Abstract
SUMMARY: Yersinia enterocoliticaserotype IX has been found to stimulate the production of vibriocidal antibody againstVibrio cholerae, particularly in Inaba serotype, in experimental rabbits and infected man to a significant degree. This activity could be absorbed by both Inaba andYersiniaantigens from anti-yersinia sera, butYersiniaantigen could not absorb vibriocidal activity from the anti-cholera sera, indicating a unilateral relation.Vibrio agglutinating antibody, particularly against Ogawa, in anti-yersinia rabbit or human sera was found to be less liable to non-specific stimulation.V. cholerae, while removing vibriocidal antibody, could not absorb theYersiniaagglutinin from anti-yersinia sera, suggesting that there is a different determinant for these two types of antibody activities.The non-specific production of vibriocidal antibody byY. enterocoliticatype IX indicates the need for caution in the interpretation of the results of vibriocidal tests where such organisms are prevalent.