Submitted to: American Association of Swine Veterinarians Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: September 15, 2003
Publication Date: June 28, 2004
Citation: Wesley, R.D., Lager, K.M. 2004. A recombinant Ad-5 swine influenza vaccine that overrides maternal antibody interference. Proceedings of the 35th Annual Meeting of the American Association of Swine Veterinarians, March 6-9, 2004, Des Moines, Iowa. p. 447-449. Technical Abstract: A recombinant human adenovirus (rAd5) vaccine was used in combination with an inactivated commercial vaccine to stimulate protective immunity in piglets that had natural field exposure levels of maternally-derived antibodies. Replication-incompetent adenoviruses expressing the H3 hemagglutinin gene and the nucleoprotein gene of swine influenza virus H3N2 were constructed. Piglets suckling gilts that were naturally infected with H3N2 influenza virus were vaccinated with the rAd5-SIV vaccine or sham-inoculated with a non-expressing rAd5 vector at 7 days of age. The hemagglutination inhibition (HI) titer of the sham-inoculated group (n = 12) showed continued antibody decay whereas piglets vaccinated with rAd5-SIV (n = 24) developed an active immune response by the second week post-vaccination. At 4 weeks old when the HI titer of the sham-inoculated group was about 40, the sham-inoculated group and half of the rAd5-SIV vaccinated pigs were boosted with a commercial bivalent vaccine. The boosted pigs that had been primed in the presence of maternal interfering antibody had a strong anamnestic response while sham-inoculated pigs did not respond to the commercial vaccine. Two weeks after the booster vaccination the pigs were challenged with a different H3N2 virulent SIV. The efficacy of the vaccination protocol was demonstrated by abrogation of clinical signs, by clearance of challenge virus from lung lavage fluids, by markedly reduced virus shedding in nasal secretions, and by the absence of moderate or severe SIV-induced lung lesions. These rAd5-SIV vaccines can be used for priming of the immune system to overcome the effects of maternally-derived antibody which interferes with conventional SIV vaccines.