Rotavirus serotypes 6 and 10 predominate in cattle

Development and application of one-step multiplex Real-Time PCR for detection of three main pathogens associated with bovine neonatal diarrhea

Introduction

Neonatal calf diarrhea (NCD) is one of the most common diseases in calves, causing huge economic and productivity losses to the bovine industry worldwide. The main pathogens include bovine rotavirus (BRV), bovine coronavirus (BCoV), and Enterotoxigenic Escherichia coli (ETEC) K99. Since multiple infectious agents can be involved in calf diarrhea, detecting each causative agent by traditional methods is laborious and expensive.

Methods

In this study, we developed a one-step multiplex Real-Time PCR assay to simultaneously detect BRV, BCoV, and E. coli K99+. The assay performance on field samples was evaluated on 1100 rectal swabs of diseased cattle with diarrhea symptoms and compared with the conventional gel-based RT-PCR assay detect BRV, BCoV, and E. coli K99+.

Results

The established assay could specifically detect the target pathogens without cross-reactivity with other pathogens. A single real-time PCR can detect ~1 copy/µL for each pathogen, and multiplex real-time PCR has a detection limit of 10 copies/µL. Reproducibility as measured by standard deviation and coefficient of variation were desirable. The triple real-time PCR method established in this study was compared with gel-based PT-PCR. Both methods are reasonably consistent, while the real-time PCR assay was more sensitive and could rapidly distinguish these three pathogens in one tube. Analysis of surveillance data showed that BRV and BCoV are major enteric viral pathogens accounting for calves' diarrhea in China.

Discussion

The established assay has excellent specificity and sensitivity and was suitable for clinical application. The robustness and high-throughput performance of the developed assay make it a powerful tool in diagnostic applications and calf diarrhea research. ​.

Genome analyses of species A rotavirus isolated from various mammalian hosts in Northern Ireland during 2013-2016

Rotavirus group A (RVA) is the most important cause of acute diarrhoea and severe dehydration in young mammals. Infection in livestock is associated with significant mortality and economic losses and, together with wildlife reservoirs, acts as a potential source of zoonotic transmission. Therefore, molecular surveillance of circulating RVA strains in animal species is necessary to assess the risks posed to humans and their livestock. An RVA molecular epidemiological surveillance study on clinically diseased livestock species revealed high prevalence in cattle and pigs (31 per cent and 18 per cent, respectively) with significant phylogenetic diversity including a novel and divergent ovine artiodactyl DS-1-like constellation G10-P[15]-I2-R2-C2-M2-A11-N2-T6-E2-H3. An RVA gene reassortment occurred in an RVA asymptomatic pig and identified as a G5-P[13] strain, and a non-structural protein (NSP)2 gene had intergenomically reassorted with a human RVA strain (reverse zoonosis) and possessed a novel NSP4 enterotoxin E9 which may relate to the asymptomatic RVA infection. Analysis of a novel sheep G10-P[15] strain viral protein 4 gene imparts a putative homologous intergenic and interspecies recombination event, subsequently creating the new P[15] divergent lineage. While surveillance across a wider range of wildlife and exotic species identified generally negative or low prevalence, a novel RVA interspecies transmission in a non-indigenous pudu deer (zoo origin) with the constellation of G6-P[11]12-R2-C2-M2-A3-N2-T6-E2-H3 was detected at a viral load of 11.1 log10 copies/gram. The detection of novel emerging strains, interspecies reassortment, interspecies infection, and recombination of RVA circulating in animal livestock and wildlife reservoirs is of paramount importance to the RVA epidemiology and evolution for the One Health approach and post-human vaccine introduction era where highly virulent animal RVA genotypes have the potential to be zoonotically transmitted.

Rapid detection of bovine rotavirus a by isothermal reverse transcription recombinase polymerase amplification assays

Background

Bovine rotavirus A (BRVA) is considered to be the most common pathogen of severe diarrhea in cattle worldwide, which could lead to the death of newborn calves and cause the significant economic losses to the cattle industry. As a novel isothermal nucleic acid amplification technique, recombinase polymerase amplification (RPA) has been applied widely for the rapid detection of different important pathogens in human and animals.

Results

An RT-RPA assay based on the real time fluorescence monitoring (real-time RT-RPA) and an RT-RPA assay combined with a lateral flow strip (LFS RT-RPA) were successfully developed by targeting the VP6 gene of BRVA. The RT-RPA assays allowed the exponential amplification of the target fragment in 20 min. After incubation of the LFS RT-RPA on a metal bath at 40 °C, the results were displayed on the lateral flow strip within 5 min, while real-time RT-RPA allowed the real-time observation of the results in Genie III at 42 °C. Both of the two assays showed high specificity for BRVA without any cross-reaction with the other tested pathogens causing diarrhea in cattle. With the standard RNA of BRVA serving as a template, the limit of detection for real-time RT-RPA and LFS RT-RPA were 1.4 × 10² copies per reaction and 1.4 × 10¹ copies per reaction, respectively. In the 134 fecal samples collected from cattle with diarrhea, the BRVA positive rate were 45.52% (61/134) and 46.27% (62/134) in real-time RT-RPA and LFS RT-RPA, respectively. Compared to a previously published real-time PCR, the real-time RT-RPA and LFS RT-RPA showed a diagnostic specificity of 100%, diagnostic sensitivity of 98.39% and 100%, and a kappa coefficient of 0.985 and 1.0, respectively.

Conclusions

In this study, BRVA was successfully detected in cattle fecal samples by the developed real-time RT-RPA and LFS RT-RPA assays. The developed RT-RPA assays had great potential for the rapid detection of BRVA in under-equipped diagnostic laboratory and the point-of-need diagnosis at quarantine stations and farms, which is of great importance to control BRVA-associated diarrhea in cattle herds.

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.

•

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

•

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

•

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

•

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

Rotavírus bovino: fatores de risco, prevalência e caracterização antigênica de amostras em rebanhos leiteiros no estado de São Paulo

O estudo de prevalência da infecção por rotavírus em bezerros abrangeu 51 rebanhos leiteiros, escolhidos ao acaso, localizados em uma região produtora de leite do estado de São Paulo. Entre 31 de maio e 20 de outubro de 2003, foram colhidas 103 amostras de fezes de bezerros com diarreia e 308 amostras de animais sem diarreia, com idade entre um e 45 dias. As amostras foram analisadas pelas técnicas de ensaio imunoenzimático (EIE) e eletroforese em gel de poliacrilamida (PAGE). Pelo EIE foi observada prevalência de rotavírus de 21,6% (11/51) nos rebanhos e 6,7% (27/404) nos bezerros. Foram diagnosticados animais infectados por rotavírus tanto em bezerros diarreicos (18,4%; 19/103) quanto em bezerros assintomáticos (2,7%; 8/301). A maior frequência de infecção foi determinada em bezerros com idade entre um e 15 dias, sendo estabelecida uma relação inversa entre a frequência de positividade e a idade dos animais (P<0,05). Além da idade, o sistema de alimentação - fornecimento manual do leite ou bezerro com a mãe, o tipo de instalação - baias individuais ou baias coletivas - e o tamanho do rebanho -, número de matrizes foram fatores que influenciaram significativamente a frequência da infecção (P<0,05). O RNA extraído de 27 amostras pelo PAGE foi classificado em sete eletroferótipos, indicando grande diversidade genômica de rotavírus. A genotipagem das amostras positivas para rotavírus foi realizada pelo método de transcrição reversa-reação da polimerase em cadeia, destacando a presença de infecções pelos genótipos G6P[5] e G10P[11].

