Identification of novel HLA-A*0201-restricted CD8+ T-cell epitopes on Ebola Zaire glycoprotein (45.26)

Abstract

Due to high morbidity and mortality rates, filoviruses are considered among the deadliest of human pathogens with case fatality rates that can reach 90% in some human outbreaks. Ebolavirus and Marburgvirus, the two genera of the family Filoviridae, pose a significant threat to military personnel, global security, and public health, and are classified as Category A bioterrorism agents by the CDC. While there is no licensed vaccine available, there are several promising vaccine candidates that have demonstrated immunogenicity and efficacy in animal models of disease. The vaccine candidates to date, have identified immunogens, usually the glycoprotein (GP), and most importantly,have demonstrated efficacy in the highly sensitive macaque models of filovirus disease. Human vaccine trials will need immunoassays that correlate with protection. Our lab has demonstrated the role of CTL in rodent models of Ebola Zaire. Here we report the first identified CTL epitopes of Ebola Zaire virus (EBOVZ) GP on HLA A*201. The binding of HLA-A*0201-restricted peptide in EBOVZ GP was determined by peptide binding alogorithiums, pentamer binding assays, and binding of overlapping or nonamers using T2 cells expressing HLA-A*0201. Potential HLA-A*0201-restricted peptides were selected from the SYFPEITHI database and screened by T2 cell-stabilization assay. In addition, overlapping peptides were used to identify potential epitopes that could be missed from the predicted algorithms. The various putative epitopes were winnowed and validated with T2-cell stabilization assays. Our results will provide a new insight into the development of therapeutic vaccines and the development of assays for future human vaccine trials for EBOVZ.