Assessing the Role of PRRSV Envelope Minor Glycoprotein 3 in the Induction of an Immune Response in Swine Using a Heterologous Prime-Boost Vaccination Schedule
The role of PRRSV envelope minor glycoprotieins in the induction of a protective immune response in swine is an area of research that may have major impact on the development of a broadly protective vaccine. The objective of this study is to assess the contribution of GP3, a minor glycoprotein present on the surface of the PRRSV envelope, to the induction of an immune response in pigs. To accomplish this, a prime-boost vaccination schedule using heterologous vector systems was tested in animals. We elected to use an adenovirus vector as a gene delivery system and a baculovirus vector for recombinant protein production. GP3 was cloned in to the Invitrogen ViraPower Adenovrial Expression System and the Invitrogen Bac-to-Bac Baculovirus Expression Vector System, and protein expression was confirmed by western blot. Virus and protein production were optimized and scaled up for use in animal studies. Adenvirus vectored GP3 served as a priming vaccination; then animals were boosted with recombinant protein produced in a baculovirus expression vector system. We detected specific anti-GP3 antibodies in pigs immunized with GP3. Prime-boost vaccination with GP3 led to a decrease in PRRSV viremia after challenge and this vaccination was able to prime the host immune system.