Laboratory assessment of protection given by an experimental Salmonella enteritidis PT4 inactivated, adjuvant vaccine

An experimental inactivated Salmonella enteritidis PT4 vaccine, containing 10(11) cfu/ml and 50 per cent oil adjuvant, was used in laboratory vaccination trials in chickens. A single subcutaneous vaccination at three weeks or two vaccinations at three and six weeks old provided good protection against challenge with 10(9) cfu or 10(8) cfu of virulent organisms administered intramuscularly or intravenously at five and eight weeks old, respectively. The degree of protection was assessed according to the severity of the clinical signs, the mortality, the post mortem lesions and the recovery of the challenge organisms from post mortem material.