Is a Dispensable Gene for Viability but Required for Proper Interaction with the Host.

Candidemia is an opportunistic mycosis with high morbidity and mortality rates. Even though is the main causative agent, other species, such as , are relevant etiological agents of candidiasis and candidemia. Compared with , there is currently limited information about biological aspects, including those related to the cell wall and the interaction with the host. Currently, it is known that its cell wall contains -linked mannans, and the contribution of these structures to cell fitness has previously been addressed using cells subjected to chemical treatments or in mutants where -linked mannans and other wall components are affected. Here, we generated a ∆ null mutant, which was affected in the first step of the -linked mannosylation pathway. The null mutant was viable, contrasting with where this gene is essential. The phenotypical characterization showed that -linked mannans were required for filamentation; proper cell wall integrity and organization; biofilm formation; protein secretion; and adhesion to extracellular matrix components, in particular to fibronectin; and type I and type II collagen. When interacting with human innate immune cells, it was found that this cell wall structure is dispensable for cytokine production, but mutant cells were more phagocytosed by monocyte-derived macrophages. Furthermore, the null mutant cells showed virulence attenuation in larvae. Thus, -linked mannans are minor components of the cell wall that are involved in different aspects of ' biology.