Molecular engineering and plant expression of an immunoglobulin heavy chain scaffold for delivery of a dengue vaccine candidate

Abstract

SummaryIn order to enhance vaccine uptake by the immune cells in vivo, molecular engineering approach was employed to construct a polymeric immunoglobulin G scaffold (PIGS) that incorporates multiple copies of an antigen and targets the Fc gamma receptors on antigen‐presenting cells. These self‐adjuvanting immunogens were tested in the context of dengue infection, for which there is currently no globally licensed vaccine yet. Thus, the consensus domain III sequence (cEDIII) of dengue glycoprotein E was incorporated into PIGS and expressed in both tobacco plants and Chinese Ovary Hamster cells. Purified mouse and human cEDIII‐PIGS were fractionated by HPLC into low and high molecular weight forms, corresponding to monomers, dimers and polymers. cEDIII‐PIGS were shown to retain important Fc receptor functions associated with immunoglobulins, including binding to C1q component of the complement and the low affinity Fcγ receptor II, as well as to macrophage cells in vitro. These molecules were shown to be immunogenic in mice, with or without an adjuvant, inducing a high level IgG antibody response which showed a neutralizing potential against the dengue virus serotype 2. The cEDIII‐PIGS also induced a significant cellular immune response, IFN‐γ production and polyfunctional T cells in both the CD4+ and CD8+ compartments. This proof‐of‐principle study shows that the potent antibody Fc‐mediated cellular functions can be harnessed to improve vaccine design, underscoring the potential of this technology to induce and modulate a broad‐ranging immune response.

Plant‐expressed Fc‐fusion protein tetravalent dengue vaccine with inherent adjuvant properties

“…(a) Schematic representation of the monomeric and polymeric human IgG1‐ cEDIII fusion protein and its interaction with high and low‐affinity Fc gamma receptors on antigen‐presenting cells; further details of the structure of these molecules are described in Kim et al . (). Red represents cEDIII domain, while dark and light blue indicate CH 2 and CH 3 domains of human IgG1, respectively.…”

“…We describe a novel vaccination approach against dengue infection based on Fc-antigen fusion approach. We previously expressed D-PIGS molecules based on murine IgG2a and showed that they were highly immunogenic in mice (Kim et al, 2017). To translate this promising vaccine approach into a potential dengue vaccine candidate in humans, we generated the human version of D-PIGS and purified them to a high degree of homogeneity.…”

“…The targeting of Fc receptors on antigen-presenting cells (APCs) leads to enhanced antigen uptake and processing, while their polymeric nature provides an additional antigen depot effect, both properties ordinarily conferred by adjuvants in conventional vaccines. Modelled on the early work of Mekhaiel et al (2011), we have previously tested the immunogenic potential of the polymeric immunoglobulin scaffold (PIGS) as a molecular platform for delivery of the dengue virus envelope domain III in mice and found that they were highly immunogenic (Kim et al, 2017). Here, we provide important new evidence for the substantial vaccine potential of the fully humanized version of the dengue PIGS (D-PIGS) that is critical for translation of this technology towards application in humans.…”

“…Molecular cloning of mouse and human versions of D-PIGS is described previously (Kim et al, 2017). Human D-PIGS were transiently expressed in Nicotiana benthamiana plants following infiltration with recombinant agrobacteria and purified by protein A chromatography.…”

“…Modelled on the early work of Mekhaiel et al . (), we have previously tested the immunogenic potential of the polymeric immunoglobulin scaffold (PIGS) as a molecular platform for delivery of the dengue virus envelope domain III in mice and found that they were highly immunogenic (Kim et al ., ). Here, we provide important new evidence for the substantial vaccine potential of the fully humanized version of the dengue PIGS (D‐PIGS) that is critical for translation of this technology towards application in humans.…”