Failure of oil adjuvants to enhance immunity induced in mice by an inactivated rabbit Pasteurella multocida vaccine.

Mice were immunized with different preparations of a killed whole cell Pasteurella multocida vaccine and challenged with successive tenfold dilutions of the homologous strain. Vaccines adjuvanted with mineral oil did not confer better protection against death than non-adjuvanted suspensions, even when the mice were challenged at 3 months after vaccination. Very good protection was obtained when the non-adjuvanted suspension had been administered twice.