Adjuvanted outer membrane protein vaccine protects poultry against infection with Salmonella enteritidis

The immunogenicity of a sonicated extract (SE) and of outer membrane protei ns (OMP) of Salmonella enteritidis was tested in birds of about 8 weeks of age. The dose, route of vaccination and the adjuvant used varied in differe nt groups of birds. Two vaccine doses with or without adjuvant were given p arenterally or orally 3 weeks apart. OMP vaccines gave significantly higher antibody titres than SE vaccines, as indicated by ELISA. The Vaccines adju vanted with oil produced higher antibody titres than those without any adju vant. A dose of 1 mg of vaccine produced higher antibody titres than 0.5 mg of vaccine. Adjuvanted vaccine given subcutaneously elicited higher antibo dy responses than oral vaccines given without adjuvant. The birds were chal lenged with Virulent S. enteritidis organisms at the end of the second week after a booster dose. None of the birds given 1 mg of OMP vaccine subcutan eously shed the organisms when tested by culturing cloacal swabs, although a few birds vaccinated with 0.5 mg of OMP vaccine did so. In general, adjuv anted OMP vaccines gave better protection than SE vaccines.