Search Results (21)

Background: Despite the availability of a killed whole-virus (KV) vaccine, diarrhea caused by equine rotavirus group A (ERVA) remains a significant health concern for foals in the United States. The vaccine is administered to pregnant mares, with foals protected by passive transfer of colostral antibodies. However, KV-induced immunity is only partially protective and maternal antibody levels in foals are often low and wane rapidly. To address these limitations, we developed a mRNA-based ERVA vaccine encoding the highly conserved VP8* protein to evaluate whether it can provide improved immune protection. Methods: Pregnant mares (n = 12 per group) were immunized either at months 8 and 10 of gestation with the VP8* mRNA or at months 8, 9, and 10 of gestation with the KV. Serum samples were collected from mares before and after immunization and from their foals at ages 1, 35, and 49 days. Serum samples were tested by indirect ELISA for VP8*-specific relative antibody concentrations and relative concentrations were compared for effects of study group and sample-time using linear mixed-effects regression. To detect functional antibodies against ERVA, a virus neutralization titer assay was performed to compare titers between mares vaccinated with the mRNA vaccine (and their foals) and unvaccinated control mares (and their foals). Results: Mares vaccinated with VP8* mRNA had significantly (p < 0.05) higher antibody concentrations after foaling than mares in the KV group, and foals of VP8* mRNA-vaccinated mares had significantly (p < 0.05) higher concentrations through age 49 days than foals in the KV group. In addition, the VP8* mRNA vaccine elicited higher titers of ERVA-neutralizing antibodies against both G3 and G14 strains. Conclusions: Longer-lasting, higher concentrations of virus-neutralizing antibodies might provide superior duration of immunity to ERVA in foals from mares vaccinated with VP8* mRNA. Full article

The porcine origin rotavirus A (RVA) G5 genotype is notable for its unique and sustained human circulation in Brazil, primarily as G5P[8] during the 1980s–2000s. This study aimed to characterize and investigate the full genome of a rare G5P[6] strain detected in 2013 (RVA/Human-wt/BRA/IAL-R406/2013/G5P[6]) to elucidate its evolutionary origin throughout RT-PCR, sequencing, and phylogenetic analysis. Whole-genome assessment revealed an atypical G5-P[6]-I1-R1-C1-M1-A8-N1-T7-E1-H1 constellation. The IAL-R406 VP7 (classified in Lineage I) was closely related to G5 strains that have circulated in both humans and pigs in Brazil for nearly three decades, showing no evidence of recent variant introduction. The VP4 P[6] (assigned as Lineage I) was genetically similar to Paraguayan and Argentinian G4P[6] porcine-like strains, indicating a regional swine reservoir and zoonotic RVA spillover in South America. The remaining nine segments support the animal–human reassortant origin of IAL-R406, showing broad similarity to porcine-like human and porcine strains described worldwide, with additional relationships to bovine (Republic of Korea, USA), feline-like human (Brazil), equine (UK), simian (Caribbean), wild boar/fox (Croatia), and classical human (Japan, USA) strains. In particular, the NSP1-A8 and NSP3-T7 genotypes, extremely rare in humans yet widespread in animals, especially swine, strongly indicate interspecies reassortment, likely resulting from porcine-to-human transmission. Together, these findings reinforce swine as a persistent reservoir for zoonotic RVA infections and highlight the importance of a One Health approach integrating human and animal surveillance to better understand RVA cross-species transmission and evolution. Full article

The equine-like G3 rotavirus is a reassortant strain in which an animal-derived G3 genotype has recombined with a human-origin genetic backbone. Recently, this strain has spread across Asia and Europe. In this study, the VP7 and VP4 genes, along with the genomic backbone of 39 G3P[8] rotavirus strains detected in South Korean children with acute gastroenteritis between 2017 and May 2025, were analyzed. All strains harbored the equine-like G3 genotype for the VP7 gene, and segmental genotyping of VP7, VP4, and VP6 suggested that these strains possessed a DS-1-like genetic backbone (I2-R2-C2-M2-A2-N2-T2-E2-H2). All VP4 genes were confirmed as P[8]. Phylogenetic analysis revealed that these strains clustered with previously reported equine-like G3 strains from various regions, including East Asia. Although individual vaccination records were not available in the EnterNet surveillance data, the overall detection rate of rotavirus infection has declined following vaccine introduction. Nevertheless, equine-like G3P[8] strains have continued to appear sporadically in Korean children, underscoring the importance of ongoing genomic surveillance in the post-vaccine era. Overall, these findings indicate that equine-like G3P[8] strains with a DS-1-like backbone have been circulating for several years in the pediatric population in South Korea, offering important insights into vaccine effectiveness and the surveillance of reassortant rotaviruses. Full article

