Ocular HSV infection is the leading cause of viral induced corneal blindness in the US. Genital HSV clinical trials using live attenuated virus or subunit vaccines given parenterally with powerful adjuvants showed poor efficacy. Rather than abandon all attempts to develop a successful ocular herpes vaccine, we think that the better response is to try to gain a better understanding of protective immunity against HSV and to develop novel, more immunogenic approaches. In particular, lipopeptide-based vaccines, which have recently gained considerable interest, represent a promising novel approach. We hypothesize that lipopeptide constructs containing critical HSV T-cell epitopes will induce powerful local cellular mucosal immune responses when delivered ocularly. This may ultimately prove to be a powerful approach for the development of a useful vaccine against ocular HSV.
Our Specific Aims i nclude: (1) Defining immuno-dominant CD4+ helper T cell (HTL) and CD8+ cytotoxic T cell (CTL) epitopes of HSV-1 glycoproteins gB & gD. Computer predicted human leukocyte antigen (HLA) restricted peptide epitopes will be examined for (a) high affinity binding to HLA molecules; (b) T-cell antigenicity using HLA phenotyped PBMC from both seropositive and seronegative donors; and (c) T-cell immunogenicity in HLA class I and II transgenic mice (i.e., mice that simulate the human immune system). (2) Construction and immunogenicity studies of lipopeptides using the epitopes determined in Specific Aim #1. Lipopeptides containing the """"""""best"""""""" CTL and HTL epitopes will be tested for induction of a broad based immune response using in vitro killing of HSV infected human dendritic cells (DC) and IFN-gamma ELISPOT assays. Protection against ocular HSV-1 challenge will be evaluated in HLA class I and class II transgenic mice models. (3) Optimize mucosal delivery of lipopeptides to the local ocular/mucosal immune system to determine if powerful mucosal immunity can be achieved at the eye. The use of different lipid moieties, and ocular vs. intranasal immunization will be explored to find the most efficacious way to provoke ocular mucosal immunity. Lipopeptides will be compared to peptide + mucosal adjuvant. Uptake and functional presentation of lipopeptide epitopes by DC to T-cells and subsequent DC maturation will be examined.
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