Coccidioides immitis antigens

Coccidioides immitis antigens are immunogenic components derived from the dimorphic fungal pathogen Coccidioides immitis, responsible for coccidioidomycosis (Valley Fever), including key proteins like the 19-kDa CS-Ag serine proteinase from the saprobic phase and SOWgp glycoproteins (58-82 kDa) from parasitic spherules. These antigens elicit both humoral and cellular immune responses, particularly T-cell mediated delayed-type hypersensitivity, where they are presented by MHC class I/II molecules to CD4+ and CD8+ T cells, triggering cytokine release and immune activation essential for controlling infection. In disease, they play roles in host-pathogen interaction, with high antibody titers or T-cell reactivity used for diagnosis via serology, PCR, or skin testing. Specific antigens like Ag2 are major T-cell-reactive wall components, while molecular markers based on genes such as csa, SOWgp82, and Ag2/PRA enable sensitive detection. Therapeutically, they are exploited in diagnostic skin tests like Coccidioides immitis spherule antigen rather than as direct drug targets, aiding in hypersensitivity detection for infection assessment. Challenges include genetic variability among isolates potentially affecting diagnostic accuracy and the need for validation across regions.

Other names

Coccidioides-specific antigen (CS-Ag)SOWgp (spherule outer wall glycoprotein)Ag2 (antigen 2)19-kDa serine proteinase antigen

Delayed-type hypersensitivity reaction via presentation to CD4/CD8 T cells, leading to cytokine secretion, vascular permeability, and induration