Analysis of Pneumocystis carinii Cyst Wall I. Evidence for an Outer Surface Membrane

JAMIE A. De STEFANO, MELANIE T. CUSHION, RICHARD G. SLEIGHT, PETER D. WALZER

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33 Scopus citations

Abstract

ABSTRACT. It has long been thought that the cyst form of Pneumocystis carinii, which can resist host defenses and antimicrobial drugs, is responsible for relapses of P. carinii pneumonia. The thick wall of the cyst is immunogenic and rich in glucosyl/mannosyl and N‐acetyl‐D‐glucosamine residues. In this study we have demonstrated the presence of a hitherto unreported outer membrane in the cyst wall of P. carinii. This membrane was detected by a combination of techniques, including transmission electron microscopy, freeze‐fracture electron microscopy, and membrane labeling with fluorescent lipid analogs following treatment of P. carinii cysts from infected rats for 30 min with Zymolyase, a β‐1–3 glucanase. As in gram‐negative bacteria and blue‐green algae, this 2nd membrane may have an important role in osmoregulation and nutrient utilization; it may also mediate the interaction of P. carinii with its host and serve as a target for drug therapy.

Original languageEnglish (US)
Pages (from-to)428-435
Number of pages8
JournalThe Journal of Protozoology
Volume37
Issue number5
DOIs
StatePublished - Jan 1 1990
Externally publishedYes

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Keywords

  • AIDS
  • Pneumocystis carinii pneumonia
  • immunosuppression
  • outer membrane

ASJC Scopus subject areas

  • Parasitology

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