A Survey of G6 and G10 Serotypes of Group a Bovine Rotaviruses from Diarrheic Beef and Dairy Calves using Monoclonal Antibodies in ELISA

Abstract

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 G lo-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. The negative samples may represent additional or undefined serotypes. The 89 samples from South Dakota were further subdivided into samples from beef (n = 43) or dairy (n = 46) herds. G6 was more prevalent in beef herd samples (67%) than in dairy herd samples (47.5%). In addition, dairy herds had higher percentages of G10-positive samples (17.5%) G6-G10 double positives (10%), and untypable samples (25%) than did beef herds, in which the prevalence of G10 positive samples was 5.5%, G6-G10 double positives was 5.5%, and untypable samples was 22%. Application of the serotype ELISA for the analysis of additional BRV samples will provide further epidemiologic data on the distribution of BRV serotypes in beef or dairy cattle, an important consideration for the development of improved BRV vaccines.