Ovine rotavirus strain LLR-85-based bovine rotavirus candidate vaccines: construction, characterization and immunogenicity evaluation

Group A bovine rotaviruses (BRVs) are the most important cause of diarrheal diseases in neonatal calves and cause significant morbidity and mortality in the young animals, and epidemiologic surveillance of bovine rotavirus G genotypes conducted in various cattle populations throughout the world has shown that approximately 90% of the bovine rotavirus isolates belong to G6 and G10. Based on the modified Jennerian approach to immunization, we constructed and characterized a reassortant rotavirus stain, which bears a single bovine rotavirus VP7 gene encoding G genotype 6 specificity while the remaining 10 genes are derived from the ovine attenuated rotavirus LLR-85. The reassortant rotavirus strain, named as R191, and its parental virus strain LLR-85 were combined as bivalent vaccine candidates to inoculate the colostrums-deprived neonatal calves for evaluation of the immunogenicity. The calves were orally inoculated with the reassortant R191 (group 1), the parental rotavirus LLR-85 (group 2), or combined the R191 and LLR-85 (group 3), and serum specimens were detected to determine the immune response of IgG and IgA antibodies. Results showed that seroconversion to positivity for IgG and IgA antibodies occurred at postinoculation day (PID) 10 in all of the inoculated calves, and the highest titers of the serum IgG (range 1:800 to 1:6400) and IgA (range 1:800 to 1:3200) antibodies were obtained at PID 21 for all calves. Meanwhile, virus shedding was detected after inoculation, showing that the inoculated virus was positive in 2 of 77 fecal specimens (2.6%) collected from the inoculated calves during the first 7 days of oral inoculation with the rotavirus vaccine candidates. The results suggested that the rotavirus strains R191 and LLR-85 are promising bivalent vaccine candidates for the prevention of bovine G6 and G10 rotavirus infection.

Changing profile of the bovine rotavirus G6 population in the south of Ireland from 2002 to 2009

Bovine group A rotavirus is one of the main causes of neonatal diarrhoea in calves. This study examined the different G and P genotypes circulating in the bovine population, from 2002-2009, in the south of Ireland. Rotavirus positive bovine faecal samples (n=332) were collected from the Cork Regional Veterinary Laboratory, between 2002 and 2009 and subjected to RNA extraction, PAGE analysis, and G and P genotyping. Genotyping analysis identified G6, G10, P[5], and P[11] to be the predominant G and P genotypes in the present study, with G6 rotavirus responsible for 70-80% of rotavirus infections. The highest combination of G and P types found was G6 P[5], followed by G6 P[5+11] mixed infection. The prevalence of G6 and G10 has shifted over the years, with an increase in the amount of G10 P[11] being detected. Novel combinations (G6+G10P[11], G6+G10P[5+11] and G10P[5+11]) were also detected for the first time. In addition to this, sequence analysis of the VP7 RT-PCR amplicons has revealed that Irish G6 strains are falling within three different lineages, III-V. During this study, two samples, initially genotyped as G8P[11] were identified through sequence analysis as being true G6, lineage III with a high nucleotide identity to Hun4, a G6 human sample from Hungary. The increase in novel G and P type combinations, as well as changes seen in G6 samples could have an impact on rotavirus vaccination programmes, as the current vaccine available may not offer protection against all of these circulating types.

Molecular characteristics of German G8P[4] rotavirus strain GER1H-09 suggest that a genotyping and subclassification update is required for G8

A rare G8P[4] rotavirus, designated GER1H-09, was detected in a stool sample from an infant suffering from repeated episodes of emesis for 2 days without diarrhea. Sequencing of all genomic RNA segments was performed, and complete coding sequences were determined. The VP7 amino acid sequence revealed a close phylogenetic relationship to human G8P[6] and G8P[8] isolates from Slovenia and Africa. GER1H-09 shared typical amino acid residues within variable regions VR3 to VR7 with those strains, and their subclassification as lineage G8-II rotaviruses is proposed. The variability in VR3 was identified as the likely reason for the failure in genotyping G8-II rotaviruses by commonly used multiplex PCR. Furthermore, the sequences of associated structural and nonstructural proteins showed high amino acid identities to DS-1-like rotaviruses. The genotype composition of GER1H-09 (G8-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2) suggests the occurrence of reassortment events between G8 genotypes and human DS-1-like G2P[4] rotaviruses.

A longitudinal cohort study in calves evaluated for rotavirus infections from 1 to 12 months of age by sequential serological assays

Using an immunocytochemical staining assay involving six different recombinant baculoviruses with each expressing one of the major bovine rotavirus VP7 (G6, G8 and G10) and VP4 (P6[1], P7[5] and P8[11]) serotypes, we analyzed IgG antibody responses to individual proteins in archival serum samples collected from 31 calves monthly from 1 to 12 months of age during 1974-1975 in Higley, Arizona. Seroresponses to VP7 and VP4, as determined by a fourfold or greater antibody response, were not always elicited concurrently following infection: in some calves, (1) seroresponses to VP7 were detected earlier than to VP4 or vice versa; and (2) a subsequent second seroresponse was detected for VP7 or VP4 only. In addition, a second infection was more likely to be caused by different G and/or P types. Analyses of serum samples showed that the most frequent G-P combination was G8P6[1], followed by G8P7[5], G8P8[11] and G6P6[1].

