Typing of IS 1311 polymorphisms confirms that bison (Bison bison) with paratuberculosis in Montana are infected with a strain of Mycobacterium avium subsp. paratuberculosis distinct from that occurring in cattle and other domesticated livestock.

Isolates of Mycobacterium avium subsp. paratuberculosis from nine bison (Bison bison) from Montana, United States of America, were compared with those from other species from the United States of America. All 16 isolates had a novel IS 1311 genotype in which all copies of the element possessed a thymidine-cytosine nucleotide variation at base position 223. Isolates from bison were termed B strain. Thirteen isolates from cattle and goats were polymorphic at this locus, a status previously recognised in isolates from cattle which are termed C strains. Differences in cultural phenotype between B and C strains which were noted upon primary isolation did not manifest upon subculture to Herrold's egg yolk medium or modified Middlebrook 7H10 agar. Rapid differentiation of these strains from each other and from S strains from sheep is possible using polymerase chain reaction and restriction endonuclease analysis. The epidemiology of paratuberculosis in bison in Montana appears to be distinct from that in cattle and other farmed livestock investigated thus far. Copyright 2001 Academic Press.