A liquid-hybridization method for typing the Vp4 and Vp7 genes of bovine rotaviruses

A simple liquid-hybridization assay was developed which allows assessment of the degree of hybridization between the two serotype-determining genes of the bovine rotavirus strain UK and the homologous genes of the isolate under test. 32P-labelled transcription probes were produced from cloned complementary DNA (cDNA) copies of UK gene segments 4 and 8 and hybridized to double stranded RNA (dsRNA) extracted from rotavirus-positive field samples. Subsequent treatment with ribonuclease A (RNase A), separation of the RNase A-resistant hybrid fragments by polyacrylamide gel electrophoresis (PAGE) and autoradiography yielded a specific, reproducible banding pattern for each isolate. A total of 74 field samples was tested by both the hybridization assay and by an enzyme-linked immunosorbent assay (ELISA) using serotype-specific monoclonal antibodies (Mabs). The results obtained were in excellent agreement and confirmed that serotype G6 rotaviruses predominated. Hybridization of these G6 viruses with the gene 4 probe suggested that viruses with Vp4s related to that of UK rotavirus are also common. The hybridization assay was more sensitive than the ELISA.