OCORRÊNCIA DOS GENÓTIPOS G E P DE ROTAVÍRUS DO GRUPO A EM BEZERROS DE REBANHOS DE CORTE NO ESTADO DE SÃO PAULO, BRASIL

RESUMO Foi determinada a ocorrência de rotavírus do grupo A e a caracterização molecular G e P de estirpes detectadas em bezerros de rebanhos de corte em propriedades rurais do Estado de São Paulo, Brasil. Foram analisadas amostras de fezes de 649 bezerros de 14 rebanhos de corte com idade entre 1 e 60 dias, independentemente da manifestação clínica de diarréia, colhidas de julho de 2003 a julho de 2004. Por meio das técnicas de ELISA e de eletroforese em gel de poliacrilamida (PAGE), determinou-se a ocorrência de rotavírus do grupo A em 64,3% (09/14) dos rebanhos e em 6,2% (40/649) dos animais. A maior freqüência de infecção foi detectada em animais com idade entre 16 e 30 dias (10,5%). Foram diagnosticados bezerros infectados por rotavírus tanto em animais com sinais clínicos de diarréia (25,8%; 22/85) quanto naqueles assintomáticos (3,2%; 18/ 564), existindo, porém, uma correlação entre a presença da infecção e a manifestação clínica da diarréia (p < 0,01). A análise do perfil do genoma do rotavírus por PAGE identificou sete eletroferótipos distintos, indicando grande diversidade genômica dos rotavírus na região estudada. A genotipagem pela reação em cadeia da polimerase (RT-PCR) das amostras de rotavírus revelou que as estirpes circulantes nos rebanhos eram G6P[5], G6P[11], G6P[5]P[11] e G10P[11].

Rotavirus diarrhea in bovines and other domestic animals

Rotavirus diarrhea is the major cause of death of millions of children in developing countries besides causing economically significant malady in neonates of many domestic animals. In neonates, the infection is non-viremic, have very short incubation period, and manifests profuse diarrhea and severe dehydration. Concurrent infection with secondary pathogens may augment the disease severity. Diarrhea occurs due to virus-mediated destruction of absorption efficient enterocytes, activation of enteric nervous system, or due to a rotavirus enterotoxin. Diagnosis of the infection relies on conventional techniques like isolation in MA 104 cell lines, electron microscopy, electro-pherotyping, and various serological tests. Presently, diagnosis and molecular typing is performed using serotype specific RT-PCR, sequencing or genomic hybridization techniques. As the rotaviruses are known to exhibit extreme genetic diversity and outplay disinfection procedures, eradication of the pathogen is often difficult. Hence, for prevention, good management practices coupled with vaccination of dam for protecting young ones, has to be practiced. Recently, new generation prophylactic strategies including DNA vaccines, subunit vaccines, virus-like particles (VLPs) and edible vaccines have been found to induce sufficient levels of passive immunity. Aside to the infection in animals, zoonotic significance of the animal rotaviruses has to be further unearthed. In this review, efforts have been made to highlight the importance and prevalence of the disease in bovines, its pathogenesis along with preventive measures, salient features of rotaviruses and their inter-species transmission abilities, zoonotic implications, and a concise account of the infection in various domestic animals and poultry.

Unexpected substitution of dominant rotavirus G genotypes in French hospitalized children over five consecutive seasons

The study was designed to evaluate the circulation of group A rotaviruses in French hospitalized children, and to detect unusual strains. This prospective study was conducted from 2001 to 2006 in children consulting for acute diarrhea at the pediatric emergency department in three French University Hospitals. The rotaviruses were detected by rapid test and genotyped by RT-PCR on the basis of their outer capsid proteins VP4 (P-type) and VP7 (G-type). The stools from 757 children were analyzed. G1P[8] strains were predominant (44.0%), followed by G9P[8] (17.7%), G3P[8] 13.1%, G4P[8] (9.5%), and G2P[4] (1.8%); mixed rotavirus infections occurred in 2.3%. G9 rotaviruses emerged during the 2004-2005 season (73.4%) and remained the second most prevalent strains. Few unusual strains, G6, G8, G12 and P[6]-types, were detected. The monitoring of rotavirus infections should be maintained to document strain distribution and to assess the emergence of new reassortants that may not respond to current rotavirus vaccines.

Human, porcine and bovine rotaviruses in Slovenia: evidence of interspecies transmission and genome reassortment

A surveillance of human, porcine and bovine rotaviruses was carried out in Slovenia in 2004 and 2005. Stool samples were collected from a total of 406 pigs (373 from asymptomatic animals), 132 cattle (126 from asymptomatic animals) and 241 humans (all with diarrhoea), tested for group A rotaviruses using RT-PCR and analysed by sequencing. The aims of the study were to determine the incidence of asymptomatic rotavirus infection in animals, to look for evidence of zoonotic transmission and to detect reassortment among rotaviruses. The rates of asymptomatic shedding of rotaviruses in pigs and cattle were 18.0 % (67/373) and 4.0 % (5/126), respectively. Evidence for zoonotic transmission was detected in one human rotavirus strain, SI-MB6, with the G3P[6] genotype combination, as the nucleotide and predicted amino acid sequences of the VP6, VP7, VP8* and NSP4 genes of strain SI-MB6 and of porcine strains showed high nucleotide and amino acid sequence identity. Two porcine rotavirus strains carried VP7 of probable human origin, suggesting an interspecies reassortment event in the past.

Molecular characterisation and analysis of bovine rotavirus strains circulating in Ireland 2002–2004

One hundred and two faecal samples were collected from calves diagnosed with rotavirus infection, in the southern region of Ireland, from 2002 to 2004. Ninety one percent (n=93) were confirmed positive for rotavirus, using latex agglutination and enzyme linked immunosorbent assay (ELISA) methods. Determination of the G- and P-types was carried out using nested reverse transcriptase polymerase chain reaction (nRT-PCR). G6 was the most prevalent genotype, accounting for 80.6% (75/93), G10 accounted for 6.5% (6/93) and G6G10 mixed types accounted for 9.7% (9/93) of the collection. Rotavirus in three of the samples (3.2%) could not be characterised with any of the five G-specific primers used in this study. A subset of the positive samples (n=54) was examined for their P-type specificities, P[5] and P[11] accounted for 77.8% (42/54), and 9.3% (5/54), respectively. One P[1] genotype (1.9%) was found in the collection. P[5] and P[11] mixed genotypes accounted for 11% (6/54) of the study. The genotypes corresponded to the UK-like strain (G6P[5]) 57.4%, KN4-like strain (G6[P11]) 7.4%, B223-like strain (G10P[11]) and NCDV-like strain (G6P[1]) 1.9% each. The unusual combination of G10P[5] accounted for 7.4%, with mixed infections G6+G10P[5] and G6P[5]+P[11] representing 13% and 11%, respectively. This is the first time that the G- and P-types of bovine rotaviruses (BRVs) have been determined in Ireland, and this study contributes to a better understanding of the epidemiology of such viruses circulating in Ireland.

