Cryptococcus neoformans and Cryptococcus gattii genes preferentially expressed during rat macrophage infection.

Cryptococcus neoformans and Cryptococcus gattii are encapsulated yeast agents of cryptococcosis and facultative intracellular pathogens. The interaction of these yeasts with macrophages is essential for containing the infection. However, Cryptococcus spp. overcome this initial host defense barrier using a unique pathogenic strategy involving intracellular replication and cytoplasmic accumulation of polysaccharide-containing vesicles. Here, we employed representational difference analysis (RDA) to identify C. neoformans and C. gattii genes differentially expressed during intracellular growth in rat peritoneal macrophages. The upregulated transcripts of C. neoformans during macrophage interaction were related to ATP-binding cassette (ABC) transporters, intra-golgi transport, chaperone activity, ribosomal maintenance, NAD metabolism, histone methylation, stress response, and monosaccharide metabolism. In contrast, with C. gattii, upregulated genes were associated with cell growth, aerobic respiration, protein binding, microtubule nucleation, monosaccharides and nitrogen metabolism, inositol or phosphatidylinositol phosphatase activity, cellular signaling, and stress response. Our findings reveal new genes that may be necessary for the intracellular parasitism of C. neoformans and C. gattii.