Comparison of Mycobacterium tuberculosis Strains with H37Rv Using Whole Genome Sequence Analysis to Identify Virulence Factors and Phylogenetic Relationships

Abstract

Mycobacterium tuberculosis (Mtb) poses a significant disease burden in developing countries, largely due to the rising issue of drug resistance. In Pakistan, the genetic and molecular characteristics of resistant strains have not been thoroughly analyzed or compared with the reference Mtb strain, H37Rv, to understand the molecular and genetic epidemiology. Mtb employs various strategies to resist anti-tuberculosis drugs, and antimicrobial resistance, including single and multidrug resistance, has increased extensively in developing nations like Pakistan. In this study, the whole genomes of three Mtb strains (335, 335-2, and 311) were uploaded to the Rapid Annotation Subsystems Technology (RAST) server to retrieve coding DNA sequences (CDS). The RAST server identified 4,454, 4,445, and 4,396 CDS for Mtb strains 335, 335-2, and 311, respectively. Mutation analysis was performed using NCBI nucleotide BLAST and CLUSTAL Omega, comparing the sequences with the H37Rv reference strain. The analysis revealed 909, 832, and 1,135 mutations in the 335, 335-2, and 311 strains, respectively. Phylogenetic analysis based on the most virulent protein (EccC3) indicated a close resemblance between all three strains and the H37Rv strain. Furthermore, Mycobacterium
canettii (accession number WP_203037448.1) was identified as the closest related bacterium to the studied strains and H37Rv.