Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/14/2011
Publication Date: 3/1/2012
Citation: Bauermann, F.V., Flores, E.F., Ridpath, J.F. 2012. Antigenic relationships between bovine viral diarrhea virus 1 and 2 and HoBi virus: Possible impacts on diagnosis and control. Journal of Veterinary Diagnostic Investigation. 24(2):253-261. Interpretive Summary: The term pestivirus refers to a group of related viruses, known as a genus, that cause disease in domestic and wild animals. Infection of domestic animals with pestiviruses results in large economic losses to producers worldwide. Historically, the pestivirus genus has been divided into three subgroups of viruses, known as species. These three species were called classical swine virus (causes disease primarily in pigs), border disease virus (causes disease primarily in sheep and goats), and bovine viral diarrhea viruses (causes disease primarily in cattle) (BVDV). New techniques that allow the comparison of the genes of pestiviruses have revealed that there are previously unrecognized species of pestiviruses circulating in domestic and wild animals. One of these newly recognized species is called HoBi-like viruses. HoBi-like viruses are of particular concern because they cause disease in cattle and have been spreading in South America and Southeast Asia. If HoBi-like viruses spread to the United States it would cause significant damage to beef and dairy production and could threaten wildlife populations. The purpose of the studies reported in this manuscript was to determine if HoBi-like viruses could be detected using testing currently used to detect other pestiviruses and if HoBi-like viral infections could be controlled using commercial BVDV vaccines. It was found that current tests and commercial vaccines are not adequate to use for surveillance and prevention of infection of cattle with HoBi-like strains. This indicates that control of this group of viruses requires the design of new diagnostics and vaccines.
Technical Abstract: The emergence of a newly recognized group of pestiviruses, the HoBi-like viruses, in cattle requires an evaluation of available diagnostic tools and vaccines. Herein, we compared antigenic characteristics between bovine viral diarrhea virus (BVDV) strains and HoBi virus. This comparison was based on detection of a HoBi virus and antibodies against a HoBi virus using commercial ELISA tests and the level of cross neutralizing antibodies present in sera from animals vaccinated against 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. These results 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. The threshold of detection of HoBi virus by an antigen capture enzyme-linked immunosorbent assays (ELISA) kit, based on detection of Erns epitopes, was statistically similar to BVDV. In contrast, two commercial ELISA kits designed to detect antibodies against BVDV, missed 22.2% and 77.7% of serum samples harboring HoBi virus neutralizing antibodies. In addition, sera of cows vaccinated with BVDV-1 and BVDV-2 presented very low neutralizing activity against HoBi virus, indicating that currently available BVDV vaccines afford limited protection against infection with a HoBi-like virus. In summary, our results demonstrate that, while there are some antigenic similarities, HoBi is antigenically distinct from both BVDV species. Detection and control of HoBi infections in cattle will require the development of new diagnostics and reformulation of current vaccines.