Detection of group C rotavirus antigens and antibodies in animals and humans by enzyme-linked immunosorbent assays

Genomic diversity and intragenic recombination of species C rotaviruses

Rotavirus C (RVC) is a major cause of diarrhoea in swine, cattle, and humans worldwide. RVC exhibits sequence diversity in all 11 genes, especially in VP4 and VP7, and all segment-based genotyping has been performed similar to rotavirus A. To date, recombination events have been reported in rotavirus A and B. However, there are no reports describing gene recombination of RVC, except for recombination in NSP3 between RVC and rotavirus H. In this study, nine porcine RVC strains identified in Japanese pigs were completely sequenced and analysed together with RVC sequences from the GenBank database. The analyses showed that sequences of the VP4, VP2, and NSP1 of several porcine RVC strains did not branch with any of those of the RVC strains in the GenBank database, suggesting new genotypes. Several homologous recombination events, between or within genotypes, were identified in the VP4, VP7, VP2, NSP1, and NSP3 genes. Of these, nine, one, and one intergenotypic recombination events in the VP4, VP2, and NSP3 genes, respectively, were supported with sufficient statistical values. Although these findings suggest occurrences of the intragenic recombination events in the RVC genome, potential sequence errors and poor sequence assemblies in the databases should be watched with care. The results in this study present data about the important recombination events of the RVCs, which influence evolution of the virus by aiding them to gain genetic diversity and plasticity, although further sequence data will be necessary to obtain more comprehensive understanding of such mechanisms.

Sources and Risk Factors for Nitrate and Microbial Contamination of Private Household Wells in the Fractured Dolomite Aquifer of Northeastern Wisconsin

BACKGROUND

Groundwater quality in the Silurian dolomite aquifer in northeastern Wisconsin, USA, has become contentious as dairy farms and exurban development expand.

OBJECTIVES

We investigated private household wells in the region, determining the extent, sources, and risk factors of nitrate and microbial contamination.

METHODS

Total coliforms, Escherichia coli, and nitrate were evaluated by synoptic sampling during groundwater recharge and no-recharge periods. Additional seasonal sampling measured genetic markers of human and bovine fecal-associated microbes and enteric zoonotic pathogens. We constructed multivariable regression models of detection probability (log-binomial) and concentration (gamma) for each contaminant to identify risk factors related to land use, precipitation, hydrogeology, and well construction.

RESULTS

Total coliforms and nitrate were strongly associated with depth-to-bedrock at well sites and nearby agricultural land use, but not septic systems. Both human wastewater and cattle manure contributed to well contamination. Rotavirus group A, Cryptosporidium, and Salmonella were the most frequently detected pathogens. Wells positive for human fecal markers were associated with depth-to-groundwater and number of septic system drainfield within 229m. Manure-contaminated wells were associated with groundwater recharge and the area size of nearby agricultural land. Wells positive for any fecal-associated microbe, regardless of source, were associated with septic system density and manure storage proximity modified by bedrock depth. Well construction was generally not related to contamination, indicating land use, groundwater recharge, and bedrock depth were the most important risk factors.

DISCUSSION

These findings may inform policies to minimize contamination of the Silurian dolomite aquifer, a major water supply for the U.S. and Canadian Great Lakes region. https://doi.org/10.1289/EHP7813.

First Detection of Rotavirus Group C in Asymptomatic Pigs of Smallholder Farms in East Africa

Abstract: Group C rotavirus (RVC) has been described to be a causative agent of gastroenteritis in humans and animals including pigs, cows, and dogs. Fecal samples collected from asymptomatic pigs in smallholder swine farms in Kenya and Uganda were screened for the presence of group C rotaviruses (RVC) using a reverse transcription-polymerase chain reaction assay. A total of 446 samples were tested and 37 were positive (8.3%). A significantly larger (p < 0.05) number of RVC-positive samples was detected in groups of older pigs (5-6 months) than in younger piglets (1-2 months). There were no significant differences in the RVC detection rate between the pigs that were full time housed/tethered and those that were free range combined with housing/tethering. After compiling these data with diagnostic results for group A rotaviruses (RVA), 13 RVC-positive samples were also positive for RVA. This study provides the first evidence that porcine group C rotavirus may be detected frequently in asymptomatic piglets (aged < 1-6 months) in East Africa. The occurrence of RVC in mixed infections with RVA and other enteric pathogens requires further research to investigate the pathogenic potential of RVC in pigs.

Whole genome sequences of Japanese porcine species C rotaviruses reveal a high diversity of genotypes of individual genes and will contribute to a comprehensive, generally accepted classification system

Porcine rotavirus C (RVC) is distributed throughout the world and is thought to be a pathogenic agent of diarrhea in piglets. Although, the VP7, VP4, and VP6 gene sequences of Japanese porcine RVCs are currently available, there is no whole-genome sequence data of Japanese RVC. Furthermore, only one to three sequences are available for porcine RVC VP1-VP3 and NSP1-NSP3 genes. Therefore, we determined nearly full-length whole-genome sequences of nine Japanese porcine RVCs from seven piglets with diarrhea and two healthy pigs and compared them with published RVC sequences from a database. The VP7 genes of two Japanese RVCs from healthy pigs were highly divergent from other known RVC strains and were provisionally classified as G12 and G13 based on the 86% nucleotide identity cut-off value. Pairwise sequence identity calculations and phylogenetic analyses revealed that candidate novel genotypes of porcine Japanese RVC were identified in the NSP1, NSP2 and NSP3 encoding genes, respectively. Furthermore, VP3 of Japanese porcine RVCs was shown to be closely related to human RVCs, suggesting a gene reassortment event between porcine and human RVCs and past interspecies transmission. The present study demonstrated that porcine RVCs show greater genetic diversity among strains than human and bovine RVCs.

