Classical swine fever virus (CSFV) is endemic and circulates in many regions of the world; therefore, the potential re-emergence of CSFV is a continual risk. It is in the pork producers’ best interests to develop an effective CSFV detection-and-response strategy, recognizing that an effective response must be based on reliable technology capable of quickly identifying and eliminating foci of infection.
The goal of this research was to evaluate the diagnostic performance characteristics of commercially-available CSFV tests. Samples used in this study were collected from pigs (n=30) intranasally inoculated with CSFV and from pigs (n=30) vaccinated with CSFV modified live vaccine. Following the CSFV inoculation, serum samples were collected on days post inoculation 0, 1, 2, 3, 4, 5, 6, 7, 10, 14, 17, 21, and 28. Serum (n=602) were tested by commercially-available CSFV assays including rRT-PCR (3 commercial assays), antigen-capture ELISAs (2 commercial assays), and antibody ELISAs (3 commercial assays). In addition, virus isolation (VI) and serum neutralization (SN) tests were also performed for comparison.
The results from the present study indicated that each CSFV assay had its limitation(s), in large part depending on the test target (virus, antigen, nucleic acid, or antibody). Notably, commercial CSFV rRT-PCRs were more sensitive for early detection, whereas antibody assays were more sensitive in later stages. Therefore, it is important to perform the assay(s) most appropriate to the stage of infection (acute vs. chronic) and intended purpose (screening vs. confirmatory). Overall, commercial rRT-PCR and antibody ELISAs are suitable for large scale screening whereas virus isolation and serum neutralization should be used exclusively as confirmatory assays.