Group A rotavirus (RVA) is the major cause of acute gastroenteritis (AGE) in young children worldwide. Introduction of two live, attenuated rotavirus vaccines, Rotarix® and RotaTeq®, has dramatically ...reduced RVA-associated AGE and mortality. High-throughput, sensitive and specific techniques are required to rapidly diagnose and characterize rotavirus strains in stool samples for proper patient treatment and to monitor circulating vaccine and wild-type rotavirus strains. New molecular assays are rapidly developed that are more sensitive and specific than the conventional assays for detection, genotyping and full genome characterization of circulating rotavirus wild-type and vaccine (Rotarix® and RotaTeq®) strains causing AGE.
In April 2008, a nucleotide-sequence-based, complete genome classification system was developed for group A rotaviruses (RVs). This system assigns a specific genotype to each of the 11 genome ...segments of a particular RV strain according to established nucleotide percent cutoff values. Using this approach, the genome of individual RV strains are given the complete descriptor of Gx-Px-Ix-Rx-Cx-Mx-Ax-Nx-Tx-Ex-Hx. The Rotavirus Classification Working Group (RCWG) was formed by scientists in the field to maintain, evaluate and develop the RV genotype classification system, in particular to aid in the designation of new genotypes. Since its conception, the group has ratified 51 new genotypes: as of April 2011, new genotypes for VP7 (G20-G27), VP4 (P28-P35), VP6 (I12-I16), VP1 (R5-R9), VP2 (C6-C9), VP3 (M7-M8), NSP1 (A15-A16), NSP2 (N6-N9), NSP3 (T8-T12), NSP4 (E12-E14) and NSP5/6 (H7-H11) have been defined for RV strains recovered from humans, cows, pigs, horses, mice, South American camelids (guanaco), chickens, turkeys, pheasants, bats and a sugar glider. With increasing numbers of complete RV genome sequences becoming available, a standardized RV strain nomenclature system is needed, and the RCWG proposes that individual RV strains are named as follows: RV group/species of origin/country of identification/common name/year of identification/G- and P-type. In collaboration with the National Center for Biotechnology Information (NCBI), the RCWG is also working on developing a RV-specific resource for the deposition of nucleotide sequences. This resource will provide useful information regarding RV strains, including, but not limited to, the individual gene genotypes and epidemiological and clinical information. Together, the proposed nomenclature system and the NCBI RV resource will offer highly useful tools for investigators to search for, retrieve, and analyze the ever-growing volume of RV genomic data.
Since 2013, group A rotavirus strains characterized as novel DS-1-like intergenogroup reassortant "equine-like G3" strains have emerged and spread across 5 continents among human populations in at ...least 14 countries. Here, we report a novel one-step TaqMan quantitative real-time reverse transcription-PCR assay developed to genotype and quantify the viral load for samples containing rotavirus equine-like G3 strains. Using a universal G forward primer and a newly designed reverse primer and TaqMan probe, we developed and validated an assay with a linear dynamic range of 227 to 2.3 × 10
copies per reaction and a limit of detection of 227 copies. The percent positive agreement, percent negative agreement, and precision of our assay were 100.00%, 99.63%, and 100.00%, respectively. This assay can simultaneously detect and quantify the viral load for samples containing DS-1-like intergenogroup reassortant equine-like G3 strains with high sensitivity and specificity, faster turnaround time, and decreased cost. It will be valuable for high-throughput screening of stool samples collected to monitor equine-like G3 strain prevalence and circulation among human populations throughout the world.
•Fecal Rotarix vaccine virus shedding and HBGAphenotype frequency were investigated.•Virus shedding was higher (23.6%) after the first dose than the second dose (4.7%).•Most of vaccine virus-shedding ...infants were secretor HBGA positive while none of the non-fecal vaccine virus shedding infants were secretor HBGA positive. Most of the virus-shedders were secretor+ compared to none of the non-virus shedders.•Low vaccine virus shedding was significantly associated with non-secretor phenotype.
