Findings concerning various clinical manifestations in cattle and sheep have made it clear that pestivirus infections in ruminants have an economic impact similar to hog cholera. Early data justified the classification of pestiviruses as a genus of nonarthopod-borne togaviruses. Since pestiviruses are difficult to work with, progress in understanding the virus and disease gradually came to a standstill because conventional techniques failed to yield further insights. About ten years ago interest in pestivirology was revived by strong impulses of modern biotechnology and a breakthrough in pathogenesis research, i.e. in vitro translation of BVD viral proteins and the ex experimental reproduction of mucosal disease in cattle. In order to summarize and discuss these exciting developments, an international community of pestivirus researchers came together in June 1990 in Hannover (Federal Republic of Germany) for the Symposium "Ruminant Pestivirus Infections: Virology, Pathogenesis and Perspectives on Prophylaxis". This book is a selection of papers presented at this symposium.

Pestiviruses-taxonomic perspectives.- Molecular characterization of hog cholera virus.- Bovine viral diarrhea virus genomic organization.- Bovine viral diarrhea virus proteins and their antigenic analyses.- A "zinc finger-like" domain in the 54 KDA protein of several pestiviruses.- BVD Monoclonal Antibodies: relationship between viral protein specificity and viral strain specificity.- Correlation of bovine viral diarrhoea virus induced cytopathic effects with expression of a biotype-specific marker.- Cytopathogenicity of pestiviruses isolated post mortem from cattle.- Diaplacental infections with ruminant pestiviruses.- The pathways for bovine virus diarrhoea virus biotypes in the pathogenesis of disease.- Border disease of sheep-Aspects for diagnostic and epidemiologic consideration.- A study of some pathogenetic aspects of bovine viral diarrhea virus infection.- Distribution of antigen of noncytopathogenic and cytopathogenic bovine virus diarrhea virus biotypes in the intestinal tract of calves following experimental production of mucosal disease.- Clinical and virological observations of a mucosal disease outbreak with persistently-infected seropositive survivors.- Insertion of cellular sequences in the genome of bovine viral diarrhea virus.- Congenital curly haircoat as a symptom of persistent infection with bovine virus diarrhoea virus in calves.- Identification and production of pestivirus proteins for diagnostic and vaccination purposes.- Surveillance of cattle herds for bovine viral diarrhoea virus (BVDV)-infection using data on reproduction and calf mortahty.- Flow cytometric detection of bovine viral diarrhoea virus.- Identification of cattle infected with bovine virus diarrhoea virus using a monoclonal antibody capture ELISA.- Detection of borderdisease virus in sheep efferent lymphocytes by immunocytochemical and in situ hybridisation techniques.- Bovine viral diarrhea virus infection: rapid diagnosis by the polymerase chain reaction.- cDNA probes for the detection of pestiviruses.- Detection of persistent bovine viral diarrhea virus infections by DNA hybridization and polymerase chain reaction assay.- Differentiation of pestiviruses by a hog cholera virus-specific genetic probe.- Poster presentations.- Lesions in aborted bovine fetuses and placenta associated with Bovine Viral Diarrhoea virus infection.- Immunological reactivity of bovine viral diarrhea virus proteins after proteolytic treatment.- Polymerase chain reaction amplification of segments of pestivirus genomes.- Production of monoclonal antibodies to study the molecular biology of bovine viral diarrhea virus.- Determination of level of antibodies to bovine virus diarrhoea virus (BVDV) in bulk tank milk as a tool in the diagnosis and prophylaxis of BVDV infections in dairy herds.- BVD-virus infection in goats - experimental studies on transplacental transmissibility of the virus and its effect on reproduction.- BVD virus isolation techniques for routine use in cattle herds with or without previous BVD history.- Molecular characterisation of the coding region for the p125 from homologous BVDV biotypes.- Progeny of sheep persistently infected with border disease virus.