In hog cholera control vaccination using both homotypic (LPC) and hetero-typic ( BVD) antigens. the serum levels of BVD and HC antibody of sows or gilts could transfer via colostrum, and would effectively interfere with actiive immunization of their offspr-ing Present studies were designed to study vaccination procedures using both homotypic and heterotypic antigens to determine protocols best suited for immunization of breeding animals, fattening pig and piglets.
The gilts inoculated of BVD antigen followed by inoculation with LPC vaccine, it was noted that the same secondary-like antibody rosponse to both BVD and HC antigens was observed. High titers against HC virus persistod and peak BVD antibody levels were recorded 2-3 wks post LPC vaccination. Because the serum colostral BVD antibody titers of the piglets', so they did not get satisfactory immunity when vaccinated with BVD antigen. However, LPC+BVD antigens were universally successfulvaccination treatments.
A secondary-like response was not recorded for either virus and although serum BVD antibody titers were observed to drop with time. in the BVD·-BVD vaccination gilts, btlt they had not dropped to a level sufficiently low to preaent interference by the BVD virus vaccine used in Piglets Repeated revaccination with BVD would also result in a low level of serum neutralizing HC antibody, a level sufficiently low, however, so no interference with immunization of their piglets with LPC or LPC+BVD vaccine would result.
It would appear that the best vaccination procedure for a practical immunization program at 3wks of age woul be as follows. Immunize all piglets with LPC+BVD vacci-ness. Pigs kept for breeders would be revaccination with the heteroimmunogen. All sows would then be revaccinated \vith BVD virus annually. And in order to export raw meat, the vaccination program for the fattening pigs must be established .