Analysis of genetic divergence among strains of porcine rotavirus C, with focus on VP4 and VP7 genotypes in Japan

Porcine rotavirus C (RVC) has been often detected in sporadic cases or outbreaks of diarrhoea in suckling and weaned pigs. Surveillance studies of RVCs have demonstrated high prevalence in the United States, and Japan, and some other countries. To date, the zoonotic impact and pathogenicity of RVCs are not well understood, and only a few complete sequences of RVCs are available. The aim of this study was to perform sequence and phylogenetic analyses for the VP4 and VP7 genes of the 22 porcine RVCs identified in Japan from 2002 to 2010. The genetic classification of the VP4 genes of the 22 porcine RVCs revealed the presence of six clusters including one cluster each from human and bovine RVCs with a cut-off value of 80%. In addition, VP7 genes of the 22 porcine RVCs were grouped into four of the seven known clusters on the basis of cut-off values of 85% at the nucleotide level reported previously. The data presented here demonstrate that multiple porcine RVC strains with distinctive genotypes based on a combination of the VP4 and VP7 genes are widely distributed and circulated among farms throughout Japan. According to establishment of dual genetic classification for VP4 and VP7 genotypes of porcine RVCs, furthermore, we discovered a possible event of gene reassortment between different rotavirus strains from the same farm. Our findings should advance the understanding of the evolution and pathogenicity of RVCs.

Phylogenetic characterization of VP6 gene (inner capsid) of porcine rotavirus C collected in Japan

Porcine rotavirus C (RVC) has been often detected in sporadic cases or outbreaks of diarrhea in suckling and weaned pigs. Previous surveillance studies using both enzyme-linked immunosorbent assays and reverse-transcription polymerase chain reaction in some countries including Japan and the United States have demonstrated a high prevalence of porcine RVCs. In order to understand the phylogenetic relatedness of RVCs, we performed genetic analysis of VP6 gene encoding inner capsid protein by using 22 porcine RVC strains collected in Japan from 2002 to 2010. Comparative analyses of the VP6 nucleotide and amino acid sequences from these porcine RVCs exhibited lower sequence identities than those from human and bovine RVCs. The phylogenetic analysis of VP6 gene of RVC indicated the presence of seven clusters (tentatively assigned I1-I7) according to host species with cut-off values of 87% at the nucleotide level, and VP6 genes of porcine RVCs were divided into five genotypes. These findings indicate that multiple porcine RVC strains with distinctive genotypes are broadly spreading and circulating among farms in Japan. Our data may provide important insights in understanding evolutionary dynamics of RVCs.

Whole-genome analysis of bovine rotavirus species C isolates obtained in Yamagata, Japan, 2003–2010

An epidemic of diarrhoea in adult cows occurred at a total of 105 dairy farms in Yamagata Prefecture, Japan, between 2003 and 2010. Reverse transcription-PCR diagnostic tests revealed the presence of bovine rotavirus species C (RVCs) in samples from each of six farms (5.7 %). In this study, we determined the full-length nucleotide sequences of 11 RNA segments from six bovine RVC strains and investigated genetic diversity among them, including two bovine RVC strains identified in a previous study. Comparisons of all segmental nucleotide and the deduced amino acid sequences among bovine RVCs indicated high identities across all genes except for the VP4 gene. Phylogenetic analysis of each gene revealed that the six bovine RVCs belonged to a bovine cluster distinct from human and porcine RVCs. Bovine RVC strains could be clearly divided into two lineages of the VP4 genes. The nucleotide sequence identity for VP4 genes between lineage I and II was 83.7–84.8 %. Moreover, bovine RVC strains belonging to lineage I exhibited one amino acid deletion and three amino acid insertions, which differed for those strains belonging to lineage II. Our data suggest that multiple bovine RVCs originated from a common ancestor, but had different genetic backgrounds, not only in Yamagata Prefecture but also in the rest of Japan.

An overview of calf diarrhea - infectious etiology, diagnosis, and intervention

Calf diarrhea is a commonly reported disease in young animals, and still a major cause of productivity and economic loss to cattle producers worldwide. In the report of the 2007 National Animal Health Monitoring System for U.S. dairy, half of the deaths among unweaned calves was attributed to diarrhea. Multiple pathogens are known or postulated to cause or contribute to calf diarrhea development. Other factors including both the environment and management practices influence disease severity or outcomes. The multifactorial nature of calf diarrhea makes this disease hard to control effectively in modern cow-calf operations. The purpose of this review is to provide a better understanding of a) the ecology and pathogenesis of well-known and potential bovine enteric pathogens implicated in calf diarrhea, b) describe diagnostic tests used to detect various enteric pathogens along with their pros and cons, and c) propose improved intervention strategies for treating calf diarrhea.

Rapid detection of human rotavirus using NSP4 gene specific reverse transcription loop-mediated isothermal amplification assay

The seasonal outbreaks of human rotavirus (RV) infection occur every winter. Most patients are diagnosed clinically by a rapid latex agglutination detection kit or polymerase chain reaction assays for RV from stool samples, but some problems have been reported on the specificity and sensitivity of such rapid detection assays. To ratify these issues, a sensitive, specific, simple, and rapid nucleic acid based diagnostic method is expected to be introduced and the reverse transcription loop-mediated isothermal amplification (RT-LAMP) was developed to detect the RV in human stool samples by incubation at 60 °C for 1 h and amplification was confirmed by electrophoretic laddering, restriction enzyme digestion, and hydroxynapthol blue discoloration. The assay established in this study was found to detect only the RVs and no cross-reaction with other viruses, demonstrating its high specificity. By using serial samples dilution as template, the detection limit of LAMP was 10 times more than that of PCR. The results showed the potential clinical feasibility of RT-LAMP as a useful diagnostic tool for the detection of RV with high sensitivity in comparison to conventional RT-PCR.

