Homotypic and heterotypic immunity, pathogenesis, and linear B cells epitopes mapping of VP5* of group A bovine rotaviruses

Group A rotaviruses, members of the reoviridae family, are important viral diarrheal agents in young animals and humans, including young calves worldwide. Bovine rotaviruses (BRV s) are characterized by a genome consisting of 11 segments of double stranded RNA (dsRNA), enclosed in a triple-layered protein capsid; BRVs possess two outer capsids proteins, VP4 and VP7, each of which independently can elicit neutralizing antibodies. Parenteral immunization with whole virus induces antibodies directed primarily against the VP7 protein, whereas recovery from natural infection is associated with the development of VP4-specific antibodies.; Information on homotypic and heterotypic immunity against BRV infection is incomplete; therefore, the antibody responses of first calf beef heifers to parenteral administration of a commercially-available inactivated whole virus group A BRV strain neonatal calf diarrhea virus-Lincoln (NCDV-L) G6:P6[1] against homotypic and heterotypic BRV strains were assessed. Strong increases in homotypic and heterotypic serum and colostrum antibody titers after vaccination of cows with the monovalent vaccine were found. These data suggest that passive immunization of new-born calves through colostrum produced by pregnant heifers vaccinated with a monovalent vaccine can provide heterologous immunity.; In an effort to address the role of conserved antigenic epitopes in heterotypic immunity, conserved antigenic epitopes within BRVs VP5* were identified using sera obtained from gnotobiotic calves 21 days post-inoculation (PI) with biologically-cloned BRVs with P7[5] or P6[1]. By day 21, all convalescent calves had high and low serum neutralizing antibody titers against homologous and heterologous BRVs, respectively. Challenge-exposure of one-day-old calves revealed that BRV strains P[6]1:G6 and P[6]1:G8 are independently pathogenic, causing severe watery diarrhea within hours after inoculation. Four cross reactive epitopes were identified by convalescent sera using a peptide scanning-ELISA encompassing the amino acids 247 to 777 encoded by VP5* region of BRV P7[5] gene.