Detection of animal and human group B rotaviruses in fecal specimens by polymerase chain reaction

Differential diagnosis of Moniezia benedeni and M. expansa (Anoplocephalidae) by PCR using markers in small ribosomal DNA (18S rDNA)

Moniezia benedeni and M. expansa are common ruminant tapeworms of worldwide distribution, causing gastrointestinal disorders and even death in sheep and goats. In this study, a polymerase chain reaction- (PCR-) based approach for precise species identification was developed and also applied to faecal DNA diagnosis of the tapeworm infection. Since nuclear ribosomal DNA (rDNA) appears to be a useful target for species and/or strain markers, the 18S regions of the rDNA of M. benedeni and M. expansa were amplified and sequenced. The lengths and GC contents of the regions sequenced were 2476-2487 bp and 51.9-52.1% for M. benedeni and 2473 bp and 51.9-52.0% for M. expansa, respectively. Alignment and comparison of the 18S sequences of the two species showed 92.5-93.3% homology. No matches for the 18S regions of M. benedeni and M. expansa were found with other species by BLAST search, which made the 18S sequences appropriate markers for the design of distinctive primers for the two Moniezia species. Our 18S-based PCR could detect as low levels as 0.5 pg genomic DNA or the DNA extracted from 0.2 g faecal sample collected from the rectum of an M. expansa-infected goat. The results indicate that this PCR approach is a reliable alternative for the differential diagnosis of Moniezia species in faecal samples.

Full genome analysis of group B rotaviruses from western India: genetic relatedness and evolution

To date, full-genome sequences of only seven human group B rotavirus (RVBs) strains have been described. Such data on more RVBs are necessary to establish the evolutionary relationship and ecological features of RVBs from different geographical regions. The present study was aimed at determining the full-length sequences of all 11 genes of 13 human RVB strains detected during 1995-2010 in sporadic and outbreak cases of acute gastroenteritis from four different cities of western India. This study also included estimation of evolutionary rates and site-specific selection pressure analysis for all gene segments. Nucleotide/deduced amino acid sequence analyses of structural and non-structural genes showed 95.1-99.8/94.1-100 % identity with the counterparts of RVB strains isolated in India, Bangladesh and Myanmar. Phylogenetic analyses of all gene segments revealed formation of a monophyletic clade of the western Indian RVB strains, reflecting their highly conserved nature. All gene segments were also found to be under negative/purifying selection pressure. These data suggest that RVB is circulating in the natural host as a series of stable viral clones. Estimates of rates of nucleotide substitution in all RVBs ranged from 1.36-4.78×10(-3) substitutions per site per year. The rate for human RVB VP7 and NSP2 genes were comparable, respectively, with the evolution kinetics of genotype G9/G12 and N1 group A rotavirus strains. The time of the most recent common ancestor of the extant human RVBs was estimated to be during 1915-1974. Evolutionary and genetic analyses carried out in this study provide data that is useful for the elucidation of evolutionary relationship/timescale, stasis or dynamics existing in the RVB population.

Evidence for Occurrence of Human group B rotavirus in Central India Based on Characterization of NSP2 Gene

