[Preliminary study on the genotyping of Mycobacterium leprae on 50 isolates from China]

To understand the genotypic mapping of Mycobacterium leprae identified in China and to compare with those from other countries to select suitable alleles for epidemiological investigation in the transmission chain of leprosy.

Various number of tandem repeat(VNTR) in genomic DNA of Mycobacterium leprae was used in the present genotyping study. 33 skin biopsies from Wenshan prefecture,Yunnan province and 17 from other parts of China were studied. DNA extracted from skin biopsies of leprosy patients was subjected to PCR followed by agarose gel analysis and DNA sequencing to determine the number of repeats.

Loci GGT-5,12-5,21-3 and 23-3 were as highly homogenous as 100%; The homogeneity of loci AC-8, 18-8, 27-5 and rpoT were 97%, 94%, 97% and 85% respectively. Loci GTA-9, AC-9 and 6-7 showed significant allelic diversity in isolates and the diversity of GTA-9 in Mycobacterium leprae isolated from China was also different from those identified other countries. We had subjected loci GTA-9 and the ten loci to phylogenetic tree analysis respectively.

The present study revealed that the genotype of Mycobacterium leprae identified from China was close to the strains from the Philippines and India although a few loci were somehow differentiate. Locus 12-5 manifested as only 3 copies in China whereas 4-5 copies predominating in other countries. 12-5 locus might serve as a useful marker to diffrentiate Chinese strains from those in other countries. However, further study on the diversity of GTA-9 was needed in China. The molecular typing of Mycobacterium leprae from different geographic areas might be useful in studying the transmission of leprosy.