A Preliminary Study On The Relationship Between Isoniazid Resistance Of Mycobacterium Tuberculosis And Fatty Acid Anabolism Genes AccD1 And Mcr Genes

Tuberculosis(Tuberculosis,TB)is a chronic and serious zoonosis caused by MTB(Mycobacterium Tuberculosis),which not only causes harm to human and animal health,but also causes huge economic losses.Despite global efforts to address the incidence and transmission of tuberculosis,about 10 million people are diagnosed with the disease each year,resulting in about 2 million deaths.The treatment of tuberculosis adopts the treatment scheme of long-term use of repetitive drugs,poor patient compliance and the gradual growth of secondary tuberculosis lead to the occurrence of more and more drug-resistant tuberculosis.China is one of the 22 countries with high TB burden in the world,and it is also one of the 27 countries with serious prevalence of MDR-TB in the world.Fatty acids are essential substances in most organisms,and they are also widely found in Mycobacterium tuberculosis.Mycobacterium tuberculosis uses fatty acids as a stable source of energy and uses fatty acids to control the permeability of the cell wall.although there are differences in physiological characteristics and fatty acid production patterns of Mycobacterium tuberculosis in different periods,but the utilization of fatty acids is similar.In order to study the effect of isoniazid resistance of Mycobacterium tuberculosis on fatty acid synthesis and metabolism,we detected the difference of fatty acids in standard strains H37 Rv,isoniazid-induced H37 Rv strains and wild strains MB-5,and analyzed the transcriptional levels of fatty acid synthesis and metabolism genes acc D1 and mcr in different strains infected with macrophages.The standard strain H37 Rv and field strain MB-5 of Mycobacterium tuberculosis preserved in the laboratory were detected by isoniazid minimal inhibitory concentration((MIC,minimum inhibitory concentration)).The MIC value of isoniazid of the standard strain H37 Rv was taken as the standard,and the standard strain H37 Rv was induced by the concentrations of 1/8MIC,1/4MIC,1/2MIC and MIC,respectively.The MIC value of the induced strain was similar to that of the standard strain.The standard strains of Mycobacterium tuberculosis H37 Rv,different gradient drug resistant strains of H37 Rv induced by isoniazid and wild strain MB-5 were detected qualitatively and quantitatively by gas chromatography-mass spectrometry(GC-MS).It was found that there were differences in fatty acids and short-chain fatty acids in different drug resistance gradients of Mycobacterium tuberculosis.Raw264.7 macrophages were infected with standard strain H37 Rv of Mycobacterium tuberculosis,different gradient drug resistant strains of H37 Rv induced by isoniazid and wild strain MB-5,respectively.The cytotoxicity after infection was detected by CCK-8 method,and the transcriptional levels of fatty acid synthesis and metabolism genes acc D1 and mcr were detected.The results showed that the cytotoxicity of isoniazid-induced drug-resistant strains was higher than that of standard strain H37 Rv and wild strain MB-5,.During the logarithmic growth phase of Mycobacterium tuberculosis,the expression of fatty acid biosynthesis metabolism genes mcr and acc D1 was correlated with drug resistance concentration.After infecting macrophages,the expression increased with the increase of isoniazid-induced gradient.