Sequence analysis on drug-resistant gene of rpoB in Mycobacterium tuberculosis L-forms among pneumoconiosis patients complicated with tuberculosis

Abstract

To study the drug-resistant characteristics genetic mutation of rpoB in Mycobacterium tuberculosis L-forms among patients of pneumoconiosis complicated with pulmonary tuberculosis. A total of 42 clinical isolated strains of Mycobacterium tuberculosis L-forms were collected, including 31 drug-resistant strains. Their genomes DNA were extracted and target genes amplified by PCR. Hot regions in the rpoB gene were analyzed by automated DNA sequenator. No mutation of rpoB was identified in 11 rifampicin-sensitive strains while conformation changes were found in 31 rifampicin-resistant strains. The mutation rate was 93.55% (29/31) in resistant strains, mainly concentrated in codon 531 (51.6%, 16/31) and 526 (32.26%, 10/31), happened base substitutions, including 27 unit point mutation and 2 two point mutation. The newly found mutation of codon 516 had not been reported by internal or overseas scholars. The substitution of highly conserved amino acids encoded by rpoB gene resulted in the molecular mechanism was responsible for RFP resistance in Mycobacterium tuberculosis L-forms. It also proved that rpoB gene was in diversiform.