Eimeria tenella, one of the seven species of chicken coccidia, elicits protective immunity against challenge infection with both homologous and heterologous strains. We endeavor to use recombinant E. tenella as a vaccine vehicle for expressing and delivering pathogen Ags and investigate immune responses against these foreign Ags. In this study, two lines of transgenic E. tenella expressing a model Ag, enhanced yellow fluorescent protein (EYFP), targeted to the micronemes and to the cytoplasm of the recombinant parasites were constructed to study the impact of Ag compartmentalization on immunogenicity. The MTT assay, intracellular cytokine staining, and real-time PCR were performed to detect the EYFP-specific proliferation and effector functions of splenic lymphocytes of immunized chickens. ELISA was used to measure anti-EYFP IgG and IgA responses. The results showed that both lines of transgenic parasites stimulated EYFP-specific lymphocyte proliferation and IFN-γ expression in CD4 and CD8 T cells, whereas a higher level of Ag-specific lymphocyte proliferation was elicited by the transgenic line expressing microneme-targeted EYFP. Furthermore, this line stimulated stronger IgA response than the one expressing cytoplasm-targeted EYFP after the second immunization. Our findings are encouraging for further investigation of the effect of Ag compartmentalization in transgenic Eimeria on immunogenicity and for the development of a eukaryotic vaccine vector using genetically modified Apicomplexa parasites.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is known to be a potential vaccine adjuvant despite contradictory results from animal and human studies. The discrepancies may be due to the different doses and regimens of GM-CSF that were used, given that either mature or immature dendritic cells (DCs) could be induced under different conditions. To test the hypothesis that GM-CSF can be used as a novel adjuvant for a hepatitis B virus (HBV) therapeutic vaccine, we administered GM-CSF once per day for three days prior to vaccination with recombinant HBV vaccine (rHBVvac) in mice. We observed greater DC maturation in these pre-treated animals at day 3 as compared to day 1 or day 2 of daily GM-CSF administration. This strategy was further investigated for its ability to break the immune tolerance established in hepatitis B surface antigen-transgenic (HBsAg-Tg) animals. We found that the levels of induced anti-HBsAg antibodies were significantly higher in animals following three days of GM-CSF pre-treatment before rHBV vaccination after the third immunization. In addition to the increase in anti-HBsAg antibody levels, cell-mediated anti-HBsAg responses, including delayed-type hypersensitivity, T-cell proliferation, interferon-c production, and cytotoxic T lymphocytes, were dramatically enhanced in the three-day GM-CSF pre-treated group. After adoptive transfers of CD8 1 T cells from immunized animals, antigen-specific CD8 1 T cells were observed in the livers of recipient HBsAg-Tg animals. Moreover, the three-day pre-treatments with GM-CSF prior to rHBVvac vaccination could significantly eliminate HBsAg-positive hepatocytes, suggesting beneficial therapeutic effects. Therefore, this protocol utilizing GM-CSF as an adjuvant in combination with the rHBVvac vaccine has the potential to become a novel immunotherapy for chronic hepatitis B patients. Cellular & Molecular Immunology

This is the first reported 'proadjuvant' that augments DNA vaccination indirectly by eliciting agonistic antibodies.

IntroductionVaccination against amyloid-β protein (Aβ42) induces high levels of antibody, making it a promising strategy for treating Alzheimer’s disease (AD). One drawback in the past was that clinical trial approval was withheld because of speculation that the Aβ42 vaccine induces CD4+ T cell infiltrations into the central nervous system. To reduce T-cell activation while concomitantly maintaining high anti-Aβ42 titers is a great challenge in immunology.MethodsWe aimed to demonstrate that coimmunization with Aβ42 protein and expression plasmid can be beneficial in a mouse AD model and can prevent inflammation. We immunized the AD mice with the coimmunization vaccine and assessed behavior change and Aβ42 deposition. Furthermore, to determine the safety of the coimmunization vaccine, we used an induced Aβ42-EAE model to mimic the meningoencephalitis that happened in the AN-1792 vaccine clinical phase II trial and tested whether the coimmunization vaccine could ameliorate T-cell-mediated brain inflammation.ResultsThe coimmunization vaccination reduced Aβ plaques and significantly ameliorated cognitive deficit while inhibiting T-cell-mediated brain inflammation and infiltration. These studies demonstrate that the coimmunization strategy that we describe in this article can ameliorate AD pathology without notable adverse effects in mice.ConclusionsA coimmunization strategy leading to the development of a safe immunotherapeutic/preventive protocol against AD in humans is warranted.

Various chemokines and cytokines as adjuvants can be used to improve efficacy of DNA vaccination. In this study, we sought to investigate if a DNA construct expressing IL-9 (designed as proV-IL9) as a molecular adjuvant enhance antigen specific immune responses elicited by the pcD-VP1 DNA vaccination. Mice immunized with pcD-VP1 combined with proV-IL9 developed a strong humoral response. In addition, the coinoculation induced significant higher level of antigen-specific cell proliferation and cytotoxic response. This agreed well with higher expression level of IFN-γ and perforin in CD8+ T cells, but not with IL-17 in these T cells. The results indicate that IL-9 induces the development of IFN-γ-producing CD8+ T cells (Tc1), but not the IL-17-producing CD8+ T cells (Tc17). Up-regulated expressions of BCL-2 and BCL-XL were exhibited in these Tc1 cells, suggesting that IL-9 may trigger antiapoptosis mechanism in these cells. Together, these results demonstrated that IL-9 used as molecular adjuvant could enhance the immunogenicity of DNA vaccination, in augmenting humoral and cellular responses and particularly promoting Tc1 activations. Thus, the IL-9 may be utilized as a potent Tc1 adjuvant for DNA vaccines.