title: Reintroduction of the PLB1 gene into Candida albicans restores virulence in vivo.
abstract: Phospholipases have been proposed to contribute to the virulence of Candida albicans. Recently, a candidal strain deleted for PLB1, the gene encoding the predominant phospholipase B (Plb1) secreted by C. albicans, was constructed and its virulence in an intravenous murine model of disseminated candidiasis was evaluated. In the present study, the PLB1 gene was reintroduced back into the plb1 null mutant to generate the revertant strain, which showed similar growth and morphology to its isogenic parent strain. Virulence of the revertant strain was found to be comparable to that of the parent strain in an intravenous murine model of disseminated candidiasis. To compare the abilities of the plb1 null mutant, the revertant and the isogenic parent strains to cross the gastrointestinal (GI) tract and cause systemic infection, an oral-intragastric infant mouse model of candidiasis was used. Histological examinations and analysis of c.f.u. of the pathogen in liver homogenates revealed that the parental and revertant strains were able to invade and traverse the GI mucosa to a significantly greater extent than the plb1 null mutant. Immunofluorescence and immunoelectron microscopic studies of infected host tissue using anti-Plb1 antibody showed that Plb1 is secreted during invasion of the gastric mucosa by the parental and revertant strains. In contrast, little or no labelling was observed in the null mutant strain. The results indicate that the Plb1 secreted by C. albicans enhances the ability of this organism to cross the GI tract and disseminate haematogenously. These studies provide unequivocal evidence supporting a role for Plb1 during the course of infection by C. albicans.
authors.affiliation: Center for Medical Mycology, University Hospitals of Cleveland and Department of Dermatology, Case Western Reserve University, Cleveland, OH 44106-5028, USA1.
authors.forename: Pranab K
authors.initials: PK
authors.lastname: Mukherjee
authors.affiliation: Department of Microbiology and Immunology, Medical College of Ohio, Toledo, OH 43614-5806, USA2.
authors.forename: K R
authors.initials: KR
authors.lastname: Seshan
authors.affiliation: Center for Medical Mycology, University Hospitals of Cleveland and Department of Dermatology, Case Western Reserve University, Cleveland, OH 44106-5028, USA1.
authors.forename: S D
authors.initials: SD
authors.lastname: Leidich
authors.affiliation: Center for Medical Mycology, University Hospitals of Cleveland and Department of Dermatology, Case Western Reserve University, Cleveland, OH 44106-5028, USA1.
authors.forename: Jyotsna
authors.initials: J
authors.lastname: Chandra
authors.affiliation: Department of Microbiology and Immunology, Medical College of Ohio, Toledo, OH 43614-5806, USA2.
authors.forename: Garry T
authors.initials: GT
authors.lastname: Cole
authors.affiliation: Center for Medical Mycology, University Hospitals of Cleveland and Department of Dermatology, Case Western Reserve University, Cleveland, OH 44106-5028, USA1.
authors.forename: Mahmoud A
authors.initials: MA
authors.lastname: Ghannoum
mesh_terms: D000818:Animals; D002176:Candida albicans / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity*; D002177:Candidiasis / Q000209:etiology / Q000473:pathology; D004195:Disease Models, Animal; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005753:Gastric Mucosa / Q000382:microbiology / Q000473:pathology; D005800:Genes, Fungal; D006801:Humans; D008099:Liver / Q000382:microbiology / Q000473:pathology; D008245:Lysophospholipase / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008854:Microscopy, Electron; D009154:Mutation; D014774:Virulence / Q000235:genetics
chemical_list: D005656:Fungal Proteins; C490271:PLB1 protein, Candida albicans; D008245:Lysophospholipase