Sulfated modification can enhance the adjuvanticity of lentinan and improve the immune effect of ND vaccine.

The purpose of this research is to study the effect of sulfated lentinan (sLNT) on immune effect of Newcastle disease (ND) vaccine. In immune response test, 14-day-old chickens were vaccinated with ND vaccine then grouped respectively to inject three sLNTs at two doses, once a day for three successive days, taking non-sulfated lentinan (LNT) as the control. The changes of serum antibody titer and peripheral lymphocyte proliferation were determined before and after vaccination. In immune protection test, 35-day-old chickens were challenged with ND virus (NDV) after treated similar to above mentioned. The morbidity and mortality of chickens were observed, and the changes of serum antibody titer and peripheral lymphocyte proliferation were measured before and after challenge. The results showed that three modified sLNTs could significantly enhance serum antibody titer and promote lymphocyte proliferation in two experimental chickens, and reduce morbidity and mortality of chickens challenged with NDV, which were better than that of non-modified LNT. Their high doses in enhancing antibody titer and low doses in promoting lymphocyte proliferation were more preferable. These results indicated that sulfated modification could enhance the adjuvanticity of LNT and improve the immune effect of ND vaccine. sLNT(2) possessed the best efficacy and would be expected as the candidate of a new-type immune adjuvant.