Controlling sexually transmitted infections requires effective vaccines aimed at stimulation of robust mucosal antibody responses in the uro-genital tract. The focus of this proposal is development of mucosally delivered subunit vaccines that provoke local and systemic immune responses to abrogate transmission of and infection viral STI agents. We hypothesize that recombinant plant-derived mucosally-targeted STI antigens can stimulate production of protective levels of mucosal antibodies. We will focus on three viral STI: human immunodeficiency virus 1 (HIV-1), human papilloma virus 16 (HPV-16) and Herpes simplex virus 2 (HSV-2). We propose to utilize fusion protein engineering and transgenic plants for vaccine production, which in combination would yield an efficacious and cost-effective needle-free vaccines. The fusion platforms will be cholera toxin B subunit (CTB), a potent ganglioside-binding mucosal immunogen; Norwalk virus capsid protein (NVCP), which forms enteric-stable virus-like particles (VLP); and hepatitis B surface antigen (HBsAg), the highly successful parenteral VLP vaccine that has shown oral immunogenicity in mica and humans. The STI antigens will be 1) HIV P1 peptide (gp41 a.a. 649-684), 2) HPV L2 capsid type-common 'Kawana' epitope (a.a. 108-120), and 3) HSV-2 glycoprotein D (a.a. 1-275). We will evaluate different fusion strategies for each platform by transient expression in tobacco leaves, and select constructs that providerobust production of antigenic epitopes assembled into ganglioside-binding or VLP complexes. The best constructs will be provided to the Production Core for development of transgenic corn and tomato plants, which we will characterize to select the optimal lines for processing to produce immunogens in corn meal and freeze-dried tomato fruit. We will then test immunogenicity in mice by mucosal delivery of the processed plant materials and evaluate ability of antibodies to inhibit virus infectivity in vitro. Promising vaccine candidates will be developed for IND evaluation in clinical trials in Project 3 of this consortium.
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