Effect of four adjuvants on immune response to F4 fimbriae in chickens

IgG antibody response in chickens immunized with F4 fimbriae extracted from local enterotoxigenic Escherichia coli (ETEC) strain was studied during a 98-day immunization period for comparing the efficacy of four adjuvants: Freund’ adjuvant, Quil A (QA), propolis and extract from Cochinchina momordica seed (ECMS). For this purpose, chickens were immunized with F4 fimbriae alone or combined with one of the above adjuvants on days 1 and 21. IgG antibody levels in serum and egg yolk (by ELISA) were measured on days 0, 7, 14, 21, 28, 35, 42, 49, 56, 70, 84 and 98. The egg production of each group was also determined during days 1–7 and the following four weeks. The results showed that QA could enhance antibody titre, as good or almost as good as Freund's adjuvant, whereas the titres of ECMS and propolis groups were relatively lower, with the overall order: Freund's adjuvant > QA > ECMS > propolis both in serum and egg yolk. However, the significant decrease of egg production was merely observed in the Freund's adjuvant group. It is concluded that the four adjuvants tested can stimulate immune response to F4 fimbriae in chickens, with Freund's adjuvant giving the best results, followed by QA.