A novel protein chip for simultaneous detection of antibodies against four epidemic swine viruses in China

BACKGROUND: At present, pig industry in China is faced with the complex situation of mixed infection caused by multiple pathogens. It is urgent to develop some new high-throughput molecular diagnosis assays to simultaneously detect pathogens or antibodies. Biochip array technology has made it possible to screen thousands of samples simultaneously; it has been twice named as one of the top 10 scientific and technological breakthroughs. Studies have reported encouraging results using protein biochips for detecting antibodies against avian infectious bronchitis virus and ruminant bluetongue virus, but the research of this technology for the diagnosis of swine diseases is still sparse. RESULTS: In this study, a novel protein chip was developed that can simultaneously detect the antibodies of four important swine viruses as follow, classical swine fever virus (CSFV), porcine parvovirus (PPV), Japanese encephalitis virus (JEV), and porcine reproductive and respiratory syndrome virus (PRRSV). Four prokaryotic expression plasmids pET-32a-E2 of CSFV, −VP2 of PPV, −EDIII of JEV, and -N of PRRSV were induced by IPTG (Isopropyl β-D-1-Thiogalactopyranoside) and overexpressed in E.coli, respectively. The purified proteins were identified by Western blotting and then printed on epoxy-coated glass slides. The optimized parameters of this diagnostic chip showed that the spotting concentrations of E2、VP2、EDIII、N proteins were 0.2, 0.4, 0.4, and 0.4 mg/mL. The optimal primary and secondary antibody dilutions were 1:50 and 1: 600. Compared with the commercial ELISA (Enzyme-linked immunosorbent assay) kits, the positive and negative coincidence rates of this chip were 95.8% ~ 100 and 86.2% ~ 100%, as well as, no cross-reaction. CONCLUSION: This protein chip provided a fast, specific, and sensitive method for simultaneous detection of antibodies in clinical serum samples. Compared with traditional methods, this protein chip can monitor very small amount of serum.