Engineered HSP90-MP65 Bivalent Fusion Antigen: A Novel Vaccine Candidate Against Invasive Candidiasis.

Invasive candidiasis represents a critical global health challenge, causing approximately 6.5 million bloodstream infections annually with mortality rates exceeding 60%. The emergence of multidrug-resistant Candida strains necessitates novel prophylactic strategies, with subunit vaccines offering a rational alternative to conventional antifungals. This study presents a structure-guided approach to engineer a novel, optimized HSP90-MP65 bivalent fusion protein as a vaccine candidate against invasive candidiasis. The central hypothesis posits that direct genetic fusion of the immunostimulatory HSP90 domain to the MP65 mannoprotein antigen creates a bifunctional molecule with enhanced antigen processing and presentation properties compared to co-administration of separate components. An integrative computational framework combining deep learning-based structure prediction, consensus B-cell and T-cell epitope mapping, rational sequence optimization (ProteinMPNN), and comprehensive biophysical characterization was employed to design multiple fusion constructs and systematically evaluate their structural integrity, conformational stability, aggregation propensity, and immunogenic potential. As a result, the most promising, rationally designed lead candidate has been designed and comprehensively optimized. The lead candidate combines superior thermodynamic preserved epitope accessibility while preserving all immunogenic features. Molecular docking and binding affinity predictions confirm maintained interactions with pattern recognition receptors and MHC molecules. This structure-based engineering approach yielded a manufacturable fusion antigen with preserved immunostimulatory domains, providing a molecular blueprint for bivalent vaccine development against fungal pathogens.