Match each medically important fungal pathogen with its primary morphologic or biochemical mechanism for evading host immune defenses.
- Cryptococcus neoformansElaboration of a thick polysaccharide capsule that acts as an antiphagocytic shield and depletes complement
- Candida albicansMorphologic transition from blastoconidia to hyphae, facilitating tissue invasion and macrophage escape
- Histoplasma capsulatumIntracellular survival and replication within non-activated macrophages by regulating phagosomal pH
- Coccidioides immitisDevelopment of large spherules in host tissue that restrict phagocytosis and release hundreds of endospores
- Aspergillus fumigatusProduction of gliotoxin, which impairs ciliary function, induces apoptosis of phagocytes, and suppresses T-cell activation
Answer
The correct matches pair Cryptococcus with its antiphagocytic capsule, Candida with its yeast-to-hyphae transition, Histoplasma with intracellular macrophage survival, Coccidioides with spherule formation, and Aspergillus with gliotoxin production.
Fungal pathogens have evolved distinct molecular and morphologic strategies to evade the human immune system. Cryptococcus neoformans is protected by a massive polysaccharide capsule. Candida albicans evades clearance by quickly switching from yeast to hyphal forms to escape macrophages. Histoplasma capsulatum thrives inside macrophages, effectively hiding from cell-mediated immunity until an adequate Th1 response is mounted. Coccidioides immitis forms large spherules that are physically impossible for macrophages to engulf. Finally, Aspergillus fumigatus secretes gliotoxin, a powerful secondary metabolite that directly induces apoptosis in host neutrophils and macrophages.
Step-by-Step Solution
Key Concept
Fungal virulence factors and immune evasion strategies