Fusobacterium leukotoxoid vaccine

A method of producing a vaccine for immunizing ruminant animals against F. necrophorum infection, comprising the steps of:

• forming a culture of F. necrophorum bacteria culture of in growth media;
• causing said bacteria to grow in said culture, and to elaborate leukotoxin in a supernate, including the steps of culturing at a temperature of from about 35.degree.-41.degree. C. and a pH of from about 6.5-8 for a period of from about 4-9 hours;
• and
• forming said vaccine by inactivating at least said leukotoxin supernate at the end of said culturing period.

A method of enhancing the elaboration of leukotoxin from F. necrophorum, comprising the steps of:

• forming a culture of a strain of F. necrophorum bacteria culture of in growth media;
• causing said bacteria to grow in said culture, and to elaborate leukotoxin in a supernate, including the steps of culturing at a temperature of from about 35.degree.-41.degree. C. and a pH of from about 6.5-8 for a period of from about 4-9 hours;
• and
• terminating said bacterial growth and leukotoxin elaboration at the end of said period, while preserving a substantial proportion of the elaborated leukotoxin.

A method of producing a vaccine for immunizing ruminant animals against F. necrophorum infection, comprising the steps of:

• forming a culture of a biotype A strain of F. necrophorum bacteria in growth media;
• causing said bacteria to grow in said culture, and to elaborate leukotoxin in a supernate, including the steps of culturing at a temperature of from about 35.degree.-41.degree. C. and a pH of from about 6.5-8 for a period of from about 4-10 hours, while preserving a substantial proportion of the elaborated leukotoxin;
• and
• forming said vaccine by inactivating at least said leukotoxin superhate at the end of said culturing period.