Detection and Differentiation of Bovine Group A Rotavirus Serotypes using Polymerase Chain Reaction-Generated Probes to the VP7 Gene

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Abstract
Dot and Northern blot hybridization assays were developed to detect and differentiate group A bovine rotavirus serotypes using radiolabeled serotype 6 (Nebraska calf diarrhea virus [NCDV] and United Kingdom [UK] strains) or serotype 10 (Cracker [Cr] strain) VP7 gene probes. Partial length VP7-specific cDNA encompassing areas of major sequence diversity were generated by the polymerase chain reaction (PCR) using either cloned VP7 genes (NCDV and UK strains) or reverse transcribed mRNA (Cr strain) as templates. Radiolabeled probes prepared from the PCR-generated cDNA were tested at various stringency conditions to optimize the hybridization assays. At high stringency conditions (52 C, 50% formamide, 5 x standard saline citrate), the NCDV, UK, and Cr probes serotypically differentiated bovine rotavirus isolates in RNA samples prepared from cell culture-propagated viruses or in fecal specimens from infected gnotobiotic calves. The sensitivity and specificity of NCDV and Cr VP7 probes were characterized in dot blot hybridization assays, and the probes were estimated to detect at least 1 ng of viral RNA. The serotyping results obtained using VP7 probes were similar to those obtained using serologic assays. Further development of these assays may provide a useful means for the rapid detection and differentiation of bovine rotavirus serotypes in fecal samples from calves in the field.