Vaccination of Chickens with Liposomal Inactivated Avian Pathogenic Escherichia coli (APEC) Vaccine by Eye Drop or Coarse Spray Administration

One hundred and twenty 30-day-old specific-pathogen-free chickens were inoculated with the liposomal inactivated avian pathogenic Escherichia coli (APEC) vaccine by eye drop or coarse spraying. All of the chickens produced antilipopolysaccharide antibodies of the IgG subclass in their sera as well as IgA antibodies in their oral mucus. The results demonstrated a rise in antibodies in the serum of chickens administered the APEC vaccine through nonparenteral mucosal routes. Bacterial counts in the blood decreased, and clinical signs were moderated in the vaccinated chickens after challenge with a strain of APEC. No harmful effects from the vaccination were observed. The liposomal inactivated APEC vaccine described in this paper would contribute to a practical method of control for avian colibacillosis.