Recently, we have successfully produced simian-human immunodeficiency virus-like particles (SHIV VLPs) which contain SIV Gag and HIV Env by using a baculovirus expression system. Furthermore, we have incorporated the influenza virus surface glycoprotein, hemagglutinin (HA), into SHIV VLPs. Taking advantage of HA having a high affinity to bind to the mucosa of the upper respiratory track, our central hypothesis is that use of SHIV VLPs containing influenza HA as a mucosal vaccine will enhance both systemic and mucosal immune responses against HIV infection. The major focus of this project is to investigate the efficiency and mechanisms of the built-in adjuvanticity of HA in SHIV VLPs for intranasal immunization in a mouse model. Specifically, we propose: 1). To determine the role of incorporation with influenza HA in SHIV VLPs as a mucosal vaccine in enhancement of immune responses against HIV. Proposed experiments will investigate: a) whether the built-in adjuvanticity of influenza HA in SHIV VLPs as a mucosal vaccine is more potent than soluble influenza HA in enhancement of both systemic and mucosal immunity; and b). whether the receptor binding or membrane fusion activity of influenza HA affects its adjuvanticity for SHIV VLPs. 2). To determine the role of incorporation with influenza HA in SHIV VLPs in dendritic cell (DC) binding, activation, cytokine production, and antigen presentation. We propose to investigate: a). whether HA/SHIV VLPs have an increased ability to DC binding, internalization, and subcellular localization; b). whether HA/SHIV VLPs have an increased effect on DC activation, and cytokine production; c). whether HA/SHIV VLP-activated DCs increase naive T cell proliferation; and d). whether HA/SHIV VLPs increase the efficiency of antigen cross-presentation of DCs to CD8+ T cells and what are the associated intracellular pathways. 3). To determine the role of incorporation with influenza HA in SHIV VLPs in specific B cell binding, activation, and antibody production without CD4+ T cell help. Experiments are designed to investigate: a). whether HA/SHIV VLPs increase their ability to bind to naive B cells; b). whether HA/SHIV VLPs have an increased effect on naive B cell proliferation; c). whether HA/SHIV VLP-activated DCs have an increased ability to adhere to naive B cells; d). whether HA/SHIV VLP-activated DCs increase naive B cell proliferation; and e). whether B cell activation and differentiation and cytotoxic CD8+ formation occur in nasal-associated lymphoid tissue (NALT), an inductive site after intranasal immunization with HA/SHIV VLPs in CD4+ T-cell-deficient mice. This project represents a novel approach to develop an effective and safe HIV vaccine. Understanding the cellular and molecular mechanisms of HA/SHIV VLP-enhanced immune responses in mice is critical for the future design and testing of a successful HIV vaccine in non-human primate models and in human trials.
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