Papel de los cambios morfológicos en la virulencia de "Cryptococcus neoformans"

Abstract

Cryptococcosisis is an infectious disease caused by yeasts from the gender Cryptococcus, being C. neoformans and C. gattii the species more offenly isolated. Cryptococcus neoformans is a cosmopolitan environmental pathogen of major concern among HIV patients which has a significant incidence in developing areas. Cryptococcus neoformans blastoconidia or desiccated spores are inhaled and can cause pneumonia and meningitis in immunosuppressed individuals. Its sibling species, Cryptococcus gattii, is more restricted to tropical areas and infects principally immunocompetent individuals and causes mainly pneumonia. Cryptococcus interaction with the host has been widely studied for its capacity to modulate the immune response, replicate within macrophages, disseminate from the lungs to the central nervous system, and/or stay in a latent state for years. The main cryptococcal virulence factors are a polysaccharide capsule and melanin accumulation, although this yeast has also other traits, such as urease and phospholipases that confer adaptation to the host. Morphogenesis is a common feature among fungal pathogens. Cryptococcus neoformans does not form filaments nor pseudohyphae. However, during infection, this yeast undergoes cellular changes which result in the appearance of different cellular types. These changes are: 1) Capsule enlargement; and 2) Significant growth of the whole cell, which leads to the formation of “Giant/Titan” cells. However, the molecular mechanisms involved in the regulation of these processes are not known...