MONOCLONAL-ANTIBODIES AGAINST CONFORMATIONALLY DEPENDENT EPITOPES ON PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS

Monoclonal antibodies (MAbs) against porcine reproductive and respirat ory syndrome virus (PRRSV) were prepared and characterized. Four MAbs were developed from the mice immunized with the recombinant GP4 protei n expressed in insect cells, and six MAbs were derived from the immuni zation with recombinant GP5 protein. All of the MAbs showed strong per inuclear fluorescence in PRRSV VR2385 infected cells by immunofluoresc ence staining. Among the MAbs to GP5 protein, one showed strong reacti vity in ELISA and recognized a 26 kDa band of PRRSV in a western blot assay, while another showed neutralizing activity against the VR2385 i solate. Out of the four MAbs to GP4 protein, one showed mild reactivit y in ELISA with detergent extracted antigen, but had no reactivity in a western-blot assay. The failure of MAb binding to detergent extracte d antigen in ELISA or in western-blot analysis indicated that the MAbs were against conformationally dependent epitopes. Reactivity patterns of the MAbs with PRRSV field isolates tested by fixed-cell ELISA show ed that then are antigenic variations in PRRSV GP4 and GP5 proteins. D evelopment of these MAbs will benefit further studies on PRRSV structu ral proteins as well as in understanding their roles in PRRSV pathogen esis. (C) 1998 Elsevier Science B.V. All rights reserved.