Study of Immunological and Molecular Analysis of Virulence Genes in Mycobacterium tuberculosis Isolates from Hilla Teaching Hospital

Abstract Background: Despite the widespread use of a live attenuated vaccine and many medications, tuberculosis (TB), remains one of the top killers among infectious diseases. Objectives: The objectives of the study were to assess the immunological and molecular aspects of certain virulence genes among Mycobacterium tuberculosis. Materials and Methods: A total of 155 infected patients and 21 healthy control patients with suspected respiratory tract infections were enrolled from June 2022 to January 2023 in the Chest Unit at Hilla Teaching Hospital. Results: Of the 150 sputum samples taken, 93 were culture positive (62%), Mycobacterium tuberculosis was responsible for 35(37.6%) of the positive culture isolates, results showed that out of 35 isolates initially diagnosed as Mycobacterium by the Vitek II method, only 20 (57.1%) tested positive by PCR. Only 18 isolates tested positive for the presence of the virulence-related inhA gene; 16(80%) of them tested positive for the katG gene, and 14 (70%) of them tested positive for the rpoB gene. Determination of TNF- α , TNF- β , IL-12, and IL-17 in 20 M. tuberculosis isolates was investigated, and the results showed that the highest mean of TNF- α level was found among patients with RTI infected with M. tuberculosis compared with the control group showed a significant difference between the two groups ( P < 0.0001). TNF- β , IL-12, and IL-17 levels were found among patients with RTI infected with M. tuberculosis compared with the control group. Conclusion: Compared to conventional biochemical tests and the automated Vitek 2 system, the identification of M. tuberculosis by employing a particular primer gene, was more specific. There were identified virulence genes that were found to be crucial to pathogenicity.