Morphological and antigenic relationships between viruses (rotaviruses) from acute gastroenteritis of children, calves, piglets, mice, and foals

Protective effects of sodium butyrate on rotavirus inducing endoplasmic reticulum stress-mediated apoptosis via PERK-eIF2α signaling pathway in IPEC-J2 cells

BACKGROUND

Rotavirus (RV) is a major pathogen that causes severe gastroenteritis in infants and young animals. Endoplasmic reticulum (ER) stress and subsequent apoptosis play pivotal role in virus infection. However, the protective mechanisms of intestinal damage caused by RV are poorly defined, especially the molecular pathways related to enterocytes apoptosis. Thus, the aim of this study was to investigate the protective effect and mechanism of sodium butyrate (SB) on RV-induced apoptosis of IPEC-J2 cells.

RESULTS

The RV infection led to significant cell apoptosis, increased the expression levels of ER stress (ERS) markers, phosphorylated protein kinase-like ER kinase (PERK), eukaryotic initiation factor 2 alpha (eIF2α), caspase9, and caspase3. Blocking PERK pathway using specific inhibitor GSK subsequently reversed RV-induced cell apoptosis. The SB treatment significantly inhibited RV-induced ERS by decreasing the expression of glucose regulated protein 78 (GRP78), PERK, and eIF2α. In addition, SB treatment restrained the ERS-mediated apoptotic pathway, as indicated by downregulation of C/EBP homologous protein (CHOP) mRNA level, as well as decreased cleaved caspase9 and caspase3 protein levels. Furthermore, siRNA-induced GPR109a knockdown significantly suppressed the protective effect of SB on RV-induced cell apoptosis.

CONCLUSIONS

These results indicate that SB exerts protective effects against RV-induced cell apoptosis through inhibiting ERS mediated apoptosis by regulating PERK-eIF2α signaling pathway via GPR109a, which provide new ideas for the prevention and control of RV.

Experimental Methods to Study the Pathogenesis of Human Enteric RNA Viruses

Every year, millions of children are infected with viruses that target the gastrointestinal tract, causing acute gastroenteritis and diarrheal illness. Indeed, approximately 700 million episodes of diarrhea occur in children under five annually, with RNA viruses norovirus, rotavirus, and astrovirus serving as major causative pathogens. Numerous methodological advancements in recent years, including the establishment of novel cultivation systems using enteroids as well as the development of murine and other animal models of infection, have helped provide insight into many features of viral pathogenesis. However, many aspects of enteric viral infections remain elusive, demanding further study. Here, we describe the different in vitro and in vivo tools available to explore different pathophysiological attributes of human enteric RNA viruses, highlighting their advantages and limitations depending upon the question being explored. In addition, we discuss key areas and opportunities that would benefit from further methodological progress.

Overview of the Development, Impacts, and Challenges of Live-Attenuated Oral Rotavirus Vaccines

Safety, efficacy, and cost-effectiveness are paramount to vaccine development. Following the isolation of rotavirus particles in 1969 and its evidence as an aetiology of severe dehydrating diarrhoea in infants and young children worldwide, the quest to find not only an acceptable and reliable but cost-effective vaccine has continued until now. Four live-attenuated oral rotavirus vaccines (LAORoVs) (Rotarix^®, RotaTeq^®, Rotavac^®, and RotaSIIL^®) have been developed and licensed to be used against all forms of rotavirus-associated infection. The efficacy of these vaccines is more obvious in the high-income countries (HIC) compared with the low- to middle-income countries (LMICs); however, the impact is far exceeding in the low-income countries (LICs). Despite the rotavirus vaccine efficacy and effectiveness, more than 90 countries (mostly Asia, America, and Europe) are yet to implement any of these vaccines. Implementation of these vaccines has continued to suffer a setback in these countries due to the vaccine cost, policy, discharging of strategic preventive measures, and infrastructures. This review reappraises the impacts and effectiveness of the current live-attenuated oral rotavirus vaccines from many representative countries of the globe. It examines the problems associated with the low efficacy of these vaccines and the way forward. Lastly, forefront efforts put forward to develop initial procedures for oral rotavirus vaccines were examined and re-connected to today vaccines.

Vitamin D Alleviates Rotavirus Infection through a Microrna-155-5p Mediated Regulation of the TBK1/IRF3 Signaling Pathway In Vivo and In Vitro

