Variable Number Tandem Repeats for Global Strain Typing and Strain Differentiation of Mycobacterium leprae

Abstract

Leprosy is chronic granulomatous disease caused by Mycobacterium leprae and associated with the disability, stigma and discrimination to the affected individuals. Though often considered a disease of antiquity, it is found most commonly today in tropical and sub-tropical regions. Global efforts to eradicate leprosy have been largely successful in controlling its spread. Despite these efforts, the disease remains endemic countries emphasizing the need for greater scrutiny of its epidemiology. Strain typing and strain differentiation by Variable Number Tandem repeats (VNTR) could be useful in tracing origins and routes of infection, general leprosy surveillance and prevalence. Strain typing of Mycobacterium leprae by VNTR has been successfully carried out and predominance of leprosy bacilli in different geographical region also done by VNTR. In the present review, we reported global distribution M. leprae by Variable Number tandem repeats in systematic way to easy understanding of leprosy distribution. ReviewLeprosy is chronic granulomatous disease caused by Mycobacterium leprae and associated with the disability, stigma and discrimination to the affected individuals [1]. Though often considered a disease of antiquity, it is found most commonly today in tropical and sub-tropical regions [2]. Global efforts to eradicate leprosy have been largely successful in controlling its spread. Despite these efforts, the disease remains endemic countries, with 232,857 cases reported cases globally in 2012 [3]. India accounted for 1.27 of cases reported in 2011-2012, emphasizing the need for greater scrutiny of its epidemiology. strain typing and strain differentiation are very helpful to identify the source of infection, transmission of infection and spreading of disease, differentiating cases of relapse from re infection, and for unravelling possible links between human and nonreservoir sources [4,5]. In recent years molecular typing methodologies have complemented conventional infectious disease.Strain tying and strain differentiation is a method which useful to distinguishing members of the same microbial species from one another on the basis of genotype. Strain typing explains that one isolate is same or it's different. Several molecular typing methods have been employed to distinguish the M. leprae strains over the years.Initially methods like surface antigen typing [6], multi-locus enzyme electrophoresis (MLEE) [7] and phage typing [8] were used for strain typing. DNA based strain typing methods were started from 1990. The methods includes fragment length polymorphism (RFLP) typing at locus such as rRNA operons [9] fingerprinting by randomly primed PCR [10] pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST) [11], variable umber tandem repeats (VNTR) and SNP. If genetic diversity less, VNTR is good source for the identification of strain variation [12,13]. VNTRs have short, tandemly repeated motifs typically ranging from 1 to 60 bp in length. Polymorphisms at those sites consist of differe...

Genotyping comparison ofMycobacterium lepraeisolates by VNTR analysis from nasal samples in a Brazilian endemic region

“…Some polymorphic loci are suitable for identifying genotypes according to the discriminatory capacity, stability, and reproducibility. There is considerably more variation in repeat numbers at VNTR locus than in non-repetitive DNA sequences, because length-altering mutations due to slipped-strand mispairing occur at a much higher rate than the inherent DNA substitution or mutation frequency of DNA polymerase [7,8].…”