A rotavirus strain isolated from pig-tailed macaque (Macaca nemestrina) with diarrhea bears a P6[1]:G8 specificity

A distinct rotavirus strain (PTRV) was isolated in cell cultures from a stool sample obtained from a diarrheic 3-year-old female pig-tailed macaque (Macaca nemestrina) that was born at the breeding colony of the University of Washington in Seattle. Unlike other known simian rotavirus strains including vervet monkey rotavirus SA11 which bears P5B[2]:G3 or P6[1]:G3 specificity, rhesus monkey rotavirus MMU18006 with P5B[3]:G3 specificity, pig-tailed macaque rotavirus YK-1 with P[3]:G3 specificity and rhesus monkey rotavirus TUCH with P[24]:G3 specificity, the cell-culture-grown PTRV strain was shown to bear P6[1]:G8 specificity as determined by VP4 (P)- and VP7 (G)-specific neutralization assays as well as gene sequence analyses. The virus in the original diarrhea stool was also shown to bear genotypes P[1] and G8. In addition, the PTRV strain exhibited a "long" electropherotype, subgroup I specificity and NSP4 genotype A specificity. The PTRV probe formed (i) 8-9 hybrid bands with genomic RNAs of various bovine rotavirus strains and (ii) only 2-3 hybrid bands with simian rotavirus RNAs as demonstrated by RNA-RNA hybridization, suggesting a possible bovine origin of the virus. Serologic analysis of serum samples obtained from selected pig-tailed macaques in the colony suggested that a rotavirus bearing P[1]:G8 specificity was endemic among macaques for at least 8 years (1987-1994). This is the first report describing an isolation of a simian rotavirus bearing a non-G3 VP7 and possibly a P6[1] specificities. Because of its unique simian serotype, this virus may prove to be valuable in challenge studies in a non-human primate model in studies of rotavirus immunity.

Molecular characterization of novel P[14],G8 bovine group A rotavirus, Sun9, isolated in Japan

In this study, a novel bovine group A rotavirus (RV-A), Sun9, isolated from calf diarrhea in the Tochigi Prefecture, Japan, was characterized genetically by the sequence analysis of the genome segments encoding VP4 and VP7. The nucleotide and deduced amino acid sequences of the genome segments encoding VP4 and VP7 of Sun9 revealed high homology with P[14] human and lapine RV-As (80.2-88.7% and 90.9-94.8%) and G8 bovine and human RV-As (83.1-95.5% and 92.3-98.2%). Sun9 was also classified into P[14] and G8 in the phylogenetic analysis of the nucleotide sequences of the genome segments encoding VP4 and VP7. Although previous reports have suggested that P[14],G8 human RV-As isolated until now were obtained from the reassortment between human and bovine RV-As, or the interspecies transmission of bovine RV-A to human, no P[14],G8 bovine RV-A has yet been reported. Sun9 may be initial direct evidence of the above hypothesis.

Survey of rotavirus infection in a Hungarian paediatric hospital. A short communication

In anticipation of a future vaccination program against rotavirus disease, a longitudinal survey has been set up to evaluate the epidemiologic features of rotavirus infections. In this report hospitalisation data and serotyping results are compiled from an epidemiologic survey conducted in Baranya County, Hungary. It was found that rotavirus-associated hospitalisation constituted a major part of infectious gastroenteritis cases (range, 14.9% to 28.5%). A higher proportion of rotavirus-positive cases was recorded when the serotype of predominant strains changed from G1 (1996-1999) to G4 (1999-2000), however, due to the short time period it was not possible to demonstrate a firm association between serotype prevalence and rotavirus-associated hospitalisation rate. In the future, such studies might help to understand if serotype-specific immunity against rotavirus infection plays an important role at the population level and if (re-)emerging rotavirus strains make an impact on the annual disease burden.

G and P genotypes of group A rotavirus strains circulating in calves in Brazil, 1996–1999

Fifty fecal samples from calves with diarrhea, positive for group A rotavirus by enzyme immunoassay (EIA) and polyacrylamide gel electrophoresis (PAGE) were analyzed by a nested multiplex reverse transcription/polymerase chain reaction (Nested multiplex/RT-PCR) for identification of P and G genotypes. Samples were collected between 1996 and 1999 from eight dairy and/or beef cattle herds located in the Mato Grosso do Sul, São Paulo, Goiás and Paraná States, Brazil. Complete genotyping was possible in 44 (88%) of the calf fecal samples. The VP7 gene could not be identified in six (12%) of the samples. Whilst the VP4 (P) gene was identified in 100% of samples. The genotypes of 35 (70%) samples corresponded to the NCDV-like (12%), UK-like (40%), B223-like (16%) and KN-4 (2%) reference rotavirus strains, which are commonly found in cattle. Mixed infections were detected in seven (14%) samples, and genotypes observed in two (4%) samples presented unusual combinations, carrying VP4 and VP7 gene of the bovine group A rotavirus (P[11],G8), in other one carrying a VP4 gene of bovine origin (P[1]) and a VP7 gene of swine origin (G5).

Eight-year survey of human rotavirus strains demonstrates circulation of unusual G and P types in Hungary

Between 1992 and 2000, a total of 4173 rotavirus-positive samples were collected from two areas of Hungary. Of these, 2020 specimens (48.4%) were analyzed for G serotype, using monoclonal antibody-based immunoassay and reverse transcription-PCR. By the two methods, 1789 samples were specified as G1 (62%), G2 (12.2%), G3 (1.4%), G4 (6.4%), G6 (1.0%), G9 (2.9%), or mixed infection (2.6%), and the remaining 231 (11.4%) could not be G typed. The linkage between G and P type, subgroup specificity, and RNA profile was investigated with a sample subset. Among these specimens, we identified both the four globally common strains (P[8],G1 subgroup II (sgII); P[4],G2 sgI; P[8],G3 sgII; and P[8],G4 sgII) and six uncommon strains (P[6],G4 sgII; P[9],G3 sgI; P[9],G6 sgI; P[14],G6 sgI; P[8],G9 sgII; and P[8],G9 sgI). All strains with P[8], P[6], P[9], and P[14] specificities had a long electropherotype, whereas most of those carrying a P[4] specificity were associated with a short electropherotype. Although once considered to be rare, P[9],G6 and P[8],G9 rotavirus strains represent potentially important new serotypes in Hungary.

Genetic and Serological Characterization of Novel Serotype G8 Bovine Group A Rotavirus Strains Isolated in Japan

G8 bovine group A rotaviruses isolated in Japan were genetically and serologically characterized. The VP7 gene nucleotide and amino acid sequences revealed high identity with each other. All Japanese G8 strains were classified into the same lineage in the phylogenetic analysis based on VP7 gene sequences. Antisera to four Japanese G8 strains neutralized other G8 strains, but their neutralizing titers were between 8-fold lower and 2-fold higher than homologous strains. These results suggest that the VP7s of Japanese G8 strains have similar genetic and serologic characteristics. Observed differences in the neutralizing abilities of antisera for each strain appear to depend on differences in the P serotypes/genotypes.

