Selenylation modification can enhance immune-enhancing activity of Chinese angelica polysaccharide

•Three selenizing Chinese angelica polysaccharide, sCAP2, sCAP6 and sCAP8, were prepared.•Three sCAPs’ immune-enhancing activities were compared taking non-modified CAP as control.•Selenylation modification could significantly raise CAP's immune-enhancing activity.•sCAP2 presented best effect and would be as a component drug of new-type immunoenhancer. On the basis of previous test that selenizing Chinese angelica polysaccharides (sCAPs) with stronger immune-enhancing activity in vitro were picked out, the immune-enhancing activity in vivo of three sCAPs, sCAP2, sCAP6 and sCAP8, at high and low dosage were compared taking the unmodified Chinese angelica polysaccharide (CAP) as control by determination of peripheral lymphocyte proliferation, serum antibody titer, IFN-γ and IL-6 contents in chicken vaccinated with Newcastle Disease vaccine. The results showed that three sCAPs at suitable dosage could significantly promote lymphocyte proliferation, enhance serum antibody titer, IFN-γ and IL-6 contents as compared with unmodified CAP, sCAP2 at low dosage possessed the strongest action. These results indicated that selenylation modification could significantly enhance the immune-enhancing activity of CAP, sCAP2 possessed the best efficacy and would be as a component drug of new-type immunoenhancer.