Immunological activities of the aqueous extracts of Cistanche deserticola as a polysaccharide adjuvant for inactivated foot-and-mouth disease vaccines

Inactivated foot-and-mouth disease (FMD) vaccines generally require adjuvants to enhance the immunogenicity. To test whether the aqueous extracts of Cistanche deserticola (AECD) could be developed into a polysaccharide adjuvant for inactivated FMD vaccines in mice. Experimental vaccines were prepared with inactivated FMD viral antigen plus AECD or inactivated FMD vaccine plus AECD to subcutaneously immunize mice. AECD developed an FMDV-specific humoral response by increasing IgG antibodies and IL-4 in CD4(+) T cells and enhanced lymphocyte proliferation and a balanced Th1/Th2 response. Importantly, AECD induced Th1 type immunity by augmenting the activation of T subsets (CD4(+), CD8(+), CD44(+)) and the induction of IFN-gamma in T lymphocytes, especially CTL response and neutralizing antibodies in sera. In addition, AECD maintained the higher levels of CD80, CD40, MHC-II, CD86 on CD11c(+) cells and decreased the Treg frequency. Our results suggested that AECD had the potential utility as an polysaccharide adjuvant for FMD vaccines.