Prevention of Bovine Viral Diarrhea Virus Persistent Infection after a Heterologous Type 1 or Type 2 Challenge in Animals Vaccinated with a Combination Modified Live Virus Vaccine Containing Bivalent BVDV

Abstract

Bovine viral diarrhea virus (BVDV) infections in cattle result in a broad spectrum of clinical syndromes ranging from asymptomatic infections to peracute hemorrhagic disease with high mortality. Acute BVDV infection causes respiratory, gastrointestinal and/or reproductive disease that results in a febrile response along with leukopenia. Due to BVDV shedding, persistently infected (PI) animals are a long term threat to herdmates, and may develop mucosal disease resulting in the death of the animal.

Acute BVDV infection of pregnant cattle with either cytopathic (CP) or noncytopathic (NCP) BVDV can result in a variety of fetal syndromes, depending on the virulence of the strain and age of the fetus. In early gestation, BVDV infection can result in early embryonic death and fetal absorption. Between 40-125 days of gestation, infection with NCP BVDV can result in PI calves that shed NCP BVDV for their entire lives.

The purpose of this study was to determine the efficacy of a commercial MLV combination vaccine containing bivalent BVDV diluted to contain minimum protective levels of BVDV type 1 and 2 in providing fetal protection against a heterologous challenge with type 1 or type 2 BVDV. Two groups of animals were vaccinated with a single dose of the commercial vaccine. Protection against persistent infection of the fetus was measured following challenge.