Two nonhuman primate efficacy studies have convincingly demonstrated that wildtype (wt) CMV/SIV vectors can 1) re-infect CMV+ rhesus macaques (RM), 2) during re-infection, elicit potent and persistent SIV-specific CD4+ and CD8+ T cell responses with a strong effector memory (TEM) bias, and 3) completely protect ~50% of vaccinated RM from progressive SIV infection after limiting dose rectal challenge with the highly pathogenic, CCR5-tropic SIVmac239 virus. The protection manifested in these RM is distinct from previous vaccines in its abruptness and extent, with protected RM exhibiting a viral burst in plasma of varying size upon initial infection, followed by immediate control to undetectable levels. Protection correlates with the extent of total SIV-specific CD8+ T cells generated during the vaccine phase, and is stable in the vast majority of protected RM (16/17) for >12 months. These data indicate a novel pattern of protection consistent with very early control, likely taking place at the site of viral entry and/or early sites of viral replication and amplification, and involving tissue-resident CD8+ TEM. Significantly, the epitope targeting of CMV-vectored, SIV-specific CD8+ T cell responses is distinct from responses elicited by conventional viral vectors or SIV itself, excluding the typical immunodominant epitopes that are internally processed in and presented by virally infected cells. This differential epitope targeting of wt CMV vector-elicited CD8+ T cell responses is due to the activity of CMV genes that inhibit class I MHC-restricted Ag presentation (US2-11 homologues), as US2-11 deletant CMV/SIV vectors elicit CD8+ T cell responses that include prominent responses to the conventional (internally processed) SIV epitopes. In this project, we seek to 1) improve the efficacy of CMV vector mediated protection with development of an optimized (epitope matched) heterologous prime for a CMV/SIV vector boost, 2) determine whether US2-11 deletant RhCMV/SIV vectors, which redirect CMV/SIV vector elicited CD8+ TEM responses to typical (directly presented) immunodominant epitopes, have increased efficacy, 3) determine the efficacy of replication-deficient and cell tropism-modified CMV vectors (developed in Projects 1 and 2, respectively), and 4) further define immunologic correlates of the unique protection afforded by CMV-vector elicited immune responses.

Public Health Relevance

Worldwide, ~2.5 million new HIV infections occurred in 2007 (with prevalence rates in some areas of southern Africa exceeding 15%), and it is generally agreed that an effective prophylactic vaccine is the only practical means by which the HIV/AIDS epidemic can be controlled. We have demonstrated that cytomegalovirus (CMV) vectors can harness tissue resident effector memory T cells to combat the AIDS virus very early in infection, and can protect rhesus monkeys from progressive infection after mucosal challenge. The work proposed in this application will enhance the safety of CMV vectors, optimize their efficacy, and provide crucial information for the further clinical development of this novel vaccine approach.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Program Projects (P01)
Project #
5P01AI094417-05
Application #
8880102
Study Section
Special Emphasis Panel (ZAI1)
Project Start
Project End
2017-06-30
Budget Start
2015-07-01
Budget End
2017-06-30
Support Year
5
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Oregon Health and Science University
Department
Type
DUNS #
096997515
City
Portland
State
OR
Country
United States
Zip Code
97239
Walters, Lucy C; Harlos, Karl; Brackenridge, Simon et al. (2018) Pathogen-derived HLA-E bound epitopes reveal broad primary anchor pocket tolerability and conformationally malleable peptide binding. Nat Commun 9:3137
Child, Stephanie J; Hickson, Sarah E; Bayer, Avraham et al. (2018) Antagonism of the Protein Kinase R Pathway in Human Cells by Rhesus Cytomegalovirus. J Virol 92:
McMichael, Andrew J; Picker, Louis J (2018) Corrigendum to 'Unusual antigen presentation offers new insight into HIV vaccine design' [Curr Opin Immunol 46 (2017) 75-81]. Curr Opin Immunol 53:217
Wu, Helen L; Wiseman, Roger W; Hughes, Colette M et al. (2018) The Role of MHC-E in T Cell Immunity Is Conserved among Humans, Rhesus Macaques, and Cynomolgus Macaques. J Immunol 200:49-60
Früh, Klaus; Picker, Louis (2017) CD8+ T cell programming by cytomegalovirus vectors: applications in prophylactic and therapeutic vaccination. Curr Opin Immunol 47:52-56
McMichael, Andrew J; Picker, Louis J (2017) Unusual antigen presentation offers new insight into HIV vaccine design. Curr Opin Immunol 46:75-81
Hansen, Scott G; Wu, Helen L; Burwitz, Benjamin J et al. (2016) Broadly targeted CD8? T cell responses restricted by major histocompatibility complex E. Science 351:714-20
Hansen, Scott G; Sacha, Jonah B; Hughes, Colette M et al. (2013) Cytomegalovirus vectors violate CD8+ T cell epitope recognition paradigms. Science 340:1237874
Hansen, Scott G; Piatak Jr, Michael; Ventura, Abigail B et al. (2013) Immune clearance of highly pathogenic SIV infection. Nature 502:100-4
Masopust, David; Picker, Louis J (2012) Hidden memories: frontline memory T cells and early pathogen interception. J Immunol 188:5811-7

Showing the most recent 10 out of 11 publications