Immune Response of Guinea Pigs to Common Enterobacterial Antigen

Abstract

Common enterobacterial antigen (CA) extracted from cultures of Escherichia coli serogroups 014 and 0111 was administered with complete Freund's adjuvant to Hartley albino guinea pigs. Nine days after the initial immunization, serum samples were taken and the animals were tested for cutaneous delayed hypersensitivity to homologous and heterologous sources of CA. Analysis of the cutaneous reactions revealed significant differences (p<0.01) between immunized and control animals. Subsequent boosting 11 days later, followed by another skin test on day 30, revealed significant differences at the p<0.001 level. Serum samples taken at the time of the first skin test revealed minimal or no antibody titers to CA. Boosted animals demonstrated an increase in humoral CA antibody titers, but at very low levels. Further studies are needed to assess the role of cellular and humoral immunity engendered by CA.