Porcine epidemic diarrhea virus (PEDV) is a highly contagious pathogen of swine. The spike glycoprotein (S) of PEDV plays a pivotal role in the induction of neutralizing antibodies against PEDV, which could be an ideal target for vaccine development. To develop a subunit vaccine for PEDV, Da-Chuan Piao of Seoul National University cloned two different fragments of S protein and expressed it as glutathione S-transferase (GST)-tagged fusion proteins, namely rGST-COE and rGST-S1D, in Escherichia coli.

The team tested various chaperone co-expression systems and found that co-expression of trigger factor (TF) with recombinant proteins at 15°C was most useful in soluble production of rGST-COE and rGST-S1D. The soluble rGST-COE and rGST-S1D were then purified and tested. Analysis revealed that the purified proteins showed immune reactivity with pig anti-PEDV immune sera.

Their results suggest that soluble rGST-COE and rGST-S1D produced by co-expressing chaperones may have the potential to be used as subunit vaccine antigens against PEDV.

For more information, read the article in BMC Biotechnology.

Fig. 1 : Chaperone assisted expression of soluble rGST-COE (a) and rGST-S1D (b). Chaperone proteins were induced at 37 °C by adding L-arabinose (0.5 mg/ml) or tetracycline (10 ng/ml) prior to the expression of recombinant proteins. Target proteins were induced by adding 0.1 mM IPTG at 15 °C for 24 h. Soluble (S) and insoluble (I) fractions were analyzed by SDS-PAGE. The protein bands for rGST-COE, rGST-S1D and chaperone proteins are indicated on the right side of the gel. Lanes: control, no chaperone; +TF, co-expression with trigger factor; +Gro, co-expression with GroEL-GroES complex; +G-KJE: co-expression with DnaKJE/GroEL-GroES complex