Molecular analysis of Rv0679c and Rv0180c genes of Mycobacterium tuberculosis from clinical isolates of pulmonary tuberculosis.

CONTEXT: Two novel proteins/genes Rv0679c and Rv0180c of Mycobacterium tuberculosis (MTB) H37Rv were classified as a hypothetical membrane and transmembrane proteins which might have a role in the invasion. Molecular analysis of these genes in human clinical isolates of pulmonary tuberculosis (PTB) patients was not well characterised.

AIMS: To assess the molecular diversity of Rv0679c and Rv0180c genes of MTB from clinical isolates of PTB patients.

SETTINGS AND DESIGN: DNA from 97 clinical isolates was extracted and subjected to amplification using selective primers by polymerase chain reaction (PCR). The PCR product obtained was sequenced commercially.

PATIENTS AND METHODS: Clinical isolates obtained from tuberculosis patients were investigated for polymorphisms in the Rv0679c and Rv0180c genes by PCR and DNA sequencing. Genomic DNA isolated by cetyltrimethylammonium bromide method was used for amplification of genes.

RESULTS: Rv0679c gene was highly conserved in 61 out of 65 clinical isolates assessed for sequence homology with wild-type H37Rv gene and was identical using ClustalW. Fifty-five out of 78 (70.5%) clinical isolates assessed for Rv0180c were positive for single nucleotide polymorphism (SNP) at 258th position where the nucleotide G was replaced with T (G to T). In clinical isolates of untreated cases, the frequency was 54.5% for SNP at 258th position which is low compared to cases undergoing treatment where the frequency was 73.1%.

CONCLUSIONS: Molecular analysis of Rv0180c in clinical isolates of PTB assessed in this study was the first report, where an SNP at 258th position G to T was identified within the gene. Rv0679c gene was highly conserved (94%), within Indian clinical isolates as compared to reports from other nations.