Human rotavirus strains bearing VP4 gene P[6] allele recovered from asymptomatic or symptomatic infections share similar, if not identical, VP4 neutralization specificities

A rotavirus VP4 gene P[6] allele has been documented in a number of countries to be characteristically associated with an endemic predominantly asymptomatic infection in neonates in maternity hospital nurseries. The mechanisms underlying the endemicity and asymptomatic nature of such neonatal infections remain unknown. Rotavirus strains sharing this same P genotype, however, have more recently been recovered from an increasing number of symptomatic diarrheal episodes in infants and young children in various parts of the world. Previously, we have shown that an asymptomatic P[6] rotavirus neonatal infection is not associated with a unique VP7 (G) serotype but may occur in conjunction with various G types. Although amino acid sequence comparisons of the VP4 gene between selected "asymptomatic" and "symptomatic" P[6] rotavirus strains have been reported and yielded information concerning their VP4 genotypes, serotypic comparisons of the outer capsid spike protein VP4 of such viruses have not been studied systematically by two-way cross-neutralizations. We determined the VP4 neutralization specificities of four asymptomatic and four symptomatic P[6] strains: two each of asymptomatic and symptomatic strains by two-way tests, and two each of additional asymptomatic and symptomatic strains by one-way tests. Both asymptomatic and symptomatic P[6] strains were shown to bear similar, if not identical, VP4 neutralization specificities. Thus, P[6] rotavirus strains causing asymptomatic or symptomatic infections did not appear to belong to unique P (VP4) serotypes. In addition, a close VP4 serotypic relationship between human P[6] rotavirus strains and the porcine P[6] rotavirus Gottfried strain was confirmed.

Close relationship between G8-serotype bovine and human rotaviruses isolated in Nigeria

A bovine rotavirus, NGRBg8, isolated from the feces of a calf with diarrhea in Nigeria was characterized by reverse transcription-PCR, nucleotide sequence analysis, and Northern blot hybridization. The nucleotide sequence of the VP7 gene of the strain was most closely related to that of a Nigerian human G8-serotype strain, HMG035 (99.9%). The NSP1 gene of strain NGRBg8 is highly related (99.4%) to that of a Thai G8 bovine strain, A5-10. Northern blot hybridization revealed a high overall genomic relatedness of bovine strain NGRBg8 with human strain HMG035; all 11 RNA segments hybridized to each other. Thus, the results show the close relationship between G8 bovine and human rotaviruses in Nigeria.

Genetic analysis of Group A rotaviruses: evidence for interspecies transmission of rotavirus genes

Rotaviruses are the major cause of severe gastroenteritis in young children and animals. The rotavirus genome is composed of eleven segments of double-stranded RNA and can undergo genetic reassortment during mixed infections, leading to progeny viruses with novel or atypical phenotypes. There are numerous descriptions of rotavirus strains isolated from human and animals that share genetic and antigenic features of viruses from heterologous species. In many cases, genetic analysis by hybridization has clearly demonstrated the genetic relatedness of gene segments to those from viruses isolated from different species. Together with the observation that some virus strains appear to have been transmitted to a different species as a whole genome constellation, these data suggest that interspecies transmission occurs naturally, albeit at low frequencies. Although interspecies transmission has not been documented directly, there is an increasing number of reports of atypical rotaviruses that are apparently derived from transmission between: humans, cats and dogs; humans and cattle; humans and pigs; pigs and cattle; and pigs and horses. Interspecies evolutionary relationships are supported by phylogenetic analysis of rotavirus genes from different species. The emergence of novel strains derived from interspecies transmission has implications for the design and implementation of successful human rotavirus vaccine strategies.

Construction and characterization of rhesus monkey rotavirus (MMU18006)- or bovine rotavirus (UK)-based serotype G5, G8, G9 or G10 single VP7 gene substitution reassortant candidate vaccines

Group A rotaviruses are the single most important etiologic agents of severe diarrhea of infants and young children worldwide and have been estimated to be responsible for approximately 650,000-800,000 deaths annually in children <5-year-old in the developing countries. Thus, the development of a safe and effective rotavirus vaccine has been a global public health goal. Epidemiologic surveillance of rotavirus VP7 (G) serotypes-genotypes conducted in various populations throughout the world has repeatedly shown that approximately 90% of the typeable rotavirus isolates belong to G1-G4. For these reasons, we have developed a rhesus rotavirus (RRV)-based or bovine rotavirus (UK)-based quadrivalent vaccine which is designed to provide antigenic coverage for G1-G4. More recently, G serotypes-genotypes other than G1-G4, including G5, G8-G10, have been detected in various parts of the world. Although the occurrence of such uncommon G types, except for G9, has been focal, still, in order to "be ready and prepared", we have constructed and characterized eight additional reassortant rotavirus vaccines, each of which bears a single human or bovine VP7 gene encoding G serotype 5, 8, 9 or 10 specificity and the remaining 10 genes of RRV strain MMU18006 or bovine rotavirus strain UK. These candidate vaccines could be evaluated singly in special populations or in combination with a RRV- or an UK-based quadrivalent vaccine to broaden its G serotype specificity.

Prevalência de rotavírus do grupo A em fezes diarréicas de bezerros de corte em sistema semi-intensivo de produção

Determinou-se a prevalência de rotavírus durante surto de diarréia em bezerros de um rebanho de corte, criado em regime semi-intensivo de produção. Analisaram-se, por meio de técnicas de eletroforese em gel de poliacrilamida (EGPA) e ensaio imunoenzimático (kit EIARA - Fiocruz), 69 amostras de fezes de bezerros, entre 30 e 60 dias de idade, colhidas em três estações de parição consecutivas (agosto a novembro/1999, janeiro a abril e agosto a novembro/2000). Pelo EIARA foram detectadas 63,8% (44/69) de amostras positivas. Na primeira estação de parição foi detectado rotavírus em 82,4% (14/17) dos bezerros que apresentaram quadro clínico de diarréia. No ano de 2000 a presença de rotavírus foi detectada em 41,7% (5/12) e 62,5% (25/40) do total de amostras examinadas. A análise do perfil eletroforético do genoma indicou grande diversidade, com quatro eletroferótipos distintos, todos com perfil longo, característico de rotavírus do grupo A.

Genetic characterization of a novel, naturally occurring recombinant human G6P[6] rotavirus

A binary classification system has been established for group A rotaviruses, with the viral capsid protein VP7 defining G types and VP4 defining P types. At least 15 G types and 21 P types have been isolated globally with various G and P combinations. Most of the currently circulating human rotaviruses belong to G1P[8], G2P[4], G3P[8], and G4P[8]. We report a human rotavirus strain (B1711) with a novel genotypic VP7/VP4 combination of G6P[6]. This unique rotavirus was isolated from a 13-month-old human immunodeficiency virus (HIV)- negative child of an HIV-seropositive Malian mother that was hospitalized with severe diarrhea in Belgium after returning from a trip to Mali. The VP7 and VP4 genes of the rotavirus strain were sequenced, and phylogenetic trees were constructed. Nucleotide and amino acid sequence comparisons with 15 known G genotypes indicated that the VP7 sequence of strain B1711 was most closely related to an American (Se584) and an Italian (PA151) human G6 strain (95 to 96% nucleotide and 98% amino acid identity). Comparison of the VP4 sequence with 21 P types showed the closest similarity to P[6] genotypes, with greatest similarity to a G8P[6] Malawi strain (mw131) (97% nucleotide and 98% amino acid identity). The B1711 strain is the first reported rotavirus isolate with a G6P[6] genotypic combination. The discovery and surveillance of novel human and nonhuman rotavirus G or P types or of novel G/P combinations is essential for the design of future rotavirus vaccines and for our understanding of rotavirus diversity and evolution.

