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

Mi‐Young Kim,Alastair Copland,Jorge Reyes‐Del Valle,Emily Julik,Moon‐Sik Yang,Yong‐Suk Jang,Rajko Reljic,Matthew John Paul,Julian K Ma,Sven Hofmann,Ivonne Ceballos‐Olvera,Craig Van Dolleweerd,Gina R Webster

doi:10.1111/pbi.12741

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.

Highlights

Since the development of safe and potent adjuvants has been a major bottleneck in vaccine development against many diseases, our focus in recent years has been to generate adjuvanticity by molecular engineering, and in that way minimise the vaccine’s reliance on powerful exogenous adjuvants that may have undesirable toxic effects
Summary In 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 antigenpresenting cells. These self-adjuvanting immunogens were tested in the context of dengue infection, for which there is currently no globally licensed vaccine yet
The consensus domain III sequence of dengue glycoprotein E was incorporated into PIGS and expressed in both tobacco plants and Chinese Ovary Hamster cells

Summary

Introduction

Since the development of safe and potent adjuvants has been a major bottleneck in vaccine development against many diseases, our focus in recent years has been to generate adjuvanticity by molecular engineering, and in that way minimise the vaccine’s reliance on powerful exogenous adjuvants that may have undesirable toxic effects Such selfadjuvanting vaccines might be sufficiently immunogenic on their own or could be applied with currently available, licensed adjuvants such as alum. An important complication has been the need to induce protective immunity against all four known serotypes of the dengue virus, while circumventing the issue of serotype cross-immunity, which can lead to antibody-dependent enhancement (ADE) of infection (Balsitis et al, 2010; Chau et al, 2008; Kliks et al, 1988; Moi et al, 2013) The latter phenomenon occurs during both natural infection and suboptimal vaccine-induced immune responses, and can lead to more severe manifestations of the subsequent infection. It may well be that an effective dengue vaccination strategy may require multiple vaccines aimed at different age groups or populations

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