Development of nanoparticle based therapies against tuberculosis in the zebrafish model.

Mycobacterium tuberculosis (M.tb), the cause of tuberculosis (TB) infects one-third of the world population, one person per second, and kills about 2 million people per year. The only effective therapy, using antibiotics, is being challenged by increasing antibiotic resistance. It has been shown that when antibiotics are encapsulated in a biodegradable nanoparticle (NP) made from a polymer such as poly (lactate-co-glycolate) acid (PLGA) the drug is significantly more effective in curing TB in different animal models; higher concentrations of antibiotics can be targeted selectively to macrophages, the infection site, where they are released slowly, while the total systemic levels is much less than with standard drug therapy .A weakness of the existing a nimal models of TB is the difficulty in visualizing the NPs in the infected live animal, which is essential if one is to optimize beads for their ability to reach infected cells after different modes of administration. This is precisely the great strength of the transparent zebrafish model of tuberculosis based on red and green variants of M.marinum, the fish TB organism. We have recently established this model using red and green fluorescent M.marinum and also successfully fabricated PLGA NPs enclosing t he antibiotic rifampicin and red or green fluorescent dyes.When these beads are injected into embryos 1-2 days after infection they reach the same cells in the granulomas as the bacteria and we have preliminary data giving hints of therapy. Now the goal i s to perfect this system for embryos and adults and find the most effective NPs that reach granulomas and provide a robust therapy. This system enables us to screen for different kinds of NPs we will formulate, as well as to compare different antibiotics and combinations thereof, and cDNA's coding for anti-microbial peptides. The most effective NPs will be given to collaborators in India to test them in a guinea pig model as a prelude to testing the NPs in humans.