PHOSPHOMANNAN AS A VACCINE CANDIDATE

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During the current MRU funding period, we established that a vaccine comprised of Candida albicans phosphomannan complex (PMC) material encapsulated into liposomes induced a protective response in mice against disseminated candidiasis. The protection appeared due to serum antibodies and a monoclonal antibody specific for a beta-1,2-mannotriose in the PMC was protective. We will aggressive pursue these observations by testing two working hypotheses. 1. The liposomal vaccine can be improved by utilizing a stabilized form of liposomes and/or eliminating the liposomal part of the vaccine by making mannan-protein conjugates. 2. A DNA vaccine that encodes peptides that mimic the critical or "protective" mannan epitopes ("peptide mimetics" or "mimotopes"), can be constructed. These new approaches give great potential for vast improvements in the vaccine effectiveness because additional components, such as Candida cell wall proteins (provided by the Edwards and Mitchell labs) may be incorporated. The hypotheses will be tested by the following specific aims: 1. Utilize stabilized liposomal constructs to improve the liposomal vaccine formulation. Protective epitopes will be covalently linked to the surface of polymerized liposomes that are stable for years. This is a novel approach, but the chemistry expertise of Dr. Jon Nagy ensures that the liposomes may be quickly and appropriately modified as needed. 2. Construct protein conjugates of the critical mannan epitopes. The mannans will be coupled to an appropriate carrier protein. This approach will allow us to exploit the use of a wide selection of Candida cell wall protein that will be supplied though the Edwards and Mitchell labs. 3. Construct a DNA vaccine based on peptide mimotopes. Candidate peptides that mimic protective mannan epitopes are being identified in our laboratory. We will clone genes the encode mimotopes into an appropriate eukaryotic expression vector and determine if vaccinated mice taking antibodies to the mimotopes and are protected against candidiasis. Additionally, peptide mimotopes fused to candida cell wall protein that will be supplied through the work of the Edwards and Mitchell laboratories will be made part of a mouse major lysosomal glycoprotein (lgp-A or LAMP-1) for diversion into an MHC class II antigen processing compartment. The expertise of Dr. Bruce Granger ensures the expeditious making of variations of DNA constructs.