Human group B rotavirus (HuGBR) was first described as the causative agent of severe gastroenteritis, affecting millions of people in China during 1982-1983. In spite of serological evidences for the presence of HuGBR in many countries of the world, the virus has only been detected from China, Bangladesh and some parts of India. The present study describes a HuGBR (designated as MP-1 isolate) which was confirmed in an adult patient suffering from gastroenteritis in 2008 in Madhya Pradesh, central India. The RNA electrophoresis in polyacrylamide gel (RNA-PAGE) and NSP2 gene based RT-PCR assays and later sequencing was used to confirm the isolate. The nucleotide and deduced amino acid sequences of this HuGBR (MP-1) isolate were analyzed and their relationship with corresponding gene of other Indian, Bangladeshi and Chinese HuGBR and animal group B rotaviruses (AnGBR) was determined. The isolate showed a typical RNA banding pattern of 4:2:2:3 in RNA-PAGE which was indicative of group B rotaviruses (GBR). The sequence comparison of MP-1 isolate with NSP2 gene revealed that MP-1 isolate had 98.6 and 97.7% nucleotide sequence homology and 93.8% amino acid similarity with Bang373 and CAL-1 strains, respectively. The nucleotide and amino acid sequence similarity of MP-1 isolate with one of the Chinese ADRV (WH-1) strain was 92.8 and 92.5%, respectively. While sequence homology with another Chinese strain ADRV (J19) was considerably lower (45.6 and 48.3%, respectively). The percent identity with AnGBRs (porcine and murine) was also lower at nucleotide and amino acid level (66 to 80%). The phylogenetic analysis suggested that MP-1 isolate is closer to Bangladeshi (Bang373) as compared to Indian strain (CAL-1). Our findings indicated that MP-1 isolate might have originated from a common ancestral HuGBR virus but distinct from AnGBR lineage. Occurrence of GBR in other parts of India warrants further epidemiological and molecular studies to develop effective control strategies for GBR infection in adults as well as children.

Clinical presentation and molecular characterization of group B rotaviruses in diarrhoea patients in Bangladesh

A total of 1106 stool samples collected from diarrhoea patients admitted to Dhaka hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh, during January-December 2008 were analysed for the presence of rotavirus-specific RNA by PAGE. The group B-specific RNA migration pattern was detected in 26 patients (2.4%) and group A-specific pattern in 259 patients (23.4%). Clinical data from group A and group B rotavirus-infected patients indicated that episodes did not differ much in the prevalence of diarrhoea, number of stools, outcome or differences in gender. However, abdominal pain was more common in group B rotavirus infections (36 vs 15%, P=0.02) and the virus was responsible for more severe dehydration compared with group A-infected patients (12 vs 3%, P=0.04). Sequence analyses of VP4, VP7 and NSP2 indicated that an Indian-Bangladeshi lineage of the virus, which is different from both the prototype (Chinese) lineage and from the animal group B rotaviruses, has been circulating in Bangladesh. Continuous monitoring of group B rotaviruses both in hospitals and in the community will be helpful to determine the true burden of group B rotaviruses.

Sequence analysis and evolution of group B rotaviruses

Human group B rotaviruses were isolated from hospitalized patients in Bangladesh between July 2003 and December 2004. Phylogenetic analyses of the gene segments encoding the hemagglutinin (VP4), glycoprotein (VP7) and RNA-binding protein (NSP2) of group B rotaviruses showed that Bangladeshi strains were more similar to the Indian strains than to the prototype Chinese strains. Moreover, all human strains were clustered together and were distantly related to the animal strains. With limited sequence data, the evolutionary rate of the glycoproteins (VP7) of human group B rotaviruses was estimated to be 1.57x10(-3) nucleotide substitutions/(siteyear), which was comparable to other rapidly evolving RNA viruses. The most recent common ancestor (MRCA) of the extant human group B rotaviruses was calculated to date to around 1976.

Amplification of ribosomal DNA of Anoplocephalidae: Anoplocephala perfoliata diagnosis by PCR as a possible alternative to coprological methods

The diagnosis of tapeworm infections in horses relies on copro-diagnostic methods, which are time-consuming and of limited sensitivity for determination of the exact prevalence. The development of serological tests has slightly improved the detection of tapeworm infections, but more sensitive methods are still required. A polymerase chain reaction (PCR)-based approach may constitute a valuable tool to improve tapeworm diagnosis. Nuclear ribosomal DNA (rDNA) is a useful target for species and/or strain markers. Partial 18S, the internal transcribed spacer 1 (ITS-1), the 5.8S, the internal transcribed spacer 2 (ITS-2), and partial 28S rDNA of the equine tapeworms Anoplocephala perfoliata and Anoplocephaloides mamillana were amplified and sequenced. The lengths and GC contents of the regions sequenced were 2087-2091bp and 49.35-49.69% for A. perfoliata, and 2110-2119bp and 49.15-49.32% for A. mamillana, respectively. Sequence alignment and comparison of both taxa showed 79.3-80.2% identity. The lowest identities were found in the ITS regions with 39.9-43.5% for the ITS-1 and 59.5-61.2% for the ITS-2. No matches of the ITS-2 of A. perfoliata and A. mamillana were found with other species by BLAST search. For this reason, ITS-2 sequences seemed appropriate as accurate species markers and A. perfoliata ITS-2 primers were developed. The ITS-2 PCR enabled the detection of genomic DNA as low as 0.5 pgs. First efforts on the practical application of the PCR-based approach were made. A 6-mg fragment of a tapeworm proglottid was detected in 0.5 and 1g of faeces.

