Clinical, virological and serological findings after intranasal inoculation of pigs with bovine viral diarrhoea virus and subsequent intranasal challenge with hog cholera virus.

Five groups of weaner pigs were intranasally inoculated with constant doses of bovine viral diarrhoea virus (BVDV) strain OSLOSS/2482. Four weeks post primary inoculation (p.p.i.) the animals were intranasally challenged with decreasing doses of hog cholera virus (HCV) strain Alfort/187. Clinical signs were not observed apart from a short febrile period (2 days, > 40 degrees C) in one animal. Another animal died intercurrently without showing any pathological signs. Virus isolation from leucocyte samples taken regularly during one week post challenge detected HC viraemia in most animals that had received HCV doses > 100 TCID50 per animal. Using monoclonal antibody (mab) analysis all isolates obtained were proven to be HCV. Serological investigations using the virus neutralization test (VNT) yielded HC neutralizing antibodies in all groups with higher titres in those animals having received HCV doses > 100 TCID50. However, HCV specific neutralizing antibodies never exceeded the BVDV antibody titre. A complex trapping blocking (CTB) ELISA applying a HCV specific mab detected HCV specific antibodies in animals that had gone through HC viraemia while discriminating BVDV specific antibodies.