VNTR for genotyping of Mycobacterium bovis isolates from cattle slaughtered in Baja California, Mexico

摘要

In Mexico, bovine tuberculosis (TB) is one of the main problems which face the national livestock sector. Currently, there are molecular methods for the detection and genotyping of bovine TB, making it possible to determine the relationship between the different strains present in the region and identify some factors influencing the control and eradication programs of the disease in Baja California. In this work the variable-number tandem repeat (VNTR) technique was applied to 11 isolates from cattleslaughtered in a slaughterhouse in Mexicali BC and 10 isolates from cattle slaughtered in a slaughterhouse in Tijuana BC. Specific primers were used to amplify ETR-A, ETR-B, QUB-lla, QUB-llb, QUB-1895, QUB-26, QUB-3232 and QUB-3336 loci, determining therelationship among the isolates, and discriminatory power for each locus in particular and for all loci as a whole. Fourteen allelic profiles were obtained when using eight loci with a discriminatory power of 0.90. The QUB-3336 locus showed the highestdiscriminatory power (h = 0.72) and the ETR-B locus showed no discriminatory power (h = 0.00). In a dendrogram, there were six genetic groups with isolates from Tijuana and Mexicali, but some isolates were observed only in one of these areas. The resultsshowed that the movement of livestock and purchase market in the region has led to the dispersal of strains in these two areas; nevertheless, it is possible to differentiate some isolates exclusive of each region.