Common Diseases

Many pathogens have been reported to cause disease in the laboratory rat. This chapter concentrates on the pathology of the more common pathogens of the laboratory rat. Based on serologic surveys, parvo viruses are some of the most common viral pathogens in wild and laboratory rat. In general, there are three main serogroups, including Rat virus (RV), H-1 virus, and Ratparvovirus (RPV). Both RPV and RV are tropic for many of the same tissues and they both may result in a persistent infection. However, RPV is antigenically and genetically distinct from RV, and it apparently does not cause clinical signs or lesions in infant rats. M. pulmonis causes natural disease in rats and mice. The infection in young rats is usually clinically silent. In older rats, there are nonspecific clinical signs such as snuffling, chromodacryorrhea, and face and ear rubbing. Several bacteria of the genus Streptococcus can cause clinical disease in rats. All of the streptococci of concern in rats are Gram-positive cocci, and are catalase-negative, nonfermentative, and generally nonmotile. Cilia-associated respiratory bacillus has been identified in rats. In rats, infection is usually asymptomatic although nonspecific clinical signs, such as weight loss and dyspnea, may be observed.

Detection of Echinococcus multilocularis in the definitive host: coprodiagnosis by PCR as an alternative to necropsy

Recently, extensions of the range of Echinococcus multilocularis in Europe and North America and drastic increases in fox populations in Europe put an increasing proportion of the human population at risk of alveolar echinococcosis. To obtain data on the local infection pressure, studies of the prevalence of the parasite in the animals that transmit the parasite, foxes, dogs, and cats, are urgently required. Such investigations, however, have been hampered by the need for necropsy of the host animal to specifically diagnose infection with the parasite. In this study, a nested PCR and an improved method for DNA extraction were developed to allow the sensitive and specific diagnosis of E. multilocularis infections directly from diluted fecal samples from foxes. The target sequence for amplification is part of the E. multilocularis mitochondrial 12S rRNA gene. The specificity of the method was 100% when it was tested against 18 isolates (metacestodes and adult worms) of 11 cestode species, including E. granulosus. The sensitivity of the method was evaluated by adding egg suspensions and individual eggs to samples of diluted feces from uninfected foxes. The presence of one egg was sufficient to give a specific signal. To confirm the PCR results, an internal probe which hybridized only with E. multilocularis amplification products but not with the DNA of other cestodes was constructed. In order to investigate the applicability of this method for epidemiological studies, 250 wild foxes from a area in southern Germany where echinococcosis is highly endemic were examined by both necropsy and PCR of rectal contents. The sensitivity correlated with the parasites' number and stage of maturity. It ranged from 100% (>1,000 gravid worms) to 70% (<10 nongravid worms). On the basis of positive PCR results for 165 foxes, the sensitivity of the traditional and widely used necropsy method was found to be not higher than 76%. We therefore present this PCR system as an alternative method for the routine diagnosis of E. multilocularis in carnivores.

