title: Protection against Experimental Cryptococcosis following Vaccination with Glucan Particles Containing Cryptococcus Alkaline Extracts.
abstract: A vaccine capable of protecting at-risk persons against infections due to Cryptococcus neoformans and Cryptococcus gattii could reduce the substantial global burden of human cryptococcosis. Vaccine development has been hampered though, by lack of knowledge as to which antigens are immunoprotective and the need for an effective vaccine delivery system. We made alkaline extracts from mutant cryptococcal strains that lacked capsule or chitosan. The extracts were then packaged into glucan particles (GPs), which are purified Saccharomyces cerevisiae cell walls composed primarily of β-1,3-glucans. Subcutaneous vaccination with the GP-based vaccines provided significant protection against subsequent pulmonary infection with highly virulent strains of C. neoformans and C. gattii. The alkaline extract derived from the acapsular strain was analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS), and the most abundant proteins were identified. Separation of the alkaline extract by size exclusion chromatography revealed fractions that conferred protection when loaded in GP-based vaccines. Robust Th1- and Th17-biased CD4(+) T cell recall responses were observed in the lungs of vaccinated and infected mice. Thus, our preclinical studies have indicated promising cryptococcal vaccine candidates in alkaline extracts delivered in GPs. Ongoing studies are directed at identifying the individual components of the extracts that confer protection and thus would be promising candidates for a human vaccine.
  
  
  OBJECTIVE
  The encapsulated yeast Cryptococcus neoformans and its closely related sister species, Cryptococcus gattii, are major causes of morbidity and mortality, particularly in immunocompromised persons. This study reports on the preclinical development of vaccines to protect at-risk populations from cryptococcosis. Antigens were extracted from Cryptococcus by treatment with an alkaline solution. The extracted antigens were then packaged into glucan particles, which are hollow yeast cell walls composed mainly of β-glucans. The glucan particle-based vaccines elicited robust T cell immune responses and protected mice from otherwise-lethal challenge with virulent strains of C. neoformans and C. gattii. The technology used for antigen extraction and subsequent loading into the glucan particle delivery system is relatively simple and can be applied to vaccine development against other pathogens.
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA charles.specht@umassmed.edu stuart.levitz@umassmed.edu.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Specht
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Chrono K
authors.initials: CK
authors.lastname: Lee
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Haibin
authors.initials: H
authors.lastname: Huang
authors.affiliation: Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Donald J
authors.identifier: http://orcid.org/0000-0002-2734-5653
authors.initials: DJ
authors.lastname: Tipper
authors.affiliation: Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Zu T
authors.initials: ZT
authors.lastname: Shen
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Lodge
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: John
authors.initials: J
authors.lastname: Leszyk
authors.affiliation: Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Gary R
authors.initials: GR
authors.lastname: Ostroff
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA charles.specht@umassmed.edu stuart.levitz@umassmed.edu.
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Levitz
mesh_terms: D000818:Animals; D000946:Antigens, Fungal / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002850:Chromatography, Gel; D002853:Chromatography, Liquid; D003453:Cryptococcosis / Q000276:immunology / Q000517:prevention & control*; D056285:Cryptococcus gattii / Q000276:immunology*; D003455:Cryptococcus neoformans / Q000276:immunology*; D004195:Disease Models, Animal; D005656:Fungal Proteins / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification; D005657:Fungal Vaccines / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification; D005936:Glucans / Q000008:administration & dosage / Q000276:immunology* / Q000302:isolation & purification; D007279:Injections, Subcutaneous; D008168:Lung / Q000276:immunology; D008810:Mice, Inbred C57BL; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D053719:Tandem Mass Spectrometry; D018417:Th1 Cells / Q000276:immunology; D058504:Th17 Cells / Q000276:immunology; D016896:Treatment Outcome; D014611:Vaccination / Q000379:methods
chemical_list: D000946:Antigens, Fungal; D005656:Fungal Proteins; D005657:Fungal Vaccines; D005936:Glucans