Humoral immune responses and safety of experimental formulations of inactivated Neospora vaccines.

Antibody titers to Neospora antigens ranged from 40 to 160 before vaccination, from 80 to 5,120 2 weeks after the first dose of vaccination, and 320 to 40,9602 weeks after the second (booster) vaccination. A peak antibody titer of 40,960 was also detected 28 days after the booster vaccination among animals vaccinated with Neospora vaccine formulated with Bay R1005 adjuvant. In heifers inoculated with experimental formulations of Neospora vaccines, transient development of injection site reactions resulted in 1 out of 15 animals. This injection site reaction was not detectable 14 days after the first observation and measurements were made. We have also demonstrated that vaccines derived from tissue-culture-grown Neospora tachyzoites are safe and would be expected to be efficacious.