While a global downward trend in rotavirus diarrhea cases has been observed following vaccine introduction, reassortment, genetic drift, and vaccine-escaping strains remain a concern, particularly in Sub-Saharan Africa. Here, we provide genomic insights into three equine-like G3P[8] rotavirus strains detected in Benin during the post-vaccine era. Whole-genome sequencing was performed using the Illumina MiSeq platform, and genomic analysis was conducted using bioinformatics tools. The G3 of the study strains clustered within the recently described lineage IX, alongside the human-derived equine-like strain D388. The P[8] is grouped within the lineage III, along with cognate strains from the GenBank database. Both the structural and non-structural gene segments of these study strains exhibited genetic diversity, highlighting the ongoing evolution of circulating strains. Notably, we identified a novel NSP2 lineage, designated NSP2-lineage VI. Amino acid comparisons of the G3 gene showed two conservative substitutions at positions 156 (A156V) and 260 (I260V) and one radical substitution at position 250 (K250E) relative to the prototype equine-like strain D388, the equine strain Erv105, and other non-equine-like strains. In the P[8] gene, three conservative (N195G, N195D, N113D) and one radical (D133N) substitutions were observed when compared with vaccine strains Rotarix and RotaTeq. These findings suggest continuous viral evolution, potentially driven by vaccine pressure. Ongoing genomic surveillance is essential to monitor genotype shifts as part of the efforts to evaluate the impact of emerging strains and to assess vaccine effectiveness in Sub-Saharan Africa. Full article

Equine rotavirus A (RVA) is a major cause of debilitating diarrhoea in neonatal foals globally. The aim of this study was to characterise RVA viruses currently circulating in Ireland and to identify risk factors associated with disease outbreaks. Of the 377 samples submitted during 2023 and 2024, 48 foals from 36 outbreaks were confirmed to be RVA-positive by real-time PCR. The viruses detected were genotyped by VP7 and VP4 gene sequencing. In 2024, the attending veterinary surgeon was contacted, and epidemiological data were collected. These included the vaccination status of the foal’s dam and the clinician’s opinion of the hygiene standard and stocking density on the farm. During the study period, 37 G3 RVAs were detected on 26 premises and 7 G14 RVAs were detected on 6 premises. Phylogenetic analysis indicated that all the viruses characterised were of the G3A subtype and the P[12]genotype and were closely related to viruses previously identified in Europe and Japan. Farm hygiene standards and stocking rates, with some exceptions, were considered satisfactory by the clinicians. However, vaccination coverage needs to be improved as the dams of the affected foals were unvaccinated on 68% of farms. Full article

This study describes a comparison of the detection of rotavirus in clinical samples from foals using two commercially available rapid antigen detection (RAD) kits, with the detection of rotavirus nucleic acid via a laboratory-based, in-house, real-time reverse transcription polymerase chain reaction (RT-PCR) assay. One hundred and forty freeze-thawed samples (70 that were RT-PCR-positive and 70 that were RT-PCR-negative on original tests) submitted to the diagnostic laboratory over a seven-year period were tested in addition to 123 fresh samples (15 RT-PCR-positive and 108 RT-PCR-negative) submitted over a four- month period in 2024. The analyst performing the RAD tests was blinded to the RT-PCR result as were the two individuals who read the results. Samples with discordant results were re-tested in duplicate using RT-PCR and the two RAD kits. Both kits demonstrated a high level of concordance with the RT-PCR (>95%). However, testing of serial dilutions of RT-PCR positive faeces samples indicated that the RADs failed to detect the virus at the higher dilutions. In conclusion, the RADs evaluated are potentially useful for screening individual foals and for the determination of the urgency of the appropriate treatment and isolation. Negative samples from suspect cases and weak positives should always be submitted to a specialist laboratory for real-time RT-PCR testing. Full article

Rotavirus alphagastroenteritidis is the leading cause of acute gastroenteritis worldwide in young humans and animals. In 2023–2024, a relatively high rotavirus detection rate (34.5%) was detected in children with diarrhea in Caracas. All rotavirus strains were typed as P[8], using a multiplex RT-PCR assay, while the G-type was not identified. This unusual pattern, not previously observed in Venezuela, prompted the VP7 gene sequencing of nineteen strains, which displayed a high sequence identity (99.3–100%) compatible with the G3 genotype. These strains clustered into a well-supported lineage IX encompassing human reassortants of equine-like G3P[8] strains described elsewhere, showing a very close genetic relationship (99.0–99.9%). Old G3 rotavirus isolates obtained from diarrheic samples in the past were included in the analysis and grouped into lineage I together with ancestral reference G3 strains. The novel G3P[8]s carry amino acid changes in VP7-neutralizing epitopes, compared with the RotaTeq-WI78-8-vaccine strain. Full genome sequencing of a representative strain revealed a genotype constellation including an equine-like G3P[8] in a DS-1-like backbone (I2–R2–C2–M2–A2–N2–T2–E2–H2), confirming the role of animal strains as a source of diversification, and the importance of unceasingly revising molecular typing strategies and vaccine efficacy to guarantee their success. Full article

