Evaluation of Loop-mediated Isothermal Amplification (LAMP), Polymerase Chain Reaction (PCR), and Non-biotin Polymerized Horseradish Peroxidase (Non-biotin HRP) Immunohistochemistry for Detection of Pseudorabies Virus in Archival Paraffin Sections of Swine Nervous Tissue

Pseudorabies is a common infectious disease in pigs and may cause severe neurological complications, resulting in fatalities in young pigs. This report is to evaluate three methods of loop-mediated isothermal amplification (LAMP), polymerase chain reaction (PCR), and non-biotin polymerized horseradish peroxidase (non-biotin HRP) immunohistochemistry to detect pseudorabies virus (PrV) in archival paraffin sections of swine nervous tissues stored up to twenty years. A total of 27 cases (14 confirmed and 13 unidentified) were used in this study. The results showed that 7/14 with non-biotin HRP, 5/14 with LAMP, and 2/14 with PCR were positive for detection of PrV in confirmed cases, and 3/13 with LAMP, 2/13 with PCR, and 1/13 with non-biotin HRP were positive for PrV in unidentified cases. The detection rate with LAMP used in either confirmed or unidentified cases is higher than the PCR assay. Based on this study, combinations of LAMP and non-biotin HRP immunohistochemistry may potentially provide a convenient and rapid detection tool for retrospective studies of viral infections. In addition, because of no use of sophisticated laboratory equipment, the LAMP assay would be advantageous for use in rapid clinical diagnosis of PrV infection in developing countries during disease outbreak.