The intensive studies conducted so
far have focused on the use of attenuated, enteroinvasive bacteria,
such as Salmonella spp., Yersinia enterocolitica, or
Listeria monocytogenes, as well as appropriately modified
E. coli cells producing O listeriolysine (L. monocytogenes)
and/or invasin (Y. enterocolitica) as DNA carriers (Daudel
et al. 2007; Schoen et al. 2008)