Development and analysis of immune-based therapy to treat HIV infection

Abstract

Immune-based therapeutics that harness the immune system have significant potential inhibit HIV-1 infection. We investigated whether an interleukin-15 (IL-15) superagonist (ALT-803) activated and mobilized natural killer (NK) and CD8+ T cells to mount an anti-HIV-1 response to inhibit H1V-1 infection.;IL-15 is a cytokine presented on IL-15-Receptor alpha (IL-15Ralpha) in trans as IL-15:IL-15Ralpha on the surface of dendritic cells and macrophages. IL-15:IL-15Ralpha can be cleaved from the cell as a soluble complex capable of activating and stimulating CD8+ T, NK and intestinal intraepithelial cells by binding IL-15Rbeta&ggr;c receptor expressed on their surface. We used an engineered 1L-15:IL-15Ralpha fusion protein which exhibits ~25-fold higher biological activity and >35-fold longer serum half-life than soluble 1L-15:IL-15Ralpha naturally cleaved from cells.;We investigated the capacity of ALT-803 to mobilize an immune response and inhibit HIV-1 in a humanized NSG mouse model. A single dose of ALT-803, twenty-four hours post-inoculation, markedly inhibited HIV-1 infection and stimulated an in-vivo expansion of CD8+ T and NK cells. NK cells were the essential effectors mediating ALT-803 inhibition of HIV-1. ALT-803 and HAART had an additive effect inhibiting HIV-1 infection. These results indicate that ALT-803 could be used as an additional component of post-exposure prophylaxis of HIV-1 infection when combined with HAART.;The cytotoxic T lymphocyte (CTL) is crucial in the adaptive immune response to HIV-1 and strong CTL responses correlate with lower viral set points and delayed progression to AIDS. CTLs recognize peptide presented by MHC Class I through its T cell receptor (TCR). HIV-1 specific soluble alphabeta-TCRs are a potentially potent treatment modality for inhibiting HIV-1 infection by delivering toxins to HIV-infected cells. Detection of HIV-1 infection using HIV-1 specific soluble alphabeta-TCRs as flow cytometry reagents can be valuable for early identification and quantification of infection. We selected TCRs that recognize two different HIV-1 epitopes.;We demonstrated binding of soluble alphabeta-TCRs, KK10 #9 and #25, to HLA- B*2705-KK10 in a dot-blot and ELISA which were then set up for crystallization so we may obtain structural information to explain why two TCRs can recognize the same epitope but have different binding affinities and confer different CTL function.