Changes in anti-group a rotavirus antibody seroprevalence and levels in the Western Gyeongnam province of Korea over 16 years

To observe how anti-group A rotavirus antibody seropositivity rates and levels have changed in the western region of Gyeongnam Province, 2,030 serum samples collected at four collection periods (1989-1990, 1994-1995, 1999-2000, and 2004-2005) were tested by Enzyme-Linked Immunosorbent Assay for IgG, and IgA antibodies reacting to recombinant VP6 protein. The seroprevalences exhibit no regular patterns over a 16-yr period. For all four collection periods, the anti-rVP6 IgG levels rose steadily during the first 5 months of life, after which they remained high. However, the 2-9 yr and 10-39 yr groups had significantly higher IgG levels in 1999-2000 and 2004-2005, respectively, than in the other collection periods. The 1-5 mo, 40- ≥ 60 yr, and 4-29 yr groups had significantly higher IgA levels in 1989-1990, 1999-2000, and 2004-2005, respectively. The 4 yr (25.0%), 5-9 yr (18.8%), 10-14 yr (41.1%), 20-29 yr (35.0%), and 30-39 yr (20.0%) groups in 2004-2005 had significant higher IgA seropositivity rate compared to the other three collection periods. These observations suggest that in the western region of Gyeongnam Province since the late 1990s, rotavirus reinfection has occurred more frequently than previously, with all ages being at risk.

Whole-genome analysis of two bovine rotavirus C strains: Shintoku and Toyama

Rotavirus C (RVC) has been detected frequently in epidemic cases and/or outbreaks of diarrhoea in humans and animals worldwide. Because it is difficult to cultivate RVCs serially in cell culture, the sequence data available for RVCs are limited, despite their potential economical and epidemiological impact. Although whole-genome sequences of one porcine RVC and seven human RVC strains have been analysed, this has not yet been done for a bovine RVC strain. In the present study, we first determined the nucleotide sequences for five as-yet underresearched genes, including the NSP4 gene, from a cultivable bovine RVC, the Shintoku strain, identified in Hokkaido Prefecture, Japan, in 1991. In addition, we elucidated the ORF sequences of all segments from another bovine RVC, the Toyama strain, detected in Toyama Prefecture, Japan, in 2010, in order to investigate genetic divergence among bovine RVCs. Comparison of segmental nucleotide and deduced amino acid sequences among RVCs indicates high identity among bovine RVCs and low identity between human and porcine RVCs. Phylogenetic analysis of each gene showed that the two bovine RVCs belong to a cluster distinct from human and porcine RVCs. These data demonstrate that RVCs can be classified into different genotypes according to host species. Moreover, RVC NSP1, NSP2 and VP1 amino acid sequences contain a unique motif that is highly conserved among rotavirus A (RVA) strains and, hence, several proteins from bovine RVCs are suggested to play important roles that are similar to those of RVAs.

Genetically diverse group C rotaviruses cause sporadic infection in Korean calves

This study examined the prevalence and genetic diversity of the bovine group C rotaviruses (GCRVs) in a total of 127 diarrhea fecal samples of calves from 52 Korean native beef calf herds using RT-PCR and nested PCR. Overall, seven of the 127 fecal samples (5.5%) from seven of the 52 herds (13.5%) tested positive for bovine GCRVs only by nested PCR. Sequence and phylogenetic analyses of a partial VP6 gene showed that Korean bovine GCRVs had marked genetic diversity; two Korean strains belonged to the bovine lineage, whereas five Korean strains belonged to the porcine lineage. These results suggest that the genetically diverse bovine GCRVs cause sporadic infections in diarrheic calves in South Korea.

Development of a panel of multiplex real-time polymerase chain reaction assays for simultaneous detection of major agents causing calf diarrhea in feces

Calf diarrhea is a major economic burden to the bovine industry. Since multiple infectious agents can be involved in calf diarrhea, and the detection of each of the causative agents by traditional methods is laborious and expensive, a panel of 2 multiplex real-time polymerase chain reaction (PCR) assays was developed for rapid and simultaneous detection of the 5 major bovine enteric pathogens (i.e., Bovine coronavirus [BCoV; formally known as Betacoronavirus 1], group A Bovine rotavirus [BRV], Salmonella spp., Escherichia coli K99(+), and Cryptosporidium parvum). The estimated detection limit (i.e., analytic sensitivity) of the panel was 0.1 TCID(50) (50% tissue culture infective dose) for BCoV and group A BRV; 5 and 0.5 colony-forming units for E. coli K99(+) and Salmonella, respectively; and 50 oocysts for Cryptosporidium per reaction. In testing 243 fecal samples obtained from submissions to the Iowa State University Veterinary Diagnostic Laboratory or from experimental animals with known infection status, the newly developed multiplex real-time PCR panel simultaneously detected all 5 pathogens directly from fecal samples and was more rapid and sensitive than the traditional diagnostic tests. The PCR panel showed 89%-97% agreement with those conventional diagnostic tests, demonstrating diagnostic sensitivity equal to or better than that of the conventional tests. In conclusion, the multiplex real-time PCR panel can be a tool for a timely and accurate diagnosis of calf diarrhea associated with BCoV, group A BRV, E. coli K99(+), Salmonella, and/or Cryptosporidium.

