Development Of A Competitive Inhibition ELISA For Detection Of Neutralizing Antibodies Against Classical Swine Fever Virus

Classical swine fever (CSF), caused by classical swine fever virus (CSFV), is a highly contagious fatal disease of pigs, and is included in the listed diseases of The World Organization for Animal Health (OIE), which belongs to the genus Pestivirus within the family Flaviviridae. The other members of the genus Pestivirus are bovine viral diarrhea virus type 1 (BVDV-1), BVDV-2, border disease virus (BDV), and Giraffe pestivirus.E2 is one of envelope glycoprotein of CSFV, which is responsible for the elicitation of neutralizing antibodies, and often be used to develop new type vaccines, clinical diagnostic reagents and study immunopathological mechanisms of the virus.Vaccination and serological testing are the key to the control and eradication of classical swine fever, while the former is also dependent on the development of the latter. Therefore, the classical swine fever antibody detection is extremely important. The purpose of this study is using the baculovirus-expressed recombinant E2 protein of CSFV as coating antigen and a neutralizing monoclonal antibody (McAb) 6E10 labeled with horseradish peroxidase (HRP) against the E2 protein as competitive antibody, a competitive inhibition ELISA (CI-ELISA) for detection of neutralizing antibody against the E2 protein was developed and the reaction condition was optimized. The optimal concentration of coating antigen in the CI-ELISA was 3μg/ml, and the optimal dilution of HPR-6E10 was 1:4000. The cut-off values of the negative and positive sera are 33% and 40%, respectively. Out of 370 porcine sera from several provinces of China, 97.6% were positive for CSFV by CI-ELISA.Neutralization antibody is an important component of immunization protective, is also an important parameter to evaluation vaccine immunization effect. NPLA is used widely to detect neutralization antibodies of classical swine fever, however, the method requires sophisticated technology and equipment, time-consuming and laborious operation, so is not conducive to the current application. Therefore set up a simple and practicable classical swine fever antibody detection method is very necessary.