Immune efficacy of a porcine circovirus type 2 vaccine purified using Gram-positive enhancer matrix surface display...

Purification of porcine circovirus type 2 (PCV2) using Gram-positive enhancer matrix (GEM) surface display technology and immunogenicity evaluation of the purified antigen.

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 (2·5 × 10⁹ particles) of GEM particles with 80 μg PL could purify 100 ml of PCV2-containing culture supernatant (viral titre: 10^6·5 TCID₅₀ per ml^-1 ) with a recovery rate up to 99·6%. 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.

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.

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.