Development of cDNA probes for typing group A bovine rotaviruses on the basis of VP4 specificity

Restriction endonucleases whose sites are predictable from the amino acid sequence offer an improved strategy for typing bovine rotaviruses

Variation in the third base of a codon hampers genotypic characterization, particularly of RNA viruses. Some restriction endonucleases, however, have a recognition site with a variable base at the third position and will always cleave when a certain amino acid pair occurs (such as glycine-proline for Sau96I and glutamic or aspartic acid followed by serine usually for HinfI). We developed a restriction fragment length polymorphism (RFLP) procedure based on these enzymes for P-typing bovine group A rotaviruses (BRV). Employing this procedure 20 BRV local strains, isolated in tissue culture as well as the original faecal sample, could be typed in one of three patterns. More variability was observed when restriction endonucleases were employed whose cleavage sites cannot be predicted from the amino acid sequence (TaqI and Tsp509I). These RFLP results agreed with the PCR-VP4 typing assay, neutralization tests, and nucleotide sequence analysis. RFLP with Sau96I and HinfI provided quick and objective P-typing of strains and could detect multiple genotypes in the same sample.

Survey of equine rotaviruses shows conservation of one P genotype in background of two G genotypes

DIG-labelled ssRNA probes were prepared from variable regions of VP4 and VP7 cognate genes, and used in hybridization assays for P and G genotyping of group A cell culture-adapted equine rotaviruses and fecal samples collected from foals with and without diarrhea. The probes confirmed known P and G serotypes of sixteen cell culture-adapted strains. From one-hundred and twenty-one rotavirus-positive samples, 83 reacted when tested for their P and G genotype specific probes. From these, 71 were found to contain G3 P12 genotypes, and 11 G14 P12 genotypes. No sample reacted with H1 or L338 P and G genotype probes. This suggests that the equine rotavirus population is conservative, containing predominantly one P genotype and two G genotypes. One isolate (26/94) whose dsRNA was visualized in an agarose gel did not react with any of the equine probes, and was found to belong to G8 and P1 genotypes. This is the fourth example of a single unique equine isolate (after H1, L338, and R-22). The remaining thirty-eight untypable field isolates had no detectable dsRNA after storage for 1 to 3 years.

Serological and genomic characterisation of group A rotaviruses from lambs

Four lamb rotaviruses were characterised serologically by reactions with monoclonal antibodies and genomically by hybridisation assays and sequencing. Each was found to be distinct. Three viruses belonged to the bovine genogroup and were of subgroup I. These viruses possessed serotypes G3, G6, and G10. Their corresponding P types were P1, P11, and P14 respectively. The only previous isolation of a rotavirus with VP4 of type P14 was also from lambs. The fourth isolate was G9P8, which is the first record of a G9 rotavirus from a species other than man.

Bovine rotavirus V1005 a P5, not a P12, type like all viruses in a German survey

Bovine rotavirus (BRV) V1005, like 34 further cell culture-adapted strains in a 6-year survey in Upper Bavaria, Germany, is not a P12 but a P5 P-type rotavirus. The conclusion is based on dot blot hybridization with P1-, P5-, and P11-specific cDNAs, encompassing the VP8* region of major sequence diversity, and on PCR using P1-, P5-, and P11-specific primer pairs derived from the VP5* region of VP4 (VP5* and VP8*, respectively, are the larger and smaller tryptic cleavage products of VP4). Sequencing of the hyperdivergent region of VP4 confirmed the close relatedness of BRV V1005 to BRV UK, the P5 prototype virus.

VP4 typing of bovine and porcine group A rotaviruses by PCR

A PCR typing assay was developed to identify rotavirus P types (VP4 specificity) of bovine NCDV, UK, and B223 strains and porcine OSU and Gottfried strains. Thirty-nine human and animal strains representing all known, and some undefined, rotavirus P types were used to develop and evaluate the specificity of the method. No cross-amplification was observed. The PCR results agreed with previous characterizations by monoclonal antibodies, sequence analysis, and hybridization assays, except for the Gottfried strain, which showed a P type distinct from the human asymptomatic strains. Analysis of a small number of field specimens suggested a high level of VP4 polymorphism among porcine strains. The assay should be of value in typing field isolates and tracing interspecies infections.

