Antigens and toxins
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Many antigens have been identified in mycobacteria. Group specificity is due to polysaccharide and type specificity is due to protein antigen.
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They do not produce any exotoxins. The cell wall of the mycobacterium is composed of peptidoglycan, arabinogalactan and mycolic acid.
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In addition to this it contains wide range of lipids. The outer layer of the cell wall is composed of mycosides. (Peptidoglycolipids or Phenolic glycolipids).
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Mycosides are responsible for the control of cellular permeability, resistance to action of water-soluble enzymes, antibiotics and disinfectants.
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Cord factor (Trehalose – 6,6’ dimycolate) and Wax D - inhibits chemotaxis, leukotaxis, responsible for delayed hypersensitivity
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Sulfatides- sulfur containing glycolipids – promote the survival of virulent tubercle bacilli within macrophages by inhibiting phagolysosome formation and avoiding exposure to hydrolytic enzymes present in the lysosomes.
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Virulence appears to reside in the lipids of the cell wall. Mycosides, phospholipids and sulpholipids are protecting the tubercle bacilli against phagocytosis.
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Last modified: Monday, 4 June 2012, 5:00 AM