Understanding the Pathogenesis of Cytopathic and Noncytopathic Bovine Viral Diarrhea Virus Infection Using Proteomics

Bovine Viral Diarrhea Virus (BVDV) is a single-stranded RNA virus in the Pestivirus genus within the Flaviviridae family. BVDV infections are seen in all ages and breeds of cattle worldwide and have significant economic impact due to productive and reproductive losses (Houe 2003). Two antigenically distinct genotypes of BVDV exist, type 1 and 2 (Ridpath et al. 1994). BVDV of both genotypes may occur as cytopathic (cp) or noncytopathic (ncp) biotypes, classified according to whether or not they produce visible changes in cell culture. Data indicate that cp biotypes of BVDV can actually be created through internal deletion of RNA of ncp biotypes, or through RNA recombination between ncp biotypes (Howard et al. 1992). Of the two BVDV biotypes, infection of a fetus by ncp BVDV can result in persistently infected (PI) calf that sheds the virus throughout its life without developing clinical signs of infection. PI animals are the major disseminators of BVDV in the cattle population and have been the cause of severe acute outbreaks (Carman et al. 1998). However cp BVDV is associated predominantly with animals that develop mucosal disease (MD), which can be acute, resulting in death within a few days of onset, or chronic, persisting for weeks or months before the afflicted animal dies (Houe 1999). The interaction of BVDV with its host has several unique features, most notably the capacity to infect its host either transiently or persistently (Liebler-Tenorio et al. 2002; Bendfeldt S 2007). Initially the virus binds to CD46, a complement receptor expressed on lymphoid cells, monocytes, macrophages and dendritic cells and serving as a “magnet” for several viral and bacterial pathogens (Cattaneo 2004). Upon entry, the virus replicates and spreads in the lymphatic system, impairing the immunity of the infected animal, particularly antigen presenting cells (APC) function and production of interferons (IFN). Cytopathic BVDV biotype but not ncp biotype (Schweizer & Peterhans 2001) is implicated in the induction of apoptosis (Zhang et al. 1996; Schweizer & Peterhans 1999; Grummer et al. 2002; Jordan et al.