Establishment of protective immunity against cerebral cryptococcosis by means of an avirulent, non melanogenic Cryptococcus neoformans strain

J Neuroimmunol. 2000 Sep 22;109(2):75-86. doi: 10.1016/s0165-5728(00)00319-2.


The opportunistic fungal pathogen, Cryptococcus neoformans, shows a marked predilection for the central nervous system (CNS). This can be partially explained by its ability to synthesize melanin starting from the catecholamines, highly concentrated at the CNS level. Two cryptococcal strains, the avirulent non-melanogenic strain Sb26 and the virulent melanogenic revertant strain Sb26Rev, were used in a murine model of intracerebral (i.c.) infection, in order to evaluate their virulence and immunomodulating properties at the cerebral level. We found that, unlike Sb26Rev, Sb26 i.c. infection was never lethal regardless of the challenging dose. Sb26Rev infection resulted in massive CNS tissue damage, associated with little or no cytokine response, as established by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). Differently, Sb26 infection failed to alter CNS structure, while inducing IL-12 p40, TNF-alpha, IL-1beta, IFN-gamma and iNOS specific-gene expression as well as IL-12, TNF-alpha and IL-1beta cytokine production. Interestingly, all Sb26 infected mice survived a subsequent lethal challenge with Sb26Rev. The phenomenon was associated with enhanced IL-12, TNF-alpha and IL-1beta production and was strictly specific, as shown by heterologous challenges and delayed type of hypersensitivity assay. Overall, we provide evidence that protective immunity against cerebral cryptococcosis is established by means of an avirulent strain of C. neoformans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / chemistry
  • Astrocytes / immunology
  • Brain Diseases / immunology*
  • Brain Diseases / microbiology*
  • Cryptococcosis / immunology*
  • Cryptococcus neoformans / immunology
  • Cryptococcus neoformans / metabolism
  • Cryptococcus neoformans / pathogenicity*
  • Female
  • Gene Expression / immunology
  • Glial Fibrillary Acidic Protein / analysis
  • Hypersensitivity, Delayed / immunology
  • Hypersensitivity, Delayed / microbiology
  • Interleukin-1 / genetics
  • Interleukin-12 / genetics
  • Lectins
  • Melanins / biosynthesis
  • Mice
  • Mice, Inbred C57BL
  • Microglia / immunology
  • Tumor Necrosis Factor-alpha / genetics
  • Virulence


  • Glial Fibrillary Acidic Protein
  • Interleukin-1
  • Lectins
  • Melanins
  • Tumor Necrosis Factor-alpha
  • Interleukin-12