(719g) Design of HIV-1 Nanovaccine Using Active Targeting Mechanisms

Infection caused by Human Immunodeficiency Virus (HIV) is one of the greatest challenges for researchers around the world. Since its outbreak in 1981, more than 25 million people have died of Acquired Immunodeficiency Deficiency Syndrome (AIDS). An ideal strategy to stop the spread of the virus is to develop a prophylactic or therapeutic intervention against HIV-1that can be easily administered and distributed and elicits a robust and balanced immune response in order to avoid the infection of the host. Due to the high mutation rate of the virus and multiple mechanisms used to evade the immune response, HIV remains a daunting challenge.

A current focus in vaccine development is the design of novel adjuvant formulations and delivery systems that can elicit strong and balanced immune responses towards a variety of pathogens. Active targeting of these adjuvants can help in the design of efficacious vaccines since the use of subunit proteins as antigens requires developing delivery platforms that will provide the appropriate environment to preserve the structure of these novel antigens, and at the same time, offers the prospect of enhancing the typically modest ability of these immunogens to elicit specific immune responses. Our work is focused on the gp41-54Q-GHC immunogen, which is based on the membrane proximal external region of an HIV-1 glycoprotein (gp41) that elicits broadly neutralizing antibodies for epitopes conserved in different virus isolates. The main goal of this study is to design a biodegradable nanoparticle-based delivery platform for gp41-54Q-GHC that stimulates a robust immune response. In particular, polyanhydride nanoparticles exhibit desirable characteristics as adjuvants and delivery vehicles, including immune modulation, activation of antigen presenting cells, induction of high titer and highly avid antibodies, sustained antigen release, and stabilization of protein antigens.

In this work, polyanhydride copolymers based on 1,6-bis(p-carboxyphenoxy) hexane (CPH) and 1,8-bis(p-carboxyphenoxy)-3,6-dioxaoctane (CPTEG) and CPH were synthesized via melt polycondensation. CPTEG:CPH nanoparticles encapsulating gp41-54Q-GHC protein were fabricated using an anti-solvent nanoencapsulation method. Surface functionalization of the antigen-loaded nanoparticles was carried out using an amine-carboxylic acid coupling reaction. Di-mannose (i.e. alpha-D-mannopyranosyl-(1,2)-D-mannopyranoside) and glycolic acid (linker) modified nanoparticles were characterized using zeta potential measurements and a phenol-sulfuric acid assay. Subcutaneous administration of these particles using footpad injections in BALB/c mice was performed. Germinal center formation and isotype switching analysis were analyzed following injection of these particles. These studies lay the groundwork for using the targeted nanovaccine platform as a dual adjuvant/delivery system for gp41-54Q-GHC in future studies.