[The immune enhancement of the C3 to the Escherichia coli vaccine].

C3b was separated and purified from the SPF chicken serum. It was linked with E. coli antigen by the glutaral. 11 days aged SPF chicken were immunized by the complex antigen and the chickens of control group were immunised by the FCA- E. coli antigen . They were boosted at the age of 18 day. The immune response was monitored by an enzyme-linked immunosorbent assay(ELISA) for anti-E. coli anitibody. The ELISA results indicated that during the early several weeks, IgG titers elicited by FCA (FCA-E. coli) were higher than those elicited by C3 (C3b-E. coli), but decreased rapidly after a peak around the end of 4th week from being immunized. Chickens immunized with C3b always gave increased response, and the IgG titers were equal to that of FCA at the end of 5th week from being immunized and then higher and higher than that of FCA. Thus the adjuvant effect of C3b is different from that of FCA, it could induce production of memory cell and make the antigens stimulate immune cells consistently and stably.