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Changes
→General Mycobacteria
*The ability of mycobacteria to survive and multiply within macrophages determines whether disease will occur within the host.
*The ability of mycobacteria to survive and multiply within macrophages determines whether disease will occur within the host.
*Mycobacteria sp. utilize several virulence factors including cord factor or trehalose dimycolate, surface glycolipid, sulfatides, lipoarabinomannan, heteropolysaccharide, heat shock protein, complement, and tubuloprotein.
*Mycobacteria sp. utilize several virulence factors including cord factor or trehalose dimycolate, surface glycolipid, sulfatides, lipoarabinomannan, heteropolysaccharide, heat shock protein, complement, and tubuloprotein.
*The types of immune responses that are critical in responding to mycobacterial infection are cell-mediated immunity and the delayed hypersensitivity response.
*The types of immune responses that are critical in responding to mycobacterial infection are cell-mediated immunity and the delayed hypersensitivity response.
*Pathogenicity of mycobacteria depends on their ability to escape phagocytic killing.
**Mostly imparted by the cell wall consitiutents…
***Cord factor (trehalose dimycolate) – surface glycolipid responsible for serpentine growth in vitro
***Suphatides – surface glycolipid containing sulphur which prevents fusion of phagosome with lysosome. cAMP secreted by the bacteria may also facilitate this. Also something about the cholesterol content of the phagosome….. nature article
***LAM – heteropolysaccharide which inhibits macrophage activation by IFNγ and induces macrophages to secrete TNFα -induces fever, etc and IL-10 which suppresses mycobacteria-induced T cell proliferation.
***The wax of the cell wall, peptidoglycans and other glycolipids are responsible for the adjuvant activity – attracts APCs.
***Tubuloprotein – important Ag, purified tubuloprotein is the basis of the tuberculin test.
==Four major disease groups are recognised:==
==Four major disease groups are recognised:==