Development of one-step real-time reverse transcription polymerase chain reaction assays for rapid detection of porcine group C rotaviruses

Although the widespread occurrence of porcine group C rotaviruses (GCRV) is assumed, precise prevalence remains largely unknown because of the absence of reliable, specific, and rapid diagnostic methods. To detect and quantify porcine GCRV, the authors evaluated and optimized SYBR Green and TaqMan real-time reverse transcription polymerase chain reaction (RT-PCR) assays and applied them to 108 piglet fecal samples. Using serially diluted standard RNA transcripts of porcine GCRV VP6 gene, both SYBR Green and TaqMan real-time RT-PCR assays detected as few as 1 x 10(1) genome copies/microl (correlation coefficiency >0.99), whereas conventional RT-PCR detected 1.0 x 10(3) copies/microl. In addition, the conventional assay detected porcine GCRV in 24% (26/108) of fecal samples, whereas the detection rates of both SYBR Green and TaqMan assays were 72% (78 of 108) and 64% (70 of 108), respectively. The current study indicated that both real-time RT-PCR assays were reliable, specific, and rapid methods for the detection of porcine GCRV in porcine fecal samples.

Anti-VP6 IgG antibodies against group A and group C rotaviruses in South India

In an epidemiological survey from South India, 936 serum samples were tested for IgG against recombinant baculovirus-expressed VP6 proteins from human group A and group C rotaviruses. The overall seroprevalence for group A was 100% and for group C was 25.32% (95% CI 22.64-28.21). The lowest seroprevalence for group C was in children aged <10 years (16.79%). An age-related rise in seroprevalence in group C, but not group A, suggests different patterns of exposure. Seroprevalence was similar in rural and urban subjects, unlike the higher prevalence in rural subjects in studies elsewhere.

Detection and characterization of group C rotavirus in Buenos Aires, Argentina, 1997-2003

The role of group C rotaviruses as a cause of diarrhea was examined among children <17 years of age admitted to a Hospital in a suburban area of Buenos Aires, Argentina between 1997 and 2003. A total of 1,579 fecal samples were screened for group A (RVA) and C (RVC) rotaviruses by two in-house ELISA methods at Quilmes University (UNQ-ELISA). Samples positive, doubtful and negative by RVC specific UNQ-ELISA (n = 246) were examined further for RVC by another in-house ELISA (CDC-ELISA), electron microscopy, RT-PCR, nested PCR, and Southern hybridization. Sensitivity, specificity, and predictive values for each test were determined. While the sensitivity was comparable for the nested PCR and CDC-ELISA methods (82.5%), the molecular methods were slightly more specific. Poorly preserved particles were often seen in fecal samples, suggesting that degradation of RNA could be a factor influencing the performance of molecular methods. The incidence of RVC was estimated to be 3% without apparent differences among seasons. RVC infected patients had a significantly (P < 0.001) higher median age (6 years vs. 1 year) than those with RVA infection. Sequence of the RVC VP7 gene from six Argentinean strains and sequences reported previously in different countries showed high nucleotide (94.4-99.9%) sequence identities, indicating a high degree of conservation for human RVC VP7 genes among strains collected on five continents over a period of 17 years. These findings indicate that RVC is a significant cause of diarrhea and it is necessary to develop simple and sensitive serological methods for its detection.

Detection of Group C Rotavirus in Juvenile Ferrets (Mustela putorius furo) with Diarrhea by Reverse Transcription Polymerase Chain Reaction: Sequencing and Analysis of the Complete Coding Region of the VP6 Gene

Nine juvenile ferrets ( Mustela putorius furo) with a history of diarrhea were severely dehydrated and had distended abdomens and thin-walled small intestines that contained gas and fluid. Histologically, small intestines exhibited acute superficial atrophic enteritis. Transmission electron microscopy of the small intestine showed rotavirus-like particles within apical vacuoles. Reverse transcription polymerase chain reaction (RT-PCR) was negative for group A rotavirus. A group C rotavirus-specific RT-PCR assay was developed using consensus primers designed from the alignment of VP6 gene sequences of porcine, bovine, and human strains. A 182-bp product of the VP6 gene was sequenced and showed significant similarity to group C rotavirus VP6 sequences. This strain was designated “Ferret Rota C-MSU.” The entire coding sequence of VP6 was determined and compared with other rotaviruses. Ferret Rota C-MSU virus was found to be most closely related to Shintoku group C rotavirus. This is the first definitive identification of a group C rotavirus in ferrets, based upon RT-PCR, sequencing, and genetic analysis.

Evidence for zoonotic transmission of group C rotaviruses among children in Belém, Brazil

The prevalence and potential zoonotic transmission of group C rotavirus (RVC) were examined by testing fecal samples collected from children during a longitudinal study that was carried out in the outskirts of Belém, Brazil, from December 1982 to March 1986. The study involved a group of 30 children who were followed from birth to 3 years. Of the 77 samples tested from 29 children, 5 (6.5%) were positive for human and 3 (4%) for porcine RVC by using nested PCR assay with primers specific for VP6 gene of human or porcine RVC and by Southern hybridization using a probe specific for VP6 gene of both human and porcine RVC. In addition, a total of 59 fecal specimens from the 30th child were tested, 1 (1.7%) and 14 (23.7%) were positive for human and porcine RVC, respectively. Partial nucleotide sequences of VP6 gene demonstrated that the six human strains detected in Brazil were homologous with other human RVC, and 14 of the 17 porcine RVC strains examined showed a complete homology among themselves but differed slightly from the porcine Cowden strain, suggesting that a single porcine RVC strain was circulating in Belém. This study is the first to provide evidence for transmission of RVC from swine to human. They also indicate that both human and porcine RVC were endemic in Belém.

