Whole genome sequencing analysis of intrapatient microevolution in Mycobacterium tuberculosis: potential impact on the inference of tuberculosis transmission.
Background. It has been accepted that the infection by Mycobacterium tuberculosis (M. tuberculosis) can be more heterogeneous than considered. The emergence of clonal variants caused by microevolution events leading to population heterogeneity is a phenomenon largely unexplored. Until now, we could only superficially analyze this phenomenon by standard fingerprinting (RFLP and VNTR).Methods. In this study we applied whole genome sequencing for a more in-depth analysis of the scale of microevolution both at the intrapatient and interpatient scenarios.Results. We found that the amount of variation accumulated within a patient can be as high as that observed between patients along a chain of t…
In-Depth Characterization and Functional Analysis of Clonal Variants in a Mycobacterium tuberculosis Strain Prone to Microevolution
The role of clonal complexity has gradually been accepted in infection by Mycobacterium tuberculosis (MTB), although analyses of this issue are limited. We performed an in-depth study of a case of recurrent MTB infection by integrating genotyping, whole genome sequencing, analysis of gene expression and infectivity in in vitro and in vivo models. Four different clonal variants were identified from independent intrapatient evolutionary branches. One of the single-nucleotide polymorphisms in the variants mapped in mce3R, which encodes a repressor of an operon involved in virulence, and affected expression of the operon. Competitive in vivo and in vitro co-infection assays revealed higher infe…