Preparation of a specific RNA probe for detection of Mycobacterium paratuberculosis and diagnosis of Johne's disease.

A species-specific recombinant clone (F57) was obtained from a genomic library of Mycobacterium paratuberculosis in the transcription vector pGem 3Z. This clone proved to be specific for all mycobacteria tested, including M. avium, and was able to recognize all of the tested M. paratuberculosis strains isolated from animals and humans (patients with Crohn's disease). The F57 insert was sequenced and a segment of 620 bp with a G + C content of 58.9% was identified. Comparison of the sequence with sequences in the EMBL and UGEN data banks revealed the uniqueness of the F57 sequence, which had no resemblance to other known genes.