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CD8(+) T cell responses restricted by MHC-E, a nonclassical MHC molecule, have been associated with protection in an SIV/rhesus macaque model. The biological relevance of HLA-E–restricted CD8(+) T cell responses in HIV infection, however, remains unknown. In this study, CD8(+) T cells responding to HIV-1 Gag peptides presented by HLA-E were analyzed. Using in vitro assays, we observed HLA-E–restricted T cell responses to what we believe to be a newly identified subdominant Gag-KL9 as well as a well-described immunodominant Gag-KF11 epitope in T cell lines derived from chronically HIV-infected patients and also primed from healthy donors. Blocking of the HLA-E/KF11 binding by the B7 signal peptide resulted in decreased CD8(+) T cell responses. KF11 presented via HLA-E in HIV-infected cells was recognized by antigen-specific CD8(+) T cells. Importantly, bulk CD8(+) T cells obtained from HIV-infected individuals recognized infected cells via HLA-E presentation. Ex vivo analyses at the epitope level showed a higher responder frequency of HLA-E–restricted responses to KF11 compared with KL9. Taken together, our findings of HLA-E–restricted HIV-specific immune responses offer intriguing and possibly paradigm-shifting insights into factors that contribute to the immunodominance of CD8(+) T cell responses in HIV infection.

A DNA vaccine encoding prM and E protein has been shown to induce protection against Zika virus (ZIKV) infection in mice and monkeys. However, its effectiveness in humans remains undefined. Moreover, identification of which immune cell types are specifically infected in humans is unclear. We show that human myeloid cells and B cells are primary targets of ZIKV in humanized mice. We also show that a DNA vaccine encoding full length prM and E protein protects humanized mice from ZIKV infection. Following administration of the DNA vaccine, humanized DRAG mice developed antibodies targeting ZIKV as measured by ELISA and neutralization assays. Moreover, following ZIKV challenge, vaccinated animals presented virtually no detectable virus in human cells and in serum, whereas unvaccinated animals displayed robust infection, as measured by qRT-PCR. Our results utilizing humanized mice show potential efficacy for a targeted DNA vaccine against ZIKV in humans., Highlights • Zika DNA vaccine elicits protective antibody response in humanized DRAG mice. • Human myeloid cells and B cells are targets of Zika virus. A Zika virus vaccine requires testing in human immune cells to determine its effectiveness. In this communication, we report that a DNA vaccine encoding Zika prM and E protein is able to elicit protective neutralizing antibodies against Zika virus in humanized DRAG mice, and that human myeloid cells and B cells are primary targets of Zika virus.

West Nile virus (WNV) causes an acute neurological infection attended by massive neuronal cell death. However, the mechanism(s) behind the virus-induced cell death is poorly understood. Using a library containing 77,406 sgRNAs targeting 20,121 genes, we performed a genome-wide screen followed by a second screen with a sub-library. Among the genes identified, seven genes, EMC2, EMC3, SEL1L, DERL2, UBE2G2, UBE2J1, and HRD1, stood out as having the strongest phenotype, whose knockout conferred strong protection against WNV-induced cell death with two different WNV strains and in three cell lines. Interestingly, knockout of these genes did not block WNV replication. Thus, these appear to be essential genes that link WNV replication to downstream cell death pathway(s). In addition, the fact that all of these genes belong to the endoplasmic reticulum-associated protein degradation (ERAD) pathway suggests that this might be the primary driver of WNV-induced cell death.