Histo-blood group antigens are recognized by rotaviruses in a P- genotype dependent manner and their frequency in a population can influence fecal virus shedding. This study investigated the rate of fecal shedding of Rotarix vaccine and its association with HBGA phenotype distribution in South Africa. Stool and saliva specimens were collected from 150 infants attending immunization on the day of both first and second doses and 7 days later. Virus shedding was detected by real-time qPCR while HBGA phenotypes in saliva were determined by enzyme linked immunosorbent assay. Vaccine virus shedding was higher (23.6%) after the first dose than the second dose (4.7%). About 77% of virus-shedding infants were secretors (OR = 129; 95% CI, 6.088 – 2733), compared with none of non-virus shedding infants. Non-secretor status was significantly associated with low vaccine virus shedding while the likelihood of shedding was significantly higher in secretors.
Since 2006, the New Vaccine Surveillance Network has conducted active, population-based surveillance for acute gastroenteritis (AGE) hospitalizations and emergency department (ED) visits in 3 United ...States counties. Trends in the epidemiology and disease burden of rotavirus hospitalizations and ED visits were examined from 2006 to 2016.
Children < 3 years of age hospitalized or visiting the ED with AGE were enrolled from January 2006 through June 2016. Bulk stool specimens were collected and tested for rotavirus. Rotavirus-associated hospitalization and ED visit rates were calculated annually with 2006-2007 defined as the prevaccine period and 2008-2016 as the postvaccine period. Rotavirus genotype trends were compared over time.
Over 11 seasons, 6954 children with AGE were enrolled and submitted a stool specimen (2187 hospitalized and 4767 in the ED). Comparing pre- and postvaccine periods, the proportion of children with rotavirus dramatically declined for hospitalization (49% vs 10%) and ED visits (49% vs 8%). In the postvaccine era, a biennial pattern of rotavirus rates was observed, with a trend toward an older median age. G1P8 (63%) was the predominant genotype in the prevaccine period with a significantly lower proportion (7%) in the postvaccine period (P < .001). G2P4 remained stable (8% to 14%) in both periods, whereas G3P8 and G12P8 increased in proportion from pre- to postvaccine periods (1% to 25% and 17% to 40%), respectively.
The epidemiology and disease burden of rotavirus has been altered by rotavirus vaccination with a biennial disease pattern, sustained low rates of rotavirus in children < 3 years of age, and a shift in the residual genotypes from G1P8 to other genotypes.
•Whole-gene characterization (11 ORFs) for 72 randomly selected, Species A Rotaviruses of common and unusual genotypes collected in Benin from the 2016 to 2018 seasons.•All study strains exhibited ...two genetic constellations designed as Wa-like, G1/G9/G12-P6/P8-I1-R1-C1-M1-A1-N1-T1-E1-H1 and DS-1-like, G2/G3/G12-P4/P6-I2-R2-C2-M2-A2-N2-T2-E2-H2.•Genetic analysis showed identification of 2-13 and 1-17 sub-genotypic alleles for DS-1-like and Wa-like strains, respectively.
