achieved in recent years, many children still die because of undiagnosed AGE. The prevalence, viral load, and circulating genotypes of rotavirus A (RVA), human adenovirus (HAdV), and norovirus GII (NoV GII) were investigated in children with AGE during 12 months in Vitoria, Espírito Santo, Southeastern Brazil. Enteric viruses were detected in stool samples, quantified by quantitative polymerase chain reaction, sequenced, and compared phylogenetically. The overall prevalence was 93.3% (125/134). Cases of single infection (41.8%) and mixed infection (51.5%) were observed; in 21.6% of cases, all the three viruses were detected. RVA had the highest number of copies in all infections. Phylogenetic analysis revealed predominantly the presence of RVA genotype G3, followed by G2 and G9. HAdV clustered within subgroup C, but some samples harbored subgroups A, D, or F. All sequenced NoV-positive samples clustered within the prevalent genotype GII.4. The high prevalence of RVA, HAdV, and NoV in diarrheal feces clarifies the etiology of AGE in this population, and the presence of RVA in vaccinated children reinforces the importance of monitoring programs to identify the causes of gastroenteritis and contribute to the reliability of diagnosis.

Molecular characterization of rotavirus group A strains circulating prior to vaccine introduction in rural coastal Kenya, 2002-2013

Background: Kenya introduced the monovalent Rotarix® rotavirus group A (RVA) vaccine nationally in mid-2014.  Long-term surveillance data is important prior to wide-scale vaccine use to assess the impact on disease and to investigate the occurrence of heterotypic strains arising through immune selection. This report presents baseline data on RVA genotype circulation patterns and intra-genotype genetic diversity over a 7-year period in the pre-vaccine era in Kilifi, Kenya, from 2002 to 2004 and from 2010 to 2013. Methods: A total of 745 RVA strains identified in children admitted with acute gastroenteritis to a referral hospital in Coastal Kenya, were sequenced using the di-deoxy sequencing method in the VP4 and VP7 genomic segments (encoding P and G proteins, respectively). Sequencing successfully generated 569 (76%) and 572 (77%) consensus sequences for the VP4 and VP7 genes respectively. G and P genotypes were determined by use of BLAST and the online RotaC v2 RVA classification tool. Results: The most common GP combination was G1P[8] (51%), similar to the Rotarix® strain, followed by G9P[8] (15%) , G8P[4] (14%) and G2P[4] (5%).  Unusual GP combinations—G1P[4], G2P[8], G3P[4,6], G8P[8,14], and G12P[4,6,8]—were observed at frequencies of <5%. Phylogenetic analysis showed that the infections were caused by both locally persistent strains as evidenced by divergence of local strains occurring over multiple seasons from the global ones, and newly introduced strains, which were closely related to global strains. The circulating RVA diversity showed temporal fluctuations both season by season and over the longer-term. None of the unusual strains increased in frequency over the observation period.   Conclusions: The circulating RVA diversity showed temporal fluctuations with several unusual strains recorded, which rarely caused major outbreaks.  These data will be useful in interpreting genotype patterns observed in the region during the vaccine era.

Resurgence of Rotavirus Genotype G12 in St. Louis During the 2014-2015 Rotavirus Season

BACKGROUND

Rotaviruses are a leading cause of gastroenteritis. Rotavirus vaccination has dramatically reduced rotavirus occurrence; however, we have noticed mild to moderate recurrences in the St. Louis area in alternate years. In 2013, we found rotavirus genotype G12 to be the dominant strain in the St. Louis region. In this study, we again determined the distribution of genotypes and ascertained vaccine history in patients infected with rotavirus G12 during the 2014-15 season.

METHODS

Samples submitted to the St. Louis Children's Hospital Microbiology Laboratory were tested for rotavirus using an antigen assay. We determined the VP7 genotype using amplicon sequence analysis. We determined genome sequences using high-throughput sequencing. We evaluated rotavirus immunization records when available.

RESULTS

Of 30 typed viruses from 2014-15, 29 were G12 (97%). Whole-genome sequencing revealed few changes from G12 viruses analyzed in 2012-13. VP4 and VP7 sequences were >99% identical to previously sequenced G12 strains from St. Louis, and immune epitopes were conserved. Vaccination histories were available from 17 patients. Of these, 4 had been vaccinated, 3 had received incomplete vaccination or had a vaccine history that could not be confirmed, and 10 had not been vaccinated.

