The role of zinc sulfate in enhancing cellular and humoral immune responses to foot-and-mouth disease vaccine

Figures

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  Fig. 1. Zinc sulfate and inactivated FMDV type O (O PA2) or A (A YC) antigen effectively induced cellular immune responses in murine peritoneal exudate cells (PECs) and porcine peripheral blood mononuclear cells (PBMCs). IFNγ-secreting cell spots in murine PECs (A); Images of IFNγ secretion in murine PECs (B); IFNγ-secreting cell spots in porcine PBMCs (C); Images of IFNγ secretion in porcine PBMCs (D). Data have been presented as spot-forming cells per number of cells in the well. ⁎p < 0.05, ⁎⁎p < 0.01, ⁎⁎⁎p < 0.001, and ⁎⁎⁎⁎p < 0.0001.

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  Fig. 2. Zinc sulfate-containing FMD vaccine mediated host defense by inducing early immune response in mice. Experimental strategy (A); Survival rates of mice after challenge with O/VET/2013 (B) and A/Malay/97 (C); Body weight change after challenge with O/VET/2013 (D) and A/Malay/97 (E).

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  Fig. 3. Zinc sulfate-containing FMD vaccine elicited early, mid-, and long-term immune responses in mice. (A–E) Experimental strategies (A); Antibody titers by SP O ELISA (VDPro® kit) (B); Antibody titers by SP A ELISA (PrioCheck™ kit) (C); VN titers for O PA2 (D); VN titers for A YC (E). ⁎p < 0.05, ⁎⁎p < 0.01, ⁎⁎⁎p < 0.001, and ⁎⁎⁎⁎p < 0.0001.

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  Fig. 4. Zinc sulfate-containing FMD vaccine effectively induced early, mid-, and long-term immune responses in pigs. (A–E) Experimental strategies (A); Percent inhibition of SP O ELISA (VDPro® kit)(B); Percent inhibition of SP A ELISA (PrioCheck™ kit) (C); VN titers for O PA2 (D); VN titers for A YC (E). ⁎p < 0.05, ⁎⁎p < 0.01, ⁎⁎⁎p < 0.001, and ⁎⁎⁎⁎p < 0.0001.

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  Fig. 5. Zinc sulfate-containing FMD vaccine induced an increase in porcine serum immunoglobulin G (IgG), IgA and IgM levels. Serum IgG (A); IgA (B); and IgM (C) concentrations. ⁎⁎⁎p < 0.001 and ⁎⁎⁎⁎p < 0.0001.

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  Fig. 6. Zinc sulfate-containing FMD vaccine effectively elicit cellular and humoral immune responses in porcine PBMCs by inducing the expression of PRRs, transcription factors, co-stimulatory molecules, and cytokines. (A–V) Gene expression levels of RIG-I (A); TLR4 (B); MyD88 (C); TRAF6 (D); NF-κB (E); CARD9 (F); STAT1 (G); CD80 (H); CD86 (I); CD28 (J); CD19 (K); CD21 (L); CD81 (M); IFNα (N); IFNβ (O); IFNγ (P); IL-1β (Q); IL-6 (R); IL-12p40 (S); IL-23p19 (T); IL-23R (U); and IL-17A (V). ⁎p < 0.05, ⁎⁎p < 0.01, ⁎⁎⁎p < 0.001, and ⁎⁎⁎⁎p < 0.0001.

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  Fig. 7. Schematic illustration of the potential mechanisms of zinc sulfate-containing FMD vaccine. The stimulation of TLR4 by zinc sulfate and antigen induces the recruitment of the adaptor protein MyD88 via downstream TRAF6, resulting in the activation of NF-κB and the mRNA expression of proinflammatory cytokines, such as IFNγ, IL-1β and IL-6 in APCs such as DCs and MФs. This is APC-dependent signaling cascade. CD80 and CD86 are then stimulated on the APC surface, which induced STAT1 and produced the proinflammatory cytokines IL-12 and IL-23. IL-23 produces IL-17A and IL-6 by binding to IL-23R on the surface of Th17 and unconventional T cells such as γδ T cells,invariant natural killer T (iNKT) cells, and mucosal-associated invariant T (MAIT) cells. IL-12 binds to IL-12R on the surface of Th1 cells and produces IFNγ and IL-12p40. Activated Th1 cell express CD28, restimulate APC through a positive feedback loop, while activating B cells and B cell core-receptor such as CD19, CD21, and CD81, resulting in immune-enhancing effect. Collectively, zinc sulfate contributes to cellular and humoral immunity by stimulating TLR4 and RIG-I and promoting the release of various transcription factors,…