Detection and characterization of group C rotaviruses in asymptomatic piglets in Ireland

Group C rotaviruses are important human enteric pathogens that have also been detected in a variety of mammalian species, including pigs. Group C rotaviruses have been identified in piglets with diarrhea, but their ecology remains to be elucidated. By screening of 292 fecal samples collected from 4- to 5-week-old asymptomatic pigs from four herds in Ireland between 2005 and 2007, 13 (4.4%) samples tested positive by reverse transcription-PCR for group C rotavirus. Group A rotaviruses were also detected in 19 samples but not in conjunction with group C viruses. The gene encoding the major group C neutralization antigen, the outer capsid protein VP7, was sequenced. The majority of the strains were very closely related to each other (>99% amino acid [aa] identity) and were characterized as genogroup G1 since they were genetically related to the prototype porcine strain Cowden (92.6% aa identity). Conversely, two strains (1GA/05/Cork/Ire and 281/07/Dublin/Ire) were characterized as genogroup G6 since they displayed the highest identity (89.2 to 94.0% aa) to porcine G6 strains (43/06-22-like). Unexpectedly, one such G6 strain, 1GA/05/Cork/Ire, lacked the 4-aa insertion in the VP7 variable region VR8 found in all the other G6 group C rotaviruses. This study provides evidence that porcine group C rotavirus may be detected not infrequently in asymptomatic piglets. In addition, it provides evidence that, unlike the human viruses, porcine group C rotaviruses display broad genetic heterogeneity, which may pose a challenge for the development of prophylactic tools.

Genetic heterogeneity in the VP7 of group C rotaviruses

Evidence for a possible zoonotic role of group C rotaviruses (GCRVs) has been recently provided. To gain information on the genetic relationships between human and animal GCRVs, we sequenced the VP7 gene of 10 porcine strains detected during a large surveillance study from different outbreaks of gastroenteritis in piglets. Four GCRV strains were genetically related to the prototype GCRV porcine Cowden strain. A completely new VP7 genotype included 4 strains (344/04-7-like) that shared 92.5% to 97.0% aa identity to each other, but <83% to human GCRVs and <79% to other porcine and bovine GCRVs. A unique 4-aa insertion (SSSV or SSTI), within a variable region at the carboxy-terminus of VP7, represented a distinctive feature for these 4 unique strains. An additional strain, 134/04-18, was clearly different from all human and animal GCRVs (<85% aa identity) and likely accounts for a distinct VP7 genotype. The VP7 of a unique strain, 42/05-21, shared similar ranges of aa sequence identities with porcine and human strains (88.0-90.7% to porcine GCRVs and 85.2-88.2% to human GCRVs). Plotting the VP7 gene of strain 42/05-21 against the VP7 of human and porcine strains revealed discontinuous evolution rates throughout the VP7 molecule, suggesting different mutational pressure or a remote intragenic recombination event. These findings provide the need for future epidemiological surveys and warrant studies to investigate the pathogenic potential of these novel GCRVs in pigs.

Detection and characterization of human group C rotaviruses in Bangladesh

Group C rotaviruses were detected by reverse transcription-PCR in 14 (2.3%) of 611 group A rotavirus-negative stool specimens from the patients admitted to the International Centre for Diarrhoeal Disease Research, Bangladesh hospital, Dhaka, Bangladesh, during July to December 2003. The low rate of detection suggested that infection with group C rotaviruses was an uncommon cause of hospitalization due to gastroenteritis. In addition, coinfections with pathogenic enteric bacteria were frequently observed in group C rotavirus-infected patients. Nucleotide sequence comparison of the VP4, VP6, and VP7 genes revealed that the Bangladeshi group C rotaviruses were most similar to Nigerian group C rotavirus strains. Phylogenetic analysis suggested that all human group C rotaviruses, including the strains isolated in our study, clustered in a monophyletic branch, which was distantly related to the branch comprised of animal group C rotaviruses.

Detection of a bovine group C rotavirus from adult cows with diarrhea and reduced milk production

Only two strains (Shintoku and porcine-like WD534tc) of group C rotavirus (GCR) from cattle have been reported to date. A GCR designated the Yamagata strain was the only pathogen detected in an outbreak of adult cow diarrhea accompanied by a decrease in milk production. The nucleotide sequences of the VP6 and VP7 genes from strain Yamagata were determined. Comparative sequence analysis showed that the sequence identities between strains Yamagata and Shintoku were markedly high in both VP6 gene (98.1%) and VP7 gene (93.5%), and that these strains belonged to the same clusters which were distinguished from GCRs from different host species in phylogenetic trees of these genes. These results suggested strongly that cattle species is one of the natural hosts of GCR infection, and that GCRs are a cause of adult cow diarrhea.

Detection of group C rotavirus in children with acute gastroenteritis in Blantyre, Malawi

Among 606 children who were treated for acute gastroenteritis at the Queen Elizabeth Central Hospital in Blantyre, Malawi, Group C rotavirus (Gp C RV) was detected by enzyme-linked immunosorbent assay in fecal specimens from 16 (3.9%) of 408 inpatients and in 4 (2.0%) of 198 outpatients. Thirteen (65%) children excreting Gp C RV were coinfected with Group A rotavirus.