Group A rotaviruses are a well-known cause of viral gastroenteritis in infants and children, as well as in many mammalian species and birds, affecting them at a young age. This group of viruses has a double-stranded, segmented RNA genome with high genetic diversity linked to point mutations, recombination, and, importantly, reassortment. While initial molecular investigations undertaken in the 1900s suggested host range restriction among group A rotaviruses based on the fact that different gene segments were distributed among different animal species, recent molecular surveillance and genome constellation genotyping studies conducted by the Rotavirus Classification Working Group (RCWG) have shown that animal rotaviruses serve as a source of diversification of human rotavirus A, highlighting their zoonotic potential. Rotaviruses occurring in various animal species have been linked with contributing genetic material to human rotaviruses, including horses, with the most recent identification of equine-like G3 rotavirus A infecting children. The goal of this article is to review relevant information related to rotavirus structure/genomic organization, epidemiology (with a focus on human and equine rotavirus A), evolution, inter-species transmission, and the potential zoonotic role of equine and other animal rotaviruses. Diagnostics, surveillance and the current status of human and livestock vaccines against RVA are also reviewed. Full article

Equine rotavirus A (ERVA) is the leading cause of diarrhea in foals, with G3P[12] and G14P[12] genotypes being the most prevalent. Recently, equine G3-like RVA was recognized as an emerging infection in children, and a group B equine rotavirus (ERVB) was identified as an emergent cause of foal diarrhea in the US. Thus, there is a need to adapt molecular diagnostic tools for improved detection and surveillance to identify emerging strains, understand their molecular epidemiology, and inform future vaccine development. We developed a quadruplex TaqMan^® RT-qPCR assay for differentiation of ERVA and ERVB and simultaneous G-typing of ERVA strains, evaluated its analytical and clinical performance, and compared it to (1) a previously established ERVA triplex RT-qPCR assay and (2) standard RT-PCR assay and Sanger sequencing of PCR products. This quadruplex RT-qPCR assay demonstrated high sensitivity (>90%)/specificity (100%) for every target and high overall agreement (>96%). Comparison between the triplex and quadruplex assays revealed only a slightly higher sensitivity for the ERVA NSP3 target using the triplex format (p-value 0.008) while no significant differences were detected for other targets. This quadruplex RT-qPCR assay will significantly enhance rapid surveillance of both ERVA and ERVB circulating and emerging strains with potential for interspecies transmission. Full article

The introduction of rotavirus A (RVA) vaccines has considerably reduced the RVA-associated mortality among children under 5 years of age worldwide. The ability of RVA to reassort gives rise to different combinations of surface proteins G (glycoprotein, VP7) and P (protease sensitive, VP4) RVA types infecting children. During the epidemiological surveillance of RVA in the Northwest Amazon region, an unusual rotavirus genotype G6P[8] was detected in feces of a 2-year-old child with acute gastroenteritis (AGE) that had been vaccinated with one dose of Rotarix^® (RV1). The G6P[8] sample had a DS-1-like constellation with a Wa-like VP3 gene mono-reassortment similar to equine-like G3P[8] that has been frequently detected in Brazil previously. The results presented here reinforce the evolutionary dynamics of RVA and the importance of constant molecular surveillance. Full article

Rotavirus species A (RVA) is a pathogen mainly affecting children under five years old and young animals. The infection produces acute diarrhea in its hosts and, in intensively reared livestock animals, can cause severe economic losses. In this study, we analyzed all RVA genomic constellations described in animal hosts. This review included animal RVA strains in humans. We compiled detection methods, hosts, genotypes and complete genomes. RVA was described in 86 animal species, with 52% (45/86) described by serology, microscopy or the hybridization method; however, strain sequences were not described. All of these reports were carried out between 1980 and 1990. In 48% (41/86) of them, 9251 strain sequences were reported, with 28% being porcine, 27% bovine, 12% equine and 33% from several other animal species. Genomic constellations were performed in 80% (32/40) of hosts. Typical constellation patterns were observed in groups such as birds, domestic animals and artiodactyls. The analysis of the constellations showed RVA’s capacity to infect a broad range of species, because there are RVA genotypes (even entire constellations) from animal species which were described in other studies. This suggests that this virus could generate highly virulent variants through gene reassortments and that these strains could be transmitted to humans as a zoonotic disease, making future surveillance necessary for the prevention of future outbreaks. Full article

