Humoral immune response and hematologic evaluation of pregnant Jersey cows after vaccination with Anaplasma centrale

The main objective of this work was to evaluate the safety of an Anaplasma centrale vaccine in pregnant pure bred Jersey cows selected from a herd located at Miranda State, Venezuela. Ten cows of 3-5 months of gestation were chosen and previous vaccination all cows were tested for Anaplasma antibodies by the indirect immunofluorescence assay (IFA), so only seronegative cows were included in the group, and for blood parameters, rectal temperature, and pregnancy. Selected cows were vaccinated intramuscularly with 1ml of an A. centrale live vaccine which had 10(8) A. centrale per ml. Over the next 2 months cows were checked weekly for hematological parameters and Anaplasma antibodies, and then for the next 2 months these evaluations were performed monthly. Among the values monitored were: A. centrale parasitemia, hematocrit, hemoglobin, and white blood cells (WBCs) (neutrophil, lymphocyte and eosinophil counts). Levels of Anaplasma antibodies were measured by IFA. Anaplasma were observed for the first time in blood films of two vaccinated cows at 14 days post-vaccination (PV), 6 out of 10 cows were A. centrale positive at 30 days PV, and all cows were A. centrale positive at 42 days PV. A. centrale often showed low parasitemia, 1-3%. Anaplasma antibodies were detected at day 14 PV in all vaccinated cows with a mean group titre of 360 (range: 80-1280). All vaccinated cows showed few changes in their hematologic parameters or in rectal temperature, and all gave birth to healthy calves. In conclusion, adult pregnant cows were safely vaccinated with this live A. centrale vaccine, which may help to develop a cross-protective immunity against field strains of A. marginale.