Immunogenicity of infectious bovine rhinotracheitis virus (BHV-1) proteins integrated into ISCOMs or liposomes.

Dynamics and persistence of antibody responses to immunization and reimmunization of rabbits with BHV-1 ISCOMs or BHV-1 liposomes were investigated for 20 weeks and compared with those induced by a commercial vaccine against infectious bovine rhinotracheitis (IBR) or free BHV-1 protein subunits. Comparable levels of antibodies to BHV-1, determined by ELISA, were found throughout the observation period in rabbits treated with BHV-1 ISCOMs or the commercial vaccine. The immunogenicity of BHV-1 liposomes was higher than that of the free virus proteins, but lower than those of BHV-1 ISCOMs or the commercial vaccine. Virus neutralization test confirmed the best immunostimulatory effect of BHV-1 ISCOMs as far as the levels and the persistence of antibodies were concerned. The reactivities of the specific virus protein subunits with anti-BHV-1 antibodies elicited in rabbits immunized with BHV-1 ISCOMs or the commercial vaccine were compared by Western blotting. The patterns of the bands were similar, but some differences were found in their numbers and intensities.