(1) Background: Vitamin D (VD) plays a vital role in anti-viral innate immunity. However, the role of VD in anti-rotavirus and its mechanism is still unclear. The present study was performed to investigate whether VD alleviates rotavirus (RV) infection through a microRNA-155-5p (miR-155-5p)-mediated regulation of TANK-binding kinase 1 (TBK1)/interferon regulatory factors 3 (IRF3) signaling pathway in vivo and in vitro. (2) Methods: The efficacy of VD treatment was evaluated in DLY pig and IPEC-J2. Dual-luciferase reporter activity assay was performed to verify the role of miR-155-5p in 1α,25-dihydroxy-VD₃ (1,25D3) mediating the regulation of the TBK1/IRF3 signaling pathway. (3) Results: A 5000 IU·kg^–1 dietary VD₃ supplementation attenuated RV-induced the decrease of the villus height and crypt depth (p < 0.05), and up-regulated TBK1, IRF3, and IFN-β mRNA expressions in the jejunum (p < 0.05). Incubation with 1,25D3 significantly decreased the RV mRNA expression and the RV antigen concentration, and increased the TBK1 mRNA and protein levels, and the phosphoprotein IRF3 (p-IRF3) level (p < 0.05). The expression of miR-155-5p was up-regulated in response to an RV infection in vivo and in vitro (p < 0.05). 1,25D3 significantly repressed the up-regulation of miR-155-5p in vivo and in vitro (p < 0.05). Overexpression of miR-155-5p remarkably suppressed the mRNA and protein levels of TBK1 and p-IRF3 (p < 0.01), while the inhibition of miR-155-5p had an opposite effect. Luciferase activity assays confirmed that miR-155-5p regulated RV replication by directly targeting TBK1, and miR-155-5p suppressed the TBK1 protein level (p < 0.01). (4) Conclusions: These results indicate that miR-155-5p is involved in 1,25D3 mediating the regulation of the TBK1/IRF3 signaling pathway by directly targeting TBK1.

Vitamin D3 supplementation alleviates rotavirus infection in pigs and IPEC-J2 cells via regulating the autophagy signaling pathway

Vitamin D had an anti-infection effect and benefited to the intestinal health. Autophagy signaling pathway was regulated by vitamin D3 to inhibit the infection of human immunodeficiency virus type-1. Rotavirus (RV) was a major cause of the severe diarrheal disease in young children and young animals. Although evidence suggested that vitamin D3 attenuates the negative effects of RV infection via the retinoic acid-inducible gene I signaling pathway, little is known of its antiviral effect whether through the regulation of autophagy. The present study was performed to investigate whether vitamin D3 alleviates RV infection in pig and porcine small intestinal epithelial cell line (IPEC-J2) models via regulating the autophagy signaling pathway. RV administration increased the Beclin 1 mRNA abundance in porcine jejunum and ileum. 5000 IU/kg dietary vitamin D3 supplementation greatly up-regulated LC3-II/LC3-I ratios and PR-39 mRNA expression under the condition of RV challenged. The viability of IPEC-J2 was significantly inhibited by RV infection. Incubation with 25-hydroxyvitamin D3 significantly decreased the concentrations of RV antigen and non-structural protein 4 (NSP4), and up-regulated the mRNA expression of Beclin 1 and PR-39 in the RV-infected IPEC-J2 cells. And then, based on the 25-hydroxyvitamin D3 treatment and RV infection, LC3-II mRNA expression in cells was inhibited by an autophagy inhibitor 3-methyladenine (3-MA). Bafilomycin A1 (Baf A1, a class of inhibitors of membrane ATPases, inhibits maturation of autophagic vacuoles) treatment numerically enhanced the LC3-II mRNA abundance, but had no effect on NSP4 concentration. Furthermore, 25-hydroxyvitamin D3 decreased the p62 mRNA expression and increased porcine cathelicidins (PMAP23, PG1-5 and PR-39) mRNA expression in the RV-infected cells. Taken together, these results indicated that vitamin D3 attenuates RV infection through regulating autophagic maturation and porcine cathelicidin genes expression.

Reverse transcription loop-mediated isothermal amplification assay for rapid detection of Bovine Rotavirus

Background

Bovine rotavirus (BRV) infection is common in young calves. This viral infection causes acute diarrhea leading to death. Rapid identification of infected calves is essential to control BRV successfully. Therefore development of simple, highly specific, and sensitive detection method for BRV is needed.

Results

A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed and optimized for rapid detection of BRV. Specific primer sets were designed to target the sequences of the VP6 gene of the neonatal calf diarrhea virus (NCDV) strain of BRV. The RT-LAMP assay was performed in a water bath for 60 minutes at 63°C, and the amplification products were visualized either directly or under ultraviolet light. This BRV specific RT-LAMP assay could detect 3.32 copies of subtype A BRV. No cross-reactions were detected with other bovine pathogens. The ability of RT-LAMP to detect bovine rotavirus was further evaluated with 88 bovine rectal swab samples. Twenty-nine of these samples were found to be positive for BRV using RT-LAMP. The BRV-specific-RT-LAMP results were also confirmed by real-time RT-PCR assay.

Conclusions

The bovine rotavirus-specific RT-LAMP assay was highly sensitive and holds promise as a prompt and simple diagnostic method for the detection of group A bovine rotavirus infection in young calves.

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.

Implications of recent virological researches

Rotaviruses (duoviruses) can be found in more than half the cases of acute diarrhoea in children up to the age of six or seven. About that age almost everyone has antibodies to them. Second infections occur and may not be as rare as laboratory findings so far suggest. Very young infants sometimes get subclinical disease-the effect of maternal antibody transmitted across the placenta? Very similar viruses, all possessing a common antigen detectable by immunofluorescence, are known to infect and/or cause diarrhoea in children, calves, piglets, mice, foals and monkeys. The calf virus and the human virus both infect piglets; piglet virus infects calves; we don't know whether any of these can infect children. Other mammals probably have similar diarrhoea viruses. An antigen common to all these viruses is probably in the inner capsid layer, and "species-specific" antigens are probably in the outer capsid layer. A precise test for comparing different strains is bably needed. Adenoviruses possibly cause a smaller proportion of cases of diarrhoea. Coronaviruses, well-known as enteric pathogens of pigs and calves, appear also to infect adults and children. 27 nm particles and 22-23 nm particles of density 1.4 (and other particles) can be found in faeces of children with natural diarrhoea and adults with experimental diarrhoea, sometimes in enormous numbers. It is not yet established whether they cause disease. Rotaviruses, animal coronaviruses and "Norwalk" virus attack the disaccharidase-producing epithelium of the small bowel; adenovirus pathology is unknown.A safe attenuated live vaccine strain of the human rotavirus urgently needs to be developed.

