Immunogenic and protective properties of GP5 and M structural proteins of porcine reproductive and respiratory syndrome virus expressed from replicating but nondisseminating adenovectors
1 Department of Biological Sciences, University of Québec at Montréal, Succursale Centre-Ville, P.O. Box 8888, Montréal, Québec, H3C 3P8, Canada
2 Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montréal, Québec, H4P 2R2, Canada
3 Adjunct professor, Department of Microbiology and Immunology, University of Montréal, Succursale Centre-Ville, P.O. Box 6128, Montréal, Québec, H3C 3J7, Canada
4 Groupe de recherche sur les maladies infectieuses du porc, Faculty of Veterinary Medecine, University of Montréal, 3200 rue Sicotte, St-Hyacinthe, Québec, J2S 7C6, Canada
5 Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, 2000 College Street, Sherbrooke, Québec, J1M 1Z3, Canada
Veterinary Research 2013, 44:17 doi:10.1186/1297-9716-44-17Published: 11 March 2013
Porcine reproductive and respiratory syndrome virus (PRRSV) is responsible for significant economic losses in the porcine industry. Currently available commercial vaccines do not allow optimal and safe protection. In this study, replicating but nondisseminating adenovectors (rAdV) were used for the first time in pigs for vaccinal purposes. They were expressing the PRRSV matrix M protein in fusion with either the envelope GP5 wild-type protein (M-GP5) which carries the major neutralizing antibody (NAb)-inducing epitope or a mutant form of GP5 (M-GP5m) developed to theoretically increase the NAb immune response. Three groups of fourteen piglets were immunized both intramuscularly and intranasally at 3-week intervals with rAdV expressing the green fluorescent protein (GFP, used as a negative control), M-GP5 or M-GP5m. Two additional groups of pigs were primed with M-GP5m-expressing rAdV followed by a boost with bacterially-expressed recombinant wild-type GP5 or were immunized twice with a PRRSV inactivated commercial vaccine. The results show that the rAdV expressing the fusion proteins of interest induced systemic and mucosal PRRSV GP5-specific antibody response as determined in an ELISA. Moreover the prime with M-GP5m-expressing rAdV and boost with recombinant GP5 showed the highest antibody response against GP5. Following PRRSV experimental challenge, pigs immunized twice with rAdV expressing either M-GP5 or M-GP5m developed partial protection as shown by a decrease in viremia overtime. The lowest viremia levels and/or percentages of macroscopic lung lesions were obtained in pigs immunized twice with either the rAdV expressing M-GP5m or the PRRSV inactivated commercial vaccine.