Efficacy and safety analyses of a recombinant human immunodeficiency virus type 1 derived vector system

HIV-1 single-transcription start-site mutants display complementary replication functions that are restored by reversion

HIV-1 transcription initiates at two positions, generating RNAs with either cap1G or cap3G 5' ends. The replication fates of these RNAs differ, with viral particles encapsidating almost exclusively cap1G RNAs and cap3G RNAs retained in cells where they are enriched on polysomes and among spliced viral RNAs. Here, we studied replication properties of virus promoter mutants that produced only one RNA 5' isoform or the other: separately, in combination, and during spreading infection. Results showed that either single-start RNA could serve as both mRNA and genomic RNA when present as the only form in cells, although cap3G RNA was more efficiently translated and spliced, while cap1G RNA was packaged into nascent virions slightly better than RNAs from the parental virus. When co-expressed from separate vectors, cap1G RNA was preferentially packaged into virions. During spreading infection, the cap1G-only virus displayed only minor defects, but the cap3G-only virus showed severe replication delays in both the highly permissive MT-4 cell line and in primary human CD4+ T cells. Passage of cap3G-only virus yielded revertants that replicated as well as the twinned (cap1G+ cap3G) transcription start-site parent. These revertants displayed restored packaging and splicing levels and had regained multiple transcription start-site use.IMPORTANCEHIV-1 generates two RNAs during its replication that differ by only two nucleotides in length. Despite this very minor difference, the RNAs perform different and complementary replication functions. When mutants that expressed only one RNA were forced to revert, they regained functions associated with the second RNA.

Disruption of LEDGF/p75-directed integration derepresses antisense transcription of the HIV-1 genome

Disruption of HIV-1 Integrase (IN) interactions with the host-factor Lens Epithelium-Derived Growth Factor (LEDGF)/p75 leads to decreased, random integration, increased latent infection, and described here, accumulation of HIV-1 antisense RNA (asRNA). asRNA increase was observed following interruptions of IN-LEDGF/p75 interactions either through pharmacologic perturbations of IN-LEDGF/p75 by treatment with allosteric HIV-1 integrase inhibitors (ALLINIs) or in cell lines with LEDGF genetic knockout. Additionally, by impairing Tat-dependent HIV transcription, asRNA abundance markedly increases. Illumina sequencing characterization of asRNA transcripts in primary T cells infected in the presence of ALLINIs showed that most initiate from within the HIV-1. Overall, loss of IN-LEDGF/p75 interactions increase asRNA abundance. Understanding the relationship between ALLINIs, integration sites, asRNA, and latency could aid in future therapeutic strategies.

HIV-1 single transcription start site mutants display complementary replication functions that are restored by reversion

HIV-1 transcription initiates at two positions, generating RNAs with either cap1G or cap3G 5' ends. The replication fates of these RNAs di\er, with viral particles encapsidating almost exclusively cap1G RNAs and cap3G RNAs retained in cells where they are enriched on polysomes and among spliced viral RNAs. Here, we studied replication properties of virus promoter mutants that produced only one RNA 5' isoform or the other: separately, in combination, and during spreading infection. Results showed that either single start RNA could serve as both mRNA and genomic RNA when present as the only form in cells, although cap3G RNA was more efficiently translated and spliced while cap1G RNA was packaged into nascent virions slightly better than RNAs from the parental virus. When co-expressed from separate vectors, cap1G RNA was preferentially packaged into virions. During spreading infection cap1G-only virus displayed only minor defects but cap3G-only virus showed severe replication delays in both the highly permissive MT-4 cell line and in primary human CD4+ T cells. Passage of cap3G-only virus yielded revertants that replicated as well as the twinned (cap1G+ cap3G) transcription start site parent. These revertants displayed restored packaging and splicing levels and had regained multiple transcription start site use.

