Bovine Rotavirus Vaccines: Immunogenicity of two strains of Bovine Rotavirus in cattle and guinea pigs

VIVIANA PARREÑO; DANIELA RODRIGUEZ; MERCEDES IZUEL; JORGE FILIPPI; LAURA MARANGUNICH; VIRGINIA LOPEZ; FERNANDO FERNANDEZ; RODOLFO BELLINZONI .; MARÍA M. VENA

Ouro Preto, Brazil.

Simposio; 8º International Veterinary Immunology Symposium; 2007

Society for Veterinary Immunology

Bovine Rotavirus (BRV) is a main cause of severe diarrhea in neonatal calves, worldwide. In Argentina BRV was diagnosed as the cause of neonatal diarrhea in 71 % and 58 % of the outbreaks registered in beef and dairy farms, respectively. The BRV strain typed as P[5]G6 was prevalent in beef herds, while P[11] was the prevalent P-type (71%), associated in similar proportions with variants of G6 and G10, in dairy herds (Garaioechea et al, 2006). Prevention strategies are based on the vaccination of pregnant cows in order to transfer high titers of maternal antibodies (Ab) to the calf through colostrum intake. Three experimental vaccines containing 10^7 FFU/dose of UK P[5]G6, or B223 P[11]G10 or both strains formulated in oil adjuvant were tested together with a commercial vaccine (Rotatec J5®) in beef cattle (with low  Ab titer due to natural RV infection) and seronegative guinea pigs. Immune response was evaluated by ELISA and virus neutralization test (VN). Bovine trial consisted of two vaccinations and serum sampling at 0, 30, 60 and 90 dpv. whereas guinea pigs received one or two doses of vaccine and were sampled weekly until 60 dpv. The kinetic of RV Ab responses by ELISA, mostly directed to VP6, was similar among all the vaccines tested in both species, with seroconvertion registered at 60 dpv in cattle and at 21 dpv in guinea pigs. All vaccinated bovines developed VN Abs against UK independently of the vaccine formulation, indicating the previous contact with that strain. In contrast only the groups vaccinated with vaccines containing B223 RV developed a VN Ab response to that strain, suggesting minimum field exposure to P[11]G10. In guinea pigs optimal Ab response was obtained by experimental and commercial vaccines. The VN responses in naïve guinea pig allowed to demonstrated that there is no cross protection between UK and B223 strains confirming that in order to obtain protection against the prevalent RV types circulating in Argentina all P[5], P[11], G6 and G10 types should be included in the vaccine.