Immunity provided by haemorrhagic septicaemia-subunit vaccine in ruminants.

A subunit vaccine against haemorrhagic septicaemia (HS), the principal killer disease in ruminants, especially cattle and carabao, in the Philippines, has been developed. Using capsules of Pasteurella multocida Group B as an active component of the vaccine, it gave solid protection against challenge with live organism in mice. An active calf protection test showed that in 24 hours, animals vaccinated with plain saline died after challenge compared to those given the subunit vaccine which survive the challenge dose. Using 104 cattle from a farm, the field trial of the HS subunit vaccine showed that the antibody titre was high for up to 14 months. A high titer is an indication of protection.