| Abstract: | Trials were conducted on rabbits and cattle to compare the immunizing effectiveness of the subunit vaccine against infectious bovine rhinotracheitis (IBR), representing antigens separated by the solubilization of the IBR virus-infected cells by means of Triton X-100 with oil adjuvant, with the inactivated oil IBR vaccine. The rabbits inoculated and re-vaccinated with both vaccines in an interval of three weeks produced neutralizing antibodies in medium titres, the values of these antibodies were balanced in both groups. Cattle immunized with the subunit vaccine reacted to the inoculation and re-vaccination by producing serum antibodies of higher titres, as compared with the cattle inoculated with the virus vaccine; secretory antibodies were detected only after re-vaccination and had balanced values in both test groups. After intranasal infection with the virulent virus performed after 14 days from re-vaccination, the calves inoculated with the subunit and virus vaccines were protected against clinical disease whereas the non-inoculated control calves fell ill with symptoms characteristic of IBR. The immunized animals of both experimental groups had a smaller amount of virus p.i. in nasal secretions and for a shorter time than the control non-inoculated calves. The intensity of multiplication and persistence of infectious virus excretion were the same in both experimental groups. |
