Diversity among bovine pestiviruses

Bovine viral diarrhoea virus (BVDV) isolates are characterized by an import ant genetic, antigenic and pathogenic diversity. The emergence of new hyper virulent BVDV strains in North America has provided clear evidence of patho genic differences between BVDV strains. The origin of BVDV diversity is rel ated to high mutation rate occurring in RNA viruses but the consequences of mutations obviously depend on the genes which are involved. Mutations in g enes encoding for structural proteins of immunological importance may have practical implications. Knowledge of BVDV diversity is important for understanding the wide variety of pathogenesis of diseases caused by the virus, for monitoring the epidem iology of the different types and for the design of optimum laboratory test s and vaccines. This review focuses on the origin and consequences of BVDV diversity with r egard to pathogenesis, biotypes, and antigenic and genetic variations. (C) 2001 Harcourt Publishers Ltd.