Immune efficacy of a porcine circovirus type 2 (PCV2) vaccine purified using gram-positive enhancer matrix (GEM) surface display technology.

Aims Purification of porcine circovirus type 2 (PCV2) using Gram-positive enhancer matrix (GEM) surface display technology and immunogenicity evaluation of the purified antigen. Methods and Results A recombinant bifunctional protein containing a protein anchor domain and a 'virus anchor' domain was designed as a protein linker (PL) between PCV2 and GEM particles. By incubating with PL and GEM particles sequentially, PCV2 could be purified and enriched through a simple centrifugation process with GEM surface display technology. Our data showed that one unit (2 center dot 5 x 10(9) particles) of GEM particles with 80 mu g PL could purify 100 ml of PCV2-containing culture supernatant (viral titre: 10(6 center dot 5) TCID50 per ml(-1)) with a recovery rate up to 99 center dot 6%. The impurity removal efficiency of this method, calculated according to decreased total protein content during purification, was approximately 98%. Furthermore, in vivo experimentation showed that piglets immunized with purified PCV2 could elicit strong immune responses to prevent against PCV2 infection. Conclusion Porcine circovirus type 2 could be efficiently purified and enriched with GEM display technology via a crucial PL, and the purified PCV2 could elicit effective immune responses against PCV2 infection. Significance and Impact of the Study The GEM-based purification method established here is cost-efficient and high-throughput, and may represent a promising large-scale purification method for PCV2 vaccine production.