PROTECTION OF PIGS AGAINST AUJESZKYS-DISEASE BY DNA VACCINATION

Vaccination with DNA constructs encoding viral antigens has been shown to induce antiviral immunity in various model hosts. However, relevan t natural virus-host systems have so far been analysed to only a very limited extent, To test the efficacy of DNA vaccination in an economic ally important large animal, pigs were immunized against Aujeszky's di sease, a serious virus infection caused by the alphaherpesvirus pseudo rabies virus (PrV), which is characterized by severe central nervous a nd respiratory symptoms, After vaccination with plasmid vectors contai ning genes for immunogenic envelope glycoproteins C or D (gC or go) of PrV under control of the major immediate early promotor of human cyto megalovirus, animals developed serum antibodies which recognized the r espective antigen in immunoblot and exhibited neutralizing activity. A nimals vaccinated with the gC expression plasmid were fully protected against a lethal challenge with PrV strain 75V19, and showed partial p rotection against the highly virulent NIA-3 strain. In contrast, prote ction was not observed after vaccination with the gD plasmid, Three in tramuscular or intradermal immunizations with as little as 1 mu g of g C plasmid DNA resulted in seroconversion and partial protection agains t lethal NIA-3 infection, Specific antibodies were detected until at l east 9 months after vaccination, In addition, a cellular immune respon se specific for gC could be demonstrated in proliferation assays of pe ripheral mononuclear lymphocytes. Our results thus demonstrate the pot ency of DNA vaccination for protection of large animals against a leth al virus infection.