Rapid variable-number tandem-repeat genotyping for Mycobacterium leprae clinical specimens

Area of Science:

• Microbiology
• Genetics
• Epidemiology

Background:

• Mycobacterium leprae is the causative agent of leprosy and cannot be cultured in vitro.
• Multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA) has emerged as a promising tool for strain typing and tracking leprosy transmission.

Purpose of the Study:

• To discover novel VNTR loci in Mycobacterium leprae.
• To develop and validate MLVA methods for analyzing clinical samples and monitoring leprosy transmission.

Main Methods:

• Applied MLVA to M. leprae isolates from armadillo hosts (n=21) using PCR, gel electrophoresis, and sequencing.
• Identified polymorphisms in 15 short tandem repeat (STR) loci.
• Developed multiplex PCR assays for fluorescent fragment length analysis.
• Extended the method to DNA from human skin biopsy specimens (n=30).

Main Results:

• Identified polymorphisms in 15 out of 25 selected STR loci.
• Achieved high concordance between sequencing and multiplex PCR fragment length analysis.
• Successfully applied the method to limited clinical DNA samples, enabling genotype differentiation.

Conclusions:

• Developed practical and cost-effective MLVA methods for M. leprae strain typing.
• These methods facilitate the mapping of transmission and epidemiological studies in leprosy-endemic regions.
• The validated techniques are suitable for monitoring M. leprae transmission dynamics globally.