ARS | Publication request: Evaluation of a real-time PCR assay for pseudorabies virus surveillance purposes

Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 9, 2012
Publication Date: July 1, 2012
Citation: Zanella, E.L., Miller, L.C., Lager, K.M., Bigelow, T.T. 2012. Evaluation of a real-time polymerase chain reaction assay for pseudorabies virus surveillance purposes. Journal of Veterinary Diagnostic Investigation. 24(4):739-745.

Interpretive Summary: The successful eradication of pseudorabies in U.S. domestic swine was accomplished through the use of modified-live virus vaccines and an accompanying blood test that could differentiate vaccinated swine from swine that have been infected with pseudorabies virus (PRV), the virus that causes pseudorabies. Some feral swine in the U.S. are infected with pseudorabies virus and they represent a potential reservoir of this virus for infection of domestic swine and other native wildlife. A critical need for the current PRV surveillance program is the rapid detection of PRV. For this reason, a real-time PCR assay was developed and evaluated for its capability in the detection and differentiation of field and vaccine strains of PRV. The aim of the present study was to evaluate the real-time PCR assay for use as a diagnostic assay to detect an acute PRV infection in experimentally infected pigs. In addition, other tissue samples had good agreement between results of VI and PCR. Diagnostic performance of the real-time PCR assay developed as a testing method indicates that it is a rapid, accurate assay that can provide reliable results on an array of clinical samples.

Technical Abstract: Pseudorabies virus (PRV) is the cause of Aujeszky’s disease, a significant economic disease for the swine industry worldwide that is also known as pseudorabies. Clinical signs are related to respiratory and nervous systems, which are the preferred site for PRV replication. Also, PRV infection can cause a high mortality in neonatal piglets, abortion in sows, and loss of body condition in growing pigs. The feral swine population is known to be infected with PRV strains, and considered to be a threat for the commercial swine industry. Real-time polymerase chain reaction (real-time PCR) is a valuable diagnostic technique that can rapidly identify nucleic acid of infectious agents in clinical specimens. A real-time PCR assay based on the gB and gE genes was designed to identify PRV nucleic acid in diagnostic samples. Using VI as the gold standard test, the assay performed well in a variety of diagnostic matrices. Testing was conducted on 1,027 nasal swabs (gB sensitivity: 94.6% [95% confidence interval (CI): 92.3–96.4%], specificity: 71.0% [95% CI: 64.0–77.3%]); gE sensitivity: 94.6% [95% CI: 92.3–96.4%], specificity: 79.3% [95% CI: 72.9–84.7%]).