DEVELOPMENT OF 2 NOVEL MONOCLONAL ANTIBODY-BASED ELISAS FOR THE DETECTION OF ANTIBODIES AND THE IDENTIFICATION OF SWINE ISOTYPES AGAINST SWINE VESICULAR DISEASE VIRUS

Two novel formats of ELISA for the detection of antibodies against swi ne vesicular disease (SVD) virus were developed. One of the tests desc ribed is a monoclonal antibody-based competitive ELISA (MAC-ELISA). In this test, specific antibodies in serum are detected due to their abi lity to compete with a neutralizing monoclonal antibody (MAb). The sec ond is an indirect trapping ELISA which employs isotype-specific MAbs to detect swine IgG or IgM specific for SVD virus. The diagnostic sens itivity and specificity of the MAC-ELISA was studied on 5671 field ser a of known origin, enabling the cut-off level to be defined. Using the MAC-ELISA, 100% of sera from infected pigs were found positive, where as only 0.45% of negative sera gave a false-positive result. A positiv e correlation between MAC-ELISA and virus neutralizing titres was reco rded for pig sera collected sequentially after experimental infections . The results from the isotype-specific ELISA revealed the dynamics of the antibody response to SVD virus in pigs. The first antibodies were detectable as early as 3 days after experimental infection. Up to the 10th day, demonstrable antibodies were exclusively of the IgM class. IgG developed later, between 11 and 14 days postinfection and remained at a plateaux level throughout the whole investigation period. The tw o tests satisfy different diagnostic requirements: the MAC-ELISA is us eful as a screening test, the isotype-specific ELISA has potential app lication for the determination of stage of infection. Both tests benef it from the use of MAbs in terms of specificity and standardization an d have advantages over the virus neutralization test.