Seroepidemiology of human group C rotavirus in Japan based on a blocking enzyme-linked immunosorbent assay

A novel blocking enzyme-linked immunosorbent assay (BL-ELISA) was developed for detection of antibodies to human group C rotavirus (CHRV). The specificity of the BL-ELISA was confirmed by using animal sera hyperimmunized to group A and group C rotaviruses and paired sera from five patients with acute CHRV gastroenteritis. Furthermore, there was concordance between the BL-ELISA and a neutralization assay for CHRV in 226 (95%) of 238 samples. By using the BL-ELISA, we determined the seroprevalence of CHRV in 704 serum samples obtained from nine different age groups of inhabitants of Okayama Prefecture, Japan, in 1992, 1994, and 1996. As a result, 211 sera (30%) were found to be positive for CHRV antibodies. The seroprevalence gradually increased with age and reached 52.7% in the oldest individuals. A further analysis of the youngest age group suggested that CHRVs predominantly prevail in persons older than 3 years of age in Japan. When comparing the three sampling years, a larger percentage of antibody-positive sera was detected in 1994 than in either 1992 or 1996 in individuals between 6 and 15 years of age, reflecting the occurrence of a CHRV outbreak among children during the winter of 1992 to 1993 that was previously documented. These results indicate that CHRV infections may occur more frequently in spite of the relatively low detection rate of the virus.

Seroepidemiology of human group C rotavirus in South Africa

Sera from three separate healthy population cohorts were used to determine the incidence of group C rotavirus infections in 1,356 South Africans. Using an enzyme-linked immunosorbent assay based on a recombinant group C rotavirus VP6 protein, the total percent positivity was found to be 34.4% (range, 33 to 38%), with almost half of the population infected after the age of 20 years.

Detection of field isolates of human and animal group C rotavirus by reverse transcription-polymerase chain reaction and digoxigenin-labeled oligonucleotide probes

Rotaviruses (RV) are important etiological agents of acute gastroenteritis in infants and young children, as well as the young of a variety of animals worldwide. These viruses belong to Reoviridae family and contain a genome of 11 segments of double-stranded RNA (dsRNA). Two major proteins, VP4 and VP7, encoded by genome segments 4 and 7, 8 or 9, respectively, evoke a neutralizing antibody response and form the basis for the current classification of group (gp) A rotavirus into P (VP4) and G (VP7) serotypes. Although much recent progress has been made on the molecular biology of gp C RV, routine methods to detect and discriminate human, porcine, and bovine strains are not available widely. In this study, a multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) and digoxigenin-labeled (dig) oligonucleotide probes using chemiluminescence has been developed to detect and discriminate VP7 genes from culture-adapted and field isolates of human, porcine and bovine gp C RV. The multiplex RT-PCR and dig-probes were specific for the VP7 genes of human, porcine and bovine gp C RV and allowed detection and characterization of single and mixed infections of porcine gp C RV with porcine gp A or gp B rotaviruses. Detection rates for gp C RV were more than 50% when compared with polyacrylamide gel electrophoresis. These new diagnostic assays may help determine the epidemiological importance of these viruses in human and animal infections.

Dual infection of gnotobiotic calves with bovine strains of group A and porcine-like group C rotaviruses influences pathogenesis of the group C rotavirus

There is serological evidence that bovine group C rotaviruses exist in the United States, but there are no reports of their isolation. Ninety fecal samples from calves with diarrhea, 81 samples from adult cows with diarrhea (winter dysentery), and 20 fecal samples from healthy adult cows were tested for group C rotaviruses by polyacrylamide gel electrophoresis, immune electron microscopy, and reverse transcription-PCR (RT-PCR). Three samples from adult cow diarrhea cases were positive only by RT-PCR, and a group C rotavirus was isolated from a positive sample in monkey kidney (MA104) cells (WD534tc/C). Genetically and serologically, the WD534tc/C strain was more closely related to the Cowden porcine group C strain than to the Shintoku bovine strain. Because the original cow feces also contained a group A rotavirus (detected after passage in cell culture), we hypothesized that such dual-rotavirus infections might play a role in the pathogenesis and host adaptation of rotaviruses. Thus, we examined the pathogenesis of WD534tc/C alone or combined with virulent (IND/A) or attenuated (NCDV/A) bovine group A rotaviruses in gnotobiotic calves. WD534tc/C alone induced diarrhea without (or with limited) virus shedding in inoculated calves (n = 3). In contrast, all calves coinfected with WD534tc/C and IND/A (n = 2) developed diarrhea and shed both viruses, whereas calves coinfected with WD534tc/C and NCDV/A (n = 3) developed diarrhea but did not shed either virus. Infection with WD534tc/C or NCDV/A alone caused only mild villous atrophy (jejunum and/or ileum), whereas dual infection with both viruses induced lesions throughout the small intestine. Although IND/A alone caused villous atrophy, more-widespread small intestinal lesions occurred in calves coinfected with WD534tc/C and IND/A. In conclusion, coinfection of calves with group A rotaviruses enhanced fecal shedding of a bovine group C rotavirus and the extent of histopathological lesions in the small intestines. Thus, our findings suggest a potential novel hypothesis involving dual infections for the adaptation of heterologous rotaviruses to new host species.