CONCLUSIONS

G12 re-emerged as the predominant rotavirus genotype in 2014-15, comprising a higher percentage of cases than in 2012-13. The majority of patients with G12 and available vaccination histories were unvaccinated. There was no genomic evidence to indicate that the G12 strains in St. Louis had evolved to escape vaccine protection. Our work emphasizes the need for continued surveillance.

Modulation of rotavirus severe gastroenteritis by the combination of probiotics and prebiotics

Annual mortality rates due to infectious diarrhea are about 2.2 million; children are the most vulnerable age group to severe gastroenteritis, representing group A rotaviruses as the main cause of disease. One of the main factors of rotavirus pathogenesis is the NSP4 protein, which has been characterized as a viral toxin involved in triggering several cellular responses leading to diarrhea. Furthermore, the rotavirus protein NSP1 has been associated with interferon production inhibition by inducing the degradation of interferon regulatory factors IRF3, IRF5, and IRF7. On the other hand, probiotics such as Bifidobacterium and Lactobacillus species in combination with prebiotics such as inulin, HMO, scGOS, lcFOS have been associated with improved generalized antiviral response and anti-rotavirus effect by the reduction of rotavirus infectivity and viral shedding, decreased expression of NSP4 and increased levels of specific anti-rotavirus IgAs. Moreover, these probiotics and prebiotics have been related to shorter duration and severity of rotavirus diarrhea, to the prevention of infection and reduced incidence of reinfections. In this review we will discuss in detail about the rotavirus pathogenesis and immunity, and how probiotics such as Lactobacillus and Bifidobacterium species in combination with prebiotics have been associated with the prevention or modulation of rotavirus severe gastroenteritis.

Predominance of unusual rotavirus G1P[6] strain in North India: An evidence from hospitalized children and adult diarrheal patients

Group A Rotavirus remains the leading cause of gastroenteritis in children and accounts for 0.2 million fatalities each year; out of which, approximately 47,100 deaths occur in India. In adults also, rotavirus is reported to be responsible for diarrhea severe enough to require hospitalizations. India has recently introduced rotavirus vaccine in the Universal Immunization Programme and Himachal Pradesh became the first Indian state to implement this project. This study is an attempt to provide the pre-vaccination data on rotavirus gastroenteritis burden and circulating genotypes in Himachal Pradesh, India. A total of 607 faecal specimens (247 children ≤5years, 50 older children and 310 adults) from hospitalized diarrheal patients from Himachal Pradesh, India were screened for rotavirus using ELISA and RT-PCR. The positive samples were further G/P genotyped using semi-nested PCR. Rotavirus was detected in 25.2% and 28.3% of samples with ELISA and RT-PCR, respectively. In children, rotavirus frequency was significantly high with positivity in 49.0% cases whereas 14.0% adult samples have rotavirus in them. Genotyping of the positive samples revealed predominance of G1 (66.0%) and P[6] (66.7%) genotypes. The most common G and P combination was G1P[6] (62.8%) followed by G1P[8] (16.5%), G9P[6] (7.4%) and G12P[6] (5.0%). Molecular analysis reveals the belonging of P[6] strains in Lineage 1a. This pre-vaccination data on rotavirus prevalence and diversity would be helpful for assessing the affect of vaccination on the disease burden and its comparison with post-vaccination data of circulating genotypes would help in studying the effect on diversity of rotavirus strains possibly due to vaccine selection pressure.

Changing distribution of age, clinical severity, and genotypes of rotavirus gastroenteritis in hospitalized children after the introduction of vaccination: a single center study in Seoul between 2011 and 2014

Background

This study aimed to explore changes in clinical epidemiology and genotype distribution and their association among hospitalized children with rotavirus gastroenteritis after the introduction of vaccines.

Methods

Between November 2010 and October 2014, hospitalized children with acute gastroenteritis were enrolled. Rotavirus genotypes were confirmed through reverse transcription-polymerase chain reaction (RT-PCR), semi-nested PCR, and sequencing. Clinical information including vaccination status and the modified Vesikari scores were collected.

Results

Among 179 children with rotavirus infection, nineteen (10.6 %) were completely vaccinated. During the study period, the number of children between three and 23 months of age decreased significantly compared to the number of children older than 24 months of age (P = 0.010), who showed lower diarrhea severity (duration, P = 0.042; frequency, P = 0.021) but higher vomiting severity (P = 0.007, 0.036) compared to the former. Vaccination status was also significantly associated with lower vomiting severity after adjustment for age (frequency only, P = 0.018). The predominant genotypes were G2P[4] (18.4 %), G1P[8] (14.5 %), and G1P[4]P[8] (12.8 %), and the prevalence of genotypes with uncommon and mixed combinations was more than 50 %. Children infected with G2P[4] strains tended to be older (P = 0.005) and had more severe vomiting (P = 0.018, 0.006) than those with G1P[8].

