Evolution of bovine viral diarrhea virus vaccines.

Control of bovine viral diarrhea virus (BVDV) infection is economically important to the cattle industry because the virus causes a variety of clinical diseases that adversely affect essentially all stages of the production cycle. Production losses primarily stem from reproductive failure and from immunosuppression during acute BVDV infection, which predisposes calves to respiratory or enteric diseases. Control is achieved by implementing herd health pro-grams focused on limiting exposure by avoiding persistently infected (PI) carrier cattle and by optimizing protective immunity through immunization. Vaccination cannot be relied upon solely to protect against fetal infection and losses due to BVD. This is because no single BVDV vaccine has been shown to give complete fetal protection. In addition to strategic use of vaccines, herd management practices should also be implemented to identify and eliminate PI carrier cattle and to avoid exposure to BVDV infection.