Characterization of group C rotaviruses associated with diarrhea outbreaks in feeder pigs

Feces and serum specimens were collected from three farms in Michigan on which approximately 50-lb (8- to 9-week-old) pigs experienced diarrhea just after placement into all-in-all-out finishing barns. The clinical signs (profuse watery diarrhea lasting about 2 weeks and no vomiting) were similar on all farms, and the morbidity rate was high (ranging from 60 to 80%) but without mortality. Eleven diarrheic fecal samples from the farms were tested for group A and C rotaviruses by immune electron microscopy (IEM) and various assays. IEM indicated that the fecal samples reacted only with antiserum against group C rotaviruses, and polyacrylamide gel electrophoresis indicated that the samples had characteristic genomic electropherotypes for group C rotavirus. Group C rotavirus was detected by cell culture immunofluorescence (CCIF) tests in nine fecal samples, but no group A rotavirus was detected by enzyme-linked immunosorbent assay or CCIF. By reverse transcription (RT)-PCR, all 11 fecal samples were positive for group C rotaviruses, with only 2 samples positive for group A rotaviruses. However, a second amplification of RT-PCR products using nested primers detected group A rotaviruses in all samples. Analysis of nucleotide and deduced amino acid sequences of the RT-PCR product (partial-length VP7) of the group C rotavirus showed 87.2 to 91% nucleotide identity and 92.6 to 95.9% amino acid identity among two strong samples from the different farms and the Cowden strain of porcine group C rotavirus. All nine convalescent-phase serum samples tested had neutralizing antibodies to the Cowden strain, and the majority of them had neutralizing antibody against group A rotaviruses (OSU or/and Gottfried strains) by fluorescent focus neutralization tests. Although group C rotaviruses have been reported as a cause of sporadic diarrhea in suckling or weanling pigs, to our knowledge, this is the first report of epidemic diarrhea outbreaks associated with group C rotavirus in older pigs.

Infection with group C rotavirus in a suburban community in Brazil

Group C rotaviruses are associated with sporadic outbreaks of gastroenteritis worldwide. Age-specific seroprevalence of group C rotavirus antibodies was investigated in sera, randomly collected and representative of a suburban community in Brazil which had previously been screened for group A rotavirus antibodies. Antibody prevalence to group C rotavirus was low in children under 5 years and increased slowly with age to 36% seropositivity in adults, reflecting continuous exposure to primary infection in all age groups. This suggests a higher incidence of infection than disease might predict. Adult antibody prevalence was similar to that in other geographical settings. No obvious patterns of infection with group A and group C rotavirus were found within individuals, which suggests independent transmission. However, further epidemiological studies are required to understand group C rotavirus dynamics and possible interactions with group A rotavirus transmission and immunity.

Enzyme-linked immunosorbent assay based on recombinant human group C rotavirus inner capsid protein (VP6) To detect human group C rotaviruses in fecal samples

A recent study showed that 43% of a population in the United Kingdom were seropositive for group C rotavirus. The higher than expected incidence may be due to limited diagnosis of acute human group C rotavirus infections because no routine test is available. Human group C rotavirus infections are routinely diagnosed by electron microscopy (EM) and a negative group A rotavirus enzyme-linked immunosorbent assay (ELISA) result. An antigen-detection ELISA was developed with hyperimmune antibodies raised to human group C rotavirus recombinant VP6 (Bristol strain) expressed in insect cells. The assay was used to screen fecal samples to determine the prevalence of group C rotavirus infection. Samples positive by ELISA were confirmed by EM, polyacrylamide gel electrophoresis of double-stranded RNA, or detection of the VP6 gene by reverse transcription-PCR. Retrospective analysis indicated a 1 to 2% detection rate of positivity among samples from patients with acute diarrhea.

Human group C rotavirus in children with diarrhea in the Federal District, Brazil

Group C rotaviruses are fastidious in their in vitro cell culture requirements. Recent serosurveys indicate that antibody to group C rotavirus is present in 3-45% of the human population in certain geographic locations, suggesting that rotavirus group C infection is more prevalent than previously believed and that the low rate of detection of these agents is probably due to the lack of sensitive diagnostic assays. From March to December 1994, 406 fecal specimens were collected from children under five years of age who were outpatients at the emergency services of nine public hospitals in Brasília, Federal District, Brazil. In addition to the samples from children, one public outpatient unit requested virological investigation of a stool sample from an HIV-seropositive adult male with diarrhea of sudden onset. All samples were analyzed by enzyme immunoassay for group A rotavirus and adenovirus (EIARA) and by polyacrylamide gel electrophoresis (PAGE). One hundred and seven (26%) were positive for group A rotavirus. Four samples from children and the sample from the HIV-seropositive patient, although negative by EIARA, showed a group C rotavirus profile by PAGE and were positive for rotavirus by electron microscopy. Using specific VP6 and VP7 primers for group C rotavirus, a reverse transcriptase-polymerase chain reaction (RT-PCR) was performed and products were detected by agarose gel electrophoresis and ethidium bromide staining. These products were confirmed to be specific for group C rotavirus by using digoxigenin-oligonucleotide probes, Southern hybridization and chemiluminescent detection. The five positive group C rotavirus samples were detected in August (3 samples) and September (2 samples). To the best of our knowledge, this is the first report of group C rotavirus detected in the Federal District, Brazil and in an HIV-seropositive patient with acute gastroenteritis.