Rotavirus A (RVA) possesses a genome of 11 double-stranded (ds) RNA segments, and each segment encodes one protein, with the exception of segment 11. NSP4 is a non-structural multifunctional protein encoded by segment 10 that defines the E-genotype. From the 31 E-genotypes described, genotype E12 has been described in Argentina, Uruguay, Paraguay, and Brazil in RVA strains infecting different animal species and humans. In this work, we studied the evolutionary relationships of RVA strains carrying the E12 genotype in South America using phylogenetic and phylodynamic approaches. We found that the E12 genotype has a South American origin, with a guanaco (Lama guanicoe) strain as natural host. Interestingly, all the other reported RVA strains carrying the E12 genotype in equine, bovine, caprine, and human strains are related to RVA strains of camelid origin. The evolutionary path and genetic footprint of the E12 genotype were reconstructed starting with the introduction of non-native livestock species into the American continent with the Spanish conquest in the 16th century. The imported animal species were in close contact with South American camelids, and the offspring were exposed to the native RVA strains brought from Europe and the new RVA circulating in guanacos, resulting in the emergence of new RVA strains in the current lineages’ strongly species-specific adaption. In conclusion, we proposed the NSP4 E12 genotype as a genetic geographic marker in the RVA strains circulating in different animal species in South America. Full article

Before the introduction of vaccines, group A rotaviruses (RVA) were the leading cause of acute gastroenteritis in children worldwide. The National Rotavirus Strain Surveillance System (NRSSS) was established in 1996 by the Centers for Disease Control and Prevention (CDC) to perform passive RVA surveillance in the USA. We report the distribution of RVA genotypes collected through NRSSS during the 2009–2016 RVA seasons and retrospectively examine the genotypes detected through the NRSSS since 1996. During the 2009–2016 RVA seasons, 2134 RVA-positive fecal specimens were sent to the CDC for analysis of the VP7 and VP4 genes by RT-PCR genotyping assays and sequencing. During 2009–2011, RVA genotype G3P[8] dominated, while G12P[8] was the dominant genotype during 2012–2016. Vaccine strains were detected in 1.7% of specimens and uncommon/unusual strains, including equine-like G3P[8] strains, were found in 1.9%. Phylogenetic analyses showed limited VP7 and VP4 sequence variation within the common genotypes with 1–3 alleles/lineages identified per genotype. A review of 20 years of NRSSS surveillance showed two changes in genotype dominance, from G1P[8] to G3P[8] and then G3P[8] to G12P[8]. A better understanding of the long-term effects of vaccine use on epidemiological and evolutionary dynamics of circulating RVA strains requires continued surveillance. Full article

Sicily was the first Italian region to introduce rotavirus (RV) vaccination with the monovalent G1P[8] vaccine Rotarix^® in May 2012. In this study, the seasonal distribution and molecular characterization of RV strains detected over 19 years were compared to understand the effect of Rotarix^® on the evolutionary dynamics of human RVs. A total of 7846 stool samples collected from children < 5 years of age, hospitalized with acute gastroenteritis, were tested for RV detection and genotyping. Since 2013, vaccine coverage has progressively increased, while the RV prevalence decreased from 36.1% to 13.3% with a loss of seasonality. The local distribution of RV genotypes changed over the time possibly due to vaccine introduction, with a drastic reduction in G1P[8] strains replaced by common and novel emerging RV strains, such as equine-like G3P[8] in the 2018–2019 season. Comparison of VP7 and VP4 amino acid (aa) sequences with the cognate genes of Rotarix^® and RotaTeq^® vaccine strains showed specific aa changes in the antigenic epitopes of VP7 and of the VP8* portion of VP4 of the Italian RV strains. Molecular epidemiological surveillance data are required to monitor the emergence of novel RV strains and ascertain if these strains may affect the efficacy of RV vaccines. Full article

Equine rotavirus group A (ERVA) is one of the most common causes of foal diarrhea. Starting in February 2021, there was an increase in the frequency of severe watery to hemorrhagic diarrhea cases in neonatal foals in Central Kentucky. Diagnostic investigation of fecal samples failed to detect evidence of diarrhea-causing pathogens including ERVA. Based on Illumina-based metagenomic sequencing, we identified a novel equine rotavirus group B (ERVB) in fecal specimens from the affected foals in the absence of any other known enteric pathogens. Interestingly, the protein sequence of all 11 segments had greater than 96% identity with group B rotaviruses previously found in ruminants. Furthermore, phylogenetic analysis demonstrated clustering of the ERVB with group B rotaviruses of caprine and bovine strains from the USA. Subsequent analysis of 33 foal diarrheic samples by RT-qPCR identified 23 rotavirus B-positive cases (69.69%). These observations suggest that the ERVB originated from ruminants and was associated with outbreaks of neonatal foal diarrhea in the 2021 foaling season in Kentucky. Emergence of the ruminant-like group B rotavirus in foals clearly warrants further investigation due to the significant impact of the disease in neonatal foals and its economic impact on the equine industry. Full article