For the last four decades, researchers have poked and prodded Escherichia coli and Listeria monocytogenes--the basic science trade names of these sometimes deadly bugs--to discover how they interact with the immune system, invade cells, rob them of nutrients, and blossom within other cells to eventually shut down necessary bodily functions. From his work with these pathogens, Darren Higgins, HMS assistant professor of microbiology, has discovered how to create a vector to promote health.
In the published study, researchers infected mice with an especially virulent line of melanoma. Six of the eight mice whose immune system was primed with the E. coli/Listeria vector remained tumor free for more than 90 days post-tumor challenge, and the remaining two mice showed significant delay in tumor growth compared to mice that did not receive the cancer vaccination. The mice in the study's control group did not live past 16 days.
"The results of this study are very positive," says Higgins. "It suggests that we could utilize this killed bacterial formulation to prime the immune system against diseases such as cancer, or other viral and bacterial pathogens."
Using killed E. coli as the main vector, Higgins stripped out the bacteria's virulence components while leaving a framework that remains attractive to macrophages, cells at the front lines of the immune system. Within this shell, his team then added large proteins for delivery to macrophages to generate an immune response (an advantage over other vectors that cannot deliver large molecules). But the key to this vector is the addition of listeriolysin, a component of Listeria
Contact: John Lacey
Harvard Medical School