Immunological adjuvant efficacy of glycyrrhetinic acid liposome against Newcastle disease vaccine.

The aim of this study is to investigate whether the activity of inducing immune response of glycyrrhetinic acid (GA) could be enhanced after GA was encapsulated with liposome. Three hundred and fifty 14-day-old chickens were randomly assigned to 7 groups and vaccinated with Newcastle disease (ND) vaccine. Simultaneously, the chickens in experimental groups were injected with the glycyrrhetinic acid liposome (GAL) at three doses, GA and blank liposome, respectively. The activity of serum antibody titer, concentrations of immunoglobulins G (IgG) and immunoglobulins M (IgM), lymphocytes proliferation, the proportions of lymphocyte subpopulations (CD4(+) and CD8(+)) was determined after vaccination. GAL was evaluated for inducing humoral immunity and cellular immunity in chicken against Newcastle disease (ND) vaccine. The results showed that GAL not only could significantly enhance the antibody titers, IgG and IgM in ND vaccine immunized chicken, but also significantly promote the lymphocyte proliferation and the proportions of CD4(+) and CD8(+), as comparison with GA, BL and VC control groups. Moreover, the effects appear a dose-dependent manner and a time-dependent manner. These indicated that GAL could significantly promote the activation potential of humoral immunity and cellular immunity in chicken and present certain dose-effect and time-effect relationships. The formulations of GA and liposome can further enhance the immune response against ND vaccine compared with the adjuvant alone.