The mechanisms of lambda carrageenan against ASFV viral factory formation

African swine fever (ASF) is a highly pathogenic disease caused by the African swine fever virus (ASFV), with nearly 100% mortality in domestic pigs, threatening the global swine industry, animal warfare, and food safety. However, no effective drug or vaccine is currently available to prevent ASFV infection. Here, by glycan microarray screening of ASFV protein glycan interactions, we discovered the recombinant ectodomain of CD2v, an outer envelope protein of ASFV, bound lambda carrageenan, a natural sulfated polysaccharide, and found the interaction between lambda carrageenan and CD2v affected the hemadsorption of ASFV. Moreover, we show that lambda carrageenan has activity in inhibiting ASFV infection of PAMs during the attachment and entry stages and could suppress the viral protein synthesizing and viral factory formation by inducing NF kappa B mediated proinflammatory factor production. Our results indicate lambda carrageenan is a potent anti-ASFV compound.