Detection and characterisation of bovine rotavirus in Ireland from 2006-2008

Molecular Epidemiology of Rotavirus A in Calves: Evolutionary Analysis of a Bovine G8P[11] Strain and Spatio-Temporal Dynamics of G6 Lineages in the Americas

Rotavirus A (RVA) causes diarrhea in calves and frequently possesses the G6 and P[5]/P[11] genotypes, whereas G8 is less common. We aimed to compare RVA infections and G/P genotypes in beef and dairy calves from major livestock regions of Argentina, elucidate the evolutionary origin of a G8 strain and analyze the G8 lineages, infer the phylogenetic relationship of RVA field strains, and investigate the evolution and spatio-temporal dynamics of the main G6 lineages in American countries. Fecal samples (n = 422) from diarrheic (beef, 104; dairy, 137) and non-diarrheic (beef, 78; dairy, 103) calves were analyzed by ELISA and semi-nested multiplex RT-PCR. Sequencing, phylogenetic, phylodynamic, and phylogeographic analyses were performed. RVA infections were more frequent in beef (22.0%) than in dairy (14.2%) calves. Prevalent genotypes and G6 lineages were G6(IV)P[5] in beef (90.9%) and G6(III)P[11] (41.2%) or mixed genotypes (23.5%) in dairy calves. The only G8 strain was phylogenetically related to bovine and artiodactyl bovine-like strains. Re-analyses inside the G8 genotype identified G8(I) to G8(VIII) lineages. Of all G6 strains characterized, the G6(IV)P[5](I) strains from "Cuenca del Salado" (Argentina) and Uruguay clustered together. According to farm location, a clustering pattern for G6(IV)P[5] strains of beef farms was observed. Both G6 lineage strains together revealed an evolutionary rate of 1.24 × 10-3 substitutions/site/year, and the time to the most recent common ancestor was dated in 1853. The most probable ancestral locations were Argentina in 1981 for G6(III) strains and the USA in 1940 for G6(IV) strains. The highest migration rates for both G6 lineages together were from Argentina to Brazil and Uruguay. Altogether, the epidemiology, genetic diversity, and phylogeny of RVA in calves can differ according to the production system and farm location. We provide novel knowledge about the evolutionary origin of a bovine G8P[11] strain. Finally, bovine G6 strains from American countries would have originated in the USA nearly a century before its first description.

Molecular surveillance of rotavirus A associated with diarrheic calves from the Republic of Korea and full genomic characterization of bovine-porcine reassortant G5P[7] strain

Group A rotavirus (RVA) is the most common diarrhea-causing pathogen among humans and animals worldwide. Rotavirus infection in neonatal calves causes major problems in the livestock industry. This study aimed to determine the prevalence and genetic diversity of bovine rotavirus (BoRVA) infections in calves with diarrhea and to perform whole genome analysis of an unusual strain, designated as RVA/Calf-wt/KOR/KNU-GJ2/2020/G5P[7], that was detected in a 2-day-old diarrheic calf. From 459 diarrheic calves aged 1-40 days, fecal samples were collected and BoRVA infections were screened using real-time RT-PCR targeting VP6 gene. BoRVA was detected in 195 (42.4%) samples and was most prevalent in calves aged 1-10 days (47.2%). No significant difference in the BoRVA infection rate was observed between calves born in herds that were (42.1%) and were not (42.6%) vaccinated against BoRVA. A binomial regression analysis revealed that calves aged 1-10 days (95% confidence intervals [CI]:1.18-24.34; P = 0.000) and 11-20 days (95% CI: 0.76-16.83, P = 0.000) had a 5.37- and 3.58-fold higher BoRVA prevalence in comparison to those aged 31-40 days, respectively. The RVA-positive samples were subsequently subjected to amplification of the VP7 and VP4 genes for determining G and P genotypes. Overall, 45 (23.1%, 45/195) and 63 (32.3, 63/195) sequences for VP7 and VP4 were obtained. In this study, four G and three P genotypes were identified. G6 (86.7%) was the most prevalent genotype, followed by G8 (8.9%), G10 (2.2%), and G5 (2.2%). P[5] (92.1%) was the most frequently detected, followed by P[11] (6.3%), and P[7] (1.6%). The G6P[5] (82.2%) is the most common combination found in Korean native calves with diarrhea, whereas G6P[11] (4.4%) and G10P[11] (2.2%) had relatively low prevalence. G8P[5] (8.9%) was identified for the first time in diarrheic calves in the KOR. The uncommon strain KNU-GJ2 exhibited a G5-P[7]-I5-R1-C1-M2-A1-N1-T1-E1-H1 genotype constellation possessing a typical porcine RVA backbone, with the exception of the VP3 gene, which is derived from bovine. Phylogenetically, except for VP3, ten gene segments of KNU-GJ2 were closely related to porcine, porcine-like, and reassortant bovine strains. Interestingly, the VP3-M2 gene of KNU-GJ2 clustered with bovine-like strains as well as reassortant porcine and bovine strains. Comparison of the NSP4s within a species-specific region of amino acids 131-141 demonstrated that KNU-GJ2 belonged to genotype B with porcine RVAs; however, it differed from porcine RVAs by one to three amino acids. The present study is fundamental to understanding the epidemiology and genotypes of circulating RVAs throughout the KOR and underscoring the importance of continuous monitoring and molecular characterization of RVAs circulating within animal populations for future vaccine development.