Expanding distribution of human serotype G6 rotaviruses in Australia

Serotype G6 rotaviruses are common pathogens of cattle but are rarely found in humans. In Australia, human G6 isolates have previously been detected in two major southern population centres. A new isolate, ASG6.02, was detected in central Australia (Alice Springs) in 1997. Comparison of the deduced amino acid sequence of the major neutralizing antigen, VP7, indicated that ASG6.02 was related to human G6 viruses isolated from children in Italy and Australia. Phylogenetic analysis supported the close relationship between ASG6.02 and other Australian isolates and indicated that G6 VP7 sequences generally clustered according to the species of origin (human, bovine or porcine). The VP4 type of ASG6.02 was determined as P-type [14], in common with other isolates from Australia and Italy. The detection of ASG6.02 indicates that the distribution of this serotype is increasing in this country and may have implications for successful vaccine development.

Generation and characterization of six single VP4 gene substitution reassortant rotavirus vaccine candidates: each bears a single human rotavirus VP4 gene encoding P serotype 1A[8] or 1B[4] and the remaining 10 genes of rhesus monkey rotavirus MMU18006 or bovine rotavirus UK

The global disease burden of rotavirus diarrhea in infants and young children has stimulated interest in the biological and clinical characteristics of these agents, leading to intensive efforts to develop a vaccine. A rhesus rotavirus (RRV)-based quadrivalent vaccine ("RotaShield") was licensed and administered to about 1 million infants and found to be highly effective. However, it was withdrawn because of a link with intussusception. This vaccine was developed according to a modified "Jennerian" approach in which one of the two major outer capsid proteins (VP7) shares neutralization specificity with one of the four epidemiologically important human rotavirus serotypes. The other outer capsid protein (VP4) is derived solely from RRV and is distinct from the VP4 of the four human rotavirus serotypes of epidemiologic importance. In an effort to further increase the immunogenicity of the existing VP7-based RRV quadrivalent vaccine, we generated three single VP4 gene substitution reassortant rotavirus candidate vaccines, each of which bears a single human rotavirus VP4 gene encoding P serotype 1A[8] or 1B[4] specificity while the remaining 10 genes are derived from the rhesus rotavirus. By incorporating one or two of these strains into the quadrivalent vaccine, a pentavalent or hexavalent RRV-based vaccine could be formulated thus providing antigenic coverage not only for VP7 serotype 1, 2, 3 and 4 but also for VP4 serotype 1A[8] or 1B[4], thus possibly augmenting its immunogenicity. Similarly, three single VP4 gene (P1A[8] or P1B[4]) substitution reassortants have also been generated in a background of 10 bovine (UK) rotavirus genes for addition to a second generation UK-based quadrivalent vaccine.

Characterization of neutralization specificities of outer capsid spike protein VP4 of selected murine, lapine, and human rotavirus strains

Neutralization specificities of outer capsid spike protein VP4 of murine rotavirus strains EW (P?[16],G3) and EHP (P?[20],G3) and lapine rotavirus strains Ala (P?[14],G3), C11 (P?[14],G3), and R2 (P?[14],G3) as well as human rotavirus strains PA169 (P?[14],G6) and HAL1166 (P?[14],G8) were determined by two-way cross-neutralization. This was done by generating and characterizing (i) three murine x human, three lapine x human, and two human x human single gene substitution reassortant rotaviruses, each of which bore identical human rotavirus DS-1 strain VP7 (G2), and (ii) guinea pig hyperimmune antiserum raised against each reassortant. Reference rotavirus strains employed in the study represented 10 established VP4 (P) serotypes, including 1A[8], 1B[4], 2A[6], 3[9], 4[10], 5A[2], 5B[2], 5B[3], 6[1], 7[5], 8[11], 9[7], and 10[16] as well as a P serotype unknown P[18]. Murine rotavirus strains EW and EB were demonstrated to share the same P serotype (P10[16]) distinct from (i) 9 established P serotypes, (ii) lapine and human rotavirus strains bearing the P[14] genotype, and (iii) an equine rotavirus strain bearing the P[18] genotype. Both lapine (Ala, C11, and R2) and human (PA169 and HAL1166) rotaviruses were shown to belong to the same VP4 serotype, which represented a distinct new P serotype (P11[14]). P serotype 13[20] was assigned to murine rotavirus EHP strain VP4, which was shown to be distinct from all the P serotypes/genotypes examined in the present study.

Changes in the prevalence of rotavirus G and P types in diarrheic calves from the Kagoshima prefecture in Japan

G8 bovine group A rotavirus was the most predominant serotype in calf diarrheal fecal specimens examined between 1995 and 1996 in Japan [Vet. Microbiol. 66 (1999) 301]. To date, no evidence that G8 was the most predominant in the typeable specimens has been observed outside Japan. To investigate whether G8 continues to be as common as G6 and G10, the incidence of the main serotypes was determined in the same area (Kagoshima prefecture) between 1997 and 1998 by reverse transcription-polymerase chain reaction. From a total of 104 rotavirus-positive specimens, we successfully identified G type in 79 (76.0%) and P type in 71 (68.3%). The combination of G and P types varied periodically; in 1995, G10P[11] was most common. The most predominant types changed drastically in 1996, and G8 and mixed P types were the most predominant. A dramatic shift of the most predominant type occurred again in 1997 when G6P[5] was most common. This frequency of G6P[5] also continued in 1998. These results suggest that the serotypes prevailing in certain areas change periodically.

