For the past four decades, researchers have poked and prodded Escherichia coli and Listeria monocytogenes – the basic science trade names of 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, Harvard Medical School assistant professor of microbiology, has discovered how to create a vector to promote health. A vector is a kind of delivery vehicle that can transport vaccines. In a 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-infection, and the remaining two mice showed significant delay in tumor growth compared with 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.”