Use of a new nanoparticle delivery system has allowed researchers to generate immunity to Chlamydia trachamotis at mucosal surfaces in mice. Chlamydia is the most common bacterial agent of sexually transmitted diseases in humans, accounting for more than a million infections in the United States each year. Infections can lead to reproductive dysfunction and severe local infection. The scientists immunized mice with a bioengineered version of cellular vaults that enclosed a component of Chlamydia. Cellular vaults are barrel-shaped nanoscale capsules found in the cytoplasm of all mammalian cells. The vaults can be engineered to serve as potential therapeutic delivery devices. When the immunized mice were exposed to a vaginal challenge with live Chlamydia, their reproductive tracts were protected from severe bacterial infection. "We are encouraged that our findings could accelerate progress toward developing a vaccine to guard against this infection," said the senior author of the study, which appeared in the April 30 edition of PLoS ONE. [Press release] [PLoS ONE article]