Nucleic acid-based analyses of non-group A rotaviruses

Simple genome profile studies on polyacrylamide gels allow all non-group A rotaviruses isolated so far to be recognized by the absence of the tight triplet (7-9) of RNA segments seen in all group A viruses. However, reliance solely on genome profile studies for rotavirus grouping can be misleading and, for virus group definition, additional corroborating nucleic acid and serological studies are essential. Terminal fingerprint analysis was the first generation of nucleic acid-based assays that allowed discrimination between the various rotavirus groups. By means of this technique the clear definition of five rotavirus groups (A-E), correlating exactly with those found by a serological assay, has been possible, with preliminary evidence for at least two additional groups. The technical sophistication of fingerprinting techniques prevents their widespread use in epidemiological studies; the development of a second generation of nucleic acid-based assays is therefore under way. These employ molecularly cloned cDNA probes to the genomes of non-group A viruses which can be widely distributed for use in 'dot-blot' screening of faecal samples and, if expressed as protein in Escherichia coli, should provide a ready source of viral antigen for use in surveying viral prevalence through the screening of serum antibody levels.

Novel porcine rotavirus of genotype P[27] shares new phylogenetic lineage with G2 porcine rotavirus strain

A novel and unusual strain of porcine rotavirus (PoRV) CMP034 was isolated from a 7-week-old piglet during the epidemiological survey of porcine rotavirus infection in Chiang Mai province, Thailand from June 2000 to July 2001. Molecular characterization of gene VP4 by sequence analysis showed a low level of amino acid sequence identity, ranging from 56.7% to 76.6%, while comparison of VP8* portion showed 41.8% to 69.9% identity, with the 26 P genotypes recognized to date. Phylogenetic analysis of the VP4 sequence revealed that CMP034 was only distantly related to the other 26 P genotypes and was located in a separate branch. Sequence analysis of gene VP7 showed the highest level of amino acid identity (94.7%) with the PoRV G2-like reference strain 34461-4 but a lower level of identity with those of human G2 rotaviruses, ranging from 87.7% to 88.0%. Phylogenetic analysis of gene VP7 revealed two major lineages among G2 rotavirus strains based on the host origin. PoRV strain CMP034 clustered exclusively with G2-like PoRV strain 34461-4 in a novel lineage that is distinct from the major G2 human lineage. Moreover, strain CMP034 displayed a porcine-like VP6 and NSP5/6 with subgroup I specificity, while bearing an NSP4 with some genetic group B human-like characteristics. These findings provide evidence that CMP034 should be considered as a novel VP4 genotype P[27].

Development of a rapid and sensitive quantitative assay for rotavirus based on flow cytometry

A very sensitive and accurate flow cytometry (FC) based method have developed to quantitate rotavirus infection in MA104 cells. Confluent cell monolayers were infected with serial dilutions of rotavirus SA11. After infection, the cells were recovered with the aid of trypsin and then reacted with monoclonal antibody M60 (specific for the rotavirus outer capsid protein, VP7), followed by a second antibody (anti-mouse IgG-FITC). A FACScan FC was used to estimate the number of infected cells, as well as the level of infection. Viral infection was optimised by varying the concentration of trypsin used in the maintenance medium. The FC method enables many cells to be screened quickly for infectivity, and can detect low levels of virus. This method can be adapted to monitor the presence of other viruses in clinical and environmental samples without the need for prolonged periods of adaptation to growth in tissue culture.

Rotavirus vaccines and vaccination potential

The development of a successful rotavirus vaccine is a complex problem. Our review of rotavirus vaccine development shows that many challenges remain, and priorities for future studies need to be established. For example, the evaluation of administration of a vaccine with OPV or breast milk might receive less emphasis until a vaccine is made that shows clear efficacy against all virus serotypes. Samples remaining from previous trials should be analyzed to determine epitope-specific serum and coproantibody responses to clarify why only some trials were successful. Detailed evaluation of the antigenic properties of the viruses circulating and causing illness in vaccinated children also should be performed for comparisons with the vaccine strains. In future trials, sample collection should include monitoring for asymptomatic infections and cellular immune responses should be analyzed. The diversity of rotavirus serotype distribution must be monitored before, during, and after a trial in the study population and placebo recipients must be matched carefully to vaccine recipients. Epidemiologic and molecular studies should be expanded to document, or disprove, the possibility of animal to human rotavirus transmission, because, if this occurs, vaccine protection may be more difficult in those areas of the world where cohabitation with animals occurs. We also need to have an accurate assessment of the rate of protection that follows natural infections. Is it realistic to try to achieve 90% protective efficacy with a vaccine if natural infections with these enteric pathogens only provide 60% or 70% protection? Subunit vaccines should be considered to be part of vaccine strategies, especially if maternal antibody interferes with the take of live vaccines. The constraints on development of new vaccines are not likely to come from molecular biology. The challenge remains whether the biology and immunology of rotavirus infections can be understood and exploited to permit effective vaccination. Recent advances in developing small animal models for evaluation of vaccine efficacy should facilitate future vaccine development and understanding of the protective immune response(s) (Ward et al. 1990b; Conner et al. 1993).

