VACCINATION OF PIGS WITH REPLICATION-DEFECTIVE ADENOVIRUS VECTORED VACCINES - THE EXAMPLE OF PSEUDORABIES

The efficacy of a recombinant human adenovirus type 5 expressing go, o ne of the immunogenic glycoprotein of pseudorabies virus, was tested i n pigs. Due to the deletion of the E1a gene, the recombinant virus is unable to replicate in non transcomplementing cells but is capable of eliciting an immune response against gp50 after inoculation into anima ls. The virus was formulated in a water/oil/water emulsion, a strategy previously shown to enhance the immune response against the virus-ind uced gp50. Pigs of 18-25 kg were vaccinated twice and the recombinant virus was not isolated from nasal and rectal swabs taken after each in jection of the vaccine. High levels of neutralizing antibodies were in duced by the vaccination. Protection against a severe challenge was ef fective, as measured by growth performance (dG = 1.73), and reduction of the time of excretion of the challenge strain (mean time: 4.4 days for the vaccinated and 7.9 days for the control pigs). These results s how that non replicating adenoviruses are able to induce a strong prot ective immune response against foreign genes in pigs, which may be of general interest for the design of pig vaccines.