The success of Histoplasma capsulatum as an intracellular pathogen depends
completely on successful conversion of the saprophytic mycelial (mold) form
of this fungus to a parasitic yeast form. It is therefore not surprising t
hat yeast phase-specific genes and gene products are proving to be importan
t for survival and proliferation of H. capsulatum within macrophages. In th
is study, we have focused on the role and regulation of two yeast-specific
characteristics: alpha-(1,3)-glucan, a cell wall polysaccharide modulated b
y cell-density (quorum) sensing, and a secreted calcium-binding protein (CB
P) that is essential for pathogenicity.