Detection and molecular characteristics of bovine rotavirus A in dairy calves in China

Background

Bovine group A rotavirus (BoRVA) is a major cause of severe gastroenteritis in newborn dairy calves. Only one study has investigated the G and P genotypes among dairy calves in a few regions of China, which were G6 and P[5]. Therefore, data on the prevalence and molecular characteristics of BoRVA in dairy calves in China remains limited.

Objectives

The purpose of this study was to investigate the prevalence and molecular characteristics of BoRVA in dairy calves in China.

Methods

269 dairy calves diarrheic samples from 23 farms in six provinces in China were collected to detect BoRVA using reverse transcription polymerase chain reaction.

Results

71% of samples were determined to be BoRVA-positive. Two G genotypes (G6, G10) and two P genotypes (P[1], P[5]) were identified, and G6P[1] BoRVA was the predominant strain. Moreover, the VP7 and VP4 gene sequences of these dairy calf BoRVA strains revealed abundant genetic diversity. Interestingly, eight out of 17 complete G6 VP7 sequences were clustered into G6 lineage VI and analysis showed the strains were closely related to Chinese yak BoRVA strains.

Conclusions

The results of this study show that BoRVA circulates widely among dairy calves in China, and the dominant genotype in circulation is G6P[1], first report on molecular characteristics of complete P[5] VP4 genes in chinese dairy calves. These results will help us to further understand the prevalence and genetic evolution of BoRVA among dairy calves in China and, thus, prevent the disease more effectively.

Occurrence and genetic diversity of rotavirus A in faeces of diarrheic calves submitted to a veterinary laboratory in Spain

A total of 237 faecal specimens from diarrheic calves younger than two months were collected and submitted for diagnosis of enteropathogens over a two-year period (2017-2018) to a veterinary laboratory. Samples originated from 193 dairy and beef farms in 29 provinces distributed throughout Spain, and were tested for the occurrence of three target enteric pathogens by reverse transcription real-time PCR (RT-qPCR): bovine rotavirus A (RVA), Cryptosporidium parvum and bovine coronavirus (BCoV). RT-PCR and nucleotide sequencing analysis were used to determine the G (VP7 gene) and P (VP4 gene) genotypes of 26 specimens positive for RVA. A total of 188 specimens (79.3 %) were positive for at least one of the three target enteric pathogens, and 101 samples (42.6 %) harbored mixed infections. The individual prevalence was 57.8 %, 50.6 % and 23.6 % for C. parvum, RVA and BCoV, respectively. Molecular analysis of selected RVA strains revealed the presence of the G6, G10, G3, P[5] and P[11] genotypes, with the combinations G6P[5] and G6P[11] being the most prevalent. Alignments of nucleotide sequences of the VP7 and VP4 markers showed a high frequency of single nucleotide polymorphisms (SNPs), with up to 294 SNPs found in 869bp of sequence at the G6 genotype (0.338 SNPs/nt), which reveals the extensive genetic diversity of RVA strains. Phylogenetic analysis of the VP7 gene of the G6 strains revealed four distinct lineages, with most strains clustering in the G6-IV lineage. The discrepancies between the RVA genotypes circulating in the sampled cattle farms and the genotypes contained in commercial vaccines currently available in Spain are discussed. We believe that this is the first study on the molecular characterization of rotavirus infecting cattle in Spain.

