Vibrio vulnificus VvhA induces Th1 and Tfh cells to proliferate against Vibrio vulnificus in a mouse model of infection

To characterize the roles of VvhA in host's acquired immune response to Vibrio vulnificus infection.The recombinant VvhA fusion protein was used to immunize mice and the anti-VvhA polyclonal antibody was produced in vivo for prophylactic and therapeutic efficacy assay. The roles of VvhA in T helper (Th) cells differentiation were analyzed by vvhA-deleted mutant during the early phase of infection, while the ratio of Th2 and T follicular helper (Tfh) cells were examined in VvhA immunization.Anti-VvhA antibody exhibited neutralization activity against V. vulnificus. Wild-type strain induced higher level of Th1 cells than the mutant, and the concentrations of IgG2a and IFN-γ were increased during the early phase of infection. The spontaneous development of Tfh was observed in immunized model, and the serum IL-21 was increased.V. vulnificus VvhA elicited cellular and humoral immune responses by Th1 and Tfh cells to provide protection against VvhA.