Detection of group B rotaviruses in fecal samples from diarrheic calves and adult cows and characterization of their VP7 genes

Groups A, B, and C rotaviruses have been identified in cattle. Group B rotaviruses are associated with sporadic cases of diarrhea in calves and adult cows. From diagnostic submissions to our laboratory, 90 fecal samples from cases of calf diarrhea, 81 fecal samples from cases of adult cow diarrhea (winter dysentery), and 20 fecal samples from case control normal adult cows were tested for group B rotaviruses by polyacrylamide gel electrophoresis (PAGE), and reverse transcription (RT)-PCR (targeting 279 bp of the VP7 gene). In addition, 53 fecal samples from diarrheic adult cows were tested for group B rotaviruses by immune electron microscopy (IEM). By RT-PCR, five samples from calves were group B rotavirus positive (5.6%). Fifteen samples from adult cows with diarrhea were group B rotavirus positive (18.5%), and none of the control fecal samples from normal cows were positive for group B rotaviruses. By PAGE, one calf sample (RT-PCR positive) was group B rotavirus positive (short electropherotype), but none of the adult cow samples were positive for group B rotaviruses. By IEM, 5 (9.4%) of the 53 fecal samples from diarrheic adult cows were group B positive (all were also RT-PCR positive). The VP7 genes of three strains (WD653 from an adult cow and the ATI and Mebus calf strains) were sequenced. The VP7 genes from the three bovine strains showed high (over 90%) nucleotide and deduced amino acid homologies, but lower homologies (48 to 61%) were seen between these genes and the genes from rodent (IDIR) and human (ADRV) group B rotaviruses. Although there were some differences of degree, all inoculated gnotobiotic calves (n = 6) showed abnormal feces between 1 and 3 days after inoculation with each of three strains of group B bovine rotaviruses, and group B rotaviruse, were detected in the feces for up to 2 weeks by RT-PCR but for shorter periods by PAGE or IEM.

Lack of evidence for rotavirus by polymerase chain reaction/enzyme immunoassay of hepatobiliary samples from children with biliary atresia

The purpose of this study was to analyze hepatobiliary samples of patients with biliary atresia for rotavirus groups. A, B, and C, because group A rotavirus had been used to produce an animal model of the disease and group C rotavirus had been found in hepatobiliary samples from one group of patients. Biliary remnants and liver tissue from 10 biliary atresia and 14 control patients with other liver diseases were examined for rotavirus groups A, B, and C using nonisotopic, reverse transcriptase polymerase chain reaction enzyme immunoassay. Biliary atresia patients had a median age of 3 mo and were from a confined geographic area. Rotaviral stocks from groups A and C were used as polymerase chain reaction-positive controls. The limits of detection for rotaviral RNA from these two groups were respectively, 5 plaque-forming units and 50 tissue culture infectious doses (ID50). Tissue culture was 100-fold less sensitive for groups A and C than the polymerase chain reaction. The nested nonisotopic probes hybridized in solution only with their homologous target DNAs as determined by the enzyme immunoassay, or by Southern blot hybridization. Although it was possible to detect mRNA from a beta-actin housekeeping gene in all of the hepatobiliary samples, no evidence of rotaviral RNA was found in either the biliary atresia or the negative control group. In conclusion, rotavirus is not a common viral etiology of biliary atresia.

Improvement of a polymerase chain reaction assay for the detection of Echinococcus multilocularis DNA in faecal samples of foxes

A polymerase chain reaction (PCR) method was developed in order to permit a sensitive and specific identification of Echinococcus multilocularis DNA from fox faecal specimens. In an attempt to overcome problems related to the presence of endogenous PCR inhibitors in faecal extracts, we investigated a DNA extraction technique using an anion binding resin (Gene-Fizz). This simple and rapid procedure was applied to 61 faecal samples. Compared with the traditional microscopic examination, the sensitivity of PCR using Gene-Fizz was 82.3% and the specificity was 95.5%. No PCR signal was obtained for 20 Echinococcus granulosus isolates, showing that this method allowed discrimination between E. multilocularis and E. granulosus. Large-scale epidemiological surveys of fox excrements may be possible by using Gene-Fizz treatment prior to PCR amplification reactions.

