Pestivirus genus of the family Flaviviridae. BVD merck microbiology manual pdf results in a wide variety of clinical signs, due to its immunosuppressive effects, as well as having a direct effect on respiratory disease and fertility.
BVDV is a member of the Pestivirus genus, belonging to the family Flaviviridae. Pestiviruses are small, spherical, single-stranded, enveloped RNA viruses of 40 to 60 nm in diameter. The genome consists of a single, linear, positive-sense, single-stranded RNA molecule of approximately 12. 3 protein is either cleaved to NS2 and NS3 or there is a duplication of viral RNA containing an additional NS3 region.
The majority of BVDV infections in the field are caused by the ncp biotype. BVD is considered one of the most significant infectious diseases in the livestock industry worldwide due to its high prevalence, persistence and clinical consequences. Prevalence has been determined in individual countries and tends to be positively associated with stocking density of cattle.
Transmission of BVDV occurs both horizontally and vertically with both persistently and transiently infected animals excreting infectious virus. Virus is transmitted via direct contact, bodily secretions and contaminated fomites, with the virus being able to persist in the environment for more than two weeks.
Persistently infected animals are the most important source of the virus, continuously excreting a viral load one thousand times that shed by acutely infected animals. Following viral entry and contact with the mucosal lining of the mouth or nose, replication occurs in epithelial cells. BVDV replication has a predilection for the palatine tonsils, lymphoid tissues and epithelium of the oropharynx.