A PRELIMINARY STUDY ON THE IMMUNE PROTECTION MECHANISM OF INACTIVATED AVIAN ESCHERICHIA COLI VACCINES
Gao Song Peng Daxin Wen Qiyi Jiao Xin′an Gan Junji Wu Yantao Teng Feng Liu Wenbo Zhang Rukuan Liu Xiufan (Dept of Vet Med, Ani Sci and Vet Med Coll, Yangzhou Univ, Yangzhou, 225009)
The cultures of Avian Escherichia coli (E. coli) isolates O 18 and O 78 were inactivated by ultrasonication and used as the potential vaccines against avian E. coli infection. Challenge experiments showed that the O 78 isolate vaccine induced the greatest protection against challenge with the homologous isolates regardless of outer membrane protein (OMP) patterns, whereas the O 18 isolate vaccine induced best protection against the homologous isolates with the same OMP patterns but not the different OMP patterns. It was not evident that these vaccines could induce immune protection against other serotypes regardless of OMP patterns. Antibody responses to OMPs and lipopolysaccharides (LPS) in sera of the vaccinated chickens were investigated by an indirect enzyme linked immunosorbent assay (ELISA) and indirect hemagglutination test. Immediately before challenge, both OMP and LPS specific antibody titers of chickens in the vaccinated group were higher than that of birds in the control group. In the vaccinated group, both antibody titers of chickens survived challenge were higher than that of birds died of the challenge. Based on these observations, it could be concluded that the O serogroups were the main factor determined the immune protection, and OMPs as LPS, may also contribute to protective immune response.