A simple touch-down polymerase chain reaction for the detection of canine parvovirus and feline panleukopenia virus in feces

A polymerase chain reaction (PCR) assay is described for the detection of parvovirus in feces of dogs and cats. A touch-down protocol was used which enabled the specific amplification of virion DNA from feces after a fast and simple boiling pretreatment. The sensitivity of PCR was as high as ten infectious particles per reaction which corresponds to a titer of about 10(3) infectious particles per gram of unprocessed feces. This renders the PCR about 10- to 100-fold more sensitive than electron microscopy, the standard method for parvovirus diagnosis. The very rapid and simple sample preparation recommends this PCR assay as an alternative technique for routine parvovirus diagnosis.

Detection of group A rotavirus by reverse transcriptase and polymerase chain reaction in feces from children with acute gastroenteritis

RT-PCR was employed to detect rotavirus infection in 450 fecal samples from children with acute diarrhoea. It was compared with enzyme-linked immunosorbent assay (ELISA) and polyacrylamide gel electrophoresis (PAGE) for rotavirus detection. A total of 67 samples were found positive by at least one of the three techniques. Of these 67 samples, 51 were positive by all three methods, 6 were positive by ELISA and RT-PCR but negative by PAGE, 3 were positive by PAGE and RT-PCR and negative by ELISA, 3 and 4 samples were exclusively positive by RT-PCR and ELISA respectively. These results indicate that RT-PCR is a sensitive and specific assay for detection of group A rotaviruses in stool samples from cases of acute diarrhoea.

Prevalence of group A and group B rotaviruses in the feces of neonatal dairy calves from California

136 fecal samples, collected from 47 dairy calves on a calf ranch and in a dairy herd in California, were tested for the presence of group A and group B rotaviruses by reverse transcription-polymerase chain reaction (RT-PCR). Samples were collected from each calf at days 1, 7 and 14. Within the 14 day period, 44 calves (94%) were positive for group A rotavirus and an unexpectedly high number of calves (38 calves, 81%) were positive for group B rotavirus. When these samples were examined by polyacrylamide gel electrophoresis (PAGE), rotavirus was found in 21 calves and all of them had group A electropherotype. Among 25 PAGE positive samples from 21 calves, 17 (68%) were of short electropherotype, 4 (28%) were of long electropherotype and 4 (28%) contained both short and long electropherotype rotaviruses. Group B and short and long electropherotype group A rotaviruses were found in both normal and diarrheic calves.

Detection of bovine group B rotaviruses in feces by polymerase chain reaction

A pair of primers designed from the sequence of genome segment 9 of group B rat rotavirus (IDIR) were employed to amplify genome segment 9 of a group B bovine rotavirus in a polymerase chain reaction (PCR) and to sequence the derived PCR products. A new pair of primers were synthesized from the obtained sequence data and used in a PCR detection assay for group B bovine rotavirus in fecal samples. In addition, another pair of primers were designed to produce a PCR-derived internal probe. This probe was used in a chemiluminescent hybridization to confirm the specificity and to increase the sensitivity of the assay. This assay could detect 0.1 fg of target double-stranded RNA. It was specific to group B bovine rotavirus and did not detect group B rat (IDIR) and porcine rotaviruses, group A bovine (NCDV), simian (SA-11), equine (H-2), porcine (OSU), human (DS-1), deer, and avian rotaviruses, coronavirus, or other enteric organisms tested in this study.

Detection of hepatitis A virus in environmental samples by antigen-capture PCR

The efficacy of the antigen-capture PCR (AC-PCR) method for the detection of hepatitis A virus (HAV) in environmental samples was demonstrated. HAV was captured from a seeded liquid waste or a shellfish sample with homologous antibody and then heat denatured and subjected to reverse transcription and the PCR, all in the same tube. Subsequently, the AC-PCR products were analyzed by oligonucleotide probe hybridization in solution, agarose gel electrophoresis, and autoradiography. The AC-PCR detected as little as 0.053 PFU of cell culture-adapted HAV strain HM175/18f. The results of cDNA-RNA hybridization indicated that the particle/PFU ratio of this virus strain is approximately 79:1. Therefore, the detection limit of the AC-PCR was estimated to be four virus particles. No amplified products were observed when poliovirus 1, coxsackievirus A9, coxsackievirus B3, echovirus 6, reovirus 1, adenovirus type 40, human rotavirus type 1, and bovine enterovirus type 2 were tested, confirming the specificity of the assay. There were no differences between the nucleotide sequences of AC-PCR products of HAV strain HM175/18f and the sequences of wild-type HAV strain HM175 derived from molecularly cloned cDNA. Of 121 waste and shellfish samples tested by both plaque assays (PA) in cell cultures and the AC-PCR, 81 (67%) were positive and 31 (26%) were negative as determined by both methods, whereas 9 (7%) were positive as determined by the AC-PCR and negative as determined by the PA, and none were positive as determined by the PA and negative as determined by the AC-PCR.