Species A rotaviruses (RVA) still play a major role in causing acute diarrhea in children under five years old worldwide. Currently, an 11-gene classification system is used to designate the full genotypic constellations of circulating strains. Viral proteins and non-structural proteins in the order VP7-VP4-VP6-VP1-VP2-VP3-NSP1-NSP2-NSP3-NSP4-NSP5/6 are represented by the genotypes Gx-Px-Ix-Rx-Cx-Mx-Ax-Nx-Tx-Ex-Hx, respectively. In Benin, ROTAVAC® vaccine was introduced into the Expanded Programme on Immunization in December 2019. To monitor circulating RVA strains for changes that may affect vaccine performance, in-depth analysis of strains prior to vaccine introduction are needed. Here we report, the whole-gene characterization (11 ORFs) for 72 randomly selected RVA strains of common and unusual genotypes collected in Benin from the 2016 to 2018 seasons. The sequenced strains were 15 G1P8, 20 G2P4, 5 G9P8, 14 G12P8, 9 G3P6, 2 G1P6, 3 G2P6, 2 G9P4, 1 G12P6, and 1 G1G9P8/P4. The study strains exhibited two genetic constellations designed as Wa-like G1/G9/G12-P6/P8-I1-R1-C1-M1-A1-N1-T1-E1-H1 and DS-1-like G2/G3/G12-P4/P6-I2-R2-C2-M2-A2-N2-T2-E2-H2. Genotype G9P4 strains possessed a DS-1-like genetic constellation with an E6 NSP4 gene, G9-P4-I2-R2-C2-M2-A2-N2-T2-E6-H2. The mixed genotype showed both Wa-like and DS-1-like profiles with a T6 NSP3 gene G1/G9P8/4-I1/I2-R1/R2-C1/C2-M1/M2-A1/A2-N1/N2-T1/T6-E1/E6-H1/H2. At the allelic level, the analysis of the Benin strains, reference strains (with known alleles), vaccine strains (with known alleles) identified 2–13 and 1–17 alleles for DS-1-like and Wa-like strains, respectively. Most of the study strains clustered into previously defined alleles, but we defined 3 new alleles for the VP7 (G3 = 1 new allele and G12 = 2 new alleles) and VP4 (P4 = 1 new allele and P6 = 2 new alleles) genes which formed the basis of the VP7 and VP4 gene clusters, respectively. For the remaining 9 genes, 0-6 new alleles were identified for both Wa-like and DS-1-like strains. This analysis of whole genome sequences of RVA strains circulating in Benin described genetic point mutations and reassortment events as well as novel alleles. Further detailed studies on these new alleles are needed and these data can also provide a baseline for studies on RVA in the post-vaccination period.
Group A rotaviruses (RVs) remain a leading cause of childhood gastroenteritis worldwide. Although the G/P types of locally circulating RVs can vary from year to year and differ depending upon ...geographical location, those with G1P8, G2P4, G3P8, G4P8, G9P8, and G12P8 specificities typically dominate. Little is known about the evolution and diversity of G2P4 RVs and the possible role that widespread vaccine use has had on their increased frequency of detection. To address these issues, we analyzed the 12 G2P4 RV isolates associated with a rise in RV gastroenteritis cases at Vanderbilt University Medical Center (VUMC) during the 2010-2011 winter season. Full-genome sequencing revealed that the isolates had genotype 2 constellations typical of DS-1-like viruses (G2P4-I2-R2-C2-M2-A2-N2-T2-E2-H2). Phylogenetic analyses showed that the genome segments of the isolates were comprised of two or three different subgenotype alleles; this enabled recognition of three distinct clades of G2P4 viruses that caused disease at VUMC in the 2010-2011 season. Although the three clades cocirculated in the same community, there was no evidence of interclade reassortment. Bayesian analysis of 328 VP7 genes of G2 viruses isolated in the last 39 years indicate that existing G2 VP7 gene lineages continue to evolve and that novel lineages, as represented by the VUMC isolates, are constantly being formed. Moreover, G2 lineages are characteristically shaped by lineage turnover events that introduce new globally dominant strains every 7 years, on average. The ongoing evolution of G2 VP7 lineages may give rise to antigenic changes that undermine vaccine effectiveness in the long term.
Little is known about the diversity of cocirculating G2 rotaviruses and how their evolution may undermine the effectiveness of rotavirus vaccines. To expand our understanding of the potential genetic range exhibited by rotaviruses circulating in postvaccine communities, we analyzed part of a collection of rotaviruses recovered from pediatric patients in the United States from 2010 to 2011. Examining the genetic makeup of these viruses revealed they represented three segregated groups that did not exchange genetic material. The distinction between these three groups may be explained by three separate introductions. By comparing a specific gene, namely, VP7, of the recent rotavirus isolates to those from a collection recovered from U.S. children between 1974 and 1991 and other globally circulating rotaviruses, we were able to reconstruct the timing of events that shaped their ancestry. This analysis indicates that G2 rotaviruses are continuously evolving, accumulating changes in their genetic material as they infect new patients.
