Stealth and opportunism: alternative lifestyles of species in the fungal genus Pneumocystis.
Pneumocystis species are ascomycetous fungi that obligatorily dwell with no apparent ill effect in the lungs of normal mammals, but they become pathogenic when host defenses are compromised. Identified more than 100 years ago, these atypical fungi manifest characteristics that are unique within the Fungi, such as the lack of ergosterol, genetic complexity of surface antigens, and antigenic variation. Thought to be confined to the severely immunocompromised host, Pneumocystis spp. are being associated with new population niches owing to the advent of immunomodulatory therapies and increased numbers of patients suffering from chronic diseases. The inability to grow Pneumocystis spp. outside the mammalian lung has thwarted progress toward understanding their basic biology, but via the use of new genetic tools and other strategies, researchers are beginning to uncover their biological and genetic characteristics including a biphasic life cycle, significant metabolic capacities, and modulation of lifestyles.
Cushion
Melanie T
MT
Department of Internal Medicine, University of Cincinnati College of Medicine, Division of Infectious Diseases, Cincinnati, Ohio 45267-0560, USA.
Stringer
James R
JR
D000818:Animals; D015825:Chromosomes, Fungal; D002908:Chronic Disease; D005656:Fungal Proteins / Q000096:biosynthesis / Q000276:immunology; D023061:Gene Order; D005800:Genes, Fungal; D006801:Humans; D016867:Immunocompromised Host; D007155:Immunologic Factors / Q000009:adverse effects / Q000627:therapeutic use; D008168:Lung / Q000382:microbiology; D008322:Mammals; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000276:immunology; D011010:Pneumocystis / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity / Q000502:physiology*; D011020:Pneumonia, Pneumocystis / Q000139:chemically induced; D026801:Synteny
D005656:Fungal Proteins; D007155:Immunologic Factors; D008562:Membrane Glycoproteins