Survey of rotavirus infection in a dairy herd: comparison between polyacrylamide gel electrophoresis and two commercial tests

A survey of rotavirus infection in a dairy herd with a history of neonatal diarrhoea was carried out. Faecal samples taken from 15 cows before and after calving as well as faeces taken from their calves daily from birth to two weeks of life were tested for rotavirus by polyacrylamide gel electrophoresis (PAGE) and compared with an ELISA and a latex agglutination commercial test. Rotavirus excretion was not detected in faeces from cows around parturition by any of the three tests. However, all of their calves shed rotaviruses during the observation period. The onset of rotavirus excretion determined by PAGE ranged from day 2 to day 8 of life (day 4.8 +/- 1.8 on average) and lasted for 4 to 7 days (5.3 +/- 1.1 days on average). Chi-square test showed a significant association (P = 0.0001) between the presence of rotavirus and the altered consistency of calves faeces. All the three tests showed similar results (overall agreement 92.5%) but discrepancies were detected mainly at the beginning or at the end of the rotavirus excretion period. Results obtained with both commercial kits closely paralleled each other and parameters other than sensitivity, specificity, diagnostic accuracy or predictive values have to be considered as selection criteria.

Isolation, characterization, and serial propagation of a bovine group C rotavirus in a monkey kidney cell line (MA104)

A virus (designated the Shintoku strain) which was morphologically indistinguishable from group A rotaviruses was detected in the feces of adult cows with diarrhea in Japan. The virus contained 11 segments of double-stranded RNA and had an electrophoretic migration pattern in polyacrylamide gels similar to that of other group C rotaviruses (4-3-2-2). Feces containing the bovine virus reacted with antiserum to porcine group C rotavirus (Cowden strain) but not group A or B rotaviruses in immunoelectron microscopy. The virus was adapted to serial propagation in roller tube cultures of a rhesus monkey kidney cell line (MA104) by using high concentrations of trypsin. Evidence for viral replication in MA104 cell cultures was demonstrated by immunoelectron microscopy and indirect immunofluorescence by using antiserum to porcine group C rotavirus and by electrophoretic analysis of extracted viral double-stranded RNA. A significant antibody response against the isolate was detected in convalescent-phase sera of cows which excreted the virus: no increased antibody response to bovine group A rotavirus was observed. To our knowledge, this is the first isolation of a group C rotavirus from cattle.

Analysis of serotypes and electropherotypes of equine rotaviruses isolated in the United States

Equine group A rotaviruses isolated over a 10-year period in New York State, New Jersey, Kentucky, and Texas were compared serotypically and electropherotypically. All isolates were determined to be serotype 3 by reaction with hyperimmune antiserum to the serotype 3 H-2 strain of equine rotavirus. All displayed RNA electrophoretic migration patterns related to that of the H-2 strain but distinct from that of serotype 5 strain H-1. A serologic survey of 184 mares in Kentucky, which was done to determine the incidence of H-1 and H-2 infections, showed geometric mean serum neutralizing titers to the H-2 strain of equine rotavirus to be significantly higher than those to the H-1 strain. These data suggest that the serotype 3 H-2 strain is the dominant equine rotavirus in Kentucky and perhaps elsewhere in the United States. We were unable to produce confirmational evidence that the H-1 strain occurs as a natural infection in the United States.

Relative prevalence of typical and atypical strains among rotaviruses from diarrheic pigs in conventional swine herds

Polyacrylamide gel electrophoresis was conducted on genomic RNA extracted from rotaviruses detected in diarrheic pigs from conventional swine herds. Ninety samples contained sufficient virus for RNA band visualization and genome classification. Genome profiles were characteristic of typical group A rotaviruses in 67.8% of the 90 samples, of group B rotaviruses in 10.0%, and of group C rotaviruses in 11.1%. In 11.1% of the samples, the presence of more than 11 bands suggested concurrent infection with more than 1 strain of rotavirus. In infections among nursing pigs, 76.4% were group A rotaviruses, 7.4% were group B, 7.4% were group C, and 8.8% were coinfections. In infections among weaned pigs, 40.9% were group A, 18.2% were group B, 22.7% were group C, and 18.2% were coinfections. Coelectrophoresis with prototype OSU and Gottfried strains revealed a great diversity in electropherotype among field strains of rotavirus.

