A trivalent leptospiral vaccine with emphasis on a Leptospira interrogans serovar hardjo component to prevent leptospiruria

Abstract

A trivalent leptospiral vaccine prepared by incorporating servovar hardjo in an existing pomona, copenhageni product has been evaluated in both hamsters and cattle.

Hamster challenge tests were performed on all 3 components. The hardjo component was initially tested as a separate entity and later in combination with the other serovars using a challenge test. In no case were vaccinated hamsters infected from a hardjo challenge which infected 8/10 non-vaccinated animals. The pomona and copenhageni components passed the European Pharmacopoea potency test for leptospiral vaccines.

Both artificial and natural exposure trials in cattle demonstrated protection against urinary shedding. Vaccinated cattle failed to develop leptospiruria when exposed to an artificial hardjo challenge which produced shedding in 7/10 unvaccinated animals. Trials conducted on 9 dairy farms with leptospirosis problems demonstrated prevention of leptospiruria by vaccination. Protection persisted for at least 12 months.