Serological characterization of bovine viral diarrhea virus isolates

Bovine viral diarrhea viruses (BVDVs) were isolated from cattle with respiratory and diarrhea signs as well as persistently infected cattle. These isolates were analysed serologically to characterize serogroups and to compare serological relationship with reference viruses of type I and II. Most isolates from calf diarrheal cases and persistently infected individuals showed a significant difference in cross-neutralization test with the viruses isolated from nasal discharges showing severe respiratory signs. Serologically most of the commercial vaccine strains could be classified into classical BVDV (type I) such as NADL strain. This serological difference among BVDV isolates suggested the need for new vaccines to protect cattle from both respiratory and enteric BVDV infections in field. The immunogenicity of BVDVs which showed a good propagation capability in MDBK cells and high rates of neutralizing activity (isolate : KD26-1, PHG, B5 and 95002) against all viruses used in this study, was confirmed in guinea pig when treated as single or combined groups.