Bioengineered bacteria have been used to produce polyester nanoparticle inclusions and these have been utilised to deliver mycobacterial antigens in vaccines for the control of tuberculosis.
Polyhydroxybutyrate (PHB) biopolyester nanoparticles (biobeads) were produced in both Escherichia coli and the generally regarded as safe (GRAS) bacterium Lactococcus lactis using relatively simple fermentation and production processes. The PHB biosynthesis pathway was engineered in these bacteria to display the mycobacterial antigens Ag85A and ESAT-6 on the surface of the bio-beads. The biobeads were purified from the bacteria and characterised using MALDI-TOF MS, ELISA and flow cytometry. Mice vaccinated with these biobeads produced cell-mediated immune responses to mycobacterial antigens and had significant protection from Mycobacterium bovis infection as shown from reductions in bacterial counts and pathology.
This unique approach to the design and production of bacterial-derived biobeads displaying antigens enables a cost-effective way to express a diverse antigen repertoire for use as vaccines to combat tuberculosis or other diseases.