Serological diagnosis of classical swine fever: a comparison of a modified direct complement fixation test with an immunofluorescence plaque neutralization test in the diagnosis of experimental subclinical infection
Eskildsen, M.; Overby, E.
Acta Veterinaria Scandinavica 17(2): 131-141
1976
ISSN/ISBN: 0044-605X PMID: 782215 Document Number: 99301
Antibody levels in post-infection serum samples from a pig inoculated with a low virulent strain of classical swine fever (SF) virus (Hannover 62) and in serum samples from two pigs inoculated with another low virulent strain (Spielbach 66) and from an in-contact pig were assayed by CF and immunofluorescence using classical SF virus (ALD strain) and bovine viral diarrhoea virus (UG 59 strain) as antigens. The CF test used was modified by addition of a preparation of porcine C1q to the complement and by mercaptoethanol treatment of the immune serum before use. The latter treatment resulted in complete elimination of a haemolytic prozone often seen with porcine immune serum. In the serum samples from the inoculated animals CF antibodies appeared earlier than neutralizing antibodies. A few weeks after inoculation there was a correlation between the presence of CF and neutralizing antibodies. During the entire observation period of 13 weeks it was not possible to demonstrate CF or neutralizing antibodies in serum from a pig exposed to infection by contact with the two pigs inoculated with the Spielbach 66 strain of classical SF virus.