Multiplexed miRNA-based shRNAs (shRNA-miRs) could have wide potential to simultaneously suppress multiple genes. Here, we describe a simple strategy to express a large number of shRNA-miRs using minimal flanking sequences from multiple endogenous miRNAs. We found that a sequence of 30 nucleotides flanking the miRNA duplex was sufficient for efficient processing of shRNA-miRs. We inserted multiple shRNAs in tandem, each containing minimal flanking sequence from a different miRNA. Deep sequencing of transfected cells showed accurate processing of individual shRNA-miRs and that their expression did not decrease with the distance from the promoter. Moreover, each shRNA was as functionally competent as its singly expressed counterpart. We used this system to express one shRNA-miR targeting CCR5 and six shRNA-miRs targeting the HIV-1 genome. The lentiviral construct was pseudotyped with HIV-1 envelope to allow transduction of both resting and activated primary CD4 T cells. Unlike one shRNA-miR, the seven shRNA-miR transduced T cells nearly abrogated HIV-1 infection in vitro. Additionally, when PBMCs from HIV-1 seropositive individuals were transduced and transplanted into NOD/SCID/IL-2R γc(-/-) mice (Hu-PBL model) efficient suppression of endogenous HIV-1 replication with restoration of CD4 T cell counts was observed. Thus, our multiplexed shRNA appears to provide a promising gene therapeutic approach for HIV-1 infection.

// Sojan Abraham 1 , Jang-Gi Choi 1,2 , Nora M. Ortega 1 , Junli Zhang 1 , Premlata Shankar 1 and N. Manjunath Swamy 1 1 Center of Emphasis in Infectious Disease, Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX, USA 2 KM Application Center, Korea Institute of Oriental Medicine, Dong-gu, Daegu, Republic of Korea Correspondence to: N. Manjunath Swamy, email: // Keywords : interferon, HIV-1, hydrodynamic injection, Immunology and Microbiology Section, Immune response, Immunity Received : May 20, 2016 Accepted : October 02, 2016 Published : October 06, 2016 Abstract Because endogenous interferon type I (IFN-I) produced by HIV-1 infection might complicate the analysis of therapeutically administered IFN-I, we tested different humanized mouse models for induction of IFN-I during HIV-1 infection. While HIV-1 induced high levels of IFN-α in BLT mice, IFN-I was undetectable following infection in the Hu-PBL mouse model, in which only T cells expand. We therefore tested the effect of treatment with Pegylated IFN-2 (pegasys), in Hu-PBL mice. Pegasys prevented CD4 T cell depletion and reduced the viral load for 10 days, but the effect waned thereafter. We next expressed IFN-I subsets (IFN-α2, -α6, -α8, -α14, and -β) in Hu-PBL mice by hydrodynamic injection of plasmids encoding them and 2 days later infected the mice with HIV-1. CD4 T cell depletion was prevented in all subtypes of IFN-I-expressing mice by day 10. However, at day 40 post-infection, protection was seen in IFN-β- and IFN-α14-expressing mice, but not the others. The viral load followed an inverse pattern and was highest in control mice and lowest in IFN-β- and IFN-α14-expressing mice until day 40 after infection. These results show that gene therapy with plasmids encoding IFN-β and -α14, but not the commonly used -α2, confers long-term suppression of HIV-1 replication.

Hypersecretion of cytokines by innate immune cells is thought to initiate multiple organ failure in murine models of sepsis. Whether human cytokine storm also plays a similar role is not clear. Here, we show that human hematopoietic cells are required to induce sepsis-induced mortality following cecal ligation and puncture (CLP) in the severely immunodeficient nonobese diabetic (NOD)/SCID/IL2Rγ −/− mice, and siRNA treatment to inhibit HMGB1 release by human macrophages and dendritic cells dramatically reduces sepsis-induced mortality. Following CLP, compared with immunocompetent WT mice, NOD/SCID/IL2Rγ −/− mice did not show high levels of serum HMGB1 or murine proinflammatory cytokines and were relatively resistant to sepsis-induced mortality. In contrast, NOD/SCID/IL2Rγ −/− mice transplanted with human hematopoietic stem cells [humanized bone marrow liver thymic mice (BLT) mice] showed high serum levels of HMGB1, as well as multiple human but not murine proinflammatory cytokines, and died uniformly, suggesting human cytokines are sufficient to induce organ failure in this model. Moreover, targeted delivery of HMGB1 siRNA to human macrophages and dendritic cells using a short acetylcholine receptor (AchR)-binding peptide [rabies virus glycoprotein (RVG)-9R] effectively suppressed secretion of HMGB1, reduced the human cytokine storm, human lymphocyte apoptosis, and rescued humanized mice from CLP-induced mortality. siRNA treatment was also effective when started after the appearance of sepsis symptoms. These results show that CLP in humanized mice provides a model to study human sepsis, HMGB1 siRNA might provide a treatment strategy for human sepsis, and RVG-9R provides a tool to deliver siRNA to human macrophages and dendritic cells that could potentially be used to suppress a variety of human inflammatory diseases.

