FAILURE OF A SINGLE DOSE OF BRUCELLA ABORTUS STRAIN 19 VACCINE TO PROTECT CATTLE WHEN GIVEN EARLY IN CALFHOOD |
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| Authors: | P. Plackett G. G. Alton P. D. Carter L. A. Corner |
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| Affiliation: | CSIRO Division of Animal Health, Animal Health Research Laboratory, Private Bag No. 1, P.O., Parkville, Victoria, 3052 |
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| Abstract: | SUMMARY 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. |
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