Abstract: The purpose of this study was to compare the levels of antibody titer to PRRSV and screen the best immunization method for PRRSV. The nucleocapsid protein of PRRSV was used as immunogen to immunize BABL/c mice by traditional immunization, NC filter immunization, intrasplenic immunization and gel particle containing special bands. Then the titer of positive sera was detected by indirect ELISA, and the specificity was analyzed by Western blotting. After the third immunization, the titers of serum in different mice groups immunized by the four groups were 1.28×105, 1.28×105, 3.2×104, and 6.4×104, respectively. The results showed that the four immunity methods had obtained high titers polyclonal antibody, comparing with traditional immunization, the other three methods had more advantage in conserving antigen. Intrasplenic immunization was the best immunization method, which had the best immunity effect，using the least antigen and the shortest time.

Key words: PRRSV; nucleocapsid protein; antibody; intrasplenic immunization; NC filter; gel particles