Development and clinical evaluation of a new gold-immunochromatographic assay for the detection of antibodies against field strains of pseudorabies virus.

An immunochromatographic strip (ICS) was developed for the detection of swine antibodies against glycoprotein E (gE) in Pseudorabies Virus (PRV). In this test, Staphylococcal Protein A (SPA) labeled with colloidal gold was dispensed on a conjugate pad as the detector. Purified PRV-gE and pig-IgG were blotted on a nitrocellulose membrane for the test (T) and control lines (C), respectively. If the tested serum contains IgG antibodies against PRV-gE, the IgG will interact with the colloidal gold-SPA to form a complex (gold-SPA-swine IgG). The complex will react with the immobilized PRV-gE on the T line and the Pig-IgG in the C line of the ICS to form two visible red bands. If there is no IgG antibody against PRV-gE in the sample serum, only the C line will be visible. The ICS was capable of specifically detecting PRV-gE antibody within 5 min, and its stability and reproducibility were quite good after storage at 4°C and use within 4 months. Using an IDEXX Pseudorabies Virus gE Antibody Test Kit (IDEXX PRV gE Ab test) as a reference, the relative specificity and sensitivity of the ICS were determined to be 81.6% and 90.7%, respectively. Furthermore, there was a good agreement between the results obtained by the commercial product and the ICS (kappa=0.7289).