Calves were immunized with two vaccines against bovine herspevirus type 1 (BHV-1; vaccine A, n=28; B, n=28) or with a vaccine containing BHV-1 and BHV-5 antigens (vaccine C, n=32) and the serum neutralizing activity against BHV-1 and BHV-5 was measured after three vaccine administrations. Neutralizing activity to BHV-1 was detected in sera of 100% (n=88) of the animals (geometric mean titers [GMT] of 13.1; 14.8 and 34.3 for vaccines A, B and C, respectively) whereas 82 sera (93.2%) reacted to BHV-5 (GMTs: 10.6; 11.5 and 29.8). In all three groups, the mean BHV-1 titers did not differ from BHV-5 titers. However, comparison among the vaccines demonstrated that the mean titers to BHV-1 and BHV-5 were higher in animals receiving vaccine C (p<0.01). This vaccine also induced a higher proportion of reagents to BHV-5 (96.9%; against 85.7% for vaccine A and 92.9% for vaccine B). These results demonstrate that vaccine C induced higher neutralizing antibody titers against both viruses; and that antibodies induced by BHV-1 antigens (vaccines A and B) cross-reacted and displayed relevant neutralizing activity against BHV-5.
bovine herpesvirus type 1; BHV-1; BHV-5; vaccine; cross-neutralization