Development of specific nucleic acid probes for the differentiation of porcine rotavirus serotypes

A dot blot hybridization assay is described for the detection and differentiation of porcine rotavirus serotypes. Recombinant complementary DNA (cDNA) representing gene 9 (the gene encoding the neutralization antigens in VP7 glycoprotein) from OSU (porcine rotavirus serotype 1) and Gottfried (porcine rotavirus serotype 2) strains were used to determine the optimal hybridization conditions which allow specific detection of group A porcine rotaviruses. Probes were prepared by excision of the inserts from the recombinant plasmids and radiolabeling of cDNA with 32P by the random primer extension method. Probes were hybridized at various stringencies with viral RNA from different rotavirus serotypes bound to nylon membranes. Hybridization at low stringency (26% base pair mismatch for stable hybrid formation) had high sensitivity but low specificity. Hybridization at high stringency (16% base pair mismatch for stable hybrid formation) produced high specificity but decreased the sensitivity observed at low stringency. Probes were specific for rotavirus at both stringencies and did not hybridize with nucleic acids from other porcine viruses. Subgenomic gene 9 fragments were then tested to provide more specific probes. A 322 bp fragment from OSU gene 9 between nucleotides 382 and 704 and a 266 bp fragment from Gottfried gene 9 between nucleotides 230 and 496 were found to be specific as hybridization probes. These studies demonstrated the feasibility of the dot blot hybridization assay using subgenomic fragments of gene 9 to detect and differentiate serotypes of porcine rotavirus. Additional studies are warranted to further evaluate the sensitivity and the capability of these probes to detect porcine field isolates of the same serotype.

Porcine group C rotavirus as a cause of neonatal diarrhea in a Quebec swine herd

A porcine group C rotavirus was found to be the unique cause of a problem of enzootic neonatal diarrhea in a minimal disease herd composed of 190 sows on a continuous farrowing program. During the outbreaks of diarrhea, 10 to 80% of the litters were affected with a morbidity rate of 100% and case fatality rates of 5 to 10%. Clinical signs began 24 to 48 h after birth and were characterized by a profuse yellow diarrhea lasting a few days. Piglets from different outbreaks of diarrhea were necropsied. They had multifocal villous atrophy in the small intestine, especially in the ileum. Group C rotavirus was demonstrated by direct immunofluorescent staining of frozen intestinal sections and by polyacrylamide gel electrophoresis of viral RNA extracted from the intestinal contents of diarrheic piglets. The infection with clinical illness and lesions was reproduced experimentally in newborn piglets by oral inoculation of a suspension prepared from a pool of intestinal contents from diarrheic piglets.

Presence of group A and non-A rotaviruses in neonatal piglets in Campinas, SP, Brazil

Rotaviruses were detected by polyacrylamide gel electrophoresis (PAGE) in 11 (84.6%) of 13 faecal specimens from neonatal piglets with acute diarrhoea in a piggery near the city of Campinas, State of São Paulo, Brazil. An immunoenzimatic assay for group A rotavirus (IEA-A) was positive in ten of the samples, all of which showed a PAGE profile typical of that group. Another sample was showed a group B profile in PAGE. An immunoenzimatic assay specific for group B (IEA-B) for this faecal sample was positive, confirming the PAGE results.

Molecular biology of rotaviruses. VIII. Quantitative analysis of regulation of gene expression during virus replication

A sensitive and quantitative solution hybridization assay recently developed in this laboratory has been applied to the study of the regulation of viral gene expression in rotavirus-infected cells. Measurement of the cumulative level of viral plus-strand (mRNA) synthesis at hourly intervals throughout the growth cycle has provided evidence for both quantitative and qualitative regulation of transcription. Qualitative control was found only when cycloheximide was used to block protein synthesis in infected cells, when transcription of four of the viral genes (genes 5, 6, 7, and 9) was independent of protein synthesis. Quantitative regulation was demonstrated by the accumulation of mRNA to much higher levels for some of the viral genes (e.g., genes 2 and 7) relative to others (e.g., genes 4 and 6). In addition to quantitative control at the level of transcription, measurement of the relative molar amounts of the various viral proteins at 6.5 h postinfection showed that their levels did not directly reflect those of their encoding RNAs, indicating the existence of translational control of gene expression in the rotavirus system. Analysis of the levels of minus strand synthesized for each viral gene showed that they were not all accumulated to the same level. The significance of this result in the light of the presumed similarities in replication strategy to that of the mammalian reoviruses is discussed.

Antigenic characterization of swine rotaviruses in Argentina

Fecal samples from 156 diarrheic piglets were collected from several herds located in two main breeding areas of Argentina. Rotaviruses were detected in 60 samples (38.4%) by polyacrylamide gel electrophoresis and in 55 samples by a group A-specific enzyme-linked immunosorbent assay (ELISA). All samples which were positive by polyacrylamide gel electrophoresis and negative by ELISA had elicited atypical electropherotypes resembling those of group B or C. ELISA-positive samples showing genome rearrangements were also detected (R.C. Bellinzoni, N.M. Mattion, O.R. Burrone, S.A. González, J.L. La Torre, and E.A. Scodeller, J. Clin. Microbiol. 25:952-954, 1987; N.M. Mattion, S.A. González, O.R. Burrone, R.C. Bellinzoni, J.L. La Torre, and E.A. Scodeller, J. Gen. Virol. 69:695-698, 1988). By subgrouping with monoclonal antibodies, it was found that of 32 positive samples, 13 belonged to subgroup I, 2 belonged to subgroup II, 2 samples had both specificities, and 15 samples were neither subgroup I nor subgroup II (non-I/II). In addition, 10 samples were adapted to grow in tissue culture, cloned, and serotyped by means of neutralization assays. Two samples were classified as serotype 5, and none of them were classified as serotype 4. The other strains showed only a one-way relationship with serotype 5 and can be tentatively classified as new porcine serotypes. Two samples with rearranged genomes had a one-way relationship with antiserum to human strain 69M, which displays a supershort electropherotype and was classified as a new human serotype (S. Matsuno, A. Hasegawa, A. Mukoyama, and S. Inouye, J. Virol. 54:623-624, 1985). At one farm, similar rearranged strains were detected during three successive years. Serotype changes were found between the isolates of the first and the second year, suggesting that a high degree of antigenic variability went on during continuous circulation of these strains in the field.

