[Diagnosis of blackleg by direct immunofluorescence in bovine bone marrow]

On smears of marrow-bone death bovines, presumptively diagnostic of black-leg, we have carried out the direct immunofluorescence test (IF). We used two labelled immunosera with fluorescein isothiocyanate. The immunosera wer prepared with the reference strain 5078 of Clostridium chauvoei as following: a) a cellular extract obtained with veronal buffer 0.045 M pH = 8.6, and b) a flagellar suspension obtained by agitation with glass beads, centrifuged at 3,500 x g, and centrifuged again at 16,000 x g during 20 min at 4 degrees C. Both antigenic preparations were injected into rabbits, five doses (0.2, 0.4, 0.8, 1.6 and 3.2 ml) each by i.v. route. Control positive strain of C. chauvoei were used, and control negative strains of C. septicum and C. perfringens were used too. Of all 56 examined samples, 26 (47.5%) gave positive IF test. These results had a 100% of correlation by culture and biochemical identification.