The genetic basis for cytopathogenicity of pestiviruses

Two biotypes of pestiviruses, cytopathogenic (cp) and noncp viruses, can be distinguished by their effects on tissue culture cells. Identification of cp bovine viral diarrhea virus (BVDV) has been frequently reported since an tigenically closely related noncp and cp BVDV can be isolated from cattle w ith fatal mucosal disease (MD) and are called a virus pair. In contrast to the BVDV system, only few cp border disease virus (BDV) and cp classical sw ine fever virus (CSFV) strains have been described. Serological analyses an d sequence comparison studies showed that cp pestiviruses arise from noncp viruses by mutation. Elaborate studies during the last 10 years revealed th at in most cases RNA recombination is responsible for the generation of the cp viruses. Recent results showed a second way for the development of a cp pestivirus which is based on the introduction of a set of point mutations within the NS2 gene. (C) 2000 Elsevier Science B.V. All rights reserved.