Convenient Auto-Processing Vector Based on Bamboo Mosaic Virus for Presentation of Antigens Through Enzymatic Coupling

We have developed a new binary epitope-presenting CVP platform based on bamboo mosaic virus (BaMV) by using the sortase A (SrtA)-mediated ligation technology. The reconstructed BaMV genome harbors two modifications: 1) a coat protein (CP) with N-terminal extension of the tobacco etch virus (TEV) protease recognition site plus 4 extra glycine (G) residues as the SrtA acceptor; and 2) a TEV protease coding region replacing that of the triple-gene-block proteins. Inoculation of such construct, pKB5G, on Nicotiana benthamiana resulted in the efficient production of filamentous CVPs ready for SrtA-mediated ligation with desired proteins. The second part of the binary platform includes an expression vector for the bacterial production of donor proteins. We demonstrated the applicability of the platform by using the recombinant envelope protein domain III (rEDIII) of Japanese encephalitis virus (JEV) as the antigen. Up to 40% of the BaMV CP subunits in each CVP were loaded with rEDIII proteins in 1 min. The rEDIII-presenting BaMV CVPs (BJLPET5G) could be purified using affinity chromatography. Immunization assays confirmed that BJLPET5G could induce the production of neutralizing antibodies against JEV infections. The binary platform could be adapted as a useful alternative for the development and mass production of vaccine candidates.

A Self-Assembling Whole-Cell Vaccine Antigen Presentation Platform

Diarrhea is the most common infection in children under the age of 5 years worldwide. In spite of this, only a few vaccines to treat infectious diarrhea exist, and many of the available vaccines are sparingly and sporadically administered. Major obstacles to the development and widespread implementation of vaccination include the ease and cost of production, distribution, and delivery. Here we present a novel, customizable, and self-assembling vaccine platform that exploits the Vibrio cholerae bacterial biofilm matrix for antigen presentation. We use this technology to create a proof-of-concept, live-attenuated whole-cell vaccine that is boosted by spontaneous association of a secreted protein antigen with the cell surface. Sublingual administration of this live-attenuated vaccine to mice confers protection against V. cholerae challenge and elicits the production of antigen-specific IgA in stool. The platform presented here enables the development of antigen-boosted vaccines that are simple to produce and deliver, addressing many of the obstacles to vaccination against diarrheal diseases. This may also serve as a paradigm for the development of broadly protective biofilm-based vaccines against other mucosal infections.IMPORTANCE Diarrheal disease is the most common infection afflicting children worldwide. In resource-poor settings, these infections are correlated with cognitive delay, stunted growth, and premature death. With the development of efficacious, affordable, and easily administered vaccines, such infections could be prevented. While a major focus of research on biofilms has been their elimination, here we harness the bacterial biofilm to create a customizable platform for cost-effective, whole-cell mucosal vaccines that self-incorporate secreted protein antigens. We use this platform to develop a sublingually administered live-attenuated prototype vaccine based on Vibrio cholerae This serves not only as a proof of concept for a multivalent vaccine against common bacterial enteric pathogens but also as a paradigm for vaccines utilizing other bacterial biofilms to target mucosal infections.