الفهرس Only 14 pages are availabe for public view
 |  | from | 162 |  |  |
| | | from | 162 | | |
Abstract
This study assessed adverse effect of E.coli infection on chickens immune systems. It was carried out to evaluate the effect of E.coli infections at different ages on immune organs, humeral, cellular immune response post vaccination with different vaccines, and evaluate of E. coli vaccine in protection against E.coli infection as follow.
Exp. (1) designed to study the effect of E. coli infection on immune response post ND vaccination using, HI, ELISA, phagocytosis, and challenge tests. The result confirmed that E. coli infection caused high significant decrease in antibody titer when infection occurred 2-5 days before vaccination as the GMT of ND HI for group infected at 5 day old and vaccinated with HB1 at 7day old (A1) was much lower than vaccinated non infected (A2). The GMT in infected group were (11.3, 22.6, and 18.4), while it was (22.6, 42.2 and 36.8) in 1, 2, and 3Ws PV respectively, the positive ELISA values showed significant decrease in antibody titer. Also the phagocytic index was (1.76, 0.983, and 0.889) in infected vaccinated group while in vaccinated non infected was (2.03, 1.43, and 1.09) in 1, 2, and 3Ws PV respectively.
No significant differences in the ND GMT, ELISA values and phagocytic index when E. coli infection was before ND vaccination by 8 daysE