Detection of Echinococcus multilocularis DNA in fox faeces using DNA amplification

In order to identify Echinococcus multilocularis DNA in fox faeces for epidemiological purposes, we have developed a new method to prepare DNA suitable for PCR amplification. DNA isolation from fox excrement was performed according to a novel procedure involving lysis in KOH, phenol-chloroform extraction and a purification step on a matrix (Prep-A-Gene). The target sequence for amplification was the E. multilocularis U1 snRNA gene. PCR products were indistinguishable for 32 different E. multilocularis isolates and no signal was observed after ethidium bromide staining with DNAs from other tapeworm species, including E. granulosus. The sensitivity of amplification was monitored by the addition of E. multilocularis DNA or eggs to faeces free of E. multilocularis and was estimated to be 1 egg per 4 g of faeces. PCR products were blotted onto nylon membranes and hybridized with an internal oligonucleotide probe in order to confirm the results. Twenty nine faecal samples from foxes shot in Franche-Comté (East France) were tested. Out of 10 samples from foxes in which no E. multilocularis adult worms could be observed after necropsy, 7 were PCR positive, showing that the PCR test is more sensitive than microscopical examination. Out of 19 samples from foxes harbouring E. multilocularis adult worms, 18 were PCR positive. The remaining PCR-negative sample could be due either to the misidentification of the species of adult worm (E. granulosus and E. multilocularis), or to DNA variation between different isolates of E. multilocularis. Further work in the field should be initiated in order to confirm these results.

Application of the polymerase chain reaction (PCR) in veterinary diagnostic virology

The polymerase chain reaction has become an important diagnostic tool for the veterinary virologist. Conventional methods for detecting viral diseases can be laborious or ineffective. In many cases PCR can provide a rapid and accurate test. In this article we explain the basic principles of PCR and supply a reference list of its uses in diagnostic veterinary virology.

Detection of Norwalk virus in stool specimens by reverse transcriptase-polymerase chain reaction and nonradioactive oligoprobes

A reverse transcriptase (RT)-polymerase chain reaction (PCR)-oligoprobe (OP), or RT-PCR-OP, method was developed for the detection of the Norwalk virus, which causes acute, epidemic gastroenteritis, in stool specimens. The Norwalk virus genome regions encoding the following two proteins were amplified by RT-PCR: the RNA polymerase (260-bp product) and a putative immunogenic protein (224-bp product). The resulting DNA fragments (amplicons) were hybridized to a digoxigenin-labeled internal OP specific to each amplicon. The detection limit of Norwalk virus, as determined by the endpoint of RT-PCR amplification for serially diluted, positive stool specimens, was similar to the actual virion titer as estimated by electron microscopy and at least 100-fold greater than the titer determined by radioimmunoassay (RIA). The RT-PCR-OP assay was specific for Norwalk virus and negative for other enteric viruses, including human and animal caliciviruses, hepatitis E virus, Snow Mountain agent, astroviruses, 16 human enteroviruses, and 5 human rotaviruses. Components of fecal specimens that interfere with RT-PCR were removed successfully by Sephadex G-200 gel chromatography. Of 20 stool specimens from human volunteers that were positive for Norwalk virus by RIA, a specific RT-PCR-OP result was obtained in 95% (19 of 20) of the samples by using the immunogenic protein primers and 75% (15 of 20) by using the polymerase primers. Twenty-six stool specimens from asymptomatic children and adults were negative by the Norwalk virus RT-PCR-OP. RT-PCR-OP detected Norwalk virus in the 4 of 21 coded fecal specimens that were also positive by enzyme immunoassay. Two samples that were positive by RIA or enzyme immunoassay were negative by RT-PCR, perhaps because viral RNA was not present or RT-PCR inhibitors were not adequately removed.

