第二型豬環狀病毒 (Porcine circovirus 2，PCV2)，是一種會感染豬隻的病毒。目前與 PCV2 相關的綜合疾病症狀被稱為豬罹患離乳後多系統消耗性綜合症(postweaning multisystemic wasting syndrome，PMWS)。 Capsid蛋白質 (Cap) 為 PCV2 的衣殼蛋白。具有抗原決定位，是生產疫苗的主要標的。本研究嘗試利用大腸菌高密度發酵生產Cap蛋白。
Cap 蛋白成功地在大腸菌 Rosetta 2 (DE3) 以 SUMO-Cap 融合蛋白型式表達，而且這個融合蛋白透過陽離子交換層析進行純化。經由 SUMO protease 可將融合伴剪切，再透過管柱層析，可以純化到 Cap 蛋白。另外，本研究也嘗試高密度發酵培養，並以乳糖當作誘導劑進行 SUMO-Cap 融合蛋白誘導表達。結果顯示，12X ZYP 饋料培養基中含有 0.42% 的甘油及0.16% 的乳糖時，有較好的表達量，比利用異丙基-β-D-硫代半乳糖苷 (IPTG)作為誘導劑的結果更好。 Porcine circovirus 2 (PCV2) is the main viral pathogen that causes the desease called powtweaning multisystemic wasting syndrome. Capsid protein (Cap) of PCV2 containing the epitopes to elicit immune reaction, is the main target of subunit vaccine. In this study, the high cell density fermentation to produce the Cap protein of PCV2 were performed.
The Cap protein was successfully expressed in E. coli Rosetta 2 (DE3) as a SUMO-Cap fusion protein, and the fusion protein was purified to homogenity by cation exchange chromatography. Through the digestion by SUMO protease, followed by coloum chromatrogaphy, Cap protein can be purified. The high cell density fermentation, coupled with lactose induction, for the production of SUMO-Cap were performed in this study. The results indicated that 12X ZYP feeding medium, containing 0.42% glycerol and 0.16% lactose as inducer, showed the highest fusion protein production, with production level even higher than that using IPTG as inducer.
