Members of the fungal genus Pneumocystis can cause a lethal pneumonia (PCP) in hosts with debilitated immune systems, such as HIV-infected persons with AIDS;patients undergoing immunosuppressive therapy;and more recently in those patients received targeted immunotherapy. The manner in which the infection is disseminated;the life cycle within the mammalian lung;and the strategies used for survival within this inhospitable environment are largely unknown due in large part to the lack of a continuous cultivation method. It is our long term goal to understand the infection process of Pneumocystis as a means to identify its survival strategies which could then be exploited for interdiction of infection. Production of biofilms is a strategy used by many microbes for protection against environmental assaults;for communication and differentiation among members;and as foci for dissemination. We posit that the attachment and growth of Pneumocystis within the lung alveoli is akin to biofilm formation. An in vitro system was identified that supports apparent biofilm formation by P. carinii (from rat) and P. murina (from mouse). The biofilms showed similar growth kinetics, confocal attributes, and morphological changes compatible with biofilm formation by other fungi. In the present proposal, this system will be optimized to provide a novel tool for understanding the survival strategies of Pneumocystis and then will be used to address questions about the biology of the process. The following specific aims are proposed: (1) Define and characterize the optimal conditions for formation of Pneumocystis biofilms. A systematic approach will be used to evaluate matrices, conditions, and additives leading to robust biofilm formation. Microscopic and quantitative methods will be used to chart the progression of biofilm formation. (2) Identify the biological process associated with biofilm formation. The morphologic changes Pneumocystis undergoes as it forms a biofilm are dramatic. Identification and verification of the genes and gene products involved in the progression using molecular and biochemical methods will provide basic information on the biology of biofilm production and lead to a new appreciation and understanding of this process. (3) Assess the pathogenicity of in vitro biofilms in vivo. The progression of infection initiated by biofilm-derived organisms vs. the standard model will be compared by microscopic and quantitative methods. The in vivo morphology and gene expression will compared to in vitro biofilms for validation of the in vitro system. Optimization and evaluation of the biofilm process will fundamentally advance the study of Pneumocystis.

Public Health Relevance

Microbial pathogens use biofilms to escape the infected host's immune defenses and antimicrobial therapy. We identified a biofilm system for the fungal pathogen, Pneumocystis, that will be used to understand the strategies it employs to survive in the lung and cause pneumonia.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
AIDS-associated Opportunistic Infections and Cancer Study Section (AOIC)
Program Officer
Duncan, Rory A
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Cincinnati
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
Linke, Michael J; Ashbaugh, Alan; Collins, Margaret S et al. (2013) Characterization of a distinct host response profile to Pneumocystis murina asci during clearance of pneumocystis pneumonia. Infect Immun 81:984-95
Porollo, Aleksey; Meller, Jaroslaw; Joshi, Yogesh et al. (2012) Analysis of current antifungal agents and their targets within the Pneumocystis carinii genome. Curr Drug Targets 13:1575-85
Maciejewska, Dorota; Zabinski, Jerzy; Kazmierczak, Pawel et al. (2012) Analogs of pentamidine as potential anti-Pneumocystis chemotherapeutics. Eur J Med Chem 48:164-73
Cushion, Melanie T; Collins, Margaret S (2011) Susceptibility of Pneumocystis to echinocandins in suspension and biofilm cultures. Antimicrob Agents Chemother 55:4513-8
Cushion, Melanie T; Linke, Michael J; Ashbaugh, Alan et al. (2010) Echinocandin treatment of pneumocystis pneumonia in rodent models depletes cysts leaving trophic burdens that cannot transmit the infection. PLoS One 5:e8524
Cushion, Melanie T (2010) Are members of the fungal genus pneumocystis (a) commensals; (b) opportunists; (c) pathogens; or (d) all of the above? PLoS Pathog 6:e1001009
Joffrion, Tiffany M; Collins, Margaret S; Sesterhenn, Thomas et al. (2010) Functional characterization and localization of Pneumocystis carinii lanosterol synthase. Eukaryot Cell 9:107-15
Beck, James M; Cushion, Melanie T (2009) Pneumocystis workshop: 10th anniversary summary. Eukaryot Cell 8:446-60
Vale, Nuno; PrudĂȘncio, Miguel; Marques, Catarina A et al. (2009) Imidazoquines as antimalarial and antipneumocystis agents. J Med Chem 52:7800-7
Cushion, Melanie T; Collins, Margaret S; Linke, Michael J (2009) Biofilm formation by Pneumocystis spp. Eukaryot Cell 8:197-206

Showing the most recent 10 out of 11 publications