Plackett P, Alton G G, Carter P D, Corner L A
Aust Vet J. 1980 Sep;56(9):409-12. doi: 10.1111/j.1751-0813.1980.tb02632.x.
Groups of heifer calves were vaccinated subcutaneously with the standard dose of strain 19 at the age of 3 to 5 weeks or 5 months. Twelve months after primary vaccination a group of the younger vaccinates were revaccinated with a small dose of strain 19 via the conjunctival sac. The effectiveness of vaccination was assessed by challenge with virulent B. abortus after 5 to 6 months of pregnancy. Animals vaccinated at 3 to 5 weeks, but given no intraconjunctival boost, were not effectively protected, but the group receiving the boost were at least as resistant as those which received the subcutaneous dose at 5 months. The intraconjunctival boost caused only slight and transient serological responses in a few animals.
