Lectin from the Late Oyster Mushroom, Hohenbuehelia serotina (Agaricomycetes), and Its Novel Effect as an Adjuvant of the HBV DNA Vaccine.

The biological macromolecule Hohenbuehelia serotina lectin (HSL) was first isolated from dried fruiting bodies of the mushroom H. serotina and identified as a heterodimer with 2 subunits of the same molecular weight (15.6 kDa) but different isoelectric points. Lactose and d-galactose inhibited the hemagglutinating activity of HSL, whereas mental ions Mn2+ and Ca2+ could stimulate its hemagglutination. The HSL hemagglutinating activity was stable for 1 hour in NaOH and HCl solutions up to a concentration of 12.5 or 6 mmol/L. In addition, HSL was stable up to 50°C for 30 minutes; its hemagglutinating activity was halved at 60°C and totally inactivated above 90°C. HSL (10 μg) as an immune adjuvant co-inoculated with the proVAX/S2 vaccine enhanced the level of hepatitis B surface antigen in C57BL/6 mice, induced a high level of T-cell proliferation, and induced the expression of IFN- of CD4+ cells. We further illustrate that HSL, as an adjuvant upregulating the expression of major histocompatibility complex II, contributed to the maturation of dendritic cells. As the first lectin isolated from H. serotina, HSL is a potential adjuvant to chronic hepatitis B virus DNA vaccines and lays a foundation for the prevention of HBV infection.