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Antigenic variation in pneumocystis

James R Stringer1

  • 1Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio 45267-0524, USA. stringjr@ucmail.uc.edu

The Journal of Eukaryotic Microbiology
|February 16, 2007
PubMed

Insights

Pneumocystis fungi evade host immunity through antigenic variation. In Pneumocystis carinii, the major surface glycoprotein gene family undergoes recombination, likely via gene conversion, to alter surface proteins and evade detection.

Area of Science:

  • Mycology
  • Immunology
  • Molecular Biology

Background:

  • Pneumocystis fungi are host-specific and non-culturable.
  • Pneumocystis pneumonia (PCP) affects immunocompromised individuals.
  • Fungal survival in immunocompetent hosts may involve immune evasion strategies.

Purpose of the Study:

  • To investigate the mechanisms of immune evasion in Pneumocystis.
  • To explore the role of antigenic variation in Pneumocystis carinii.

Main Methods:

  • Analysis of gene families encoding the major surface glycoprotein (MSG) in P. carinii.
  • Investigation of gene expression control and recombination mechanisms.

Main Results:

  • P. carinii possesses nearly 100 MSG genes for antigenic variation.
  • MSG gene expression is regulated by a unique transcription-linked expression site.
  • Recombination between MSG genes, potentially through gene conversion, alters expressed surface proteins.

Conclusions:

  • Antigenic variation via MSG gene recombination is a key survival strategy for Pneumocystis in immunocompetent hosts.
  • Gene conversion is the likely mechanism driving sequence changes in the expressed MSG gene.

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