Maximizing detection of dengue virus serotypes by a modified reverse transcription-polymerase chain reaction assay in India: presence of co-infection with multiple serotypes

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Plant-expressed Fc-fusion protein tetravalent dengue vaccine with inherent adjuvant properties.

Dengue is a major global disease requiring improved treatment and prevention strategies. The recently licensed Sanofi-Pasteur Denvaxia vaccine does not protect children under the age of nine and additional vaccine strategies are thus needed to halt this expanding global epidemic. Here, we employed a molecular engineering approach and plant-expression to produce a humanised and highly immunogenic Poly-Immunoglobulin G Scaffold (PIGS) fused to the consensus dengue envelope protein III domain (cEDIII). The immunogenicity of this IgG Fc receptor targeted vaccine candidate was demonstrated in transgenic mice expressing human FcγRI/CD64, by induction of neutralising antibodies and evidence of cell-mediated immunity. Furthermore, these molecules were able to prime immune cells from human adenoid/tonsillar tissue ex vivo as evidenced by antigen-specific CD4+ and CD8+ T cell proliferation, IFN-γ and antibody production. The purified polymeric fraction of dengue PIGS (D-PIGS) induced stronger immune activation than the monomeric form, suggesting a more efficient interaction with the low affinity Fcγ receptors on antigen-presenting cells. These results show that the plant-expressed D-PIGS have the potential for translation towards a safe and easily scalable single antigen based tetravalent dengue vaccine. This article is protected by copyright. All rights reserved

Altered T Cell Memory and Effector Cell Development in Chronic Lymphatic Filarial Infection That Is Independent of Persistent Parasite Antigen

Chronic lymphatic filarial (LF) infection is associated with suppression of parasite-specific T cell responses that persist even following elimination of infection. While several mechanisms have been implicated in mediating this T cell specific downregulation, a role for alterations in the homeostasis of T effector and memory cell populations has not been explored. Using multiparameter flow cytometry, we investigated the role of persistent filarial infection on the maintenance of T cell memory in patients from the filarial-endemic Cook Islands. Compared to filarial-uninfected endemic normals (EN), microfilaria (mf) positive infected patients (Inf) had a reduced CD4 central memory (TCM) compartment. In addition, Inf patients tended to have more effector memory cells (TEM) and fewer effector cells (TEFF) than did ENs giving significantly smaller TEFF ∶ TEM ratios. These contracted TCM and TEFF populations were still evident in patients previously mf+ who had cleared their infection (CLInf). Moreover, the density of IL-7Rα, necessary for T memory cell maintenance (but decreased in T effector cells), was significantly higher on memory cells of Inf and CLInf patients, although there was no evidence for decreased IL-7 or increased soluble IL7-Rα, both possible mechanisms for signaling defects in memory cells. However, effector cells that were present in Inf and CLInf patients had lower percentages of HLA-DR suggesting impaired function. These changes in T cell populations appear to reflect chronicity of infection, as filarial-infected children, despite the presence of active infection, did not show alterations in the frequencies of these T cell phenotypes. These data indicate that filarial-infected patients have contracted TCM compartments and a defect in effector cell development, defects that persist even following clearance of infection. The fact that these global changes in memory and effector cell compartments do not yet occur in infected children makes early treatment of LF even more crucial

Cd8 enhancer E8I and Runx factors regulate CD8α expression in activated CD8+ T cells

Cd8a and Cd8b1 coreceptor gene (Cd8) expression is tightly controlled during T-cell development by the activity of five Cd8 enhancers (E8I–E8V). Here we demonstrate a unique transcriptional program regulating CD8 expression during CD8+ effector T-cell differentiation. The Cd8 enhancer E8I and Runx/core-binding factor-β (CBFβ) complexes were required for the establishment of this regulatory circuit, because E8I-, Runx3-, or CBFβ-deficient CD8+ T cells down-regulated CD8α expression during activation. This finding correlated with enhanced repressive histone marks at the Cd8a promoter in the absence of E8I, and the down-regulation of CD8α expression could be blocked by treating E8I-, Runx3-, or CBFβ-deficient CD8+ T cells with the histone deacetylase inhibitor trichostatin A. Moreover, Runx/CBFβ complexes bound the Cd8ab gene cluster in activated CD8+ T cells, suggesting direct control of the Cd8a locus. However, CD8+ effector T cells maintained high levels of CD8α when CBFβ was conditionally deleted after activation. Thus, our data suggest an E8I- and Runx3/CBFβ-dependent epigenetic programming of the Cd8a locus during T-cell activation, leading to Runx/CBFβ complex-independent maintenance of CD8α expression in effector T cells

T cell exhaustion in protozoan disease

Protozoan parasites cause severe morbidity and mortality in humans worldwide, especially in developing countries where access to chemotherapeutic agents is limited. Although parasites initially evoke a robust immune response, subsequent immunity fails to clear infection, ultimately leading to the chronic stage. This enigmatic situation was initially addressed in chronic viral models, where T cells lose their function, a phenomenon referred to as ’exhaustion‘. However, recent studies demonstrate that this paradigm can be extended to protozoan diseases as well, albeit with notable differences. These studies have revealed that T cell responses generated against Toxoplasma gondii, Plasmodium sp. and Leishmania sp. can become dysfunctional. This Review discusses T cell exhaustion in parasitic infection, mechanisms of development, and a possible role in disease outcome