Terminal sequence conservation among the genomic segments of a group B rotavirus (IDIR strain)

Terminal nucleic acid sequences were determined for all 11 segments of the IDIR strain of group B rotavirus. Consensus sequences were defined at both ends of the (+) RNA strands as 5' GGN(A/U)NA(A/U)(A/U)(A/U)---and---(A/U)NA(A/G)N(A/C)(C/A)CC3 '. The 5' and 3' terminal sequences of the (+) strand IDIR RNA were not complementary to one another. The IDIR terminal sequences and those of group A rotaviruses (GAR) were similar in that each of the (+) strands began with "GG" and ended with "CC." Otherwise, the IDIR terminal sequences did not match the consensus sequences that have been reported for the ends of the GAR genomic segments.

Molecular cloning, sequence analysis, in vitro expression, and immunoprecipitation of the major inner capsid protein of the IDIR strain of group B rotavirus (GBR)

The sixth genomic segment of the infectious diarrhea of infant rats (IDIR) strain of group B rotavirus (GBR) was cloned from double-stranded RNA purified from infected rat feces. Sequence comparison with group A rotaviruses (GAR) and the human ADRV strain of GBR indicated that IDIR gene 6 encoded the major inner capsid protein. The nucleic acid sequences of the two GBR genes were 72.9% conserved, and 83.4% of the amino acids were identical. Sequence substitutions between IDIR and ADRV were more numerous than reported for heterologous GAR strains, indicating that the two GBR strains may have diverged from one another over a longer period of time. Despite the sequence heterogeneity exhibited by the major inner capsid proteins of ADRV and IDIR, hydrophilicity plots of the two gene products were nearly indistinguishable. The GBR hydrophilicity plots displayed little similarity with those of rotavirus groups A or C, indicating substantial differences in the structures of those major inner capsid proteins. In vitro transcription and translation of IDIR gene 6 yielded a polypeptide product consistent in size with that predicted from the deduced amino acid sequence and the virion major inner capsid protein. The IDIR 6 polypeptide was immunoprecipitated by antisera directed against IDIR as well as antisera directed against ADRV and a heterologous bovine strain of GBR. No immunoprecipitation was observed with control sera or antisera directed against GAR. These results confirmed that group-specific epitopes were displayed by the major inner capsid protein encoded by IDIR gene 6. Reactivity with heterologous GBR antisera also indicated that the IDIR gene 6 product may prove useful as a standard reagent in immunoassays for the detection of GBR.

Identification of cognate genes among heterologous strains of group B rotavirus

The genetic relatedness of group B rotavirus (GBR) strains has previously been documented by hybridization with probes derived from whole genomic sequences, but the relationship of individual genes of heterologous GBR strains has not been evaluated. Definition of cognate GBR genes would facilitate investigation of the determinants of group specificity, serotype identity, and neutralization epitopes. Therefore, we investigated the genetic relatedness of three GBR strains by means of Northern (RNA) blot hybridization with isotopically labeled probes prepared from each of the 11 genes of the IDIR strain of GBR. Under low-stringency conditions, hybridization between each of the IDIR gene probes and genomic RNA from the ADRV strain of GBR was observed. Genomic RNA obtained from a bovine strain of GBR hybridized with 9 of the 11 IDIR gene probes. In most cases, cognate genes of each of the GBR strains appeared to migrate to similar positions following polyacrylamide gel electrophoresis. However, the electropherotype positions of GBR genes 5, 6, and 7 were different for each of the three GBR strains. Identification of these genomic segments among GBR strains should prove helpful in future evaluations of GBR structure and function.