Sulfated polysaccharides (SP) from seaweeds exhibit numerous biological activities and are less toxic than conventional antiviral drugs. However, little is known about their mode of action. This study aims at extracting the polysaccharides from brown seaweed Sargassum ilicifolium and then evaluating its antiviral activity against fish Betanodavirus. The extracted SP was characterized through FT-IR, ¹H NMR, and thermal gravimetric analysis (TGA). The antiviral activity of SP was tested on SGA cell line by syncytia reduction and the polysaccharide represented a prominent antiviral activity to Betanodavirus by reducing the cytopathic effect (CPE) formation in vitro. The study revealed that SP effectively blocked viral attachment and entry. Moreover, during the in vivo challenge experiment in Gambusia affinis, SP treatment showed a significant decrease in the viral titers. Hence, these results indicate that the polysaccharides obtained from S. ilicifolium exhibited the high antiviral potential to Betanodavirus infection in fishes both in vitro and in vivo.

海藻中的硫酸化多糖（SP）具有许多生物活性，并且比常规抗病毒药物毒性低。但是，对其作用方式知之甚少。这项研究旨在从褐藻海藻Sargassum ilicifolium中提取多糖，然后评估其对鱼类Betanodavirus的抗病毒活性。提取的SP通过FT-IR表征¹1 H NMR和热重分析（TGA）。通过合胞体减少测试了SP对SGA细胞系的抗病毒活性，并且多糖通过减少体外的细胞病变作用（CPE）形成了对Betanodavirus的显着抗病毒活性。研究表明，SP有效地阻止了病毒的附着和进入。此外，在球菌的体内挑战实验中，SP处理显示病毒滴度显着降低。因此，这些结果表明，从所获得的多糖S. ilicifolium所表现出的高的抗病毒潜能Betanodavirus感染在体外和体内的鱼。