Seroepidemiology of human group C rotavirus in the UK

The gene coding for the major inner capsid protein VP6 of human group C rotavirus was cloned into baculovirus using the pBlueBac2 vector and expressed in insect cells. When cultured in High Five cells, VP6 was expressed at a high level and exported to the cell culture medium. Purified VP6 was used to immunise rabbits. Hyperimmune rabbit serum, which reacted with native human group C rotavirus in infected cells, was used to develop and optimise an EIA for the detection of antibodies to group C rotavirus using the recombinant VP6 as a source of antigen. In a local epidemiological survey of 1000 sera grouped by age, an average of 43% of samples were found to have antibodies to human group C rotavirus with the highest proportion (66%) in the 71-75 year age group. In comparison, 97% of adults and 85% of children had antibodies to recombinant VP6 from the bovine RF strain of group A rotavirus. These results suggest that infection with human group C rotavirus is a common occurrence despite the apparent rarity of reports of human group C rotavirus in clinical samples from patients with gastroenteritis.

Epidemiology of group C rotavirus infection in Western New York women of childbearing age

Umbilical cord serum samples (380), an average of 10 per month for 3 years (1990 to 1992), were tested by indirect immunofluorescence assay for group C rotavirus immunoglobulin G. Thirty percent were positive, suggesting that approximately one-third of women of childbearing age in western New York have experienced group C rotavirus infection.

Rapid vertical agarose: silver stain detection of rotavirus

Human rotaviruses (HRV) are the most important etiologic agents of acquired diarrhea in infants and young children worldwide. Therefore, the early diagnosis is essential for effective patient management and infection control. We have developed a rapid, simple technique for the diagnosis of rotavirus based on the sensitive detection of rotavirus double-stranded RNA genome segments separated in vertical agarose gels and developed by silver staining (AGE-SS). This method also has the ability to detect differences in the electrophoretic mobility of RNA bands among group C rotaviruses, reovirus, and group A rotaviruses. The results indicate that this assay is as sensitive and specific as the polyacrylamide gel electrophoresis and silver stain method (PAGE/SS) and it could be applied on large scale for the screening of stool suspected of rotaviral diarrhea. This assay does not need sophisticated equipment and the cost per sample is minimal compared with other available assays.

An outbreak of diarrhoea associated with atypical rotaviruses in goat kids

The presence of rotaviruses was investigated in the faeces of 31 goat kids in a dairy herd that experienced an outbreak of severe diarrhoea which caused dehydration, anorexia and prostration in seven (22.6 per cent) of them. All the affected animals were two to three days old. A group A-specific ELISA failed to detect rotaviruses in any of the samples but the characteristics electropherotype of group B rotaviruses was observed by electrophoresis in polyacrylamide gels in six of the animals. A highly significant statistical association between the shedding of rotavirus and the occurrence of diarrhoea was demonstrated. All the rotaviruses were detected in animals three to four days old. Cryptosporidium parvum, Clostridium perfringens and enterotoxigenic Escherichia coli were not detected in the seven diarrhoeic animals.

The rotavirus genus

Human rotaviruses, discovered nearly 20 years ago, have been proven to be major cause of paediatric diarrhoeal disease morbidity and mortality. The clinical significance of these viruses stimulated basic studies on their biology, molecular and antigenic properties and epidemiology. General features, clinical relevance, epidemiologic pattern and laboratory diagnosis of human rotavirus infections are here reviewed.

Production and characterization of monoclonal antibodies to porcine group C rotaviruses cross-reactive with group A rotaviruses

Five monoclonal antibodies (MAbs) to porcine group (gp) C rotaviruses (Cowden and Ah strains) reactive with both gp A and C rotaviruses in cell culture immunofluorescence (CCIF) tests were produced and characterized. These MAbs reacted with three strains of gp A and two strains of gp C rotaviruses in a CCIF test and were classified into two groups based on their CCIF titers. The MAbs also reacted to various degrees with cell-culture-propagated porcine gp C rotavirus (Cowden) and bovine gp A rotavirus (NCDV) in an enzyme-linked immunosorbent assay by using the MAbs as capture antibodies. Fecal samples containing human, bovine, and porcine strains of gp A and C rotaviruses were positive when tested using one of the MAbs in this assay. The MAbs recognized VP6 of gp A rotavirus and the VP6 counterpart (41-kDa protein) of gp C rotavirus in a Western blot assay. Results of competitive binding assays on four MAbs indicated that gp A and gp C rotaviruses share three overlapping epitopes within a single antigenic domain. These results suggest that gp A and C rotaviruses share a common antigen located on the VP6 protein, which is recognized by certain MAbs in various serologic assays.

Evidence of serologic diversity within group C rotaviruses

The Cowden strain of porcine group C rotavirus and the Shintoku strain of bovine group C rotavirus were classified as different serotypes by two-way cross-neutralization tests. Two neutralization patterns against the Cowden and Shintoku strains were observed when hyperimmune or convalescent-phase antisera to three noncultivatable porcine group C rotaviruses and a human group C rotavirus were used in one-way cross-neutralization tests. Antisera to two porcine group C rotaviruses and the human group C rotavirus neutralized the Cowden strain at high titers but did not neutralize the Shintoku strain, suggesting that these three strains are serotypically related to the Cowden strain. The remaining antisera to a porcine group C rotavirus (HF strain) reacted with the Cowden and Shintoku group C rotaviruses in cell culture immunofluorescence tests but did not neutralize either virus in one-way cross-neutralization, suggesting that the HF strain belongs to a third serotype. However, confirmation of these findings requires additional analysis by two-way cross-neutralization. Our findings support the existence of at least two distinct serotypes of group C rotaviruses, and possibly a third, among animals and humans. The serotypic similarity observed between the Cowden strain and a human group C rotavirus suggests that the cultivatable Cowden strain and antiserum to this virus may provide important reagents for the diagnosis of group C rotaviruses in humans.