Correlation study between Mycobacterium tuberculosis PhoPR two-component system and drug resist-ance of widespread clinical isolates of Mycobacterium tuberculosis / 中华微生物学和免疫学杂志

ABSTRACT

Objective To explore the correlation between Mycobacterium tuberculosis ( MTB ) PhoPR two-component system and drug resistance of MTB clinical isolates widespread in Xinjiang region by analyzing the expression of PhoP gene and PhoR gene among different isolates .Methods Total RNA of MTB was extracted from drug-susceptible strains , the strains only resistant to a single first-line anti-TB drugs (INH, RFP, SM and EB) and multidrug-resistant (MDR) strains, respectively.The purity of total RNA was checked by agarose gel electrophoresis .The expressions of PhoP gene and PhoR gene were quantified by using SYBR Green I qRT-PCR and the differences of their gene expression in different isolates were ana-lyzed.Results Compared with the drug-susceptible strains of MTB, the expression of PhoP gene was up-regulated for about 1.48 times in MTB strains resistant to RFP (RFP-MTB) and 2.74 times in MDR strain (P<0.05).Compared with MDR strain, the expressions of PhoP gene in the isolates resistant to INH (IN-HMTB), RFP (RFP-MTB), SM (SM-MTB) and EB (EB-MTB) were down-regulated for 0.70, 0.50, 0.25 and 0.21 times respectively.The expressions of PhoR gene were down-regulated for 0.36, 0.54, 0.35 and 0.19 times, respectively (P<0.05).The expressions of PhoR gene in the isolates of INH-MTB, RFP-MTB, SM-MTB and EB-MTB were up-regulated for 6.33, 4.56, 2.34, 1.85 and 9.06 times, respectively as compared with the drug-susceptible strains (P<0.05).Conclusion Significant differences of PhoR gene and PhoP gene expressions were observed among drug-susceptible strains , INH-MTB, RFP-MTB, SM-MTB, EB-MTB and MDR strains.Therefore, the Mycobacterium tuberculosis PhoPR two-component system is asso-ciated with the drug resistance of MTB strains prevalent in Xinjiang region .