EBV LMP1, a viral mimic of CD40, activates dendritic cells and functions as a molecular adjuvant when incorporated into an HIV vaccine

Abstract

HIV-1 does not significantly activate cellular immunity, which has made it difficult to use attenuated forms of HIV-1 as a vaccine. In contrast, EBV induces robust T cell responses in most infected individuals, perhaps as this virus contains LMP1, a viral mimic of CD40, which is a key activating molecule for DCs and macrophages. Consequently, studies were conducted using LMP1 and LMP1-CD40, a related construct formed by replacing the intracellular signaling domain of LMP1 with that of CD40. Upon electroporation into DCs, LMP1 and LMP1-CD40 mRNAs were sufficient to up-regulate costimulatory molecules and proinflammatory cytokines, indicating that these molecules can function in isolation as adjuvant-like molecules. As a first step toward an improved HIV vaccine, LMP1 and LMP1-CD40 were introduced into a HIV-1 construct to produce virions encoding these proteins. Transduction of DCs and macrophages with these viruses induced morphological changes and up-regulated costimulatory molecules and cytokine production by these cells. HIV-LMP1 enhanced the antigen-presenting function of DCs, as measured in an in vitro immunization assay. Taken together, these data show that LMP1 and LMP1-CD40 are portable gene cassettes with strong adjuvant properties that can be introduced into viruses such as HIV, which by themselves, are insufficient to induce protective cellular immunity.

Peripheral T Follicular Helper Cells Are the Major HIV Reservoir within Central Memory CD4 T Cells in Peripheral Blood from Chronically HIV-Infected Individuals on Combination Antiretroviral Therapy

“…HIV-1 NL4-3/Ba-L-EGFP is a macrophage-tropic recombinant clone of pNL4-3 containing the CCR5-utilizing envelope from HIV-1 BaL and expressing enhanced green fluorescent protein (EGFP) in infected cells. Construction of the proviral construct HIV-1 NL4-3/Ba-L-EGFP has been previously described by our group (31). HIV stocks were prepared by harvesting the supernatant of 293T cells transfected with NL4-3/Ba-L-EGFP.…”

A Targeted and Adjuvanted Nanoparticle for Immunochemotherapy of Leishmania Infections

“…CD40L is a powerful inducer of macrophage and dendritic cell activation, and would be expected to increase antigen presentation and T-cell-mediated immune responses. Similarly, we have examined the use of the Epstein Barr Virus protein LMP1 as a gene-based adjuvant [24]. LMP1 is a molecular mimic of CD40 stimulation, and delivery of LMP1 expression plasmid to macrophages via PDD/LAmB should enhance macrophage control of infection and anti-leishmanial immunity.…”

Design of vaccine adjuvants incorporating TNF superfamily ligands and TNF superfamily molecular mimics

“…We evaluated LMP1 in the context of HIV-1 infection by incorporating the LMP1 gene into the HIV-1 genome in front of the nef gene [59]. An IRES sequence allowed the expression of both LMP1 and Nef by this recombinant virus.…”

“…As has been observed by others [60], native HIV-1 virus or a HIV-GFP control virus (expressing GFP in place of LMP1) failed to induce maturation and activation of DCs and macrophages. In contrast, HIV-LMP1 and HIV-LMP1-CD40 were able to significantly enhance markers of activation and maturation including CD80, CD40, and CD83 surface expression on both DCs and macrophages [59]. This was accompanied by a significant increase in the secretion of pro-inflammatory cytokines IL-6, IL-8, IL-1β, and TNF-α, suggesting that LMP1 and LMP1-CD40 are potent immune stimulators of DCs and macrophages.…”

“…While culture of DCs infected with native HIV-1 or HIV-GFP induced only a small population of HIV Gag-specific T cells (<300 per million cells), HIV-LMP1 generated >1,000 cells secreting interferon-γ per million cells. HIV-LMP1-CD40 also increased the number of Gag-specific T cells by ELISPOT assay, but did not reach statistical significance [59]. These studies provided the first evidence that LMP1 functions as a potent molecular adjuvant in dendritic cells, either as a full-length protein or as a chimera with CD40.…”