Conclusions

Increase in age of infected, hospitalized children was accompanied by change in clinical severity during 2011–2014 after the introduction of vaccines in Seoul. Clinical severity was also associated with vaccination status and genotype. Long-term large scale studies are needed to document the significance of the increase in genotypes of uncommon and mixed combinations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1623-y) contains supplementary material, which is available to authorized users.

The cost effectiveness of rotavirus vaccination in Iran

Rotavirus is the most common cause of severe diarrhea leading to hospitalization or disease-specific death among young children. Effective vaccines have recently been approved and successful vaccination program implemented. The aim of this study was to evaluate the cost effectiveness of mass rotavirus vaccination program in Iran. We developed a Markov model that reflects key features of rotavirus natural history. Parameters of the model were assessed by field study or developed through literature search and published data. We applied the model to the 2009 Iranian birth cohort and evaluated the cost-effectiveness of including the rotavirus vaccine (Rotarix®) into Iranian expanded immunization program (EPI). With an estimated hospitalization rate of 0.05 and outpatient rate of 0.23 cases per person-year, vaccinating cohort of 1231735 infants in Iran with 2 doses of (Rotarix®), would prevent 32092 hospitalizations, 158750 outpatient visits, and 1591 deaths during 5 y of follow-up. Under base-case assumption of $10 cost per course of vaccine, the vaccination would incur an extra cost of $1,019,192 from health care perspective and would avert 54680 DALYs. From societal perspective, there would be $15,192,568 saving for the society with the same averted DALYs. The incremental cost effectiveness ratio showed a cost of $19 US dollars per averted DALY from health care perspective and a saving of $278 US dollars for each averted DALY from societal perspective. Introducing rotavirus vaccine into EPI program would be highly cost-effective public health intervention in Iran.

Viruses Surveillance Under Different Season Scenarios of the Negro River Basin, Amazonia, Brazil

The Negro River is located in the Amazon basin, the largest hydrological catchment in the world. Its water is used for drinking, domestic activities, recreation and transportation and water quality is significantly affected by anthropogenic impacts. The goals of this study were to determine the presence and concentrations of the main viral etiological agents of acute gastroenteritis, such as group A rotavirus (RVA) and genogroup II norovirus (NoV GII), and to assess the use of human adenovirus (HAdV) and JC polyomavirus (JCPyV) as viral indicators of human faecal contamination in the aquatic environment of Manaus under different hydrological scenarios. Water samples were collected along Negro River and in small streams known as igarapés. Viruses were concentrated by an organic flocculation method and detected by quantitative PCR. From 272 samples analysed, HAdV was detected in 91.9%, followed by JCPyV (69.5%), RVA (23.9%) and NoV GII (7.4%). Viral concentrations ranged from 10(2) to 10(6) GC L(-1) and viruses were more likely to be detected during the flood season, with the exception of NoV GII, which was detected only during the dry season. Statistically significant differences on virus concentrations between dry and flood seasons were observed only for RVA. The HAdV data provides a useful complement to faecal indicator bacteria in the monitoring of aquatic environments. Overall results demonstrated that the hydrological cycle of the Negro River in the Amazon Basin affects the dynamics of viruses in aquatic environments and, consequently, the exposure of citizens to these waterborne pathogens.

Prevalence of rotavirus, norovirus and enterovirus in diarrheal diseases in Himachal Pradesh, India

Diarrheal diseases are responsible for a significant proportion of mortality and morbidity all around the globe. The contribution of viruses to gastroenteritis incidences in humans is well established. In the present study, we have studied the prevalence of rotavirus, norovirus and enterovirus in Himachal Pradesh, a north Indian state. A total of 287 (111 children and 176 adults) stool samples of gastroenteritis patients were screened for the viruses using RT-PCR method. 34.5 % samples were positive for the viral pathogens of gastroenteritis. Rotavirus was the predominant virus detected in the study with 49.5 and 14.8 % positivity in children and adults, respectively. Enterovirus was present in 5.6 % cases whereas norovirus had least prevalence (1.4 %). Co infection (rotavirus and enterovirus) was witnessed at the prevalence rate of 0.6 %. Among different age groups, the prevalence of studied viruses was highest in the children belonging to the age groups of <5 years. Rotavirus infections were found to be significantly associated with vomiting and trend of higher rates of fever and dehydration was seen in children along with diarrhea. Seasonal distribution shows circulation of diarrheagenic viruses throughout the year. This is the first report of prevalence of various diarrheagenic viruses circulating in this region. The outcome of the study from this cohort provides a baseline data which can be used to design the preventive strategies in the otherwise unexplored state of Himachal Pradesh.

