Immunological studies on avian E.coli vaccine with special reference to preparation and evaluation

Local prepared E.coli F11 fimbriae vaccine was prepared and compared with an imported one against chicken E.coli infection. The antibody response in sera of chickens vaccinated with the prepared E.coli F11 fimbriae vaccine [group 1] and the antibody response in sera of chickens vaccinated with oil imported E.coli vaccine [group 2] as determined by ELISA were similar. The antibody response in sera of chickens of groups 1 and 2 appeared from the first week post vaccination and reached the maximum at the third week post second vaccination. Challenge of vaccinated and control chickens were done at the third week post second vaccination. Chickens of groups 1 and 2 have decreased number of lesion scores than the control one. Also, chickens of groups 1 and 2 and challenged with heterologous. E.coli strains [08, 114, and 119] have increased number of lesion scores than that challenged with homologous E.coli strains [01, 02, and 078]. In addition, chickens of groups 1 and 2 have higher percent of protection [PIS: had 84, 70, 80, and 67% respectively] than the control one [PIS: 34%]. In conclusion, the prepared F11 fimbriae vaccine from a combination of 01, 02 and 078 E.coli strains was seemed to cover good range of protection and has been elicited a protective immune response against virulent E.coli challenge with homologous and hetorologous strains. Over all, strong correlation was found between antibody response in vaccinated groups and low lesion score that indicated a good protection