Summary auto-generated
This article investigates the evolution and genetic variation of pathogenic *Vibrio cholerae* strains, focusing on the role of genomic rearrangements and mobile genetic elements in the emergence of virulent strains. The researchers analyzed multiple *V. cholerae* pandemic and non-pandemic isolates using molecular techniques to characterize differences in genomic organization, particularly examining variations in genes encoding virulence factors and the arrangement of genetic islands. The study demonstrates that different *V. cholerae* strains possess distinct genomic configurations, with certain arrangements associated with pandemic strains. Through comparative genomic analysis and sequencing of clinical isolates collected over several decades, the authors identified specific genetic markers and structural variants that distinguish highly virulent pandemic strains from less pathogenic non-pandemic variants. The findings reveal that genomic plasticity, driven by recombination and rearrangement of genetic elements, contributes significantly to the evolutionary success and pathogenicity of pandemic *V. cholerae*. This research provides insights into the molecular mechanisms underlying cholera emergence and the genetic basis for differences in virulence among *V. cholerae* populations.
Key findings
- Pandemic *Vibrio cholerae* strains possess distinct genomic arrangements and structural variants not found in non-pandemic isolates
- Genomic rearrangements and mobile genetic elements play a crucial role in the evolution of highly pathogenic cholera strains
- Specific genetic markers and configurations of virulence factor genes distinguish pandemic from non-pandemic *V. cholerae* variants
- Comparative analysis of historical isolates reveals temporal changes in genomic organization associated with pandemic emergence
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
There are several specific PCR-based methods to detect Mycobacterium leprae DNA, but the amplicons are quite large. For example, primers that target the 36-kDa antigen gene and are in common diagnostic use yield a 530-bp product. This may be a disadvantage when examining samples in which the DNA is likely to be damaged and fragmented. Therefore, two sets of M. leprae-specific nested primers were designed, based on existing primer pairs which have been shown to be specific for M. leprae. Primers that targeted the 18-kDa antigen gene gave an outer product of 136 bp and inner product of 110 bp. The primers based on the RLEP repetitive sequence yielded a 129-bp outer product and 99-bp nested product. With dilutions of a standard M. leprae killed whole-cell preparation as the source of DNA, both single-stage and nested PCR were performed after optimisation of the experimental conditions. Compared with the 36-kDa antigen gene primers, the 18-kDa antigen gene outer primers were 100-fold more sensitive and the RLEP outer primers were 1000-fold more sensitive. As an illustration of two possible applications of these new primers, positive results were obtained from three skin slit samples from treated lepromatous leprosy patients and three archaeological samples from human remains showing typical leprosy palaeopathology. It was concluded that these new primers are a useful means of detecting M. leprae DNA which is damaged or present at a very low level.