Vaccines produced by conventional means to control major infectious diseases of man and animals

This chapter reviews the development of some of vaccines and their use in controlling such major diseases as diphtheria, rinderpest, Newcastle disease, smallpox, pertussis, yellow fever, rabies, etc. Park–Williams Number 8 (PW8) strain is used to make diphtherial toxoid for vaccines. As a source of toxin, it is rendered nontoxic by incubation with formalin under alkaline conditions. The product's retention of antigenicity, enabling it to induce antitoxin antibodies, makes it an excellent pediatric vaccine. Vaccine against Rinderpest Virus was developed by Koch in 1897 by administering bile from infected cattle. Animals that survived were permanently immune. Formalin- and chloroform-inactivated vaccines were developed using tissues from the infected animals. For the control of Newcastle disease, a number of attenuated live-virus vaccines have been developed which are widely used to control the disease. The Bl strain, the LaSota strain, and the F strain are used to immunize birds of all ages by different routes, including by addition to drinking water and by spraying. Protection against rabies correlates with SN antibody, which can be assessed by a number of tests. Pasteur's classical vaccine, developed from infected spinal cord tissue dried at room temperature for 3–14 days, was given in a series of 21–28 inoculations beginning with material dried the longest and progressing through material dried for only 3 days.

Human viral gastroenteritis

During the last 15 years, several different groups of fastidious viruses that are responsible for a large proportion of acute viral gastroenteritis cases have been discovered by the electron microscopic examination of stool specimens. This disease is one of the most prevalent and serious clinical syndromes seen around the world, especially in children. Rotaviruses, in the family Reoviridae, and fastidious fecal adenoviruses account for much of the viral gastroenteritis in infants and young children, whereas the small caliciviruses and unclassified astroviruses, and possibly enteric coronaviruses, are responsible for significantly fewer cases overall. In addition to electron microscopy, enzyme immunoassays and other rapid antigen detection systems have been developed to detect rotaviruses and fastidious fecal adenoviruses in the stool specimens of both nonhospitalized patients and those hospitalized for dehydration and electrolyte imbalance. Experimental rotavirus vaccines have also been developed, due to the prevalence and seriousness of rotavirus infection. The small, unclassified Norwalk virus and morphologically similar viruses are responsible for large and small outbreaks of acute gastroenteritis in older children, adolescents, and adults. Hospitalization of older patients infected with these viruses is usually not required, and their laboratory diagnoses have been limited primarily to research laboratories.

The structure of tubes of bovine rotavirus nucleocapsid protein (VP6) assembled in vitro

The structure of tubes of reassembled nucleocapsid protein (VP6) from bovine rotavirus (BRV) was determined using optical diffraction of electron micrographs. The tubes consist of a five-start helix of hexagons, with 38 hexagons per helix in a true repeat of three turns. The morphological subunits comprising the hexagons are probably elongated trimers. The structure of naturally occurring tubes (D. Chasey and J. Labram, 1983, J. Gen. Virol. 64, 863-872) was also examined and shown to be similar but not identical to that of tubes assembled in vitro. Considerations of the assembly process are discussed.

Isolation of a bovine rotavirus with a "super-short" RNA electrophoretic pattern from a calf with diarrhea

A rotavirus with a "super-short" RNA electropherotype was isolated from a calf with diarrhea and was designated VMRI strain. Segments 10 and 11 of this rotavirus migrated more slowly than did those of bovine rotavirus strains NCDV, B641, and B223. The electrophoretic pattern of the VMRI strain was similar to that reported for rotaviruses with super-short RNA electropherotypes from humans and rabbits. Northern (RNA) blot hybridization indicated that gene 11 of the VMRI strain was altered and migrated between gene segments 9 and 10. The subgroup of the VMRI strain was shown to be subgroup I. The VMRI strain of bovine rotavirus was neutralized by antisera containing polyclonal antibodies to rotavirus serotype 6 (bovine rotavirus serotype I) strains NCDV and B641 and by ascitic fluid containing monoclonal antibodies directed to VP7 of serotype 6 rotavirus. The VMRI strain was not neutralized by either polyclonal or monoclonal antibodies to strain B223 (bovine rotavirus serotype II). Collective data on the neutralization of the VMRI strain with monoclonal antibodies and polyclonal antibodies suggest that this virus is a member of the NCDV group (serotype 6) of rotaviruses (bovine rotavirus serotype I).

