Bacterial polyester inclusions can be engineered to display candidate antigens for use as a novel vaccine delivery system.

PolyBatics has developed a unique technology for the high-density display of engineered proteins on the surface of biocompatible polyester beads. The in vivo production of these beads provides for a simple single-step method for the production of a wide variety of protein displaying biopolyester beads with applications in vaccine delivery, diagnostics, drug delivery and the creation of nanofactories through the display of enzymes.

In a vaccine model system, a fusion protein consisting of Antigen 85A (Ag85A) and early secreted antigenic target (ESAT-6) from Mycobacterium tuberculosis and polyester synthase (PhaC) were used to investigate an immune response in mice. It was shown that immunizing mice with the antigen displaying beads induced both humoral and cell-mediated immune response. The beads showed no toxicity to the mice as indicated by weight gain and lack of lesions at the injection site.

It was shown that immunization with the antigen displaying beads provided a stronger response than the antigen fusion protein alone. This was further enhanced by administration of the beads in an oil-in-water emulsion.