title: Cryptococcal phospholipase B1 is required for intracellular proliferation and control of titan cell morphology during macrophage infection.
abstract: Cryptococcus neoformans is an opportunistic fungal pathogen and a leading cause of fungal-infection-related fatalities, especially in immunocompromised hosts. Several virulence factors are known to play a major role in the pathogenesis of cryptococcal infections, including the enzyme phospholipase B1 (Plb1). Compared to other well-studied Cryptococcus neoformans virulence factors such as the polysaccharide capsule and melanin production, very little is known about the contribution of Plb1 to cryptococcal virulence. Phospholipase B1 is a phospholipid-modifying enzyme that has been implicated in multiple stages of cryptococcal pathogenesis, including initiation and persistence of pulmonary infection and dissemination to the central nervous system, but the underlying reason for these phenotypes remains unknown. Here we demonstrate that a Δplb1 knockout strain of C. neoformans has a profound defect in intracellular growth within host macrophages. This defect is due to a combination of a 50% decrease in proliferation and a 2-fold increase in cryptococcal killing within the phagosome. In addition, we show for the first time that the Δplb1 strain undergoes a morphological change during in vitro and in vivo intracellular infection, resulting in a subpopulation of very large titan cells, which may arise as a result of the attenuated mutant's inability to cope within the macrophage.
authors.affiliation: Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Evans
authors.affiliation: Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Zhongming
authors.initials: Z
authors.lastname: Li
authors.affiliation: Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham, United Kingdom University of Warwick, Coventry, United Kingdom.
authors.forename: William S
authors.initials: WS
authors.lastname: Hughes
authors.affiliation: Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, Westmead, New South Wales, Australia.
authors.forename: Julianne T
authors.initials: JT
authors.lastname: Djordjevic
authors.affiliation: Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Nielsen
authors.affiliation: Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham, United Kingdom NIHR Surgical Reconstruction and Microbiology Research Centre, University Hospitals of Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom r.c.may@bham.ac.uk.
authors.forename: Robin C
authors.initials: RC
authors.lastname: May
mesh_terms: D000818:Animals; D002460:Cell Line; D003453:Cryptococcosis / Q000276:immunology / Q000382:microbiology / Q000473:pathology*; D003455:Cryptococcus neoformans / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D005260:Female; D005656:Fungal Proteins / Q000235:genetics*; D055786:Gene Knockout Techniques; D008245:Lysophospholipase / Q000235:genetics*; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008805:Mice, Inbred A; D037521:Virulence Factors / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D037521:Virulence Factors; D008245:Lysophospholipase