DETECTION OF MYCOBACTERIUM-AVIUM SUBSP PARATUBERCULOSIS IN INFECTED-TISSUES BY NEW SPECIES-SPECIFIC IMMUNOHISTOLOGICAL PROCEDURES

We have previously described the cloning and sequencing of a gene port ion coding for the terminal part of a 34-kDa protein of Mycobacterium avium subsp. paratuberculosis, the etiological agent of Johne's diseas e (P. Gilot, M. De Kesel, L. Machtelinckx, M. Coene, and C. Cocito, J. Bacteriol. 175:4930-4935, 1993). The recombinant polypeptide (a362) c arries species-specific B-cell epitopes which do not cross-react with other mycobacterial pathogens (M. De Kesel, P. Gilot, M.-C. Misonne, h i. Coene, and C. Cocito, J. Clin. Microbiol. 31:947-954, 1993). The pr esent work describes the preparation of polyclonal and monoclonal anti bodies directed against a362 and the use of these immunoglobulins for histopathological diagnosis of Johne's disease. The new immunohistolog ical procedures herewith detailed proved to be able to identify M. avi um subsp. paratuberculosis antigens in the intestinal tissues and lymp h nodes of cattle affected by either the paucibacillary or pluribacill ary form of the disease. They yielded negative responses not only with healthy animals but also with those affected by tuberculosis (Mycobac terium bovis). Both immunohistological procedures proved to be as sens itive as or more sensitive than Ziehl-Neelsen staining and, in additio n, to be endowed with species specificity.