Differential diagnosis of Classical Swine Fever and Border Disease: Serological investigations of a pestivirus infection on a mixed farm

During recent years neutralising antibodies against Border Disease Virus (B DV) were found repeatedly in German pig herds. Consequently there was a dem and for a differential diagnostic system. A permanent sheep cell line and B DV reference strain Moredun were chosen and were applyed in a could be used case study. A pestivirus could be isolated from piglets on a mixed farm an d was characterised as,non-Classical Swine Fever' (CSF) by using monoclonal antibodies. Due to a CSF suspicion the pig herd was destroyed immediately. Serum samples of sheep from the same farm were used for further characteri sation of the new virus isolate. A neutralisation test of the sheep sera wa s performed against different pestiviruses and the new isolate. Neutralisin g antibody titres against the new virus pig isolate were significantly high er than against all other pestiviruses. BDV strain Moredun recognised the a ntibodies clearly, whereas CSF viral strain Alfort 187 and several isolates of bovine viral diarrhoea virus (BVDV) strains scored the lowest cross rea ction.