Table 1.
A Synopsis of the m Tuberculosis Main Virulence Factor and Their Pathogenic Mechanism
| Virulence Factor | Mechanism of Bacterial Virulence |
|---|---|
| ● Lipoarabinomannan (LAM) and Mannose-capped-LAM | Bacterial Adherence and phagocytosis by macrophages43 |
| Inhibits phagosome maturation44 and phagolysosomal fusion45 | |
| Block transcription of IFN-g, antioxidative defense and inhibition of protein kinase C activity46 | |
| DownregulateTh1 cytokine expression47 | |
| Induction of IL-10 production and Inhibition of dendritic-cell maturation48 | |
| ● Lipomannan | Induction of IL-12 production and apoptosis in macrophages49,50 |
| ● Cord factor (Trehalose-6,6´-dimycolate) | Inhibits acidification of phagolysosome, delayed maturation of phagosomes, phagosome-lysosome fusion51,52 |
| TB-granuloma development and maintenance(dependent mainly on TNF-α and IL6 increased production) and cachexia53,54 | |
| Damage to mitochondria membranes and oxidative phosphorylation impairment55,56 | |
| Induction of apoptosis and thymus atrophy57 | |
| ● Phosphatidylinositol mannosides | Granuloma development and maintenance58 |
| Inhibition of TNF, IL-12p40 production within macrophages59 | |
| ● Phthiocerol dimycocerosate and phenolic glycolipids | Evade recruitment of MyD88-dependent macrophage populations60 |
| Intracellular bacterial survival (bacterial protection against nitrogen intermediates species)61 | |
| Bacterial Adherence and phagocytosis by macrophages62 | |
| Phagosome membrane rupture followed by apoptosis63 | |
| ● Twin-arginine transporter | Cell wall biogenesis and resistance to beta-lactam antibiotics64,65 |
| ● Exported repetitive protein (Erp) | Intracellular MTb growth66 |
| ● ESAT-6 family | T cell stimulation (gamma interferon release)67 |
| Delayed-type hypersensitivity68 | |
| Downregulate ROS production and LPS‐induced nuclear factor‐κB activity in macrophage69 | |
| Inhibit TLR2-mediated signaling in macrophage70 | |
| Apoptosis of macrophage71 | |
| Cytolysis of macrophages, red blood cells,72 and pneumocytes73 by pore formation | |
| Bacterial translocation from the phagolysosomes to the cytoplasm74 | |
| ● Phenolic glycolipids | Immunosuppression (release of this pro-inflammatory mediators)75 |