Did Large-Scale Vaccination Drive Changes in the Circulating Rotavirus Population in Belgium?

Vaccination can place selective pressures on viral populations, leading to changes in the distribution of strains as viruses evolve to escape immunity from the vaccine. Vaccine-driven strain replacement is a major concern after nationwide rotavirus vaccine introductions. However, the distribution of the predominant rotavirus genotypes varies from year to year in the absence of vaccination, making it difficult to determine what changes can be attributed to the vaccines. To gain insight in the underlying dynamics driving changes in the rotavirus population, we fitted a hierarchy of mathematical models to national and local genotype-specific hospitalization data from Belgium, where large-scale vaccination was introduced in 2006. We estimated that natural- and vaccine-derived immunity was strongest against completely homotypic strains and weakest against fully heterotypic strains, with an intermediate immunity amongst partially heterotypic strains. The predominance of G2P[4] infections in Belgium after vaccine introduction can be explained by a combination of natural genotype fluctuations and weaker natural and vaccine-induced immunity against infection with strains heterotypic to the vaccine, in the absence of significant variation in strain-specific vaccine effectiveness against disease. However, the incidence of rotavirus gastroenteritis is predicted to remain low despite vaccine-driven changes in the distribution of genotypes.

The prevalence and genotype diversity of Human Rotavirus A circulating in Thailand, 2011-2014

Human rotavirus A (RVA) is the major infectious virus causing acute watery diarrhea in children, especially those younger than 5 years of age, and is a major public health problem in Thailand. Outbreaks of this virus have been reported worldwide. Besides the common genotypes, unusual genotypes providing evidence of inter-species transmission have also been described. Therefore, the aim of this study was to investigate the prevalence and genotypes of RVA in Thailand. A total of 688 samples were collected from children who were hospitalized with acute diarrhea in Chumphae Hospital in Khon Kaen and Chulalongkorn Hospital in Bangkok. RVA was detected using one-step RT-PCR and the genotypes were evaluated by sequencing. Overall, 204 of the 688 samples (30%) were positive for RVA. Nine genotypes were identified: three common in humans (G1P[8] [53%], G2P[4] [18%], G3P[8] [12%]), one feline-like (G3P[9] [1%]), four porcine-like (G4P[6] [0.5%], G5P[6] [0.5%], G9P[8] [0.5%], G12P[6] [1.5%]), and one bovine-like (G8P[8] [13%]). The variation in virus genotypes and the animal-like genotypes detected in this study suggested that a high diversity of RVA types is circulating in the Thai population. Therefore, continuous molecular epidemiological monitoring of RVA is essential and has implications for the national vaccination program.

Molecular characterization of rotavirus strains from pre- and post-vaccination periods in a country with low vaccination coverage: the case of Slovenia

Rotavirus vaccination started in Slovenia in 2007 on a voluntarily basis. The vaccination rate is relatively low (up to 27%) and no increasing trend is observed. We present rotavirus genotype distribution among children hospitalized for rotavirus gastroenteritis in Slovenia. Eight consecutive rotavirus seasons were followed, from 2005/06 to 2012/13, and 113 strains of the most common rotavirus genotypes were randomly selected for molecular characterization of rotavirus VP7 and VP4 (VP8(∗)) genome segments. During the vaccine introduction period, from 2007 to 2013, rotavirus genotype prevalences changed, with G1P[8] decreasing from 74.1% to 8.7% between 2007/08 and 2010/11 seasons, replaced by G4P[8] and G2P[4], with up to 52.0% prevalence. Comparable analysis of VP7 and VP8(∗) genome fragments within G1P[8] genotype lineages revealed considerable differences for rotavirus strains circulating before and during the vaccination period. The G1P[8] rotavirus strains from the pre-vaccination period clustered in a phylogenetic tree within Rotarix®-like VP7 and VP8(∗) lineages. However, since 2007, the majority of G1P[8] strains have shifted to distant genetic lineages with lower nucleotide (88.1-94.0% for VP7 and 86.6-91.1% for VP8(∗)) and amino acid (93.8-95.2% for VP7 and 85.3-94.6% for VP8(∗)) identities to the vaccine Rotarix® strain. This change also resulted in a different deduced amino acid profile at the major VP7 and VP8(∗) antigenic epitopes.