DEVELOPMENT AND EVALUATION OF AN ELISA USING RECOMBINANT FUSION PROTEIN TO DETECT THE PRESENCE OF HOST ANTIBODY TO EQUINE ARTERITIS VIRUS

A recombinant glutathione-S-transferase fusion protein expressing amin o acids 55-98 of equine arteritis virus (EAV) G(L) (rG(L)55-98) was te sted in an ELISA for its ability to detect serum antibodies to EAV. Ho st antibodies induced following EAV infection bound the recombinant an tigen by ELISA. The ELISA specificity and sensitivity were determined with a panel of equine sera including postinfection and postvaccinatio n samples. A good correlation existed between EAV neutralizing antibod y titers and ELISA absorbance values (r = 0.827). The sensitivity and specificity of the ELISA were 99.6 and 90.1%, respectively, compared w ith the EAV neutralization test and the recombinant antigen did not cr ossreact in ELISA with equine sera directed against other common equin e respiratory viruses. Three post-EAV infection equine sera raised aga inst different EAV isolates reacted strongly in the ELISA, as did two equine sera raised against EAV vaccines, indicating that the viral epi tope was conserved between the viruses tested. Following vaccination w ith an inactivated whole virus vaccine, antibody detected with the rec ombinant antigen ELISA preceded the development of a virus-neutralizin g response. The study demonstrates the potential application of rG(L)5 5-98 as a diagnostic antigen.