Pathogenicity and diagnostics of non-group A porcine rotaviruses

Rotavirus-associated diarrhea is a common enteric disease in piglets. Group A, B, and C rotaviruses have been implicated in US swine. While group A rotaviruses have been widely studied and attributed as a major cause of the disease, little known about group B and C rotaviruses with respect to their pathogenicity/pathogenesis as well as diagnostics and prevention/control. To address such shortfalls, three studies were carried out. The objective of the first study was producing monoclonal antibodies (MAbs) against PoRV A, B, and C. To that goal, full-length VP6 protein gene of each serogroup was cloned from feces positive for respective virus and expressed in a baculovirus system using Bac-to-Bac cloning and expression kits. The recombinant proteins, purified in their native conditions, were used to immunize mice. A VP6-based ELISA and an indirect fluorescent antibody test using Sf9 cells expressing VP6 of PoRV A, B or C were used to screen hybridomas. The protein specificity of selected MAbs were further verified by Western immunoblot, and the isotype of each MAb was determined using a commercial murine antibody isotyping kit. Based on all these evaluations, MAb 10A11, 10B1 and 11H3, which were of IgG isotype, were selected for PoRV A, B and C, respectively. The MAbs specific for PoRV A and C were proven to be useful for immunohistochemical staining to detect these viruses in formalin-fixed intestinal tissues, which can aid more accurate diagnostic investigation of rotavirus-associated diarrhea. The second study was to compare the pathogenicity of porcine rotavirus (PoRV) A, B and C individually or in combinations in immunologically naïve newborn piglets. Forty-eight one-day-old Cesarean-Derived Colostrum-Deprived (CDCD) pigs were divided into eight groups. Pigs in each group were challenged with rotaviruses that belong to individual group A, B, C or all combinations. Clinical