Cryptococcal genotype influences immunologic response and human clinical outcome after meningitis

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Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans
08:24

Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans

Published on: February 27, 2018

Darin L Wiesner1, Oleksandr Moskalenko, Jennifer M Corcoran

  • 1Department of Microbiology, Medical School, University of Minnesota, Minneapolis, Minnesota, USA.

Mbio
|September 28, 2012
PubMed
Abstract

Insights

Cryptococcal meningitis (CM) in AIDS patients is linked to fungal strain variations. Specific genotypes, like Burst group 1, are associated with higher mortality and distinct immune responses, suggesting genotype impacts disease outcomes.

Area of Science:

  • Mycology
  • Infectious Diseases
  • Immunology

Background:

  • Cryptococcal meningitis (CM) is a leading cause of death in individuals with AIDS, particularly in sub-Saharan Africa.
  • While virulence factors are known, the influence of Cryptococcus neoformans strain genotype on disease progression and patient outcomes remains unclear.

Purpose of the Study:

  • To investigate the association between Cryptococcus neoformans strain genotypes and clinical outcomes in Ugandan patients with AIDS and CM.
  • To understand how fungal strain variation influences host immune responses and mortality risk.

Main Methods:

  • Analysis of 140 Cryptococcus isolates from 111 Ugandan patients with AIDS and CM.
  • Multilocus sequence typing (MLST) to characterize fungal genotypes.
  • Phylogenetic and in vitro assays (e.g., capsule shedding, cytokine release) to assess strain-specific virulence and immune responses.

Main Results:

  • Identified 15 sequence types and 4 clonal clusters among the isolates, with 107 Cryptococcus neoformans var. grubii and 8 hybrid strains.
  • Patient mortality was significantly associated with different evolutionary groups (P = 0.04), with highest mortality in Burst group 1, Burst group 2, and hybrid strains.
  • Burst group 1 strains showed higher mortality (P = 0.02), increased capsule shedding (P = 0.02), and a more pronounced Th2 immune response (P = 0.02) compared to Burst group 3.

Conclusions:

  • Cryptococcal strain genotype is a significant determinant of human immune responses and mortality in CM.
  • Understanding strain variation can help predict disease outcomes and guide the development of targeted treatment strategies.
  • Genotypic information may lead to improved management of cryptococcal infections in HIV-infected individuals.

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