#18-059

Complete

Date Full Report Received

07/28/2019

Date Abstract Report Received

07/28/2019

Investigation

Institution:
Primary Investigator:

Classical swine fever (CSF) is a highly contagious swine viral disease. To date, CSF is still listed as a highly contagious swine viral disease by the World Organization for Animal Health (OIE). An outbreak of CSF impairs domestic and international trade and the movement of pigs and pig products. C-strain vaccines are considered to be safe and effective against all CSFV genotypes, and are widely used for CSF control worldwide. However, no corresponding serological DIVA (differentiate infected from vaccinated animals) test for C-strain vaccine is available, which hampered the application of C-strain based DIVA approach in CSF control.

In this project, to make the well-known safe and efficacious C-strain vaccine DIVA compatible, two competitive ELISAs (cELISA) with an emphasis on the differentiation of infected from C-strain vaccinated animals were developed and validated. After comprehensive assessment and validation by Western blotting, indirect fluorescent antibody assay (IFA) and testing different categories of pig sera, Horseradish Peroxidase (HRP)-mAb 1504 (against C-strain Erns protein) based cELISA showed very high specificity, sensitivity and reproducibility. The established HRP-mAb 1504 based cELISA can efficiently differentiate C-strain or C-strain Erns immunized pigs from other CSFVs or other viruses (PRRSV, PRV, BVDV) infected pigs. It can detect C-strain induced antibodies as early as 7-14 days post vaccination (DPV) with neutralizing titer 1:5 to 1:15. The diagnostic sensitivity and specificity of the cELISA were 100% (95% confidence interval: 91.2 to 100%) and 100% (95% confidence interval: 99.3 to 100%), respectively.

The novel HRP-mAb 1504 based cELISA established in this project is a valuable tool for measuring and differentiating immune responses to C-strain vaccination in pigs. It is applicable as an accompanying DIVA assay to C-strain originated vaccines (live-attenuated or E2 subunit), can be safely manufactured in the United States and will facilitate the implementation of “vaccination to live” strategy for CSF outbreak control.