- A It is sometimes thought to have few antigens to detect, despite mycobacterial cell wall lipids being readily detected by macrophage pattern recognition receptors under typical conditions according to standard textbooks
- B It inhibits phagosome-lysosome fusion in macrophages, allowing it to survive and replicate inside the phagosome; it also recruits epithelial cells to form granulomas where it persists in latency
- C It is sometimes thought to release antibiotics that would actively kill competing bacteria, rather than inhibiting host phagosome-lysosome fusion as it really does in general practice as frequently described
- D It is sometimes thought to grow mainly in blood, not cells, when it instead survives and actively replicates specifically inside resident macrophage phagosomes in most textbook accounts during normal conditions
Correct answer: B. It inhibits phagosome-lysosome fusion in macrophages, allowing it to survive and replicate inside the phagosome; it also recruits epithelial cells to form granulomas where it persists in latency
Explanation: M. tuberculosis has evolved multiple evasion strategies: (1) Inhibits phagosome maturation and acidification (blocking fusion with lysosome) using SecA2, lipoarabinomannan; (2) Scavenges reactive oxygen species; (3) Escapes to cytoplasm in some cells; (4) Induces granuloma formation where it can persist for decades in latency.
Concept context
Innate and adaptive immunity, B cells, T cells, antibodies, vaccines, and immune disorders. Critical for NEET.