Identification of a group-reactive epitope of group B rotaviruses recognized by monoclonal antibody and application to the development of a sensitive immunoassay for viral characterization

Group B rotaviruses (GBRs) are fastidious agents which cause enteric disease in humans and a number of other animal species. Detailed study of the role of GBRs in human disease has been hampered by the lack of immunoreagents suitable for large-scale studies. We developed a monoclonal antibody which recognizes a group-reactive antigen contained in a number of strains of GBRs. When utilized in conjunction with a hyperimmune guinea pig antiserum to GBR, this monoclonal antibody can be used in an enzyme immunoassay system to detect a wide range of GBRs. Alternatively, this monoclonal antibody can be combined with sera obtained from GBR-infected animals to devise assays which are largely specific for the homologous strain of GBR. Reactivity was not noted in either system with strains of group A or group C rotaviruses or with other members of the family Reoviridae. These results indicate that GBRs contain both group-reactive and species-specific antigens which are distinct from those found in group A rotaviruses. The availability of well-defined immunoreagents will facilitate detailed studies of GBR infections in humans and animals.

Analysis of the structural polypeptides of a porcine group C rotavirus

Polyacrylamide gel analysis of the structural polypeptides of purified group C virions allowed six major proteins to be identified. Of these, two (52,000- and 39,000-molecular-weight polypeptides) were shown to be in the outer virion shell as judged by the ability to strip them from virions by treatment with EDTA. Treatment of purified particles with endo-beta-N-acetylglucosaminidase F showed that the 39,000-molecular-weight outer shell polypeptide is probably posttranslationally glycosylated. Serological cross-comparison of groups A and C by using Western blotting (immunoblotting) extended the previously demonstrated lack of cross-reaction for the group antigen to show that none of the structural polypeptides cross-reacted. Possible implications of these findings for the epidemiology of rotaviruses are discussed.

Isolation and characterization of rotavirus from feral pigeon in mammalian cell cultures

Avian rotaviruses were isolated from feral pigeon faeces treated with trypsin using roller tube cultures of mammalian cells. Two pigeon strains, designated as strains PO-8 and PO-13, produced a marked cytopathic effect (CPE), small intracytoplasmic inclusion bodies and high titres of infectious particles in infected MA-104 and MDBK cell lines without cell adaptation and roller drum apparatus. The pigeon rotaviruses shared a common group specific antigen with the Lincoln strain of bovine rotavirus by indirect immunofluorescence, but differed from both the Lincoln strain and the Wa strain of human rotavirus in neutralization tests. The RNA segment profile of this virus on polyacrylamide gel electrophoresis differed from that of group A mammalian rotaviruses. The results of a serological survey suggested that antibody to pigeon rotaviruses was widespread in avian species in Japan.

Comparison of direct electron microscopy and enzyme immunoassay for the detection of rotaviruses in calves, lambs, piglets and foals

Direct electron microscopy (EM) and enzyme-immunoassay (rotazyme) results for the detection of rotaviruses in 346 enteric specimens from calves, lambs, piglets and foals were compared. The rotazyme test was at least 3 times more sensitive than direct EM in diagnosing infection. Rotavirus antigen was demonstrated by rotazyme in 22% of 280 scour samples and in 27% of 66 samples from non-scouring animals. There was an association between diarrhoea and higher amounts of rotavirus antigen. This prevalence of rotaviruses detected in animals with diarrhoea highlights the significant involvement of other pathogens identified in the study including Eimeria, Cryptosporidia, Escherichia coli, Campylobacter, and other viruses.

Subgroups, serotypes, and electrophoretypes of rotavirus isolated from children in Bangui, Central African Republic

The subgroups and serotypes of 178 strains of rotavirus isolated from diarrheic and healthy children in Bangui, Central African Republic, during a 27-month period were determined by enzyme-linked immunosorbent assay. The subgroup was determined for 152 of the viral strains, 18.4% being subgroup I and 81.6% being subgroup II. Of the 143 strains which could be serotyped, 71.3% were serotype 1, 15.4% were serotype 2, and 13.3% were serotype 3. Serotypes 1 and 3 were detected throughout the study, while serotype 2 was detected only during 8 months. No serotype exhibited any special epidemiological properties. The serotypes were found to consist of three different electrophoretypes, two long ones (A and B) and a short one (C). All subgroup I, serotype 2 strains presented short electrophoretypes. Strains with identical long electrophoretypes A were either serotype 1 or serotype 3.

The antigenic diversity of rotaviruses: significance to epidemiology and vaccine strategies

Rotaviruses are the major cause of infantile gastroenteritis world-wide. Much antigenic diversity exist amongst them. This has important implications to diagnosis, epidemiology and vaccination strategies. The nature of this diversity is now well understood. This review outlines and discussed our current knowledge of the subject from a historical perspective.

