Mimotope Conversion of HIV-1 Carbohydrate Antigens

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Carbohydrate antigens have been the basis for eliciting protective immune responses against many pathogens, yet this approach has not been adequately assessed in HIV research. Anti- carbohydrate antibodies may facilitate the inhibition of infected cell binding to dendritic cells on mucosa to thwart early infection. We have developed a program concerned with the inter- conversion of carbohydrate epitopes associated with HIV into a peptide based vaccine strategy to augment carbohydrate cross- reactive systemic and mucosal responses. In specific aim 1, we test the hypothesis that immunity induced by peptide mimeotopes of HIV-1 associated carbohydrate antigens differs qualitatively and quantitatively from the immunity induced by the carbohydrate antigen itself. Of interest is the evaluation of polyclonal responses in terms of i. kinetics of antibody induction; ii. Carbohydrate/gp120 reactive isotype profiles; and iii. Carbohydrate/gp120 reactive antibody affinity/avidity. Evaluation of serum binding to epitopes exposed on native forms of gp120 and gp160, and heterologous strains of monomeric gp120 and cell surface-expressed oligomeric gp120/gp41 are evaluated. In specific aim 2, we explore ways to enhance carbohydrate reactive titers and expand on the breadth of HIV immunoreactivity. Systemic and mucosal responses are evaluated following priming with mimetic or carbohydrate formulations and boosting with oligomeric-gp160 formulates. Serum and mucosal lavages are tested for i. Neutralization of Lab and primary isolates ii. Inhibition of Dendritic cell adherence and infection iii. Evaluation of serum antibody binding to gp120 epitopes as in aim 1 are also evaluated. In specific aim 3, systematic approaches involving molecular modeling and phage display libraries are used to analyze and exploit topological similarities to further define prototypic peptide mimeotope templates of HIV-1 associated carbohydrate antigens. In this aim, topological relationships between HIV-1 associated mannosyl and lactoseries carbohydrate structures are correlated with binding properties of peptide mimeotopes reactive with selected lectins and a highly effective carbohydrate reactive HIV-1 neutralizing antibody 2G12. We further define variants of peptides that display high affinity binding to these receptors by 1.) Synthesizing and biopanning defined peptide array libraries representative of secondary structure elements reflective of carbohydrate and peptide structures; and 2.)Evaluation of the affinity of ligand binding by Biacore and computer modeling studies.