INTESTINAL CHLAMYDIA IN FINISHING PIGS

Gut and blood samples from 119 finishing pigs derived from 11 farms we re collected during routine slaughter at an abattoir. Sections of form alin-fixed, paraffin-embedded tissues were labeled immunohistochemical ly using genus-specific, mouse monoclonal antibody against chlamydial lipopolysaccharide; goat polyclonal antiserum against the major outer membrane protein of Chlamydia trachomatis; and mouse monoclonal antibo dy against the ovine abortion subtype of C. psittaci. Gut samples from 33 of 111 (29.7%) individual pigs stained positive with the genus-spe cific monoclonal antibody, and of these 30 of 32 (93.7%) also reacted with the C, trachomatis-specific antiserum. Labeled inclusions were re stricted to mature enterocytes of the large intestine in 33 of 111 cas es. Infection of small intestinal enterocytes was noted in only one of 82 ileal samples. The blood samples were tested for antichlamydial an tibodies by enzyme-linked immunosorbent assay (ELISA) and complement f ixation test (CFT). With ELISA, 95 of the 115 sera tested (82.6%) yiel ded positive antichlamydial reactions. With CFT, 34 of the 119 sera te sted (28.6%) were unequivocally positive (greater than or equal to 1:1 0, 100% binding), and 10 (7.6%) yielded doubtful positive reactions (1 :10, 50-75% binding). Positive ELISA and CFT titers showed poor agreem ent (kappa = 0.112), whereas the agreement between positive findings b y immunohistochemical labeling and CFT was fair (kappa = 0.205).