Diagnosis of Classical Swine Fever: rapid, simple, innovative

Classical swine fever (CSF) is a highly contagious disease that needs to be confirmed by laboratory diagnosis due to highly variable, often unspecific clinical symptoms. Extensive serological investigations in the context of surveillance programs are required to demonstrate freedom from infection.

In the European Union, a strict ‘stamping-out’ strategy is applied in case of a CSF outbreak. Given ethical and socio-economic concerns, application of marker vaccines for emergency vaccination is a promising alternative in future outbreak scenarios. The successful use of a marker vaccine requires a reliable diagnostic test to differentiate infected from marker-vaccinated animals (DIVA strategy). The most promising DIVA strategy involving the recently approved marker vaccine Suvaxyn^® CSF Marker is based on the absence of a Classical Swine Fever Virus (CSFV) E^rns-specific immune response. QIAGEN’s new double-antigen ELISA pigtype^® CSFV E^rns Ab detects antibodies to the CSFV protein E^rns and thus addresses an alternative target protein to conventional E2-specific antibody ELISAs. It also offers the possibility to be used as accompanying DIVA test for suitable marker vaccines. The aim of the present study was to validate the test for both applications.

Sensitivity and specificity of pigtype CSFV E^rns Ab were evaluated by testing a serum sample panel comprising CSFV antibody positive and negative sera in comparison to a commercially available E2-specific antibody ELISA. Furthermore, application as a discriminatory test was validated using sera taken from animals vaccinated with the marker vaccine Suvaxyn CSF Marker as well as sera from vaccinated and subsequently CSFV challenged pigs.

The new pigtype CSFV E^rns Ab proved highly specific and sensitive in comprehensive validation with CSFV antibody positive and negative sera. Compared to a commercial E2-specific antibody ELISA, pigtype CSFV E^rns Ab was more sensitive to sera obtained very soon after infection (≤21 days). The novel test reliably detected E^rns antibodies to a variety of isolates belonging to various CSFV genotypes. pigtype CSFV E^rns Ab showed comparable specificity for sera obtained after vaccination with the marker vaccine when compared to the only other commercially available E^rns-specific antibody ELISA, but demonstrated to be more sensitive for CSFV challenge sera obtained from marker-vaccinated and CSFV challenged pigs.

The pigtype CSFV E^rns Ab ELISA can be applied as antibody screening test in the context of CSF surveillance, but can also be employed as an accompanying differentiation test with Suvaxyn CSF Marker or another suitable marker vaccine.

Disclosure of Interest: D. Meyer Conflict with: Zentrales Innovationsprogramm Mittelstand, grant number: KF2097205MD1, S. Fritsche Conflict with: employed by the company producing the presented kit, C. Engemann Conflict with: employed by the company producing the presented kit, C. Schroeder Conflict with: employed by the company producing the presented kit, P. Becher Conflict with: Zentrales Innovationsprogramm Mittelstand, grant number: KF2097205MD1, A. Postel Conflict with: Zentrales Innovationsprogramm Mittelstand, grant number: KF2097205MD1.