Activities of polysaccharides in combination with aluminum adjuvant in varicella-zoster subunit vaccines

Objective To evaluate the immunostimulatory effects of polysaccharides, including Lycium barbarum polysaccharides (LBP), Angelica polysaccharides (AP), Licorice polysaccharides (LP) and Inulin polysaccharides (IP), used alone or in combination with aluminum adjuvant on the recombinant protein of varicella-zoster virus (VZV) glycoprotein (gE) as an immunogen in mice. Methods BALB/c mice were randomly divided into 11 groups with five in each group. Intramuscular injection was given at Days 0 and 14. Serum samples were collected at weeks 0, 2, 3, 4 and detected for total anti-gE IgG titers and antibody subtypes by indirect ELISA. The mice were sacrificed at week 4 to collect spleen lymphocytes aseptically. CCK-8 method was used to evaluate the proliferation of spleen lymphocytes. The levels of IFN-γ and IL-4 were measured by ELISA. The percentages of CD3+ CD4+ and CD3+ CD8+ T cell subsets were determined by flow cytometry. Results The four plant-derived polysaccharides in combination with aluminum adjuvant showed good adjuvant activities. LP combined with aluminum adjuvant effectively increased the titer of IgG2, promote the proliferation of splenocytes and enhanced the secretion of IFN-γ and IL-4. Furthermore, it also induced CD3+ CD4+ and CD3+ CD8+ T cell proliferation in vivo. Conclusions The four plant-derived polysaccharides in combination with aluminum adjuvant could all enhance antibody production. LP combined with aluminum adjuvant could induce cell-mediated immune responses, suggesting that it might be a promising adjuvant for varicella-zoster subunit vaccines. Key words: Varicella-zoster virus; Vaccine; Plant-derived polysaccharide; Aluminum adjuvant; Immunostimulatory effect