RESUMO
A monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) was described and evaluated for use as a presumptive screening test for detection of Campylobacter fetus in bovine preputial washing and vaginal mucus samples. A total of 725 diagnostic samples collected in the field and submitted in Clark's transport enrichment medium (TEM) were analyzed. Cultural isolation of C. fetus was used as the standard for comparison. After incubation of the TEM vials for 4-5 days, fluid was removed for culture and ELISA testing. A sandwich ELISA format was used and the target antigen was C. fetus lipopolysaccharides (LPS). A rabbit anti-C. fetus polyclonal antiserum was used as the capture antibody. Murine monoclonal antibodies (MAbs) to C. fetus serotype A and B LPS core and O-polysaccharides and a goat anti-mouse horseradish peroxidase conjugate were used as detection antibodies. ELISA and culture results for the diagnostic samples were in complete agreement. Seven hundred and eight samples were negative by both tests. All 17 culture positive samples were positive by ELISA with a MAb to LPS core. The ELISA with MAbs to LPS O-polysaccharides detected all culture positive samples with the homologous C. fetus serotype. Sixty-six preputial wash samples from three known C. fetus culture positive bulls were also analyzed. Forty-nine of these samples were positive by both ELISA and culture, 16 were positive by ELISA only, and one was negative by both ELISA and culture. The results indicate that this ELISA is useful as a screening test for the detection of C. fetus in diagnostic samples.
