PRESENCE OF ANTIGEN AND ANTIBODIES IN SERUM AND GENITAL DISCHARGES OFCOWS FROM DAIRY HERDS NATURALLY INFECTED WITH LEPTOSPIRA-INTERROGANS SEROVAR HARDJO

Samples of cervico-vaginal mucus from 163 bulling cows (group 1) and p ost calving discharges from 59 newly calved cows (group 2) in five dai ry herds naturally infected with Leptospira interrogans serovar hardjo were examined for the presence of antigen and IgG and IgA antibodies by using two ELISA systems which were protein or carbohydrate based. C orresponding serum samples were examined for systemic immune responses by using a microscopic agglutination test (MAT) and IgG-ELISA tests. Antigen was detected by direct immunofluorescence in six of the 163 sa mples of cervico-vaginal mucus. Both IgG and IgA antibodies were detec ted by ELISA in the genital discharges with a prevalence much higher t han that obtained by the MAT but lower than that observed with the ser um IgG-ELISA. Combining both groups, none of the MAT-positive cattle w as negative by serum-ELISA. By using the protein or carbohydrate fract ion serum IgG-ELISA assays, respectively, 29 or 41 per cent of the MAT -negative cows were positive at a titre of at least 1:40. Similarly, e ight or 23 samples (10 or 27 per cent) had titres of at least 1.20 in the gen ital discharge ELISA for IgG and IgA antibodies, respectively. The serum IgG-ELISA was the most efficient in detecting hardjo antibo dies, but in group 2 the IgG- and IgA-ELISA of the post calving discha rge proved to be equally effective.