A DNA vaccine co-expressing Trichinella spiralis MIF and MCD-1 with murine ubiquitin induces partial protective immunity in mice

摘要

Co-expression of Trichinella spiralis macrophage migration inhibitory factor (TsMIF) with T. spiralis cystatin-like domain protein (TsMCD-1) in a DNA vaccine induces a Thl immune response and partial protection against T. spiralis infection. The present study evaluated whether co-expression of mouse ubiquitin (Ub) with TsMIF and TsMCD-1 might improve the immune response against T. spiralis infection. Groups of BALB/c mice were immunized twice at 2-week intervals with 100 mu g of plasmid DNA encodingeither a TsMIF-TsMCD-1 fusion protein (pVAXl-Tsmif-Tsmcd-1) or an Ub-co-expressing triple fusion protein Ub - TsMIF - TsMCD-1 (pVAXl-Ub-Tsmif-Tsmcd-1). Control animals were immunized with pVAXl-Ub or blank vector plasmid. Specific antibody levels (IgG, IgGl, IgG2a, IgG2b, IgM, IgA, IgE) against the recombinant protein TsMIF- TsMCD-1, serum cytokines (interferon (IFN)-gamma, interleukin (IL)-4, IL-5, transforming growth factor (TGF)-(31 and IL-17), CD4~+/CD8~+ T cells and cytotoxic T lymphocyte (CTL) responses were monitored. Challenge infection was performed 2 weeks after the second immunization and worm burden was assayed at 35 days post-challenge. Antibody responses induced by pVAXl-Ub-Tsmif-Tsmcd-1 were significantly lower than for TsMIF-TsMCD-1, but the vaccine induced increased levels of Thl cytokine (IFN-gamma) and increased T-cell cytotoxicity. The reduction of worm burden (37.95%) following immunization with pVAXl-Ub-Tsmif-Tsmcd-1 was significantly greater than that induced by the pVAXl-Tsmif-Tsmcd-1 vaccine (23.17%; P < 0.05).