MODERN TB DETECTION · Multidrug-resistant and hypervirulent tuberculosis: integral approach to rapid detection and evolution

Final Activity Report Summary - MODERN TB DETECTION (Multidrug-resistant and hypervirulent tuberculosis: integral approach to rapid detection and evolution)

In this project, we: 1. searched for novel informative markers for molecular epidemiology of tuberculosis (TB) 2. Developed and optimised new tools for the detection of drug-resistant and virulent m. tuberculosis strains 3. modelled the co-evolution of m. tuberculosis with humans. The abovementioned objectives were basically achieved. The Beijing genotype is a globally spread lineage of m. tuberculosis which is often associated with drug resistance and increased virulence. Genome mapping identified two specific IS6110 insertions for the Beijing strain. This information was used for the development of the fast real-time polymerase chain reaction (PCR) method for the detection of Beijing strain, whose patent was under preparation by the time of the project completion. Based on extensive analysis of multiple molecular markers we proposed a cost-effective format of seven variable number tandem repeat (VNTR) loci for high-resolution epidemiological screening of these strains. Bayesian simulation showed that the Beijing B0 variant was a successful clone, rapidly and widely spread in Russia because of its specific pathogenic properties. M. tuberculosis population in Kaliningrad exclave of Russia was shown to share a joint pool of strains with the European part of Russia, while, at the same time, it exhibited a certain relatedness to the northern European neighbours, such as Poland and Germany. The high prevalence of the multidrug resistant (MDR) Beijing genotype strains was a major cause of the highly adverse epidemiological situation of MDR-TB in the Kaliningrad region of Russia that also had an impact on health situation in the European Union. Bulgaria, a new EU member, had a high rate of MDR-TB among new TB cases equal to 10.7 % with TB incidence being also high, at a rate of 41 per 100 000. Our analysis showed that emergence and spread of drug-resistant TB in Bulgaria were not associated with any particular genotypic variant but might be due to insufficient TB control measures. A reduced 5-locus VNTR set was recommended for the first-line screening of m. tuberculosis isolates in Bulgaria. Rifampicin (RIF) and Ofloxacin (OFL) are key components of anti-TB treatment and resistance to them serves as surrogate marker of MDR and extensively drug resistant TB (XDR-TB). We either developed or optimised macroarrays and real-time PCR methods to genotypically detect RIF and OFL resistance via the detection of rpoB and gyrA gene mutations in cultured strains and clinical samples. A new measure of genetic distance between geographic populations within a microbial species based on the observed difference in the frequencies of its subtypes was proposed. It was applied to phylogeographic analysis of m. Tuberculosis, while geographic distribution of VNTR-subtypes within Beijing genotype was interpreted in light of human historical and recent migrations. The comparative analysis revealed strong geographic specificities of the local clonal variants of M. tuberculosis. Large water masses were the most efficient and drastic generators of the genetic divergence between human populations. The same situation appeared also true for m. tuberculosis, whose general diversity pattern amazingly resembled that of its human host. At the same time, less expected affinities that were observed between distant populations of m. tuberculosis could reflect hidden patterns of human migrations or yet unknown epidemiological links between distant regions. Beijing genotype likely originated from north-central China, appearing more than 2 000 years ago. Its historic introduction to other world regions was driven by human movements either medieval, to Russia, or more recent, to South Africa since the 17th century and to Australia during the 19th century.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз