Abstract
Plesiomonas shigelloides, an organism commonly found in water, is only rarely associated with diarrhoea in man. P. shigelloides serotype O:17 (SVC O1), which is antigenically similar to Shigella sonnei, was found to be neither virulent nor toxic for rabbits. Rabbits immunised by feeding with P. shigelloides (SVC O1) were completely protected against an oral challenge with 10(10) cells of S. sonnei but non-immunised rabbits were not. P. shigelloides (SVC O1) may be a useful vaccine strain for shigellosis.