454. A Cellular Epitope (R7V) Stimulates INF-gamma Production In HIV-1 Infected Non-Progressors
Session: Poster Abstract Session: HIV Pathogenesis and Immunity
Friday, October 21, 2011
Room: Poster Hall B1
Background: R7V is a host-derived epitope incorporated into the envelope of HIV-1 during budding and eliciting a strong antibody response in non progressors (reviewed by Bremnaes and Meyer, 2009). These antibodies have been investigated as possible prognostic indicators and the epitope as potential vaccine component. Stimulating cells with HIV-derived peptides and measuring the associated cytokine responses also present as useful prognostic indicators (for example, a loss of IL2+ and IL2+INF-γ+ Gag-specific T cells was shown to be associated with HIV/AIDS disease progression (Jansen et al., 2006). The objective of this work was therefore to investigate the frequency of HIV+ T cells producing INF-γ in response to R7V and its association with disease progression.

Methods: PBMCs from HIV infected clinically stable and asymptomatic individuals were exposed to antigens (R7V and Gag peptide pool) and the cells stained for intracellular INF-γ. Flow cytometry was used to determine the frequencies of cytokine producing T cells. The levels of anti-R7V antibodies in the serum of the individuals were determined using an in-house ELISA.

Results: Cells (CD4+ and CD8+) that were not stimulated for high levels of IFN-γ production by the Gag peptide pool responded to R7V, in some cases with a frequency of 100%. Anti-R7V antibodies were highest in infected individuals but not consistently so for individuals infected and clinically stable the longest.

Conclusion: During HIV-induced immune activation, the production and secretion of various cytokines is increased (e.g. INF-γ). Here, unstimulated T cells do not produce INF-γ but exposure to R7V and Gag peptide pools significantly increases the frequency of T-cells producing the cytokine. Cellular antigens have a role to play in stimulating beneficial immune responses and perhaps to the same extent as viral antigens.


Subject Category: H. HIV/AIDS and other retroviruses

Aurelia Williams, MSc, Biochemistry, University of Pretoria , Pretoria, South Africa, Christiane Bremnaes, MSc, Biochemistry, University of Pretoria, Pretoria, South Africa and Debra Meyer, PhD, Biochemistry, University of Pretoria, Pretoria , South Africa

Disclosures:

A. Williams, Technology Innovation Agency (TIA): Investigator and TIA is a funder of our research, Research grant

C. Bremnaes, None

D. Meyer, Technology Innovation Agency (TIA): TIA is a funder of our research, Research grant

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.