[Innovative strategies to diagnose and monitor tuberculosis patients]

Molecular assessment, drug-resistant profile, and spacer oligonucleotide typing (spoligotyping) of Mycobacterium tuberculosis strains from Tamaulipas, México

BACKGROUND

Tuberculosis remains a serious global health problem involving one-third of the world population. A wide diversity of Mycobacterium tuberculosis strains cause about 1.5 million deaths/year worldwide, but in developing countries, the genetic diversity of M. tuberculosis strains remains largely unknown. We conducted a first insight into the population diversity of M. tuberculosis strains from Tamaulipas, Mexico.

METHODS

Seventy-two M. tuberculosis strains were identified and genetic diversity determined by spoligotyping. Drug sensibility testing and punctual mutations in inhA, ahpC, rpoB, and katG genes were assessed.

RESULTS

Spoligotyping analysis showed a higher prevalence of LAM9 > T1 > Haarlem3 subfamilies among 53 spoligotype patterns. Unexpectedly, five Beijing strains conforming four unique spoligopatterns were recovered. The more frequently isolated strains (LAM9 and T1), but none of the Beijing strains, were found resistant to INH or RIF. Also, no drug resistance was found among Haarlem3 isolates. The katG(315) gene mutation was found in 83% of INH-resistant strains, whereas rpoB(526) were associated in only 43% of RIF M. tuberculosis drug-resistant strains.

CONCLUSIONS

This and other studies report a high rate of orphan spoligotypes, which highlights the need for genotyping implementation as a routine technique for better understanding of M. tuberculosis strains in developing countries such as Mexico.

[From genetics to genomics in the rational design of new Mycobacterium tuberculosis vaccines]

Tuberculosis (TB) is an infectious disease affecting people from all ages all over the world. It is estimated that one third of the world population lives infected with the causal agent: Mycobacterium tuberculosis. Despite availability and systematic administration of BCG vaccine in endemic areas, TB transmission remains elusive to control, partly because BGC efficacy has been shown to have wide variability (0-80%). Such variability in protection is attributed to factors including: the BCG strain used for immunization, pre-existing exposure to environmental saprophytic Mycobacterium species, and host genetic factors. In this context, efforts regarding to re-engineering BCG vaccines with the ability to prevent latent TB reactivation, providing long lasting protection, and devoid from collateral effects in immunosuppressed people are urgent. In this work we review the actual molecular «gene-by-gene» strategies aimed at generating BCG alternatives, and discuss the urgent necessity of high throughput technology methods for a rational design for a new TB vaccine.