Detection of antibodies to equine arteritis virus by enzyme linked immunosorbant assays utilizing G(L), M and N proteins expressed from recombinant baculoviruses

Indirect enzyme linked immunosorbant assays (ELISAs) utilizing the three ma jor structural proteins (M, N, and G(L)) of equine arteritis virus (EAV) ex pressed from recombinant baculoviruses were developed. A large panel of ser a collected from uninfected horses, and from animals experimentally and nat urally infected with EAV or vaccinated with the modified live virus vaccine against equine viral arteritis, were used to characterize the humoral immu ne response of horses to the three major EAV structural proteins. The data suggest that the M protein was the major target of the equine antibody resp onse to EAV. The responses of individual animals varied and ELISAs that uti lized individual EAV structural proteins were not reliable for detecting an tibodies in all sera that contained neutralizing antibodies to EAV. An ELIS A based on a cocktail of all three EAV structural proteins, however, was us ed successfully to detect antibodies in most equine sera that were positive in the standard serum neutralization assay following natural or experiment al EAV infection (100% specificity, 92.3% sensitivity). In contrast, this E LISA did not reliably detect antibodies in the sera of vaccinated horses. E AV frequently causes a persistent infection in stallions and all sera from carrier stallions evaluated in this study had obvious reactivity with the N protein, whereas seropositive non-carrier stallions, mares and geldings di d not respond consistently to the N protein. (C) 1998 Elsevier Science B.V. All rights reserved.