![]() ![]() The identification of RD Rio strains outside of Brazil points to the ongoing intercontinental dissemination of this important genotype. Overall, the high prevalence of this genotype may be related to enhanced virulence, transmissibility, and/or specific adaptation to a Euro-Latin American host population. However, trends in the data did suggest that RD Rio strains may cause a form of TB with a distinct clinical presentation. ![]() Limited retrospective reviews of bacteriological and patient records showed a lack of association with multidrug resistance or specific risk factors for TB. The RD Rio lineage is therefore the predominant clade causing tuberculosis (TB) in Rio de Janeiro and, as indicated by genotypic clustering in MIRU-VNTR analysis, the most significant source of recent transmission. Genetic testing by principal genetic group, spoligotyping, variable-number tandem repeats of mycobacterial interspersed repetitive units (MIRU-VNTR), and IS 6110-based restriction fragment length polymorphism analysis cumulatively support the idea that RD Rio strains are derived from a common ancestor belonging solely to the Latin American-Mediterranean spoligotype family. The flanking regions of the RD Rio locus were identical in all strains bearing the deletion. Homologous recombination between two similar protein-coding genes is proposed as the mechanism for deleting or modifying 10 genes, including two potentially immunogenic PPE proteins. ![]() A single novel long sequence polymorphism (>26.3 kb) was characterized and designated RD Rio. One locus in our panel of PCR targets failed to amplify in ∼30% of strains. The current study evaluated Mycobacterium tuberculosis isolates from Rio de Janeiro, Brazil, for genomic deletions. ![]()
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