Study On The Dynamics Of Structural Protein Antibodies Of Classical Swine Fever Virus Vaccine Strain

Classical swine fever(CSF),caused by the classical swine fever virus(CSFV),is a highly contagious disease of swine worldwide.It is widely distributed and has high mortality,which is an important infectious disease that seriously endangers the development of the pig industry.At present,the prevention and control of CSF in China is mainly carried out by the method of vaccination.Regular serum antibody detection of post-immunized herds can be used to assess the immune effect of vaccines,improve and optimize vaccination programs,and effectively prevent and control CSF.In this study,the structural proteins E0 and C of CSFV were expressed in E.coli,then purified and identified its immunoreactive.Recombinant proteins E0 and C were used as antigens to establish indirect ELISA methods,respectively,which provided new choices for CSFV antibody monitoring.The solid-phase blocking ELISA based on recombinant E2 protein as antigen proved to be of good sensitivity,specificity and stability.It can be applied to the work of clinical antibody level monitoring after immunization and epidemiological investigation.Experimental pigs were immunized by using the C-strain vaccine of CSFV,and serum samples were collected on 0,7,14,21,28,35,50 days after immunization(dpi),respectively.Antibody against E2 was detected by solid-phase blocking ELISA based on recombinant E2 protein.The indirect ELISA methods,developed based on recombinant proteins E0 and C,were used to evaluate E0 and C protein specific antibodies.The detection results of serum antibodies showed that the specific antibodies against structural proteins E2,E0 and C could be detected at 7 dpi,and the levels of E2 and E0 antibodies peaked after 21 dpi.Initially,level of antibody against E2 raised,then gradually dwindled,and the level of E0 antibody displayed decreased after 21 dpi,then showed stabilization trend;The antibody against C protein produced at 7 dpi and then decreased gradually,turning negative after 28 dpi.The changes of antibodies titer against the structural proteins E2,E0 and C of CSFV vaccine strain were monitored by the ELISA methods developed by recombinant antigens in this study,which provided a reference for the prevention of CSFV on reasonable vaccination schedule.