Characterization of nontypeable rotavirus strains from the United States: identification of a new rotavirus reassortant (P2A[6],G12) and rare P3[9] strains related to bovine rotaviruses

Among 1316 rotavirus specimens collected during strain surveillance in the United States from 1996 to 1999, most strains (95%) belonged to the common types (G1 to G4 and G9), while 5% were mixed infections of common serotypes, rare strains, or not completely typeable. In this report, 2 rare (P[9],G3) and 2 partially typeable (P[6],G?; P[9],G?) strains from that study were further characterized. The P[6] strain was virtually indistinguishable by hybridization analysis in 10 of its 11 gene segments with recently isolated P2A[6],G9 strains (e.g., U.S.1205) from the United States, but had a distinct VP7 gene homologous (94.7% a.a. and 90.2% nt) to the cognate gene from P1B[4],G12 reference strain L26. Thus, this serotype P2A[6],G12 strain represents a previously unrecognized reassortant. Three P3[9] strains were homologous (97.8-98.2% aa) in the VP8 region of VP4 to the P3[9],G3 feline-like reference strain AU-1, but had a high level of genome homology to Italian bovine-like, P3[9],G3 and P3[9],G6 rotavirus strains. Two of the U.S. P3[9] strains were confirmed to be type G3 (97.2-98.2% VP7 aa homology with reference G3 strain AU-1), while the other was most similar to Italian bovine-like strain PA151 (P3[9],G6), sharing 99.0% a.a. homology in VP7. Cross-neutralization studies confirmed all serotype assignments and represented the first detection of these rotavirus serotypes in the United States. The NSP4 genes of all U.S. P3[9] strains and rotavirus PA151 were most closely related to the bovine and equine branch within the DS-1 lineage, consistent with an animal origin. These results demonstrate that rare strains with P and G serotypes distinct from those of experimental rotavirus vaccines circulate in the United States, making it important to understand whether current vaccine candidates protect against these strains.

Sequence analysis of the VP4, VP6, VP7, and NSP4 gene products of the bovine rotavirus WC3

The bovine rotavirus (BRV) WC3 serves as the background strain in the development of a multivalent reassortant vaccine against rotavirus gastroenteritis in infants. The genes encoding the outer capsid spike protein VP4, the inner capsid protein VP6, the outer capsid glycoprotein VP7, and the viral enterotoxin NSP4 of BRV WC3 were sequenced. Comparative analysis of the deduced amino acids of the sequenced genes indicated that the BRV WC3 strain shares a high degree of amino acid identity with serotype P7 VP4 (93-96%), serotype G6 VP7 (91-97%), subgroup (SG) I VP6 (96-99%), and NSP4 genogroup A (96-98%) BRV strains. Our results confirm and extend previous studies which suggested that the VP4 of BRV WC3 was closely related to that of the P7 prototype, BRV UK. In addition, the VP6 and VP7 of BRV WC3 were very similar to the VP6 and VP7 of both SG I and G6 BRV NCDV and UK strains. However, the NSP4 of BRV WC3 was more closely related to that BRV NCDV, the P6 prototype, than to that of BRV UK.

Bovine rotavirus G and P types and sequence analysis of the VP7 gene of two G8 bovine rotaviruses from Japan

A total of 1481 fecal specimens were collected from diarrheic calves under 1 month of age on 29 dairy and beef farms in 11 prefectures in Japan during the period from 1987 to 2000. Those calves and their dams were not vaccinated against rotavirus. One hundred and forty-two bovine rotaviruses were isolated on MA-104 cell cultures and detected by latex agglutination test. They were classified into 18 G6P[1] (11.2%), 53 G6P[5] (37.3%), 15 G6P[11] (10.6%), 12 G10P[5] (8.5%), 42 G10P[11] (29.6%) and 1 G8P[11] (0.7%) by reverse transcription-polymerase chain reaction. One serotype G8 virus was untypable for the P genotype suggesting a new type of bovine origin. The least common G8 serotype viruses were isolated from the samples of farms from Niigata and Tokushima prefectures. The VP7 gene sequences of the two isolates exhibited a high degree of homology as well as previously reported G8 viruses with 93.3-98.8% identity of deduced amino acids. A phylogenetic analysis of the VP7 gene of the two G8 viruses and 13 previously reported G8 viruses by the neighbor-joining method indicated that the two newly isolated G8 rotaviruses had a common origin and they were assigned to a new disparate cluster.

Detection of human rotavirus in faeces from diarrhoeic calves in north-east Nigeria

Information on the epidemiology of rotavirus in any particular area is necessary for vaccine development against the disease caused by the virus. This study presents preliminary information on the prevalence of human rotavirus in diarrhoeic calves in North-east Nigeria. Faecal samples from 188 diarrhoeic calves in various farms in North-east Nigeria, obtained between November 1998 and February 1999, were analysed by ELISA for the presence of rotaviruses. A prevalence rate of 3.2% was recorded, with the virus being prevalent among calves aged 29-56 days (p < 0.05). The implications of these findings are discussed with respect to the close association between the herdsmen and their animals and the sharing of a common source of drinking water in the predominantly livestock-producing communities of North-east Nigeria.

Molecular and serologic characterization of novel serotype G8 human rotavirus strains detected in Blantyre, Malawi

During a 2-year study of diarrhea among children in Blantyre, Malawi, greater than 50% of rotavirus strains genotyped by using reverse transcription-polymerase chain reaction possessed previously unrecognized combinations of the neutralization proteins VP7 and VP4. Serotype G8 rotaviruses, which have been identified recently in several African countries, were found to possess P[4] or P[6] VP4 genotype specificity. Two of these short electropherotype rotaviruses were further investigated: these comprised a P[6], G8 representative strain (MW23) and a P[4], G8 representative strain (MW333). The VP7 gene sequences of both strains exhibited greatest homology to human and animal serotype G8 rotaviruses. Sequence analysis of the VP4 gene of MW23 indicated closest identity to the P2A[6], G9 strain US1205 from the United States. The VP4 gene of MW333 was most closely related to the P[4], G12 strain L26 isolated in the Philippines and the Australian P[4], G2 strain RV-5. The NSP4 gene sequences of both strains were classified in NSP4 genetic group I. RNA-RNA hybridization demonstrated that each of these two strains is related to the DS-1 genogroup of human rotaviruses. Subgroup analysis and virus neutralization confirmed complete antigenic characterization of MW23 as subgroup I, P2A[6], G8 and MW333 as subgroup I, P1B[4], G8. The similarity of the VP7 gene sequences of the prototype strains described in this report to bovine serotype G8 rotaviruses suggests that they may represent human/bovine reassortant viruses.

Determination of bovine rotavirus G and P serotypes in italy by PCR

Determination of the G and P serotypes of group A bovine rotaviruses from 149 samples of feces or intestinal contents collected from calves showing clinical signs of neonatal diarrhea was performed by a nested reverse transcription-PCR typing assay. The G6 serotype was the most prevalent, accounting for viruses in 55.7% of the samples; viruses of the G10 and G8 serotypes were found in 34.9 and 4.7% of the samples, respectively. The virus in one sample (0.7%) was not classified due to concomitant infection with G6 and G8 strains, whereas viruses in six samples (4.0%) could not be characterized with any of the three G serotype-specific primers selected for the present study. When examined for their P-serotype specificities, viruses in 55 and 42.3% of the samples were characterized as P[11] and P[5], respectively, no P[1] serotype was identified, and viruses in 2.7% of the samples could not be classified due to multiple reactivity with both P[5]- and P[11]-specific primers. Various combinations of G and P serotypes were observed, the most frequent being G6,P[5] (38.3%), G10,P[11] (31.5%), and G6,P[11] (15.4%). The results of the present study, while contributing to a better understanding of the epidemiology of bovine rotaviruses in Italy, address the relevance of serotype specificity with regard to the constancy of the quality of bovine rotavirus vaccines under different field conditions.

