Molecular epidemioloic analysis of Mycobacterium bovis isolates from Mexico

Abstract

Objective - To assess phylogenetic relationships among Mycobacterium bovis isolates by use of random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) fingerprinting and to relate genetic profiles of isolates to epidemiologic characteristics. Animals - 400 cattle with tuberculosis. Procedure - Mycobacterium bovis was isolated from various organs of cattle slaughtered in 6 geographic regions of Mexico. Most cattle were adult Holsteins from large herds that did not participate in a tuberculosis control program. Four random primers and 2 selected primers were used in RAPD-PCR fingerprinting of 88 isolates. Pairwise genetic distance between isolates was obtained and subjected to cluster analysis with bootstrapping to test for levels of support. Results - 98 different fragments were obtained; there was broad genetic diversity among isolates, and each isolate had a unique RAPD-genotype, including those originating from the same herd. Clustering by geographic location, affected organ, or severity of lesion was not detected. Linkage disequilibrium analysis suggested that M bovis was highly clonal and that mutations develop at a rapid rate among isolates. Conclusions and Clinical Relevance - Use of RAPD-PCR could not differentiate M bovis isolates by epidemiologic characteristics or identify common sources of infection. (Am J Vet Res 2000;61:90-95).