A T cell-based vaccine to HIV with its highly variable genome is a formidable challenge, since it will have to protect against many viral variants. As a novel vaccine approach, we propose to focus the T cell immune response to four highly conserved regions of the HIV proteome, which may be invariant due to functional or structural constraints. This is a simple and testable vaccine approach designed to overcome HIV variability. The HLA-B*57 class I molecule (B*57) is linked with better disease outcome. Here we will characterize responses to our T cell vaccine components in B*57+ donors in a proof-of-principle study.
Specific Aim 1 will map new B*57-restricted epitopes in the four highly conserved regions of the HIV proteome. Targeting several proteins (Gag, Pol and Env) should help reduce virus escape for long term control. Known dominant epitopes found in the Gag regions will be extinguished by reverse genetics. CD8+ T cells from healthy donors will be primed by autologous DCs transduced by lentiviral vectors to express these polypeptides. Optimal minimal epitopes will be mapped and binding to B*5701 verified.
Specific Aim 2 will characterize the CD8+ T cells to selected epitopes generated by ex vivo priming from healthy donors. We will assess i) various in vitro CTL functions;ii) the ability of these responses, individually or in combination, to suppress the in vitro replication of wild type or attenuated variant NL4-3 viruses;and iii) the epitope-specific pre-vaccination TCR repertoire reserve. We will focus on shared (commonly recognized) epitopes and in particular, to those found linked to greater disease control in Specific Aim 3.
Specific Aim 3 will seek responses to all novel epitopes in B*57+ patients, to determine whether any is linked to relative control of disease. They will be monitored ex vivo directly or after one re-stimulation with cognate epitopic peptides, to measure recall T cell responses. Their functional profiles will be further assessed by polychromatic flow cytometry and, if possible, compared to contemporaneous responses to other known B*57 responses within the same individuals. Longitudinal studies which are more informative than cross-sectional ones will also be performed to further elucidate promising responses. A secondary goal is to develop an ex vivo human model useful for advancing future vaccine candidates to clinical testing. In summary, this study should provide new insights into the characteristics of HIV-specific CD8+ T cells important for HIV control and the qualities that should be sought in vaccine-induced T cells as well as to determine whether the most conserved portions of HIV proteins are valuable vaccine candidates.

Public Health Relevance

A T cell-based vaccine to HIV with its highly variable genome is a formidable challenge, since it will have to protect against many viral variants. We propose a simple and testable vaccine approach designed to overcome HIV variability by focusing the T cell response to highly conserved regions of the HIV proteome. We expect to learn more about how responding T cells contribute to HIV control and will evaluate an ex vivo human vaccination model that may help advance future vaccine candidates to clinical testing.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
3R01AI077413-02S1
Application #
8061848
Study Section
AIDS Immunology and Pathogenesis Study Section (AIP)
Program Officer
Bradac, James A
Project Start
2008-09-01
Project End
2012-08-31
Budget Start
2010-05-01
Budget End
2010-08-31
Support Year
2
Fiscal Year
2010
Total Cost
$24,205
Indirect Cost
Name
University of Texas El Paso
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
132051285
City
El Paso
State
TX
Country
United States
Zip Code
79968
Xu, Weidong; Watts, Douglas M; Costanzo, Margaret C et al. (2013) The nucleocapsid protein of Rift Valley fever virus is a potent human CD8+ T cell antigen and elicits memory responses. PLoS One 8:e59210
Schaubert, Keri L; Price, David A; Salkowitz, Janelle R et al. (2010) Generation of robust CD8+ T-cell responses against subdominant epitopes in conserved regions of HIV-1 by repertoire mining with mimotopes. Eur J Immunol 40:1950-62