A survey of G6 and G10 serotypes of group A bovine rotaviruses from diarrheic beef and dairy calves using monoclonal antibodies in ELISA

Group A bovine rotaviruses (BRV) have been identified worldwide as a major cause of diarrhea in the young of many species, including humans. Group A rotaviruses are classified into serotypes on the basis of the outer capsid proteins, VP7 (G types) and VP4 (P types). To date, there are 14 G types of group A rotaviruses, with G1, G6, G8, and G10 described for BRV isolates. In this study, G6- and G10-specific monoclonal antibodies (MAbs) were used in an enzyme-linked immunosorbent assay (ELISA) for the G typing of BRV-positive stool samples from diarrheic beef and dairy calves from South Dakota, Ohio, Michigan, Nebraska, and Washington, USA, and Ontario, Canada. ELISA plates were coated using a broadly reactive VP7 MAb (Common 60) or with G6- or G10-specific MAbs. BRV-positive fecal samples were diluted and added to duplicate wells, followed by the addition of polyclonal guinea pig anti-group A rotavirus serum as the secondary antibody. Several reference G6 and G10 BRV strains as well as other G types previously reported in cattle (G1, G2, G3, G8) and BRV-negative samples were included as G type specificity and negative controls. From a total of 308 field samples analyzed, 79% (244/308) tested positive by the broadly reactive VP7 MAb; of these, 54% (131/244) were G6 positive, 14% (35/244) were G10 positive, 4% (9/244) were both G6 and G10 positive, and 28% (69/244) were G6 and G10 negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Relative frequencies of G (VP7) and P (VP4) serotypes determined by polymerase chain reaction assays among Japanese bovine rotaviruses isolated in cell culture

The relative frequencies of both the G (VP7) and P (VP4) serotypes of 40 bovine rotaviruses isolated in cell culture from diarrheic calves in Japan between January 1983 and February 1991 were determined by recently developed polymerase chain reaction assays. Isolates with G serotype 6 and P serotype 5 (UK-like strains) were most frequently found (42.5%) followed by isolates with G6P11 (17.5%), G6P1 (10%), or G10P5 (10%). Isolates with G10P11 (B223-like strains) were least frequently found (7.5%). The presence of various combinations of G and P serotypes suggests frequent reassortment in nature among bovine rotaviruses.

Characterization of field strains of group A bovine rotaviruses by using polymerase chain reaction-generated G and P type-specific cDNA probes

Dot and Northern blot hybridization assays were used to analyze field strains of group A bovine rotaviruses (BRVs) by using nucleic acid probes representing P and G type specificities. The probes were prepared by polymerase chain reaction amplification of hyperdivergent regions of the cloned VP4 (nucleotides 211 to 686) and VP7 (nucleotides 51 to 392) genes from four serotypically distinct (in P or G types) strains of rotaviruses: NCDV (G6, P1), IND (G6, P5), 69M (G8, P10), and Cr (G10, P11). The P and G type cDNA probes were radiolabeled with [32P]dCTP and hybridized with RNA extracted from reference cell culture-passaged rotavirus strains or the field samples. The field samples were obtained from young diarrheic calves from Ohio, Nebraska, Washington State, and Canada. The cDNA probes were specific for their respective G or P types on the basis of analysis of known P and G type reference strains. The G typing analysis of 102 field samples revealed that 36.3% (37 of 102) were G6, 2.9% (3 of 102) were G8, 12.7% (13 of 102) were G10, and 23.5% (24 of 102) were untypeable. The P typing results for 93 samples indicated that 2.2% (2 of 93) were P1 (NCDV-like), 20.4% (19 of 93) were P5 (UK-like), 9.3% (10 of 93) were P11 (B223-like), and 40.8% (38 of 93) were untypeable. This is the first report of the identification among BRV strains in North America of a G type other than G6 or G10. Our report further confirms that G6, P5 rotaviruses are predominant among the BRV field strains that we examined, and the P types of these strains differ from that of the BRV vaccine strain used in the United States (G6, P1). The large number of untypeable G (23.5%) and P (40.8%) types suggests that other or new P and G types exist among BRV field strains.