Study on the immune mechanism of a recombinant Bb-ipaB vaccine against Shigella flexneri

Objective To explore the immunity provided to BALB/c mice by immunization with a Bifidobacterium bifidum-mediated Bb-ipaB vaccine against Shigella flexneri.Methods Female BALB/c mice were randomly divided into 3 groups: a vaccine group,Bb control group,and PBS control group.Mice were orally immunized once a week a total of four times.Changes in antibodies(IgG,IgE,and IgA) in serum,sIgA in the mucosa,and cytokines of splenocytes(IFN-γ,IL-4) were detected in mice using ELISA and the capacity for splenic cell proliferation was detected using MTT.Results The S.flexneri vaccine group had a higher level of antigen-specific antibodies(IgG,IgE,and IgA) and cytokines(IFN-γ and IL-4) of splenocytes,greater capacity for splenic cell proliferation,and higher thymus and spleen index than these of controls.Conclusion The S.flexneri vaccine Bb-ipaB can produce higher levels of antigen-specific antibodies(IgG,IgE,IFN-γ,IL-4,and IgA) and cytokines(IFN-γ and IL-4) of splenocytes after oral immunization.This vaccine may be a potentially valuable oral vaccine to prevent infection with S.flexneri.