Evaluation of cell-surface displayed synthetic consensus dengue EDIII cells as a potent oral vaccine candidate

Abstract

BackgroundDengue is a rapidly spreading mosquito borne tropical viral disease affecting hundreds of millions of people across the globe annually. The dengue virus (DENV) includes four genetically distinct serotypes that cause serious life-threatening infections, including dengue hemorrhagic fever/dengue shock syndrome. Dengue vaccine development is complicated by the possibility of vaccine-enhanced severe dengue disease due to antibody-dependent enhancement by pre-existing cross-reactivity, as well as homotypic antibodies. Thus, the development of an efficacious dengue vaccine conferring simultaneous and durable immunity to each of the four DENV serotypes has not yet been developed despite years of research. For mass immunization in deeply affected resource-limited countries, oral vaccination is considered more beneficial than conventional approaches. Therefore, in a continuing effort towards designing economical and potent vaccine candidates, the current study applied yeast surface display technology to develop an oral dengue vaccine candidate using whole recombinant yeast cells displaying the recombinant fusion protein of M cell targeting ligand Co1 fused to the synthetic consensus dengue envelope domain III (scEDIII). Female Balb/c mice were orally fed with recombinant yeast cells and immunogenicity in terms of systemic and mucosal immune responses was monitored.ResultsImmunofluorescence microscopy with dengue specific antibody and fluorescein isothiocyanate-conjugated anti-mouse IgG antibody clearly showed that recombinant protein Co1-scEDIII-AGA was localized on the cell surface of the respective clones in comparison with scEDIII-Co1 and Mock cells with no fluorescence. Oral dosage applications of surface displayed Co1-scEDIII-AGA stimulated a systemic humoral immune response in the form of dengue-specific serum IgG, as well as a mucosal immune response in the form of secretory immunoglobulin A (sIgA). Antigen-specific B cell responses in isolated lymphoid cells from the spleen and Peyer’s patches further supported an elevated mucosal immune response. In addition, surface displayed Co1-scEDIII-AGA feeding elicited strong immune responses in comparison with scEDIII-Co1 and Mock following intraperitoneal booster with purified scEDIII antigen.ConclusionsSurface displayed preparations of Co1-scEDIII-AGA induced strong immunogenicity compared with non-displayed scEDIII-Co1. Prior studies have supported the neutralization potential of scEDIII constructs against all four serotypes. Thus, the oral administration of genetically engineered yeast whole cells displaying biologically active Co1-scEDIII fusion protein without any further processing shows prospective as a potent oral vaccine candidate against dengue viral infection.

Expression of an immunocomplex consisting of Fc fragment fused with a consensus dengue envelope domain III in Saccharomyces cerevisiae

“…3). This is consistent with our previous results (Nguyen et al 2013;Bal et al 2018a) and may be explained by the fact that in nonselective media, episomal plasmids will gradually dilute out.…”

“…immune responses in vivo (Howland et al 2008;Liu et al 2016). In addition, S. cerevisiae tends to trigger potent innate as well as adaptive T cell immune responses (Bucarey et al 2009;Bal et al 2018a). In our previous papers, we used a yeast-expressed synthetic consensus sequence of EDIII (scEDIII) as a proof-of-concept Dengue tetravalent antigen to test various strategies for developing tetravalent Dengue vaccines.…”

“…The E. coli strains were maintained in Luria Bertani broth supplemented with appropriate antibiotics. The Saccharomyces cerevisiae 2805 strain ( MATα pep4::HIS3 prb 1-δ Can1 GAL2 his3 ura3-52 ) used previously by our group in other yeast-based oral vaccine development work (Kim et al 2011 ; Bal et al 2018a , b ) was used as the host for scEDIII-Fc complexes (scEDIII-PIGS). The recipient strain was maintained in YEPD liquid and agar media.…”

“…Escherichia coli and Saccharomyces cerevisiae chemical transformations were employed as previously described (Nguyen et al 2013 ; Bal et al 2018a ). For scEDIII-PIGS production, a single colony of the transformant was inoculated into 5 ml of Ura − liquid medium for 48 h in a shaking incubator at 200 rpm and 30 °C.…”

Addition of Partial Envelope Domain II into Envelope Domain III of Dengue Virus Antigen Potentiates the Induction of Virus-Neutralizing Antibodies and Induces Protective Immunity

“…DNA encoding the 103 amino acid (aa) cEDIII protein was synthesized as described previously [25]. To amplify the partial EDII (50-130 aa, 1062-1304 nt) gene and partial EDII hinge region (264-279 aa, 1710-1757 nt) (GenBank: MF004387.1), cDNA was prepared from DENV4-infected cells.…”