Epitope mapping Candida albicans proteinase (SAP 2)

Area of Science:

• Immunology
• Microbiology
• Infectious Diseases

Background:

• Candida albicans is a major cause of invasive fungal infections.
• Understanding host immune responses to Candida antigens is crucial for developing diagnostics and therapeutics.
• SAP2 is a secreted aspartic proteinase virulence factor of Candida albicans.

Purpose of the Study:

• To identify continuous B-cell epitopes on Candida albicans SAP2 protein.
• To investigate the antibody response against these epitopes in patients with various Candida infections.
• To assess the potential of these epitopes as biomarkers for candidiasis.

Main Methods:

• Epitope mapping using sera from patients with oral, disseminated, and recovered candidiasis.
• Indirect ELISA to confirm peptide reactivity.
• Analysis of antibody levels (IgM and IgG) against identified epitopes.
• Evaluation of antibody activity in a lethal mouse model of candidal infection.

Main Results:

• Continuous epitopes on SAP2 were identified for IgM and IgG in Candida albicans infections.
• Specific epitopes were also identified for Candida tropicalis and Candida parapsilosis infections.
• IgM antibodies against two specific peptides (KTSKRQAVPVTL and SLAQVKYTSASSI) were associated with survival in recovered disseminated candidiasis patients.
• IgG antibody levels were generally disappointing, and human recombinant antibodies showed no protective effect in a mouse model.

Conclusions:

• Specific B-cell epitopes on Candida albicans SAP2 can elicit differential antibody responses in patients.
• IgM responses to certain SAP2-derived peptides may serve as potential indicators of survival in disseminated candidiasis.
• Further research is needed to explore the therapeutic potential of targeting these epitopes.