Development of Biodegradable Nanobeads As Vaccines Against Tuberculosis, 2016

One third of the world's population is infected with Mycobacterium tuberculosis (M.tb) and two million die annually of tuberculosis (TB). The standard therapy, using antibiotics, is increasingly ineffective due to multi-drug resistance. The only available, 80 year-old vaccine using M.bovis BCG has little therapeutic value, and no other vaccines have reached the market, despite enormous efforts. This project proposed to develop technology to encapsulate whole mycobacteria inside biodegradable nano/microbeads to facilitate delivery of intact live or killed bacteria to vertebrate antigen-presenting cells (APC) to initiate the immune response.

The Oslo nano-bead group of Nystrom investigated different polymer materials that could encapsulate live and killed myco bacteria, focusing on the fish TB bacterium M.marinum, BCG and the mouse/human pathogen M.avium and Mycobacterium w, a promising antituberculous vaccine candidate. The Oslo cell microbiology group of Griffiths has established a system using GFP-M.marinum lethal infection of transparent zebrafish. After first experiments with BCG- and M.avium-beads in macrophages in vitro we searched for the most effective GFPbacteria-enclosing beads that when injected or fed to zebrafish crosses mucosal barriers and induces protection against subsequent infection with M.marinum. This rapid fish screening system would narrow down the promising polymer candidates/conditions for testing beads enclosing M.avium, Mw and later virulent M.tb, for their vaccine potential in mice and guinea pigs against subsequent challenge with these pathogens by Verma and Khuller in India. Different oral, intranasal and subcutaneous vaccination routes were planned to be tested. A crucial advantage of nanobeads over freely-administered immunogens is their established ability to cross mucosal barriers intact. This strategy ensures that the first location where mycobacteria become exposed to antigen digestion/ presentation systems is in the phago-lysosomes of APC's.