Submitted to: Keystone Symposia
Publication Type: Abstract Only
Publication Acceptance Date: 2/14/2013
Publication Date: 4/28/2013
Citation: Spear, A.R., Lager, K.M., Faaberg, K.S. 2013. The use of epitope tags in modified porcine respiratory and reproductive syndrome virus vaccines to differentiate infected from vaccinated animals. Positive Strand RNA Viruses, Keystone Symposia on Molecular and Cellular Biology. Paper No. 2079, p. 94.
Technical Abstract: Porcine respiratory and reproductive syndrome virus (PRRSV) is a positive sense single-stranded RNA virus which has been a significant cause of economic loss to the global pork industry since its emergence in the late 1980's. Despite the availability of modified live virus (MLV) vaccines since the mid-1990's, PRRSV vaccination strategies have been of only moderate success due to the high genetic diversity and rapid rate of viral evolution. This extensive strain diversity has also complicated field surveillance, making the need to differentiate infected from vaccinated animals (DIVA) even more essential. Any effective next generation PRRSV vaccine must take advantage of the DIVA concept to simplify disease surveillance protocols and better track the effects of vaccination within herds. To this end, we have designed potential DIVA vaccines using the Ingelvac® PRRS MLV backbone. Deletions in the highly immunogenic nsp2 protein, previously shown to have minimal effects on virus replication in other strains, were engineered into an MLV cDNA clone. These viral sequences were replaced with well established epitope tags for which commercial reagents are readily available. The epitope tags chosen are completely foreign to vaccinated animals, and thereby generate an immune response to the tag correlated only with vaccination with a DIVA MLV. The genetic stability of these deletion MLVs and the corresponding tagged MLVs were investigated in vitro as an indicator of potential replicative success in animals. Further, DIVA-MLVs were tested in vivo to ascertain replication levels of the vaccine strains as well as immunogenicity of the epitope tags. Long term implementation of a DIVA-MLV vaccination strategy will significantly improve PRRSV surveillance as well as local outbreak control, and can serve as a model for the development of next generation DIVA PRRSV vaccines.