NEW YORK (Reuters Health) - Exploiting a mechanism that Listeria monocytogenes uses to invade cells could enhance the delivery of vaccine antigens to target cells, according to a report published in the January issue of Molecular Pharmaceutics. The mechanism makes use of a protein that helps the bacterium erode through phagosomes.
“We harnessed the clever invasive machinery of Listeria and developed it into a potentially safer and more effective vaccine delivery formulation,” senior author Dr. Kyung-Dall Lee, from the University of Michigan in Ann Arbor, said in a statement.
“We’ve shown that vaccines produced using the listeriolysin O protein can dramatically boost the immune response” in mice, he noted. Listeriolysin O (LLO) is an endosome-disrupting protein that helps L. monocytogenes escape phagosomes.
Using a murine infection model, Dr. Lee’s team tested the ability of LLO-containing liposomes to deliver a viral antigen to antigen-presenting cells and stimulate a specific cytotoxic T lymphocyte response. Lymphocytic choriomeningitis virus nucleoprotein (NP) served as the viral antigen.
Mice treated with the LLO-containing liposomal NP showed a more robust immune response than animals that received either non-LLO NP or LLO-containing liposomal control protein. Moreover, such animals were completely protected against subsequent lethal challenge with lymphocytic choriomeningitis virus.
“We’re very excited about this promising vaccine delivery system, which could pave the way for the next generation of safer, more effective vaccines,” noted Dr. Lee, who holds a patent related to the LLO delivery method.
Source: Mol Pharm 2004;1:2-8. [ Google search on this article ]
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