Pseudorabies virus (PRV) is ranked fourth in the Swine Health Information Center (SHIC) Swine Disease Matrix in large part due to the potential for the introduction of highly pathogenic PRV into the US from Asia – an event which would have a highly negative impact on pork exports. In addition, while PRV was officially eliminated from US domestic swine in 2004, it is occasionally introduced into “transitional” herds via contact with feral swine. For these reasons, improvements in PRV diagnostics, surveillance, control, and elimination remain relevant. The final report on a study conducted at Iowa State University (ISU) to evaluate the detection of PRV in swine oral fluid, providing additional testing resources using real-time PCR assays, has been posted. This research involving PCR PRV oral fluid testing was supported by a grant from SHIC.
Widely used PRV PCRs were developed for individual animal nasal swabs, but not for swine oral fluid. Therefore, ISU researchers set out to evaluate the detection of PRV in swine oral fluid collected from vaccinated and/or inoculated pigs using a contemporary real-time PCR assay targeting PRV gB genes. The results showed that PRV DNA could be detected in swine oral fluid specimens using a PRV gB PCR. Based on comparisons of detection rates in nasal swab vs oral fluid samples, the researchers also found that oral fluid could be used as an alternative to individual pig (nasal swab) sampling for PRV surveillance. They cautioned that further improvements in the performance of the gB PCRs would be recommended before its use in routine surveillance.
A separate study conducted at ISU and published in 2020 addressed the detection of PRV antibody in oral fluids. Analyses of an oral fluid PRV indirect IgG ELISA showed good binary diagnostic performance and excellent assay repeatability. Importantly, this study demonstrated the feasibility of detecting PRV antibodies in oral fluid specimens. This represents the first step toward the development of a DIVA-compatible oral fluid–based ELISA for use in PRV control and elimination programs.
Together, these two bodies of work illustrate the progress being made to prevent and respond to potential PRV outbreaks in the US swine herd.
As the world deals with the COVID-19 pandemic, SHIC continues to focus efforts on prevention, preparedness, and response to novel and emerging swine disease for the benefit of US swine health. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. SHIC is funded by America’s pork producers to fulfill its mission to protect and enhance the health of the US swine herd. For more information, visit http://www.swinehealth.org or contact Dr. Sundberg at [email protected].