Escherichia coli Heat-Labile Enterotoxin B Subunit Combined with Ginsenoside Rg1 as an Intranasal Adjuvant Triggers Type I Interferon Signaling Pathway and Enhances Adaptive Immune Responses to an Inactivated PRRSV Vaccine in ICR Mice

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major pathogen that has threatened the global swine industry for almost 30 years. Because current vaccines do not provide complete protection, exploration of new preventive strategies is urgently needed. Here, we combined a heat-labile enterotoxin B subunit of Escherichia coli (LTB) and ginsenoside Rg1 to form an intranasal adjuvant and evaluated its enhancement of immune responses in mice when added to an inactivated-PRRSV vaccine. The combination adjuvant synergistically elicited higher neutralizing and non-neutralizing (immunoglobulin G and A) antibody responses in the circulatory system and respiratory tract, and enhanced T and B lymphocyte proliferation, CD4+ T-cell priming, and cytotoxic CD4+ T cell activities in mononuclear cells from spleen and lung tissues when compared to the PRRSV vaccine alone, and it resulted in balanced Th1/Th2/Th17 responses. More importantly, we observed that the combination adjuvant also up-regulated type I interferon signaling, which may contribute to improvement in adaptive immune responses. These results highlight the potential value of a combined adjuvant approach for improving the efficacy of vaccination against PRRSV. Further study is required to evaluate the efficacy of this combined adjuvant in swine.

Intranasal delivery of inactivated PRRSV loaded cationic nanoparticles coupled with enterotoxin subunit B induces PRRSV-specific immune responses in pigs

“…Consistent with our results, previous studies showed that DDA is capable of producing high levels of IFN-γ in CD4 + CD8 − lymphocytes 54 , 55 . Additionally, LTB could potentially induce the production of IFN-γ in both CD4 + CD8 − and CD4 − CD8 + lymphocytes 56 . Mechanisms involving LTB and DDA and lymphocyte stimulation are not well understood.…”

Safety and Efficacy of the Bordetella bronchiseptica Vaccine Combined with a Vegetable Oil Adjuvant and Multi-Omics Analysis of Its Potential Role in the Protective Response of Rabbits

“…This study indicates that the E515-adjuvanted Bb vaccine activates Th1/Th2/Th17 cell responses. Recently, a virus vaccine containing GS adjuvant was found to evoke balanced Th1/Th2/Th17 responses in a mouse model [ 41 ]; thus, the role of GS in the effects of the E515 adjuvant is worthy of further exploration.…”

Immune Enhancement of Nanoparticle-Encapsulated Ginseng Stem-Leaf Saponins on Porcine Epidemic Diarrhea Virus Vaccine

“…Our antibody results demonstrated that the ability of GSLS-NPs to improve antibody responses was not dose dependent, and the optimal GSLS-NPs dose for adjuvant activities appeared to be 5 mg/kg, which elicited a stronger serum IgG antibody response, specifically responses involving the IgG1 and IgG2a isotypes, 14 days after a booster immunization than vaccination alone. The predominant IgG subclass changes progressively during an immune response, which is dependent on the pattern of cytokines secreted by CD4 + T cells [14]. In mice, IL-10 favours IgG1 isotype (Th2 type) production by activated B cells, while IFN-γ promotes IgG2a production (Th1 type).…”

“…IgA + cells were identified with an immunohistochemical staining method described previously [14]. Briefly, fixed intestinal samples were embedded in paraffin, sectioned at a thickness of 6 µm, and mounted onto glass slides.…”