Efficient entry inhibition of human and nonhuman primate immunodeficiency virus by cell surface-expressed gp41-derived peptides

Abstract

Membrane-anchored C-peptides (for example, maC46) derived from human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp41 effectively inhibit HIV-1 entry in cell lines and primary human CD4+ cells in vitro. Here we evaluated this gene therapy approach in animal models of AIDS. We adapted the HIV gp41-derived maC46 vector construct for use in rhesus monkeys. Simian immunodeficiency virus (SIV and SHIV) sequence-adapted maC46 peptides, and the original HIV-1-derived maC46 expressed on the surface of established cell lines blocked entry of HIV-1, SIVmac251 and SHIV89.6P. Furthermore, primary rhesus monkey CD4+ T cells expressing HIV sequence-based maC46 peptides were also protected from SIV entry. Depletion of CD8+ T cells from PBMCs enhanced the yield of maC46-transduced CD4+ T cells. Supplementation with interleukin-2 (IL-2) increased transduction efficiency, whereas IL-7 and/or IL-15 provided no additional benefit. Phenotypic analysis showed that maC46-transduced and expanded cells were predominantly central memory CD4+ T cells that expressed low levels of CCR5 and slightly elevated levels of CD62L, b7-integrin and CXCR4. These findings show that maC46-based cell surface-expressed peptides can efficiently inhibit primate immunodeficiency virus infection, and therefore serve as the basis for evaluation of this gene therapy approach in an animal model for AIDS.

Potent and Broad Inhibition of HIV-1 by a Peptide from the gp41 Heptad Repeat-2 Domain Conjugated to the CXCR4 Amino Terminus

“…Building on the theme that soluble peptides from the HIV-1 envelope heptad repeat-2 domain (HR2) can inhibit viral entry by blocking formation of the gp41 6-helix bundle that is required for membrane fusion, inhibitory proteins containing the C-terminal 46 (C46) or 36 (C36) amino acids from HR2 conjugated to a membrane-associated scaffold protein have been shown to broadly inhibit R5- and X4-tropic HIV-1s [26–29]. These membrane anchored constructs exhibited antiviral effects when introduced into primary CD4 T cells [26, 27, 30, 31] and were well tolerated and non-immunogenic in a human trial [32]. However, their antiviral activity is dependent on high levels of expression on the cell surface, which can vary considerably in different cell types, and is further influenced by the design of the anchoring protein and cis -acting regulatory elements in the vector [33, 34].…”

Targeting Cellular Cofactors in HIV Therapy

“…Candidates like T1249, C34, Sifuvirtide, and C46 exhibited longer half-lives and were also effective against T20-resistant strains supporting their ongoing clinical development. For C46, efficient inhibition of viral entry as well as selection of cells expressing the membrane-bound peptide was observed [89][90][91]. Further peptidic and small molecule candidates are under development to directly target the critical hydrophobic gp41 pocket.…”

Stem cell-based therapies for HIV/AIDS

“…It interacts with the N-terminal hydrophobic α-helix of HIVgp41, and therefore, interferes with the six-helix bundle formation of HIV and subsequent HIV and cell membrane fusion, all the while rendering cells resistant to HIV [58,59]. C46 is highly potent for inhibition of both R5 tropic and X4 tropic HIV strains in vitro and in vivo humanized mice [59,60]. It has been tested for anti-HIV HSPC based gene therapy experiments in non-human primates [61].…”