USE OF THE PROTECTIVE ANTIGEN OF ERYSIPELOTHRIX-RHUSIOPATHIAE IN THE ENZYME-LINKED-IMMUNOSORBENT-ASSAY AND LATEX AGGLUTINATION

To establish a safe and convenient serodiagnostic method for swine ery sipelas, a purified protective protein antigen of Erysipelothrix rhusi opathiae, which included a large amount of protective protein (64 kDa protein), was used for enzyme-linked immunosorbent assay (ELISA) and t he lates agglutination (LA) test. In the ELISA, the antisera to four d ifferent serovars (la, 2, 5 and 20) of E. rhusiopathiae exhibit a posi tive reaction, while antisera to other species of bacteria (Listeria m onocytogenes, Staphylococcus aureus, Streptococcus sr,5 Rhodococcus eq ui and Corynebacterium pseudotuberculosis) exhibit a negative reaction . In the LA test, the antisera to three different serovars (la, 2 and 5) of E. rhusiopathiae reacted with P64-sensitized latex beads, while the antiserum to serovar 20 (2553 strain) did not. Moreover, the antis era to other spec:ies of bacteria (Listeria monocytogenes, Staphylococ cus aureus, Streptococcus suis, Rhodococcus equi and Corynebacterium p seudotuberculosis) did not in this test. Comparing the results of the growth agglutination (GA), ELISA and LA tests of 284 swine sera, there was a high degree of correlation among the results. The detection of anti-E. rhusiopathiae antibodies in the GA, ELISA and LA tests were co mpared using sera from pigs immunized with P64, alkaline extract (AE) and live-cell vaccine (LV). In all three tests, anti-E. rhusiopathiae antibodies could be detected 1 week after immunization. The serum anti body titre as determined by the LA test increased moderately, as did t hat by the GA test, while that determined by ELISA increased rapidly T hese results suggested that ELISA could be used to monitor changes in anti-E. rhusiopathiae antibody titre and the LA test could be used in the screening test for swine erysipelas.