Identification and Distribution of Mycobacterium leprae Genotypes in a Region of High Leprosy Prevalence in China: a 3-Year Molecular Epidemiological Study

Abstract

Multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA) has been proposed as a means of strain typing for tracking the transmission of leprosy. However, empirical data for a defined population are lacking. To this end, a study was initiated to assess the diversity and distribution of prevalent Mycobacterium leprae strains in Qiubei County, Yunnan Province, People's Republic of China, where the annual detection rate of leprosy is 10-fold higher than the national average rate. Sixty-eight newly diagnosed leprosy patients were included in the study. MLVA at eight M. leprae loci was applied using DNA extracts from skin biopsies. The number of alleles per locus ranged from 4 to 24, providing adequate strain discrimination. MLVA strain typing identified several clusters of patients whose M. leprae specimens shared similar VNTR profiles. Two of these clusters were comprised of patients who resided predominantly in the north and northwest parts of Qiubei County. Furthermore, it was found that multicase families are common in this county: 23 of the 68 patients were from 11 families. Intrafamilial VNTR profiles closely matched within six families, although they were different between the families. Moreover, VNTR patterns related to those found in some multicase families were also detected in patients in the same or adjacent townships, indicating the utility of VNTR strain typing to identify and detect short-range transmission events. Social contact through village markets is proposed as a means of transmission.

Distribution of Mycobacterium leprae Strains among Cases in a Rural and Urban Population of Maharashtra, India

“…35 (14) was calculated and compared for each of the 16 loci among different PHC areas and rural and urban samples. Western Maharashtra VNTR profiles were also compared to global VNTR profiles as recorded in the M. leprae database (1,3,4,7,9,16,19,21,22). The 18-8 locus was not assessed in the urban samples, as it failed to amplify in all samples.…”

“…Currently available knowledge of the M. leprae genome has revealed a very high degree of conservation with a limited number of identified genetic markers, which may aid in genotyping M. leprae strains. Among the markers identified, variable-number tandem repeats (VNTRs) with a broad range of allelic diversity have been shown to be effective in tracking strain transmission within and among strains in different regions of the world (1,3,9,16,17,19,21,22). In addition to these, single-nucleotide polymorphisms (SNPs), which have revealed a global pattern of distinct types of M. leprae strains (SNP types 1 to 4), have been identified (10).…”

Are Variable-Number Tandem Repeats Appropriate for GenotypingMycobacterium leprae?

“…An interesting observation was made when comparing the allelic diversity of four of the five VNTR surveyed in this work with that of their counterparts in 68 strains of M. leprae isolated from patients in the Yunnan Province of the People's Republic of China (20). The Chinese strains were all members of SNP type 3 and displayed far greater diversity at the trinucleotide VNTR loci than those from Mali.…”

“…While the SNP are useful in studies of long-range transmission of leprosy, the VNTR, owing to their more dynamic nature, appear more appropriate for monitoring the spread of M. leprae over shorter epidemiological distances, such as within a region or a large city. A number of reports have appeared that present the findings of VNTR studies of leprosy bacilli from different Asian countries (20,25) and in one case from patients belonging to the same family (24). Here we present the findings of a study aimed at comparing the performance of three SNP and five VNTR markers in typing strains present in different biopsy samples from the same leprosy patients living in Mali.…”

DNA Fingerprinting of <em>Mycobacterium leprae</em> Strains Using Variable Number Tandem Repeat (VNTR) - Fragment Length Analysis (FLA)

“…Multiple locus VNTR analysis (MLVA) 10 has been used to study leprosy evolution and transmission in several countries including China 11,12 , Malawi 8 , the Philippines 10,13 , and Brazil 14 . MLVA involves multiple steps.…”