Comparative studies of human rotavirus serotype G8 strains recovered in South Africa and the United Kingdom

Epidemiological studies on the VP7 serotype prevalence of human rotaviruses in South Africa and the United Kingdom identified several strains which could not be serotyped as G1-G4 by monoclonal antibodies. Further analysis of these strains with a G8-specific monoclonal antibody and with probes for human rotaviruses confirmed them as G8 rotaviruses. These G8 strains exhibited a high degree of sequence identity when compared with each other and with other rotavirus G8 strains. Five South African strains were further characterized as VP6 subgroup I, but with a long RNA electropherotype, which is similar to the G8 strains previously isolated in Finland. In the UK strains, one was VP6 subgroup II with a long RNA electropherotype (similar to the Italian G8 strain). The other two were subgroup I with a short RNA electropherotype. None of these strains exhibited the super-short RNA electropherotype described in the prototype G8 strains recovered from Indonesia (69M).

Relative frequencies of G and P types among rotaviruses from Indian diarrheic cow and buffalo calves

While an increasing number of studies suggest that there is a high prevalence of rotaviruses with P8[11], a typical P type of bovine rotavirus (BRV), among human neonates or infants in India, no data are available on the distribution of G and P types of Indian BRVs. Thus, fecal specimens were collected from cow and buffalo calves under 1 month of age on organized dairy farms in India during the period between 1994 and 1997, and 36 rotavirus-positive specimens were used to determine the relative frequencies of the G and P types of Indian BRVs. As to the G type, G10 was predominant (83%), followed by G6 (6%). The majority (94%) of BRVs had P8[11], and only one isolate possessed P6[1]. The most common combination of G and P types was G10P8[11] (81%), followed by G6P6[1] (3%) and G6P8[11] (3%). The high prevalence of BRVs possessing P8[11] VP4s strongly supports the hypothesis that BRVs may cross the host species barrier and circulate among neonates in India.

Prevalence of calf diarrhea caused by bovine group A rotavirus carrying G serotype 8 specificity

One hundred and seventeen rectal fecal specimens were collected in 1995 and 1996 from calves with diarrhea in Kagoshima Prefecture in Japan. The bovine group A rotavirus was detected by enzyme immunoassay in 43 of 117 specimens and isolated from 33 of the 43 specimens that were positive. G serotype, P serotype, and P genotype of 33 isolates were identified by reverse transcription-polymerase chain reaction, and 20 of 33 isolates (60.6%) were identified as G serotype 8. Thus, we discovered that calf diarrhea caused by bovine group A rotavirus carrying G serotype 8 specificity was prevalent in this research area during this research period. To our knowledge, this is the first report on the prevalence of calf diarrhea caused by the bovine group A rotavirus carrying G serotype 8 specificity.

Rotavirus G-type restriction, persistence, and herd type specificity in Swedish cattle herds

G-typing of rotavirus strains enables the study of molecular epidemiology and gathering of information to promote disease prevention and control. Rotavirus strains in fecal specimens from neonatal calves in Swedish cattle herds were therefore characterized by using G1 to -4-, G6-, G8-, and G10-specific primers in reverse transcription (RT)-PCR. Fecal samples were collected from one dairy herd (herd A) for 4 consecutive years and from 41 beef and dairy herds (herd B) experiencing calf diarrhea outbreaks. Altogether, 1, 700 samples were analyzed by group A rotavirus enzyme-linked immunosorbent assay, and 98 rotavirus-positive specimens were selected for G-typing by RT-PCR. The effect of herd type, time, geographic region, and clinical symptoms on the G-type distribution was evaluated. Altogether (herds A and B), G10 was found in 59 (60. 2%) fecal specimens, G6 was found in 30 (30.6%) specimens, G3 was found in 1 (1.0%) specimen, and G8 was found in 1 (1.0%) specimen. Seven (7.1%) fecal specimens were not typeable. Herd type specificity in the G-type distribution was demonstrated in the herds in herd B. In the 6 beef suckler herds, only G6 was detected, while rotavirus strains from the 35 dairy herds were predominantly (54%) G10. The G-type distribution was restricted in herds A and B. Twenty-nine of 30 strains from herd A were characterized as G10. In the vast majority of herds in herd B, a single G-type was identified. The serotype G10 and the electropherotype persisted over time in herd A. No characteristic G-type variation in the geographic distribution of cattle herds in herd B was obvious. There was no difference in the G-type distributions between the strains from clinically and subclinically rotavirus-infected calves in dairy herd A. The results from this study strongly indicate a pronounced stability in the rotavirus G-type distribution in Swedish cattle herds, which emphasizes the importance of continuous preventive measures for control of neonatal calf diarrhea. A future bovine rotavirus vaccine in Sweden should contain G10 and G6 strains.

Distribution of G serotypes and P genotypes of bovine group A rotavirus isolated in Japan

OBJECTIVE

To identify the distribution of G serotype and P genotype of bovine group A rotavirus in Japan.

DESIGN

Detection, isolation, electropherotyping, G serotyping and P genotyping of bovine group A rotavirus in 167 diarrhoeal faecal samples.

PROCEDURE

Bovine group A rotavirus was detected and isolated, and bovine group A rotavirus isolates were identified electropherotype by polyacrylamide gel electrophoresis and G serotype and P genotype by reverse transcription-poly-merase chain reaction.

RESULTS

Twenty-eight bovine group A rotavirus strains were isolated from 167 samples. Electropherotypes of the bovine group A rotavirus isolates were identified as long-genome electropherotype and the most prevalent combination of G serotype and P genotype of the bovine group A rotavirus isolates was G6P5 (25/28; 89.3%), followed by G6P11 (2/28; 7.1%) and G10P11 (1/28; 3.6%).

CONCLUSION

These results suggest that the bovine group A rotavirus exhibiting G6P5 is the most common in Japan.

Identification of bovine rotaviruses in Venezuela: antigenic and molecular characterization of a bovine rotavirus strain

Two serotypes of bovine group A rotaviruses were demonstrated by enzyme-linked immunoassay (ELISA) and polyacrylamide gel electrophoresis (PAGE) in 20 of 171 faecal samples collected from diarrhoeic calves in two dairy farms in Venezuela. By serotyping ELISA using G and P serotype-specific monoclonal antibodies, bovine rotaviruses (BRV) circulating on one farm were identified as serotype G6, while BRVs circulating on the other farm were identified as serotype G10. Only one BRV (033) could be successfully isolated in MA104 cells, and the nucleotide sequences of the VP7 and the VP8* trypsin-cleavage product of the VP4 were determined. Cross-neutralization tests and comparative sequence analysis showed that BRV 033 belonged to serotype G6 and genotype P1. This is the first report of BRVs identified in Venezuela.