Growth and airborne transmission of cell-sorted life cycle stages of Pneumocystis carinii

PLoS One. 2013 Nov 6;8(11):e79958. doi: 10.1371/journal.pone.0079958. eCollection 2013.


Pneumocystis organisms are airborne opportunistic pathogens that cannot be continuously grown in culture. Consequently, the follow-up of Pneumocystis stage-to-stage differentiation, the sequence of their multiplication processes as well as formal identification of the transmitted form have remained elusive. The successful high-speed cell sorting of trophic and cystic forms is paving the way for the elucidation of the complex Pneumocystis life cycle. The growth of each sorted Pneumocystis stage population was followed up independently both in nude rats and in vitro. In addition, by setting up a novel nude rat model, we attempted to delineate which cystic and/or trophic forms can be naturally aerially transmitted from host to host. The results showed that in axenic culture, cystic forms can differentiate into trophic forms, whereas trophic forms are unable to evolve into cystic forms. In contrast, nude rats inoculated with pure trophic forms are able to produce cystic forms and vice versa. Transmission experiments indicated that 12 h of contact between seeder and recipient nude rats was sufficient for cystic forms to be aerially transmitted. In conclusion, trophic- to cystic-form transition is a key step in the proliferation of Pneumocystis microfungi because the cystic forms (but not the trophic forms) can be transmitted by aerial route from host to host.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Air Microbiology
  • Animals
  • Pneumocystis Infections / microbiology
  • Pneumocystis Infections / transmission*
  • Pneumocystis carinii / pathogenicity*
  • Rats
  • Rats, Nude

Grant support

This work was supported by ANR-ERA-NET ‘Pneumocystis’ PathoGenoMics (ANR-06-PATHO-009-01). We also thank the Lille-Nord-de-France University, the Pasteur Institute of Lille and the microscopy and flow cytometry platform of the BioImaging Center of Lille Nord de France (BiCeL, IFR142) for their support. The funders (ANR-ERA-NET, Lille Nord de France University and Pasteur Institute of Lille) had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.