Effects on humoral immune response to classical swine fever vaccine after experimental infection of porcine circovirus type 2

The levels of the antibody response against classic swine fever(CSF) vaccine were measured by blocking ELISA at different time for pigs vaccinated with CSF vaccine(CSFV group,n=3),pigs inoculated with porcine circovirus type 2(PCV2) and with CSF vaccine two weeks later(when PCV2 viremia was detected by PCR,PCV2/CSFV group,n=3),or inoculated with both CSF vaccine and PCV2 at the same time(CSFV/PCV2 group,n=3),respectively.And distribution of genome or antibodies specific to PCV2 of the PCV2 infection group,PCV2/CSFV group and CSFV/PCV2 group were also detected by indirect ELISA or PCR,respectively.The results showed that experimental infection of PCV2 was successful.In pigs inoculated with both PCV2 and CSF vaccine,the antibody response to CSF vaccine was significantly lower than that of animals treated with CSF vaccine vaccination alone at 52 days postinoculation(DPI).The average titers of antibodies against CSFV in animals of CSFV group were obviously higher than those of the PCV2/CSFV or CSFV/PCV2 group at 49 and 52DPI,respectively.The positive rate of antibodies against CSFV in pigs of CSFV group was 100% in comparison with that of animals inoculated with PCV2 and the vaccine(only 67%).The results suggested that the infection of PCV2 could suppress the antibody response to classical swine fever vaccine.