Adjuvanticity of aqueous extracts of Artemisia rupestris L. for inactivated foot-and-mouth disease vaccine in mice

Abstract

Several methods have been developed to improve the efficacy of foot-and-mouth disease virus (FMDV) vaccine. The study aims to determine whether aqueous extracts of Artemisia rupestris L. (AEAR) as an immunoactivator in combination with inactivated FMDV vaccine can promote immune responses in mice. Intramuscular co-immunization in ICR mice with different doses of AEAR plus FMDV vaccine could substantially improve the FMDV-specific antibody production (IgG, IgG1, and IgG2a) and lead to significant lymphocyte proliferative responses. Th1-type immune responses were also observed, including proliferative responses of CD8+, CD4+, CD4+CD44+, and CD8+CD44+ T cells and the killing efficacy of cytotoxic T lymphocyte (CTL) responses. AEAR also elicited the higher levels of IL-4 and IFN-γ in CD4+ T cells as well as the higher level of IFN-γ in CD8+ T cells. The medium dose of AEAR induced the significant adjuvant activity. Further tests in mice indicated that AEAR could activate DCs maturation by increasing the expression levels of co-stimulatory molecules (CD40, CD86, CD80, and MHC-II) on dendritic cells (DCs) from splenocytes and reduce the activity of regulatory T cells (Treg). Abnormal behaviors, side effects or death were not observed in immunized mice. AEAR could boost humoral and cell-mediated immunity elicited by FMDV vaccine, especially Th1-type immune responses.