Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/12/2011
Publication Date: 11/17/2011
Citation: Bauermann, F.V., Flores, E.F., Ridpath, J.F. 2011. Antigenic differences between bovine viral diarrhea viruses and HoBi virus: Possible impacts on diagnosis and control [abstract]. In: Proceedings of the U.S. Bovine Viral Diarrhea Virus Symposium, November 17-18, 2011, San Diego, California. p. 73. Interpretive Summary:
Technical Abstract: Compare antigenic differences between HoBi virus and BVDV strains that might impact on diagnostics and control. Eighteen non-cytopathic isolates of pestiviruses including the 5 genotypic groups (BVDV1a-c, BVDV2, BDV) and HoBi virus, were tested using antigen capture enzyme-linked immunosorbent assay (ELISA) HerdCheck Kit® (IDEXX). Dilutions of the viruses were performed (10**6-10**3 TCID/ml). Statistical methods were used to analyze differences in the titer detected between viruses. A monoclonal antibody (MAb) panel, composed of 16 MAbs with specificity against epitopes in Erns, E2, or NS3 BVDV peptides was also used to evaluate antigenic difference between these viruses. Additionally, convalescence sera from 9 calves experimentally infected with HoBi virus were tested by virus neutralization test (VNT) and two commercial ELISA kits: SVANOVIR BVDV p80-Ab® (SVANOVA) and BVDV Ab Test kit® (IDEXX). Cross-neutralization between 2 HoBi antibodies positive sera samples and 12 viruses, including the 5 genotypic groups (BVDV1a-c, BVDV2, BDV) and HoBi, were also performed using VNT. In addition, 50 cows were immunized against BVDV 1 and 2, two doses, 30 days apart. Eight weeks later, the sera was collected and tested by VNT against 12 pestiviruses. The threshold of detection of HoBi virus by the antigen capture ELISA kit, was statistically similar to BVDV. Reactivity with a panel of monoclonal antibodies (MAbs) revealed greater cross reactivity between either BVDV species (BVDV1, BVDV2) and HoBi epitopes within Erns and NS2/3 proteins than between epitopes located in the E2 glycoprotein. Commercial antibody detection ELISA kits, missed 22.2% (IDEXX) and 77.7% (SVANOVA) of serum samples harboring HoBi virus neutralizing antibodies. VNT using 2 HoBi antibody positive sera samples against BVDV1 strains showed very low to negative cross neutralization titers. In addition, sera of cows vaccinated with BVDV1 and BVDV2 presented very low neutralizing activity against HoBi virus. Our results demonstrate that, while there are some antigenic similarities, HoBi is antigenically distinct from both BVDV species. MAb binding suggest that a diagnostic designed to detect both BVDV species and HoBi could be based on detection of Erns or NS2/3 epitopes, while variation among E2 epitopes could be exploited in tests for pestivirus species differentiation. Although antigen capture ELISA kit may be adequate for HoBi virus detection, two commercial ELISA kits designed to detect antibodies against BVDV, missed significant part of samples harboring HoBi virus neutralizing antibodies. These results indicate that the detection and control of HoBi infections in cattle and the differential of HoBi-like viral infections from BVDV infections will require the development of new diagnostics and reformulation of current vaccines.