Seroconversion to BVDV in cows coinfected with BLV and BHV-1: basis of colostrogenesis and effect of persistent infection caused by BVDV

Abstract

Bovine viral diarrhea virus (BVDV), enzootic bovine leukosis virus (EBLV), and bovine herpesvirus-1 (BHV-1) are very important pathogens in specialized dairies due to the negative impact on productive and reproductive parameters, as well as by the immunosuppressive effect they cause. BVDV usually causes transient infection and immunosuppression. Meanwhile, EBLV and BHV-1 cause chronic and persistent infection and immunosuppression, which reduces the quality of colostrum and promotes failure of passive transfer of immunity. Vaccination with BVDV is essential to reduce its incidence and enrich colostrum during colostrogenesis, however, vaccination programs are controversial. This study evaluated whether the change in the vaccination program using attenuated live virus at one or two doses modified the serological status against BVDV in cows infected with EBLV and HVB-1. A BVDV vaccination trial using the EXPRESS® FP 10-HS vaccine was conducted from November 8 to December 20, 2018. The study included 20 BVDV seronegative Holstein cows but coinfected with EBLV and HVB-1. The health status and follow-up of the seroconversion of each cow was established at 0, 21 and 42 days post-vaccination by means of enzyme-linked immunosorbent tests, as well as polymerase chain reaction or sequencing to confirm doubtful cases. The BVDV vaccination program was very efficient in achieving seroconversion independently of the dose, except in one animal with persistent infection. Likewise, the presence of EBLV and BHV-1 did not inhibit the production of antibodies. The information obtained suggests that mobilization of antibodies against BVDV to colostrum would occur without difficulty in coinfected animals that do not experience persistent infection with BVDV.