Herpes simplex virus (HSV-1) is a major cause of vision loss worldwide. The long term goal of this competitive renewal application is to develop an effective vaccine that will produce protective immunity against ocular herpes. Natural HSV-1 immunity does not efficiently protect against recurrent infections or new infections, suggesting that an effective vaccine will have to induce different and/or more vigorous immune responses than the sub-optimal natural immunity. The research in this application will specifically focus on: (1) Identifying human HSV-1 epitopes recognized by CD4+ and CD8+ T cells from individuals with high (symptomatic) and no (asymptomatic) recurrent herpes disease. (2) Using asymptomatic epitopes only to design a powerful """"""""protective"""""""" T cell based herpes vaccine. During the initial funding cycle (2003-2009) and one year of ARRA funding (2009-2010), we have discovered that some HSV-1 gB and gD epitopes were strongly recognized by CD4+ and CD8+ T cells from asymptomatic patients but not from symptomatic patients, while other gB and gD epitopes were strongly recognized by T-cells from symptomatic but not from asymptomatic patients (P<0.005). Lack of strong response is not due to clonal deletion of an epitope specific TCR, since the response is not missing, it is just much lower. We obtained proof-of-principle that intranasal immunization of double transgenic mice expressing both class 1 and class 2 Human Leukocyte Antigens (i.e. HLA-DR and HLA-A2.1) with """"""""asymptomatic"""""""" CD4+ and CD8+ peptide epitopes linked to a lipid moiety (lipopeptides), but not with """"""""symptomatic"""""""" CD4+ and CD8+ peptide epitopes, induced strong local HSV-specific T cells and provided protection against ocular challenge with HSV-1. Besides, gB and gD, HSV-1 tegument proteins VP11/12 and VP13/14 are also major targets for effector T cells. These intriguing results, together with relate reports by others in the field, lead us to hypothesize that: (1) Some HSV-1 epitopes are recognized differently by T cells from symptomatic compared to asymptomatic individuals. (2) Some epitopes recognized only by T cells from symptomatic individuals are pathogenic (""""""""symptomatic epitopes"""""""");whereas some epitopes recognized only by T cells from asymptomatic individuals are protective (""""""""asymptomatic epitopes"""""""").
Our Specific Aims i nclude:
Aim 1 : Test the hypothesis that, although most HSV-1 epitopes are recognized by both asymptomatic and symptomatic patients, there are human CD4+ and CD8+ T cell epitopes from gB, gD, VP11/12 and VP13/14 that are strongly recognized only by asymptomatic patients or only by symptomatic patients;
Aim 2 : Test the hypothesis that immunization with a combination of multiple """"""""asymptomatic"""""""" epitopes from gB, gD, VP11/12 and VP13/14, will increase the magnitude, breadth and duration of T-cell protective immunity. A vaccine that incorporates only asymptomatic HSV-1 human T-cell epitopes and excludes symptomatic epitopes is a novel approach that should break new ground in our understanding of the immune mechanisms underlying ocular herpes disease and may ultimately lead to an effective vaccine.
Over 100 million individuals in the US are infected by HSV-1 and approximately 450,000 adults have a history of recurrent ocular disease that can cause loss of vision. This competitive renewal application for an R01 research grant is to identify epitopes specifically recognized by CD4+ and CD8+ T cells from individuals with high (symptomatic) and low (asymptomatic) recurrent ocular herpes disease. The information will be used to design a powerful T cell-based lipopeptide vaccine against ocular herpes.
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