ABSTRACT
Recently about 500 new cases of leprosy have been reported each year in Thailand. In addition to a steady rate of new case detection, Thailand is in Southeast Asia where leprosy is endemic in neighbouring countries; therefore, strain differentiation could be useful in tracing origins and routes of infection, and general leprosy surveillance. To identify suitable markers for differentiation of M. leprae strains in different global geographic regions and to determine the applicability of a systematic genotyping method for tracing leprosy transmission, variable nucleotide tandem repeats (VNTRs) of 14 loci were evaluated using DNA extracts from a total of 97 skin biopsies and slit skin smear samples. The alleles per locus ranged from 2-26 providing adequate strain differentiation. Microsatellite loci (GAA)21, (AT)17 are highly polymorphic followed by (GTA)9, (AC)8a, (AC)8b, and (AC)9. The minisatellites 6-7, 21-3 and 27-5 exhibited a limited number of alleles. The repeat of 23-3 showed no polymorphism. Overall, the strain types can be divided into two distinct Thai groups, according to the alleles at the (GGT)5 and 21-3 loci. However, there are no obvious geographical patterns of distribution of VNTR strain types. Closely matched VNTR profiles found in household members of two multi-case families suggested infection through a common source.
Subject(s)
Leprosy, Multibacillary/microbiology , Leprosy, Paucibacillary/microbiology , Minisatellite Repeats , Mycobacterium leprae/genetics , Adolescent , Adult , Aged , Aged, 80 and over , Child , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , Female , Genetic Variation , Humans , Leprosy, Multibacillary/epidemiology , Leprosy, Paucibacillary/epidemiology , Male , Middle Aged , Molecular Epidemiology/methods , Thailand/epidemiology , Young AdultSubject(s)
Antigens, Bacterial/genetics , Antigens, Bacterial/immunology , Antigens, Bacterial/isolation & purification , Cloning, Molecular , Escherichia coli , Statistics as Topic , Gene Expression , Genes, Bacterial , /biosynthesis , Monocytes/immunology , Mycobacterium leprae/genetics , Mycobacterium leprae/immunology , Mycobacterium leprae/isolation & purification , Molecular Weight , Protein Precursors/genetics , Protein Precursors/immunology , Protein Precursors/isolation & purification , Bacterial Proteins/genetics , Bacterial Proteins/immunology , Bacterial Proteins/isolation & purificationABSTRACT
A novel Mycobacterium leprae lipoprotein LpK (accession no. ML0603) was identified from the genomic database. The 1,116-bp open reading frame encodes a 371-amino-acid precursor protein with an N-terminal signal sequence and a consensus motif for lipid conjugation. Expression of the protein, LpK, in Escherichia coli revealed a 33-kDa protein, and metabolic labeling experiments and globomycin treatment proved that the protein was lipidated. Fractionation of M. leprae demonstrated that this lipoprotein was a membrane protein of M. leprae. The purified lipoprotein was found to induce production of interleukin-12 in human peripheral blood monocytes. The studies imply that M. leprae LpK is involved in protective immunity against leprosy and may be a candidate for vaccine design.
