2012 Annual Report 1a.Objectives (from AD-416): The purpose of this collaboration is to construct and test an alphavirus replicon particle vaccine that expresses the E2 regions of three different BVDV strains, one being a BVDV1a, one a BVDV1b, and one a BVDV2a. 1b.Approach (from AD-416): Construct an alphavirus replicon particle vaccine that expresses the E2 regions of three different BVDV strains, one being a BVDV1a, one a BVDV1b, and one a BVDV2a. This prototype vaccine would be administered to BVDV naïve calves and the immune response evaluated. 3.Progress Report: Replicon particles that expressed bovine viral diarrhea virus sub-genotype 1b E2 glycoprotein were generated and expression was confirmed in vitro using polyclonal and monoclonal antibodies specific to E2. Vaccine made from particles was generated in Vero cells and administered to BVDV free calves in a prime/boost regimen at two dosage levels. Vaccination resulted in neutralizing antibody titers that cross-neutralized both type 1 and type 2 BVD genotypes following booster vaccination. Additionally, high dose vaccine administration demonstrated some protection from clinical disease and significantly reduced the degree of leukopenia caused by viral infection.