ABSTRACT
The Shigella genus includes four species: Shigella dysenteriae, Shigella flexneri, Shigella boydii, and Shigella sonnei. Shigella species are crucial causes of traveler's diarrhea in individuals from industrialized countries visiting developing areas. In a few cases, only watery diarrhea is present. In humans, remarkably low bacterial loads are able to trigger severe shigellosis. The cellular pathogenesis of shigellosis is the result of the complicated actions of a large number of bacterial virulence factors. Mice have been the most frequently used small animal species in preclinical studies of shigellosis. Rabbits are not naturally susceptible to shigellosis, but may acquire the infection under preparatory conditions. The rhesus monkey model mimics human shigellosis and the human immune response, making it ideal for assembling preclinical data before human trials of vaccine candidates. The use of various animal models has already improved our understanding of the in vivo consequences of intracellular defense mechanisms as well as protective measures against Shigella spp.
