Anatomical locus of the common enterobacterial antigen.

Cell walls, membrane vesicles and the soluble cytoplasmic components have been isolated from Escherichia coli 0:14 and Salmonella typhimurium and examined by electron microscopy as well as hemagglutination inhibition with heterologous antisera for enterobacterial common antigen (ECA). The outer and cytoplasmic membranes also were isolated and examined for common antigen. Although common antigen was present in the isolated surface structures it was not localized exclusively in these fractions. Additional experiments revealed that, whatever the nature of the integration of ECA of Kunin into the cell envelope, it is a much more stable association in E. coli 0:14 than in S. typhimurium.