The CRISPR/Cas9 system provides an easy way to edit specific site/s in the genome and thus offers tremendous opportunity for human gene therapy for a wide range of diseases. However, one major concern is off-target effects, particularly with long-term expression of Cas9 nuclease when traditional expression methods such as via plasmid/viral vectors are used. To overcome this limitation, we pre-packaged Cas9 protein (Cas9P LV) in lentiviral particles for transient exposure and showed its effectiveness for gene disruption in cells, including primary T cells expressing specific single guide RNAs (sgRNAs). We then constructed an 'all in one virus' to express sgRNAs in association with pre-packaged Cas9 protein (sgRNA/Cas9P LV). We successfully edited CCR5 in TZM-bl cells by this approach. Using an sgRNA-targeting HIV long terminal repeat, we also were able to disrupt HIV provirus in the J-LAT model of viral latency. Moreover, we also found that pre-packaging Cas9 protein in LV particle reduced off-target editing of chromosome 4:-29134166 locus by CCR5 sgRNA, compared with continued expression from the vector. These results show that sgRNA/Cas9P LV can be used as a safer approach for human gene therapy applications.

Although patients with GVHD have elevated serum levels of IL10, whether its role is protective or pathogenic remains unclear. Here, we used a humanized mouse model to study the role of IL-10 in GVHD. When human PBMCs were engrafted in NOD-scid IL2rγc(null) mice expressing human IL-10, the T cells underwent massive expansion resulting in lethality by day 21, whereas control mice survived for at least 40 days. Histopathology of the liver showed extensive mononuclear cell infiltration in IL-10 expressing but not in control mice. Corresponding to their aggressiveness, the T cells in the IL-10 group exhibited predominantly an effector memory phenotype (CD45RO(+)CD27(-)) while in control mice, the T cells were of transitional memory phenotype (CD45RO(+)CD27(+)). Further, IL-10 receptor blocking antibody was able to protect the animals from GVHD. Since our results demonstrate a direct pathogenic role for IL-10, blockade of IL-10 signaling may provide a therapeutic option for GVHD.

Dengue is a common arthropod-borne flaviviral infection in the tropics, for which there is no vaccine or specific antiviral drug. The infection is often associated with serious complications such as dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS), in which both viral and host factors have been implicated. RNA interference (RNAi) is a potent antiviral strategy and a potential therapeutic option for dengue if a feasible strategy can be developed for delivery of small interfering RNA (siRNA) to dendritic cells (DCs) and macrophages, the major in vivo targets of the virus and also the source of proinflammatory cytokines. Here we show that a dendritic cell-targeting 12-mer peptide (DC3) fused to nona- d -arginine (9dR) residues (DC3-9dR) delivers siRNA and knocks down endogenous gene expression in heterogenous DC subsets, (monocyte-derived DCs [MDDCs], CD34 + hematopoietic stem cell [HSC])-derived Langerhans DCs, and peripheral blood DCs). Moreover, DC3-9dR-mediated delivery of siRNA targeting a highly conserved sequence in the dengue virus envelope gene (siFvE D ) effectively suppressed dengue virus replication in MDDCs and macrophages. In addition, DC-specific delivery of siRNA targeting the acute-phase cytokine tumor necrosis factor alpha (TNF-α), which plays a major role in dengue pathogenesis, either alone or in combination with an antiviral siRNA, significantly reduced virus-induced production of the cytokine in MDDCs. Finally to validate the strategy in vivo , we tested the ability of the peptide to target human DCs in the NOD/SCID/IL-2Rγ −/− mouse model engrafted with human CD34 + hematopoietic stem cells (HuHSC mice). Treatment of mice by intravenous (i.v.) injection of DC3-9dR-complexed siRNA targeting TNF-α effectively suppressed poly(I:C)-induced TNF-α production by DCs. Thus, DC3-9dR can deliver siRNA to DCs both in vitro and in vivo , and this delivery approach holds promise as a therapeutic strategy to simultaneously suppress virus replication and curb virus-induced detrimental host immune responses in dengue infection.

