Bovine Viral Diarrhea Virus

Abstract

Bovine viral diarrhea virus (BVDV) is an umbrella term for two species of viruses, BVDV1 and BVDV2, within the genus Pestivirus of the family Flavivirus. BVDV viruses are further subclassified as cytopathic and noncytopathic based on their activity in cultured epithelial cells. Noncytopathic BVDV predominate in nature. BVDV are found worldwide and acute infections may result in enteric, respiratory, and/or reproductive disease of varying severity, depending on the BVDV strain, the immune and reproductive status of the host, and the presence of secondary pathogens. Acute BVDV infections are always accompanied by immune suppression due, at least in part, to the death of immune cells within lymph nodes and gut-associated lymphoid tissue and reduction of numbers of circulating white blood cells. The suppression of the immune system leaves infected animals vulnerable to secondary infections. BVDV infections are most commonly associated with cattle but can occur in a wide variety of domesticated and wild ruminants including white tail and mule deer, bison, elk, and sheep. In addition to acute infections, BVDV strains may establish persistent infections which result from exposure in utero to a noncytopathic BVDV. Persistently infected animals that become superinfected with cytopathic BVDV may develop mucosal disease (MD).