Molecular characterization of unusual G10P[33], G6P[14] genomic constellations of group A rotavirus and evidence of zooanthroponosis in bovines

Group A rotaviruses (RVA) are a major cause of diarrhea in neonatal calves and children. The present study examined G/P combinations and genetic characteristics of RVAs in diarrheic bovine calves in Western India. RVAs were detected in 27 samples (17.64%) with a predominance of G10P[11] (51.85%), followed by previously unreported genomic constellations, G6P[14] (14.81%), and, G6P[4] (7.40%) and G10P[33] (3.70%). Sequencing and phylogenetic analysis revealed circulation of G10 (Lineage-5), G6 (Lineage-2), P[11] (Lineage-3), P[14] (proposed Lineage-8) and P[4] (Lineage-3) genotypes. The predominant G10P[11] strains were typical bovine strains and exhibited genotypic homogeneity. The rare, G10P[33] strain, had VP7 and VP4 genes of bovine origin but, a resemblance of the VP6 gene with simian strain indicated possible reassortment between bovine and simian (SA11-like) strains. The VP6 and VP7 genes of two rare strains, G6P[14] and G6P[4], were identical to those of bovine stains, but the VP4 was closely related to those of the human-bovine like and human strains, respectively. Additionally, in the VP4 gene phylogenetic tree, Indian P[14] strains constituted a closely related genetic cluster distinct from the other P[14] strains. Hence Lineage-8 was proposed for them. These findings indicated that bovines could serve as a source for anthropozoonotic transmission of G6P[14] strains while zooanthroponotic transmission followed by reassortment with human strain gave rise to G6P[4] strains. The observations of a present study reinforce the potential of rotaviruses to cross the host-species barrier and undergo reassortant to increase genetic diversity which, necessitates their continuous surveillance for development and optimization of prevention strategies against zoonotic RVAs.

Immune response of mature cows subjected to annual booster vaccination against neonatal calf diarrhoea with two different commercial vaccines: A non-inferiority study

Neonatal calf diarrhoea can have important economic consequences. Scour vaccines are available against some of the most frequent pathogens responsible for this disease: Bovine Rotavirus (BoRV), Bovine Coronavirus (BoCV) and E. coli K99. In this multi-centre, randomised, blinded study, adult cows vaccinated with a trivalent vaccine marketed for years (Rotavec™ Corona, MSD Animal Health - RC) prior to last parturition were revaccinated 12–15 months later, prior to the upcoming parturition, with either a single injection of a recently marketed vaccine (Bovigen™ Scour, Virbac - BS), or RC. The aim of this trial was to verify whether BS is not inferior to RC for the stimulation of the immune response and the passive transfer to calves in these conditions.

A total of 136 multiparous dairy cows, from 5 different herds and located in 3 countries (France, UK and Germany) were enrolled in the study. Sixty-five cows were vaccinated with BS and 71 with RC. Antibody levels, measured by competitive ELISA and represented as percentage of inhibition (PI), were assessed in the cow's serum (on the day of vaccination: D0 and on days 21, 42 and at calving), in the colostrum and in the serum of calves in the first week of life. Differences in means of PI between groups and the 95% confidence interval (CI) were calculated. The non-inferiority threshold was set at −10%. The relationships between antibody levels in the colostrum and the vaccination-calving interval (VCI) or the inter-booster vaccination interval (IBVI) were also analysed.

