Exploration of the relationship between Sigma factor gene expression and isoniazid resistance in Mycobacterium tuberculosis
Objective To investigate whether the expression regulation of regulatory gene Sigma factors(sigA-sigM)is related to isoniazid resistance phenotype in isoniazid-resistant Mycobacterium tuberculosis(MTB)caused by katG mutations,and to provide reference for the study of the molecular mechanism of isoniazid resistance.Methods A total of 90 strains were collected from the patients undergoing first-line treatment at the Tianjin Tuberculosis Control Center during drug resistance testing from 2020 to 2022,of which 30 strains were sensitive strains without katG mutation,and 65 strains were isoniazid-resistant strains caused by katG mutation,including 11 strains resistant only to isoniazid,24 strains resistant to both isoniazid and streptomycin,and 30 strains multidrug-resistant to isoniazid,streptomycin,and rifampicin.After the strains were collected on the isoniazid drug-containing medium,the RNA of the strains was extracted,and the relative expression levels of Sigma factors were detected by reverse transcription-polymerase chain reaction(RT-PCR).The expression differences of Sigma factors in different isoniazid drug-resistant phenotypes were analyzed by the Mann-Whitney U test.Results The gene expression levels of sigA,sigC,sigF,sigG,sigH,sigI,sigJ,sigK,sigL in isoniazid mono-resistant group were significantly higher than those in pan-isoniazid-sensitive group(Z=4.368,5.701,6.865,4.021,5.126,2.670,5.983,4.701,5.490,P all＜0.001).The gene expression levels of sigA,sigC,sigF,sigG,sigH,sigI,sigJ,sigK,sigL in poly-resistance group were significantly higher than those in pan-sensitivity group(Z=-5.017,-4.670,-4.667,-5.456,-4.083,-5.393,-4.712,-6.971,-8.206,-5.211,P all＜0.001).In multidrug-resistant(MDR)group,the gene expression levels of sigC,sigD,sigE,sigF,sigG,sigH,sigI,sigJ,sigK,sigL were significantly higher than those in pan-isoniazid-sensitive group(Z=-5.537,-4.003,-5.216,-7.328,-7.730,-5.658,-4.440,-6.036,-4.862,-4.312,P all＜0.001).The expression levels of sigB,sigF,sigG showed statistically significant differences in gene expression between the isoniazid mono-resistant,isoniazid poly-resistant,and isoniazid multidrug-resistant groups(Z=10.139,7.735,14.532,P all＜0.001).The expression rates of sigF,sigG,sigl,sigJ,and sigL in the isoniazid-resistant group were significantly higher than those in isoniazid sensitive group(x2=17.410.45.673.57.661.42.896.26.363,P all＜0.001).Conclusions sigF,sigG,sigI,sigJ,and sigL are associated with isoniazid resistance due to katG mutations.
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