Effect of sulfated astragalus polysaccharide on cellular infectivity of infectious bursal disease virus

Four kinds of astragalus polysaccharides (APSs), APS(t), APS(40), APS(50) and APS(60), were extracted by water decoction and one-step or stepwise ethanol precipitation methods, and modified by chlorosulfonic acid-pyridine method to obtain four sulfated APSs (sAPSs) (sAPS(t), sAPS(40), sAPS(50), sAPS(60)), respectively. The effects of four sAPSs on cellular infectivity of bursal disease virus (IBDV) were compared by MTT method taking non-modified APS(t) as control. The results showed that modified sAPSs inhibited IBDV to infect CEF significantly in comparison with non-modified APS(t), which indicated that sulfated modification could enhance the antiviral activity of the APS, by which it would be expected to develop a new-type antiviral drug.