Development of a Dual Fluorescent Microsphere Immunological Assay for Detection of Pseudorabies Virus gE and gB IgG Antibodies

Abstract

Pseudorabies, also known as Aujezsky’s disease, is an acute viral infection caused by pseudorabies virus (PRV). Swine are one of the natural hosts of pseudorabies and the disease causes huge economic losses in the pig industry. The establishment of a differential diagnosis technique that can distinguish between wild-type infection and vaccinated responses and monitor vaccine-induced immunoglobulin G(IgG) is crucial for the eventual eradication of pseudorabies. The aim of this study was to develop a rapid dual detection method for PRV gE and gB protein IgG antibodies with high specificity and sensitivity. PRV gE codons at amino acid residues (aa) 52–238 and gB codons at aa 539–741 were expressed to obtain recombinant PRV gE and gB proteins via a pMAL-c5x vector. After purification with Qiagen Ni–nitrilotriacetic acid (NTA) agarose affinity chromatography, the two proteins were analyzed via SDS-PAGE and immunoblotting assays. Two single fluorescent-microsphere immunoassays (FMIAs) were established by coupling two recombinant proteins (gE and gB) to magnetic microbeads, and an effective dual FMIA was developed by integrating the two single assays. Optimal serum dilution for each assay, correlation with other common swine virus-positive sera, and comparison with ELISA for two PRV antigens were tested for validation. Compared with ELISA, the specificity and sensitivity were 99.26% and 92.3% for gE IgG antibody detection, and 95.74% and 96.3% for the gB IgG antibody detection via dual FMIA. We provide a new method for monitoring PRV protective antibodies in vaccinated pigs and differentiating wild-type PRV infection from vaccinated responses simultaneously.