Internalization assays for Listeria monocytogenes.

Listeria monocytogenes is a model intracellular pathogen that can invade the cytoplasm of host mammalian cells. Cellular invasion can be measured using standard techniques such as the classical gentamicin protection assay, based on the quantification of colony-forming units from lysates of infected cells. In addition, there are methods based on immunofluorescence microscopy which allow for assaying invasion in a medium- to high-throughput manner. In the following sections we detail two different assays that can be used alone or in combination to quantify the internalization of L. monocytogenes in host cells.