Biosynthesis and Immunogenicity of Glucosylceramide inCryptococcus neoformansand Other Human Pathogens

Cryptococcus species are encapsulated basidiomycetous yeasts found ubiquitously in the environment, notably in pigeon guano and eucalyptus trees. Two species of this genus, Cryptococcus neoformans and Cryptococcus gattii, are human pathogens capable of causing a life-threatening meningoencephalitis. Currently, C. neoformans is divided into the varieties Cryptococcus neoformans var. grubii (serotype A) and Cryptococcus neoformans var. neoformans (serotype D), and C. gattii comprises serotypes B and C (47). Infection occurs primarily during environmental exposure via inhalation of either desiccated yeast or basidiospores. In the alveolar spaces of lungs, the fungus is initially exposed to alveolar macrophages followed by other inflammatory cells, which can lead to a successful adaptive immune response and containment or clearance of the fungal pathogen. However, C. neoformans and C. gattii can survive and proliferate in the human host, leading to dissemination to other organs, most importantly to the central nervous system, where meningoencephalitis can develop, with 100% mortality if untreated.