OBJECTIVETo 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.

METHODSVarious 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.

RESULTSLoci 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.

CONCLUSIONThe 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.

Alleles ; China ; epidemiology ; DNA, Bacterial ; Genotype ; Humans ; Leprosy ; epidemiology ; transmission ; Molecular Epidemiology ; Mycobacterium leprae ; genetics ; isolation & purification ; Polymerase Chain Reaction ; Skin ; microbiology

Objective To understand the genotypes of Mycobacterium leprae collected from Guangdong province,China and to analyze the routes of leprosy transmission both inside and outside of Guangdong.The impact of emigrant leprosy patients to the endemic nature of the disease in Guangdong was also studied.Methods Typing on strains with variable number of tandem repeats (VNTR) and single nucleotide polymorphism (SNP) were performed on the local cases and emigrant cases based on skin biopsy.Results Most isolates from local patients belong to SNP type 1 and SNP type 3 isolates were found just in a small part of local isolates.However,all the emigrants were carrying SNP type 3.Within the SNP type 1 strain from Guangdong,alleles at the 18-8,12-5,ML-1,(TA) 10 and (GGT)5 differed from SNP 3 strains collected from other areas in China.However,all the SNP type 1 and SNP type 3 local isolates identified from Guangdong were having close VNTR profiles and the main differences appeared in the alleles at ML-1,(TA) 10 and (GGT)5.Conclusion The transmission of strain with SNP type 1 seemed to be associated to the "Silk Road on the Sea",calling for monitoring and confirming the transmission of patients with SNP type 3 in Guangdong were from the secondary transmission,by the emigrant patients.Further study on the historic spread and phylogenetic relationships between SNP type 1 and novel SNP type 3 in Guangdong is needed.

OBJECTIVEMultiple locus variable number-tandem repeat (VNTR) analysis (MLVA) had been proposed as a means of strain typing for tracking of source and studying the transmission chain of pathogens. However, empirical data for a defined population from scale and duration were lacking for studying the transmission chain of leprosy.

METHODSMLVA on 7 VNTR loci was applied to the strain typing on prevalent Mycobacterium leprae isolates collected from Qiubei county, Yunnan province during 2002-2006 in the study on the relationship between geographic distribution and genotypes of M. leprae. The strain typing, combined with conventional epidemiological investigation was performed to trace the transmission chain.

RESULTS(1) Phylogenetic analyses through application of PAUP 4.0, The M. leprae were grouped into A, B, C, D and E strains according to the allelic range 9, 11-13, 15-26 and > 26 on the GTA9 locus. The strains with 9 copies on GTA9 locus, was named A. (2) Genotypes of strains from the five multi-case families located at North and North-West parts were similar and belonged to A strains. VNTR patterns of intra-family were identical or similar but not identical inter-family. (3) Not only A cluster appeared higher proportion in total isolates but also distributes cluster, indicating ongoing transmission from recent findings.

CONCLUSIONVNTR strain typing was suitable to trace the short chain of transmission in both small area and intra-families. Multi-case families might constitute epidemic foci and source of M. leprae in villages, causing the predominant strain or cluster which tends to be those identified in multi-case families and resulted in the spreading of leprosy. A long-term study was underway to reveal whether A strain was predominant strain and to observe the evolution of M. leprae in this spatially and temporally defined endemic population.

Female ; Genotype ; Humans ; Leprosy ; microbiology ; Male ; Minisatellite Repeats ; genetics ; Molecular Epidemiology ; Mycobacterium leprae ; classification ; genetics ; Phylogeny ; Polymerase Chain Reaction

Objective To explore the factors influencing the steady transmission of leprosy as indicated by new case detection rate in Qiubei county, Yunnan province, China despite the implementation of MDT for the last 25 years. Methods Information related to case-finding was collected. ELISA and PCR were applied to detect anti-PGL-1 antibody in sera and Mycobacterium leprae in nasal secretions respectively, in leprosy patients, their household contacts and the general population. M. leprae by PCR was also detected from water in the highly endemic villages. VNTR typing was performed to explore the mode and chain of transmission of M. leprae. Results Prior to 2001, the proportion of new cases detected from the examination of household contacts of leprosy patients was low (number, compared to), while the proportion of patients whose identification was delayed by more than 2 years, was high (number, compared to). Qualities of these two indicators has been improved, along with the improvement of leprosy control program since 2001, but the detection rates has been steady at 4-5/ 100 000 during 1986-2010. The PGL-1 seropositivity rate was 20%-30% in general population, with the peak rate (30%) detected in the teenage population in the endemic villages. In addition to the fact that M. leprae was detected in nasal secretion from patients, their contacts and from water, the M. leprae VNTR genotypes were found to be highly similar between skin biopsy and nasal secretion in untreated cases. Families with multi-cases were clustered and located in the Northern part of the County, and the genotypes of M. leprae were identical within those families. The percentage of clusters was considerably higher in Northern rather than Southern parts of the County. Conclusion Results from this molecular study demonstrated evidence that transmission of leprosy within the families and in the endemic-villages was severe. M. leprae were detected in waters from the endemic villages and others areas which might have a relation to the continued transmission of leprosy.