Leishmania donovani evades intracellular killing inside macrophages primarily by which mechanism?

• A Escaping from the phagosome into the cytosol before fusion with lysosomes
• B Producing catalase to neutralize H2O2 in the phagolysosome
• C Inducing apoptosis of the macrophage to escape before killing occurs
• D Inhibiting phagosome-lysosome fusion and surviving low pH through surface LPG-mediated inactivation of protein kinase C ✓

Explanation

Leishmania amastigotes reside in the parasitophorous vacuole (phagolysosomes) but resist killing because the surface glycoconjugate lipophosphoglycan (LPG) inhibits protein kinase C, impairs the oxidative burst, and scavenges reactive oxygen species. Additionally, the parasite surface metalloprotease GP63 inactivates complement C3b to iC3b, promoting CR3-mediated entry that generates weaker killing signals than FcγR-mediated phagocytosis.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.