Nonclassical MHC Class 1b antigens differ from classical MHC class 1a antigens in having a restricted polymorphism as well as varied surface expression in different cell types. They have been hypothesized to play a role in bridging adaptive and innate immune responses.We examined the effects of JEV infection on the expression of classical MHC class 1a and nonclassical MHC class 1b genes in five different cell lines. Among the nonclassical genes, H-2Q4 was induced in H-6 hepatoma, primary astrocytes, mouse embryo fibroblasts, L929 and 3T3 cells. H-2T23 and H-2T10 genes were not induced in H-6 and 3T3, respectively, but were induced in the other cell lines examined. Both H-2Q4 encoded Qb1 and H-2T23 encoded Qa-$1^b$ antigens were induced on the cell surface upon JEV infection in primary astrocytes and mouse embryonic fibroblasts. Classical MHC-I genes and the genes associated with antigen presentation such as Tap1, Tap2, Tapasin, Lmp2, Lmp7 and Lmp10 as well as type 1 (\alpha/\beta) IFNs were induced in all cell lines. However, IFN\gamma was not induced. Further, induction of H-2Q4 and H-2T23 by JEV was independent of NF-\kappa B but type 1 IFN dependent while H-2T10 was dependent on NF-\kappa B and type 1 IFN independent. Thus, while classical MHC genes were induced by JEV in all cell lines tested despite high levels of constitutive expression in L929 and 3T3, nonclassical genes were not inducible in all cell lines tested and involved different mechanisms of induction.

Regulatory T cells are essential to maintain immune homeostasis and prevent autoimmunity. Therapy with in vitro expanded human nT(Regs) is being tested to prevent graft versus host disease, which is a major cause for morbidity and mortality associated with hematopoietic stem cell transplantation. Their usefulness in therapy will depend on their capacity to survive, migrate appropriately and retain suppressive activity when introduced into a transplant recipient. The lack of a suitable animal model for studying the in vivo reconstitutive capability of human nT(Regs) is a major impediment for investigating the behavior of adoptively transferred nT(Regs)in vivo. We show that injection of a plasmid encoding human IL-2 is necessary and sufficient for long term engraftment of in vitro expanded nT(Regs) in NOD-SCID IL2rγc(null) mice. We also demonstrate that these in vivo reconstituted T(Regs) traffic to different organs of the body and retain suppressive function. Finally, in an IL-2 accelerated GVHD model, we show that these in vivo reconstituted T(Regs) are capable of preventing severe xenogenic response of human PBMCs. Thus, this novel 'hu-T(Reg) mouse' model offers a pre-clinical platform to study the in vivo function and stability of human nT(Regs) and their ability to modulate autoimmune diseases and GVHD.

RNA interference can be mediated by fully complementary siRNA or partially complementary miRNA. siRNAs are widely used to suppress viral replication and the fully complementary siRNA bound Ago-2 in the RISC is known to degrade the target RNA. Although other argonaute proteins lacking slicer activity can also bind oligonucleotides with both si and miRNA structures, whether they can also contribute to antiviral effects is not entirely clear. We tested si and miRNA structured oligos for target repression in dual luciferase assays as well as for inhibition of Dengue and West Nile virus replication in ES cells expressing individual Ago proteins. In luciferase assays, both fully complementary and partially complementary oligos effectively repressed their targets in all individual Ago expressing cell lines, although the efficacy with fully complementary oligos was higher in Ago-2+ cells. However, partially complementary oligos had no effect on virus replication in any cell line, while fully complementary siRNAs were highly effective in Ago-2 expressing, but not in cells expressing other Ago proteins. This occurred irrespective of whether the target sequences were located in the coding region or 3'UTR of the virus. We conclude that Ago-2 slicer activity is essential for anti-viral efficacy of siRNAs and miRNA-mediated translational repression/transcript destabilization is too weak to suppress the abundantly expressed flaviviral proteins.