Rational Engineering of HIV gp 120 Miniprotein Mimetics

North Dakota State University, Fargo ND

Investigators

Abstract

DESCRIPTION (provided by applicant): The long-term goal of the proposed research is to design vaccines and small molecule inhibitors to prevent the onset of HIV infection. The viral envelope glycoprotein gp120 facilitates the entry of human immunodeficiency virus (HIV) into host cells by interacting with the CD4 glycoprotein and a chemokine receptor on the host cell surface. The native structure of gp120 and its ability to undergo conformational changes during such events, help the virus to evade the human defense system. Even the antibodies designed to block receptor binding to gp120, induce conformational changes in gp120, hence enabling the virus to enter host cells with impunity. Our rationale for designing effective protective HIV vaccine and small molecule fusion inhibitors is based on a strategy to downsize the viral gp120 glycoprotein to a mini-protein system. Multiple discontinuous functional elements of gp120 antigenic CD4 and chemokine receptor binding sites, will be transferred to a structurally compatible small scaffold. This will reproduce native-like conformation and binding function of the gp120 discontinuous epitopes. Such engineered mini-proteins represent a unique tool to study the interaction of gp120 with antibodies, CD4 and chemokine receptors at the molecular level in the complex process of HIV entry into the host cells. This information thus would be useful in designing and testing therapies against viral entry in host cells. The multi-epitope approach constrains the epitopes to their native conformations, and ensures the induction of immunity against multiple antigenic targets, and would be more likely to produce protective immunity compared to using epitope only (synthetic peptide) approach. In order to accomplish these objectives; we have set the following specific aims for this grant proposal: 1) To make recombinant miniprotein mimetics containing HIV gp120 epitopes expressed within the molecular scaffold provided by dendroaspin. 2) To evaluate the conformational nature of the gpl20 epitopes transferred to the miniprotein system by NMR spectroscopy. 3) To test the ability of the engineered miniproteins to bind to CD4 and chemokine receptors, and their ability to elicit antibodies. This approach of engineered mirtiprotein mimeties may also have utility in probing other complex biological processes and a means to test newer therapies for other diseases as well.