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-G3P8 ...RVA strains from the Dominican Republic collected in 2014–16. Whole-gene analysis of RVA in stool specimens revealed 16 EQL-G3P8 strains, 3 of which appear to have acquired an N1 NSP1 gene from locally-circulating G9P8 strains and a novel G2P8 reassortant possessing 7 EQL-G3-associated genes and 3 genes from a locally-circulating G2P4 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-G3P8 strains were introduced into the Dominican Republic from Thailand. The emergence of EQL-G3P8 strains in the Dominican Republic and their reassortment with locally-circulating RVA could have implications for current vaccination strategies.
Despite the global roll-out of rotavirus vaccines (RotaTeq/Rotarix / ROTAVAC/Rotasiil), mortality and morbidity due to group A rotavirus (RVA) remains high in sub-Saharan Africa, causing 104,000 ...deaths and 600,000 hospitalizations yearly. In Cameroon, RotarixTM was introduced in March 2014, but, routine laboratory diagnosis of rotavirus infection is not yet a common practice, and vaccine effectiveness studies to determine the impact of vaccine introduction have not been done. Thus, studies examining RVA prevalence post vaccine introduction are needed. The study aim was to determine RVA prevalence in severe diarrhoea cases in Littoral region, Cameroon and investigate the role of other diarrheagenic pathogens in RVA-positive cases. We carried out a study among hospitalized children < 5 years of age, presenting with acute gastroenteritis in selected hospitals of the Littoral region of Cameroon, from May 2015 to April 2016. Diarrheic stool samples and socio-demographic data including immunization and breastfeeding status were collected from these participating children. Samples were screened by ELISA (ProSpecTTM Rotavirus) for detection of RVA antigen and by gel-based RT-PCR for detection of the VP6 gene. Co-infection was assessed by multiplexed molecular detection of diarrheal pathogens using the Luminex xTAG GPP assay. The ELISA assay detected RVA antigen in 54.6% (71/130) of specimens, with 45, positive by VP6 RT-PCR and 54, positive using Luminex xTAG GPP. Luminex GPP was able to detect all 45 VP6 RT-PCR positive samples. Co-infections were found in 63.0% (34/54) of Luminex positive RVA infections, with Shigella (35.3%; 12/34) and ETEC (29.4%; 10/34) detected frequently. Of the 71 ELISA positive RVA cases, 57.8% (41/71) were fully vaccinated, receiving two doses of Rotarix. This study provides insight on RVA prevalence in Cameroon, which could be useful for post-vaccine epidemiological studies, highlights higher than expected RVA prevalence in vaccinated children hospitalized for diarrhoea and provides the trend of RVA co-infection with other enteric pathogens. RVA genotyping is needed to determine circulating rotavirus genotypes in Cameroon, including those causing disease in vaccinated children.
We report the genome of a novel human triple-recombinant G4P6-8_R mono-reassortant strain identified in a stool sample from the Dominican Republic during routine facility-based rotavirus strain ...surveillance. The strain was designated as RVA/Human-wt/DOM/2013840364/2013/G4P6-8_R, with a genomic constellation of G4-P6-8_R-I1-R1-C1-M1-(A1-A8_R)-N1-(T1-T7_R)-E1-H1. Recombinant gene segments NSP1 and NSP3 were generated as a result of recombination between genogroup 1 rotavirus A1 human strain and a genotype A8 porcine strain and between genogroup 1 rotavirus T1 human strain and a genotype T7 bovine strain, respectively. Analyses of the RNA secondary structures of gene segment VP4, NSP1 and NSP3 showed that all the recombinant regions appear to start in a loop (single-stranded) region and terminate in a stem (double-stranded) structure. Also, the VP7 gene occupied lineage VII within the G4 genotypes consisting of mostly porcine or porcine-like G4 strains, suggesting the occurrence of reassortment. The remaining gene segments clustered phylogenetically with genogroup 1 strains. This exchange of whole or partial genetic materials between rotaviruses by recombination and reassortment contributes directly to their diversification, adaptation and evolution.
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