Development of Bovine Ephemeral Fever G Protein Subunit Vaccines

AP Hsu*, YJ Lin, YL Lee, LJ Ting, CH Tseng, TS Huang

Animal Health Research Institute, Council of Agriculture, Executive Yuan

Abstract

Bovine ephemeral fever (BEF) caused by bovine ephemeral fever virus (BEFV), is an arthropod-borne disease. In Taiwan, the first outbreak recorded was in 1967; since then, these have occurred every three to six years. This febrile disease induces serious economic loss in the dairy industry through reduction of milk production and raising cull rates. Currently available killed vaccine produced by cell culture has a high production cost as it is labor extensive, as well as a lower-titer virus production. Since the G protein of BEFV can induce high neutralizing antibody titers, the G protein was cloned and expressed in a baculovirus expression system. A nucleic acid fragment of G protein, generated by RT-PCR using a Taiwan isolate (from 2007) as template, was fused to baculovirus genomic DNA and transfected recombinant DNA to insect cells Sf9. The recombinant progeny baculovirus was screened to select the clones expressing G protein. Currently, a vaccine trial using the recombinant protein derived from the baculosvirus system with adjuvant showed strong neutralization antibody titers (32× and 128×) in cows, thus achieving higher titers than the required national standard.

Keyword:bovine ephemeral fever, G protein, baculovirus, subunit vaccine.