Determination Of The Function Of M.Semegmatis Whole Cell Lysis For Defending The Attack From The Macrophage

Tuberculosis (TB) is one kind of intracellular bacteria, which can survive and show slow growth in the lung cell. TB can burst out and cause severe pulmonary infection once there is a function decline of the immune system. As one kind intracellular bacteria, TB can escape from the attack of immune cells, so finding out the way how the bacterial invade the immune system is very important for finding new medicine and new detection method for anti-tubuculosis. Lipopolysaccharide linked to the out-membrane of the bacterial cell wall can induce varied immune response, LAMs/LMs(lipoarabinomannans/lipomannans) was thought to induce the Th1/Th2 cell immune response, which can determine whether the bacterial can survive or not.But as we all know, it is a very complex and various response during the bacterial infect the cells, virulence factors definition must have to come out from different gradations, we have to check from the bacterial level to the molecule level, such as LAMs/LMs, before we can represent the cross-talk actually between TB and the host cell.For the high pathogenicity character of TB, M. Smegmatis often acts as substitute bacterial to study the relevant characteristics.In this article use smeg and the whole cell lysis(WCL) infect the mouse by aerosol, and use macrophage do the similar experiment at the same time.The event of bacterial infect the host has been study from cell and lung tissue, those work can provide experimental evidence for the virulence factors for TB survive, and work as a platform for further study.In this study M. Smegmatis and Escherichia coli were used to infect the lung of the mouse, and it turn out very different survive and eliminate rate. At the low dose(MOI≤10 or≤108CFU/mouse),the bacterial will soon be eliminated, while at the high dose (MI≥100 or≥109CFU/mouse) the bacterial is out of control. So chose the infection dose MOI=10 and 107CFU/mouse for the following experiment. Both bacterial show the tend of being eliminating during 24-72h, but M. Smegmatis show a slow eliminating rate than the Escherichia coli, and in this experiment we use WCL to interval the infection event finding that it change the eliminating rate of the bacterial. Especially for the WCL(S), it can decrease the eliminating rate of Escherichia coli and help the bacterial survive in the cell. We use LAMs separate from the cell wall interval the bacterial infection, the macrophage ability of eliminating the bacterial is influenced and it show more protective immune response and decrease the eliminating rate of the bacterial in the cell. We find that the tissue damage is accordance with the bacterial number in the lung.The result show that, when we use high dose smeg to infect the mouse, the lung shows inflammation and come out some similar character as TB, so we can use this model to study the early event of TB; M. Smegmatis show slow eliminating rate and can survive long time than Escherichia coli; WCL and material from the cell wall can influent the ability of immune cell to eliminating the intracellular bacterial, in this study we find that the WCL(S) help the Escherichia coli to survive in the cell.