Infection by Enterotoxigenic Escherichia coli is a common cause of diarrhea in animals. The development of vaccines against enterotoxins can effectively control the infection. We have previously constructed a recombinant antigen SLS fused by STa, LTB and STb enterotoxin and it showed a high immunogenicity in mice. Herein, we evaluated the expression of SLS in three different E. coli cells with corresponding plasmids. SLS proteins expressed in E. coli BL21 (DE3) and Rosetta-gami B (DE3) were aggregated as inclusion bodies, and the proteins solubility were not obviously promoted in low temperature combined with adjustment of inducer concentration. In contrast, SLS protein with maltose-binding protein (MBP) yielded from TB1 (DE3) cells were partially soluble. After increasing the IPTG concentration in the medium up to 2 mM and incubating at 37 ℃ for 4 h, the soluble protein yield reached the highest level (4.533 mg/0.2 L culture), which was significantly higher than the expression of SLS protein in Rosetta-gami B (DE3) (P < 0.05). Therefore, the TB1-pMAL expression system can be used for mass extraction and purification of SLS antigen prior to measuring its immunogenicity in pregnant mammals.

产肠毒素大肠杆菌感染 是动物腹泻的常见原因。开发肠毒素疫苗可以有效控制感染。我们之前已经构建了由 STa、LTB 和 STb 肠毒素融合的重组抗原 SLS，它在小鼠中显示出高免疫原性。在此，我们用相应的质粒评估了 SLS 在三种不同的大肠杆菌细胞中的表达。在大肠杆菌中表达的 SLS 蛋白BL21（DE3）和Rosetta-gami B（DE3）以包涵体的形式聚集，低温结合诱导剂浓度的调节对蛋白质溶解度没有明显促进。相比之下，从 TB1 (DE3) 细胞产生的带有麦芽糖结合蛋白 (MBP) 的 SLS 蛋白是部分可溶的。将培养基中IPTG浓度提高至2 mM并在37 ℃培养4 h后，可溶性蛋白产量达到最高水平（4.533 mg/0.2 L培养），明显高于SLS蛋白在Rosetta中的表达-gami B (DE3) (P < 0.05)。因此，TB1-pMAL 表达系统可用于大规模提取和纯化 SLS 抗原，然后测量其在怀孕哺乳动物中的免疫原性。