Summary
The
results of an enzyme-linked immunosorbent assay (ELISA) implemented
for the detection of gamma interferon (g-interferon)
production in cattle vaccinated with Brucella abortus strain
RB51 are presented. A purified protein fraction derived from RB51
(RB51 brucellin) has been used as antigenic stimulus for whole blood.
The test was evaluated for 300 days in ten heifers vaccinated at
calfhood with 10 × 109 colony-forming units of RB51 and
in five control heifers. All animals came from officially brucellosis-free
herds. Vaccinated animals started to give positive results from
day 17 post vaccination (pv) until day 239 pv. All vaccinated animals
gave a positive reaction at least once (with a stimulation index
exceeding 2.5). Nevertheless, if sampling on day 20 pv is excluded
(90% of vaccinated animals gave positive results), the sensitivity
of the test varies from 20% to 70%, with a 40% average. A stimulation
index over 2.5 was also recorded in three control animals. The results
suggest that the g-interferon
test is not suitable for the detection of cattle vaccinated with
RB51, either at the individual or at the herd level.
Keywords
Brucella
abortus, Brucellosis, Eradication, ELISA, Enzyme-linked immunosorbent
assay, Gamma interferon, RB51, Vaccination. |