Infectivity and antigenicity reduction rates of human rotavirus strain Wa in fresh waters

The rates of inactivation of human rotavirus type 2 (strain Wa) (HRV-Wa) and poliovirus type 1 (strain CHAT) were compared in polluted waters (creek water and secondary effluent before chlorination) and nonpolluted waters (lake water, groundwater, and chlorinated tap water). Viral infectivity titers were determined by plaque assays, while HRV-Wa antigenicity also was monitored by an enzyme-linked immunosorbent assay. Both viruses persisted longest in lake water and shortest in tap water. The actual inactivation times (i.e., times required for two-log10 reductions of initial viral titers) for the two viruses were significantly different in all waters except tap water. With the exception of the groundwater and secondary effluent results, the HRV-Wa inactivation times in the fresh waters tested were significantly different. Owing perhaps to aggregation, HRV-Wa appeared less susceptible to the effects of chlorine than previously reported for this virus and for the simian rotavirus SA11. HRV-Wa displayed prolonged survival in lake water and groundwater exceeding that previously reported for the SA11 virus. The HRV-Wa infectivity reduction rate (ki) was significantly correlated with the water pH (i.e., as pH increased, ki increased). The water pH may have influenced viral aggregation and thereby HRV-Wa susceptibility to other virucidal factors in the water. Enzyme-linked immunosorbent assay results showed similar inactivation patterns with the most significant reduction in HRV-Wa antigenicity occurring in polluted waters and tap water. In all waters, particularly tap water, infectivity declined at a faster rate than antigenicity. It is proposed that HRV-Wa can be used as a model for future studies of rotaviral persistence in the aquatic environment.

First report of an epidemic of diarrhoea in human neonates involving the new rotavirus and biological characteristics of the epidemic virus strain (KMB/R85)

An outbreak of diarrhoea in neonates occurred at the nurseries of the Department of Obstetrics of Zhao Tong Regional Hospital, Yunnan Province, from the middle of August to the end of November, 1985. Fifty-one percent of children were affected 2-8 days after birth. The clinical symptoms were mild; patients mainly had diarrhoea and did not vomit. Rotaviruses were detected in 66.7% by RNA PAGE and in 72.7% by EM. The virus strain designated as KMB/R85 had a typical morphology, which was indistinguishable from that of infantile rotaviruses by EM. The viral RNA genome was composed of 11 segments. The buoyant density in CsCl was 1.377 g/cm3. The KMB/R85 strain possessed a hemagglutinin for rhesus monkey erythrocytes. By ELISA, IEM, and HAI, it was found that KMB/R85 strain did not possess the common group antigen shared by group A rotaviruses and was antigenically similar to the Chinese adult diarrhoea rotavirus (serogroup B).

Microbiological studies of wild rodents in farms as carriers of pig infectious agents

In 15 breeding and fattening pig herds, 85 mice (Mus musculus) and 40 rats (Rattus norvegicus) were captured and bacteria and viruses looked for. Bordetella bronchiseptica, Pasteurella sp., E. coli, Campylobacter jejuni and Treponema sp. were isolated from different samples. Rota-virus was also identified and neutralizing transmissible gastroenteritis antibodies were detected in the serum of one rat and mice from three different farms. Wild rats were also orally infected with Aujeszky's disease virus (ADV) and classical swine fever (CSF) virus. All the rats survived the ADV experimental infection and some of them showed ADV neutralizing antibodies in their sera. No multiplication of the SF virus was obtained.

Three different forms of tubular structures associated with the replication of bovine rotavirus in a tissue culture system. Brief report

We demonstrated by electron microscopy that three different forms of tubular structures are present both within infected cells and in cultured fluid of bovine rotavirus in a tissue culture system.

Comparison of electron microscopy with three commercial tests for the detection of rotavirus in animal feces

Three commercial test kits were evaluated to detect the presence of rotavirus antigens in bovine, porcine, and turkey feces. Two of the assays, Rotalex (Medical Technology Corporation, Somerset, NJ) and Virogen-Rotatest (Wampole Labs, Cranbury, NJ) are latex agglutination tests (LA), while the third, Pathfinder (Kallestad, Austin, TX) is an enzyme immunoassay. The clinical usefulness of these assays was elevated by comparing their results with those of direct electron microscopy (EM). A total of 135, 92, and 211 samples of animal feces were tested by Rotalex, Virogen, and Pathfinder, respectively. All samples were examined by EM as a reference procedure. The overall agreement of the three commercial assays with EM was 53%, 66%, and 83% for Rotalex, Virogen, and Pathfinder, respectively. Based on these results, we consider Pathfinder as an attractive alternative to EM for the detection of rotavirus in animals. Of the two LA tests, Virogen was found to be a little more sensitive and specific.

Expression of a major bovine rotavirus neutralisation antigen (VP7c) in Escherichia coli

Sequences from genomic RNA segment 8 of the United Kingdom tissue-culture (t.c.)-adapted bovine rotavirus encoding a major viral neutralisation antigen VP7c have been expressed in Escherichia coli. Expression under the regulated control of the bacteriophage lambda pR promoter was as a C-terminal extension to E. coli beta-galactosidase (beta Gal). Following temperature induction, high levels of the fusion protein were synthesised and accumulated in induced cells, making up 5%-15% of total bacterial cell protein after 2 h of induction. Immunisation of sero-negative rabbits and mice with gel-purified fusion-protein raised antibodies, which gave specific immunofluorescence with virus-infected cells and were able to immunoprecipitate proteins of the VP7 complex from such cells. Hyperimmune sera also gave a virus-type-specific reaction in a solid-phase enzyme-linked immunoabsorbant assay and neutralised virus infectivity in standard plaque-reduction assays.