Formalin-inactivated,aluminum phosphate gel-adsorbed vaccine of bovine ephemeral fever virus

Summary An inactivated vaccine prepared from virus grown in hamster lung cells produced specific neutralizing antibody by intramuscular inoculation in cattle as well as in mice. Antibody response of cattle after one dose of vaccine was poor both in antibody level and seroconversion rate. However, a second dose given at intervals of 3 or more weeks induced a rapid and high-titered antibody formation in almost all animals. The antibody levels thus attained declined rather rapidly in several months, yet a booster dose given one year later provoked a rapid antibody response. Considering this pattern of antibody response together with the seasonal incidence of the disease it seems adequate that the initial immunization with two doses and the booster inoculation be made in late spring or early summer, immediately before the epizootic season. The vaccination prevented the disease in calves challenged with virulent virus. The vaccine exerted little side effects in cattle. Cows vaccinated during pregnancy gave birth to healthy calves in term. No adverse effects of vaccination on milk production was shown. All these findings indicate efficacy and safety of the vaccine, although the final evaluation rests on largescale field trials.