All the lower margins of the 95% CI of the difference in means of PI, in all samples and for the 3 pathogens assessed, were above −10%. This result shows that BS is not inferior to RC for the stimulation of the immune response against BoRV, BoCV and E. coli K99 and the passive transfer of immunity to calves when this vaccine is administered to their dams previously vaccinated with RC. Furthermore, no correlation was found between PI values in the colostrum and the VCI or IBVI. The ratio of animals with a PI ≥ 95% in the colostrum, among cows with similar intervals, was not significantly different between groups, for all antigens tested.

Therefore, this study shows that a single injection of the heterologous vaccine BS can be used as a booster in cattle previously vaccinated with RC.

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Vaccinating adult cows against NCD results in high antibody levels in the serum and in the colostrum.

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Vaccination between 9 to 4 weeks prior to the expected due date results in highest antibody levels.

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Time elapsed between two annual single injections does not have consequences on antibody levels.

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Two differently adjuvanted BoRV, BoCv and F5 vaccines, was not found statistically inferior.

Longitudinal study of bovine rotavirus group A in newborn calves from vaccinated and unvaccinated dairy herds

Reports of rotavirus excretion in calves usually result from cross-sectional studies, and in face of the conflicting results regarding protection of calves born to vaccinated dams against diarrhea, the aim of the present study was to evaluate rotavirus excretion in dairy calves born to vaccinated or unvaccinated dams, to identify the genotypes of bovine rotavirus group A (RVA) strains isolated from these animals as well as to investigate characteristics of the disease in naturally occurring circumstances throughout the first month of life. Five hundred fifty-two fecal samples were taken from 56 calves, 28 from each farm and, in the vaccinated herd, 11/281 samples (3.91%) taken from six different calves tested positive for RVA while in the unvaccinated herd, 3/271 samples (1.11%) taken from 3 different calves tested positive. The genotyping of the VP7 genes showed 91.2% nucleotide sequence identity to G6 genotype (NCDV strain), and for the VP4 gene, strains from the vaccinated herd were 96.6% related to B223 strain, while strains from the unvaccinated herd were 88% related to P[5] genotype (UK strain). Genotypes found in this study were G6P[11] in the vaccinated herd and G6P[5] in the unvaccinated herd. All calves infected with rotavirus presented an episode of diarrhea in the first month of life, and the discrepancy between the genotypes found in the commercial vaccine (G6P[1] and G10P[11]) and the rotavirus strains circulating in both vaccinated and unvaccinated herds show the importance of keeping constant surveillance in order to avoid potential causes of vaccination failure.

Molecular epidemiology of rotavirus in cats in the United Kingdom

Rotaviruses are leading causes of gastroenteritis in the young of many species. Molecular epidemiological studies in children suggest that interspecies transmission contributes to rotavirus strain diversity in people. However, population-based studies of rotaviruses in animals are few. We investigated the prevalence, risk factors for infection, and genetic diversity of rotavirus A in a cross-sectional survey of cats housed within 25 rescue catteries across the United Kingdom. Morning litter tray fecal samples were collected during the winter and summer in 2012 from all pens containing kittens and a random sample of those housing adult cats. Group A rotavirus RNA was detected by real-time reverse transcription-PCR, and positive samples were G and P genotyped using nested VP4 and VP7 PCR assays. A total of 1,727 fecal samples were collected from 1,105 pens. Overall, the prevalence of rotavirus was 3.0% (95% confidence interval [CI], 1.2 to 4.9%). Thirteen out of 25 (52%; 95% CI, 31.3 to 72.2%) centers housed at least one rotavirus-positive cat. The prevalence of rotavirus was associated with season (odds ratio, 14.8 [95% CI, 1.1 to 200.4]; P = 0.04) but not age or diarrhea. It was higher during the summer (4.7%; 95% CI, 1.2 to 8.3%) than in winter (0.8%; 95% CI, 0.2 to 1.5%). Asymptomatic epidemics of infection were detected in two centers. G genotypes were characterized for 19 (33.3%) of the 57 rotavirus-positive samples and P genotypes for 36 (59.7%). Two rotavirus genotypes were identified, G3P[9] and G6P[9]. This is the first population-based study of rotavirus in cats and the first report of feline G6P[9], which questions the previous belief that G6P[9] in people is of bovine origin.