Studies on development of a method for prolonging immune response following a single vaccination against foot-and-mouth disease.

Muchiri, M. N. 1975. Studies on development of a method for prolonging immune response following a single vaccination against foot-and-mouth disease. MSc thesis in Veterinary Science. University of Wisconsin-Madison.

Control of foot-and-mouth disease (FMD) in countries which are unable to eradicate itby the 'slaugher method' is complicated mainly by lack of a good vaccine. Single vaccinations with current vaccines stimulate an antibody protection lasting for 4 to 9 months. It is therefore necessary to revaccinate animals in order to protect them from infection for a period of 12 months. This study is an attempt to prepare a vaccine which on initial administration would stimulate a long lasting immune response. The strategy has been to find a way to prolong the release of antigen, in response to which the animal would produce antibodies of broad specificity, that would be cross-reactive and possibly give more protection to related subtypes. Newcastle disease virus (NDV) was used to study methods which might later be applied to FMD. Thermostability of. freeze-dried virus in mineral oil, a vehicle for slowing hydration and oxidation, was studied at 40 C, which was considered to be the maximum body temperature for animals involved. Sustained release was attempted by incorporating formalin-inactivated virus into oil-wax matrixes which were then surgically implanted. The results were promising. The principle of sustained release was supported by the finding that antibody response was as good or better in animals that received antigen daily over a 30 day period as in those that received the same quantity in two or three injections.