Pestivirus infections in Norway. Epidemiological studies in goats.

During one breeding season, 2335 female goats in 39 herds in different parts of Norway were examined for pestivirus infection and for reproductive performance. Before breeding, all animals were examined for neutralizing antibodies against the NADL strain of pestivirus, 83 (3.6 per cent) positive animals in 12 herds being demonstrated. The herd prevalences ranged from 1 to 63 per cent. Antibody titres varied from 1 in 4 to 1 in 2048. Of 1816 females in 30 herds for which post-breeding information was available, a total of 178 (9.8 per cent) animals in 25 of the herds demonstrated gestation failure. Three of these goats began to produce antibodies against the NADL strain during gestation. Sera from the 83 animals with NADL antibodies were titrated for neutralizing antibodies against three additional strains of pestivirus, the highest geometrical mean titre being found for antibodies against a Norwegian bovine strain.

Intracellular virus-induced polypeptides of pestivirus border disease virus.

Intracellular virus specific polypeptides of pestivirus, border disease virus (BDV) in bovine turbinate cells were analysed by radio-immunoprecipitation with specific antisera. Eleven viral polypeptides with molecular weights of 220, 165, 118, 84, 66, 58, 55, 53, 45, 37 and 31 kDa, respectively, were detected in infected cells. Of these, the 165, 118, 84, 66, 58, 55, 53, 45 and 31 kDa proteins were found to be glycosylated. Comparative studies indicated that the polypeptides induced by BDV share many antigenic epitopes with those of the polypeptides induced by bovine viral diarrhea virus (BVDV), a serologically related virus of the same genus, pestivirus. The polypeptide profile of BDV appeared to be more similar to that of the noncytopathic BVDV strain NY1 compared to that of cytopathic BVDV strains NADL and Singer. Peptide mapping analysis of homologous polypeptides from BVDV and BDV confirmed their structural relatedness.

Bovine viral diarrhea virus proteins: heterogeneity of cytopathogenic and non-cytopathogenic strains and evidence of a 53K glycoprotein neutralization epitope.

Intracellular virus-induced polypeptides from 3 cytopathogenic and 2 non-cytopathogenic bovine viral diarrhea (BVD) virus reference strains were analyzed by radioimmunoprecipitation and polyacrylamide gel electrophoresis, using a specific bovine multivalent antiserum and a neutralizing BVD-virus monoclonal antibody. Electrophoretic patterns of major proteins demonstrate extensive variation between strains. Most notably, a major 80,000 (80K) polypeptide was present in all cytopathogenic strains but absent in both non-cytopathogenic strains. Furthermore, a neutralizing monoclonal antibody produced against the NADL strain immunoprecipitated a 53K glycoprotein indicating that this protein carries an important neutralization epitope that is not present in all strains tested.

Characterization of bovine viral diarrhoea-mucosal disease virus-specific proteins in bovine cells.

The presence of virus-specific polypeptides in bovine viral diarrhoea-mucosal disease (BVD) virus-infected bovine cells was studied by radiolabelling in the presence of a hypertonic initiation block (HIB) and by analysis by SDS-PAGE. These experiments were complemented by radioimmunoprecipitations with anti-BVD hyperimmune serum of infected cells labelled under isotonic conditions. A total of 12 polypeptides (Mr 165, 135, 118, 80, 75, 62, 56 to 58, 48, 37, 32, 35 and 19, all X 10(-3)) were identified in infected cells. Time course analysis of the induction of the viral polypeptides indicated that they could be detected as early as 4 h post-infection and their synthesis reached a plateau between 12 and 20 h post-infection. The most abundant polypeptides were the ones that could be detected earliest. HIB was found to be an excellent adjunct to existing techniques in the identification of viral polypeptides. Seven of these polypeptides had not been reported previously. This is the first report of the direct detection of BVD virus-induced polypeptides in infected cells without the aid of immunoprecipitation. The sum of the molecular masses of these polypeptides is greater than the coding capacity of the genome; therefore precursor-product relationships must exist between these polypeptides.

Glycoproteins of bovine viral diarrhoea-mucosal disease virus in infected bovine cells.

Bovine cell cultures infected with bovine viral diarrhoea-mucosal disease (BVD) virus were radiolabelled with L-[35S]methionine or D-[2-3H]mannose followed by analysis of the labelled polypeptides by radioimmunoprecipitation and polyacrylamide gel electrophoresis in one and two dimensions. Six glycoproteins were detected in infected cells. Two abundant species had Mr of 48K and 56K to 58K while the less abundant species had Mr of 118K, 75K, 65K and 25K. When cells were radiolabelled with L-[35S]methionine in the presence of tunicamycin 56K to 58K migrated with apparent masses of 54K (a minor species) and 48K to 50K (the major molecular species) in PAGE. Endoglycosidase F digestion of virus-induced polypeptides caused a 4K to 6K reduction in the apparent molecular mass of 56K to 58K yielding a single 52K digested product, indicating that the heterogeneity of 56K to 58K was due to differences in the oligosaccharide moieties. Tunicamycin caused a drastic reduction in the yield of infectious virus indicating that the carbohydrate moieties serve a critical role in the infectious cycle of BVD virus.

Bovine viral diarrhea virus: purification of surface proteins in detergent-containing buffers by fast protein liquid chromatography.

Bovine viral diarrhea virus was purified by lectin chromatography. The glycoprotein peplomers were dissociated from the virion by treatment with detergent. By a second lectin gel chromatography the glycoconjugates containing terminal galactose were prepared. In combination with lectin affinity chromatography, ion-exchange chromatography on Mono-Q in the presence of the low-UV-absorbing detergent Berol 172 proved to be a powerful technique both for analytical and preparative applications.

Characterization of the major structural proteins of purified bovine viral diarrhea virus.

Bovine viral diarrhea virus (BVDV) was concentrated and purified by a combination of ultrafiltration, hydroextraction using polyethylene glycol and affinity chromatography. A lectin from Crotalaria juncea that has an affinity for galactose was used in the affinity chromatography. Virions of BVDV with classic envelopes were observed by electron microscopy. Four major proteins with estimated molecular weights of 75,000, 66,000, 54,000, and 26,000 were identified in sodium dodecyl sulfate--polyacrylamide gel electrophoresis slab gels. The proteins of 75,000 and 54,000 were glycoproteins as shown by staining with dansyl hydrazine.