Enterotoxigenic Escherichia coli (ETEC) is an important diarrhea-causing pathogen for humans. Heat-stable enterotoxin (ST) plays a crucial role in triggering diarrhea and ETEC pathogenesis. However, ST is a small peptide that lacks immunogenic activity itself but becomes immunogenic when it is coupled to a carrier molecule. In this study, the β-glucans (BG) from yeasts have been used to test their immunomodulatory activity and adjuvant effect on the properties of ST. This study aimed to synthesize and characterize a conjugate of yeast-derived β-glucan with the ST enterotoxin (BG-ST) and evaluate the antigenic and antioxidant activities in mouse splenocytes. Fourier transform infrared spectroscopy and scanning electron microscopy analysis showed new bands and changes in morphology, respectively, confirming ST was successfully coupled to beta glucan. Additionally, according to the enzyme-linked immunosorbent assay (ELISA), conjugation efficiency was almost 90%. Cellular viability, phagocytic cell proportion, and respiratory burst enhanced splenocytes stimulated by BG-ST. In addition, nitric oxide production and antioxidant enzymes increased in cells stimulated with BG-ST, BG and ST. In conclusion, the results revealed the successful conjugation of β-glucan with ST peptide enhancing immune and antioxidant parameters to a greater extent than their individual components.

产肠毒素大肠杆菌（ETEC）是人类重要的引起腹泻的病原体。热稳定肠毒素（ST）在引发腹泻和ETEC发病机理中起着关键作用。但是，ST是一种小肽，本身本身没有免疫原性活性，但是当它与载体分子偶联时会变得具有免疫原性。在这项研究中，来自酵母的β-葡聚糖（BG）已用于测试其免疫调节活性和对ST性质的佐剂作用。这项研究旨在合成和表征酵母来源的β-葡聚糖与ST肠毒素（BG-ST）的结合物，并评估小鼠脾细胞的抗原和抗氧化活性。傅里叶变换红外光谱和扫描电子显微镜分析分别显示了新的谱带和形态变化，证实了ST已成功偶联至β-葡聚糖。另外，根据酶联免疫吸附试验（ELISA），偶联效率几乎为90％。细胞活力，吞噬细胞比例和呼吸爆发增强了BG-ST刺激的脾细胞。此外，BG-ST，BG和ST刺激的细胞中一氧化氮的产生和抗氧化酶增加。总之，结果表明，β-葡聚糖与ST肽的成功结合比其单个组分在更大程度上增强了免疫和抗氧化参数。