The Immunologic Role of the Ethanol-Soluble Enterobacterial Common Antigen Versus Experimental Renal Infection

Abstract

Members of the Enterobacteriaceae contain a common antigen (CA) which is found in the ethanol-soluble fraction (ESF) of heat-killed culture supernates. The ESF of an E. coli 06 strain was shown to be virtually endotoxin-free. Preliminary chemical studies revealed that the dry ESF, including salts, contained 20% protein and less than 1% carbohydrate. Chloroform/methanol-soluble lipid accounted for approximately 2% of the material.

Vaccination of rabbits with such enterobacterial CA elicited protection against renal disease due to retrograde challenge with Proteus mi rabil is or to hematogenous challenge with E. coli 075. Protection was not demonstrated against a heavily encapsulated strain of Klebsiella pneumoniae which, as demonstrated by in vitro phagocytosis, was not opsonized by antibody to CA. These results suggest that further investigation of enterobacterial CA as a vaccine is warranted.