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Updated: Dec 31, 2025

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Published on: December 2, 2022
Pyrifenox, an ergosterol inhibitor, differentially affects Cryptococcus neoformans and Cryptococcus gattii
Vanessa K A Silva1, Robin C May2, Marcio L Rodrigues3,4
1Programa de Pós-Graduação em Biologia Parasitária, Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil.
Pyrifenox inhibits fungal growth and capsule export in Cryptococcus, but is less effective against Cryptococcus gattii due to efflux pumps. This study explores pyrifenox as a potential antifungal agent.
Area of Science:
- Mycology
- Infectious Diseases
- Drug Discovery
Background:
- Cryptococcosis is a severe fungal infection with limited treatment options.
- Current therapies for cryptococcosis are costly and cause adverse effects.
- Pyrifenox, an ergosterol biosynthesis inhibitor, shows potential as a novel antifungal.
Purpose of the Study:
- To investigate the efficacy of pyrifenox against Cryptococcus neoformans and Cryptococcus gattii.
- To analyze pyrifenox's impact on fungal growth, capsule structure, and glucuroxylomannan (GXM) export.
- To elucidate the mechanisms of pyrifenox resistance in Cryptococcus species.
Main Methods:
- Growth inhibition assays for C. neoformans and C. gattii.
- Gene expression analysis of efflux pump genes (AFR1, AFR2).
- Microscopic analysis (India ink, immunofluorescence, SEM) of cryptococcal capsules and GXM export.
Main Results:
- Pyrifenox inhibited C. neoformans growth but was less effective against C. gattii.
- C. gattii resistance was linked to efflux pump genes AFR1 and AFR2.
- Pyrifenox altered capsule architecture and reduced GXM secretion in both species.
- Pyrifenox treatment led to cell chain formation in C. gattii.
Conclusions:
- Pyrifenox exhibits differential effects on C. neoformans and C. gattii.
- Efflux pumps play a role in C. gattii resistance to pyrifenox.
- Pyrifenox shows potential as an inhibitor of GXM export in pathogenic cryptococci.
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