Some Observations on the Antigenic Structure of Trichloroacetic Acid Extracts in Escherichia and the Paracolon Group

Abstract

TCA extracts of 6 Escherichia strains were tested against antisera prepared from the same strains in rabbits. Two strains with shared O antigen showed no cross reaction. Further study showed that their common somatic antigen was extractable by heat or mechanical disintegration, but not by TCA. The reason for the failure of TCA to extract certain somatic antigens is not known. The experiments presented indicate that TCA extracts may be unsatisfactory for serological classification unless the results are controlled by other methods.