Listeria monocytogenes is responsible for severe food-borne infections, but the mechanisms by which bacteria cross the intestinal barrier are unknown. Listeria monocytogenes expresses a surface protein, internalin, that interacts with a host receptor, E-cadherin, to promote entry into human epithelial cells. Murine E-cadherin, in contrast to guinea pig E-cadherin, does not interact with internalin, excluding the mouse as a model for addressing internalin function in vivo. In guinea pigs and transgenic mice expressing human E-cadherin, internalin was found to mediate invasion of enterocytes and crossing of the intestinal barrier. These results illustrate how relevant animal models for human infections can be generated.

Polydnaviruses of Braconid Wasps Derive from an www.sciencemag.org (this information is current as of February 13, 2009 ):The following resources related to this article are available online at