Polymorphisms in IS1311, an insertion sequence common to Mycobacterium avium and M. avium subsp. paratuberculosis, can be used to distinguish betweenand within these species

IS1311 is an insertion sequence from Mycobacterium avium and M. avium subsp . paratuberculosis. Using a 180 bp fragment of IS1311 as a probe, 7-10 copi es of IS1311 were revealed in strains of M. avium subsp. paratuberculosis. With a given restriction enzyme, the restriction fragment length polymorphi sm patterns obtained from isolates of M. avium subsp. paratuberculosis from cattle were all identical, but they differed from those of isolates from s heep, which could be separated into two types A 1259 bp fragment of IS1311 produced by polymerase chain reaction (PCR) from two isolates of M. avium s ubsp. paratuberculosis from cattle and two isolates from sheep was sequence d and compared to the sequence known from M. avium. Apart from five point d ifferences the sequences were identical. Restriction endonuclease analysis (REA) of the PCR product was used to distinguish isolates of M. avium subsp . paratuberculosis from M. avium, in addition to the conventional test for IS900. In isolates of M. avium subsp. paratuberculosis from cattle the IS13 11 gene was polymorphic at position 223, which enabled isolates from sheep and cattle to be distinguished by PCR-REA. These simple tests will be used to enhance disease control programmes for Johne's disease in ruminants. The findings of this study raise interesting questions about the evolution of M. avium subsp. paratuberculosis. (C) 1998 Academic Press.