Cryptococcus and Beyond—Inositol Utilization and Its Implications for the Emergence of Fungal Virulence

There are over one million fungal species in nature, but only a handful of them cause human diseases. A variety of distinct factors aid the virulence of fungi in their transition from environmental reservoirs to mammals. One important factor is their ability to acquire nutrients efficiently so that they can survive and thrive in a nutrient-limiting host environment. The human fungal pathogen Cryptococcus neoformans (C. neoformans) is the most common cause of fungal meningitis, yet the mechanisms of Cryptococcus neurotropism remain poorly understood. Recent studies have revealed that Cryptococcus has evolved sophisticated acquisition systems to utilize the carbohydrate inositol both in plant niches and in human brains, where abundant inositol is available. Inositol utilization in Cryptococcus and its likely contribution to Cryptococcus virulence may represent one example of a common trait for the emergence of pathogens from environmental reservoirs.