Genetic diversity of Mycobacterium leprae isolates from Brazilian leprosy patients

Abstract

By use of a PCR-RFLP-based procedure that allows the recognition of SNP types 3 and 4 without the need for the more expensive DNA sequencing steps, characterisation of the main M. leprae genotypes was easy. When applied on the study population, it was found that the SNP type 3 is most frequent in these two states of Brazil, and that VNTRs provided further discrimination of the isolates. Two Short Tandem Repeats (STRs) were monomorphic, with the remaining 14 STRs represented by two to 18 alleles. Epidemiological associations with township or state were not evident in this random collection and require further investigations. In phylogenetic trees, branches formed by all 16 STRs clearly separated SNP type 3 organisms from the other types while the allelic patterns of two minisatellite loci 27-5 and 12-5 were highly correlated with SNP type 3. This strain typing study provide the basis for comparison of M. leprae strain types within Brazil and with those from other countries, and informed selection of genomic markers and methods for future studies.