Post-Transcriptional Induction of the Antiviral Host Factor GILT/IFI30 by Interferon Gamma

Gamma-interferon-inducible lysosomal thiol reductase (GILT) plays pivotal roles in both adaptive and innate immunities. GILT exhibits constitutive expression within antigen-presenting cells, whereas in other cell types, its expression is induced by interferon gamma (IFN-γ). Gaining insights into the precise molecular mechanism governing the induction of GILT protein by IFN-γ is of paramount importance for adaptive and innate immunities. In this study, we found that the 5' segment of GILT mRNA inhibited GILT protein expression regardless of the presence of IFN-γ. Conversely, the 3' segment of GILT mRNA suppressed GILT protein expression in the absence of IFN-γ, but it loses this inhibitory effect in its presence. Although the mTOR inhibitor rapamycin suppressed the induction of GILT protein expression by IFN-γ, the expression from luciferase sequence containing the 3' segment of GILT mRNA was resistant to rapamycin in the presence of IFN-γ, but not in its absence. Collectively, this study elucidates the mechanism behind GILT induction by IFN-γ: in the absence of IFN-γ, GILT mRNA is constitutively transcribed, but the translation process is hindered by both the 5' and 3' segments. Upon exposure to IFN-γ, a translation inhibitor bound to the 3' segment is liberated, and a translation activator interacts with the 3' segment to trigger the initiation of GILT translation.

Phase I clinical trial of intracerebral injection of lentiviral-ABCD1 for the treatment of cerebral adrenoleukodystrophy

This was a single-arm, multicenter, open-label phase I trial. Lentiviral vectors (LV) carrying the ABCD1 gene (LV-ABCD1) was directly injected into the brain of patients with childhood cerebral adrenoleukodystrophy (CCALD), and multi-site injection was performed. The injection dose increased from 200 to 1600 μL (vector titer: 1×109 transduction units per mL (TU/mL)), and the average dose per kilogram body weight ranges from 8 to 63.6 μL/kg. The primary endpoint was safety, dose-exploration and immunogenicity and the secondary endpoint was initial evaluation of efficacy and the expression of ABCD1 protein. A total of 7 patients participated in this phase I study and were followed for 1 year. No injection-related serious adverse event or death occurred. Common adverse events associated with the injection were irritability (71%, 5/7) and fever (37.2-38.5 ℃, 57%, 4/7). Adverse events were mild and self-limited, or resolved within 3 d of symptomatic treatment. The maximal tolerable dose is 1600 μL. In 5 cases (83.3%, 5/6), no lentivirus associated antibodies were detected. The overall survival at 1-year was 100%. The ABCD1 protein expression was detected in neutrophils, monocytes and lymphocytes. This study suggests that the intracerebral injection of LV-ABCD1 for CCALD is safe and can achieve successful LV transduction in vivo; even the maximal dose did not increase the risk of adverse events. Furthermore, the direct LV-ABCD1 injection displayed low immunogenicity. In addition, the effectiveness of intracerebral LV-ABCD1 injection has been preliminarily demonstrated while further investigation is needed. This study has been registered in the Chinese Clinical Trial Registry (https://www.chictr.org.cn/, registration number: ChiCTR1900026649).

CRISPR library screening to develop HEK293-derived cell lines with improved lentiviral vector titers

Lentiviral (LV) vectors have emerged as powerful tools for treating genetic and acquired human diseases. As clinical studies and commercial demands have progressed, there has been a growing need for large amounts of purified LV vectors. To help meet this demand, we developed CRISPR library screening methods to identify genetic perturbations in human embryonic kidney 293 (HEK293) cells and their derivatives that may increase LV vector titers. Briefly, LV vector-based Human CRISPR Activation and Knockout libraries (Calabrese and Brunello) were used to modify HEK293 and HEK293T cells. These cell populations were then expanded, and integrated LV vector genomes were rescued by transfection. LV vectors were harvested, and the process of sequential transduction and rescue-transfection was iterated. Through this workflow, guide RNAs (gRNAs) that target genes that may suppress or enhance LV vector production were enriched and identified with Next-Generation Sequencing (NGS). Though more work is needed to test genes identified in this screen, we expect that perturbations of genes we identified here, such as TTLL12, which is an inhibitor of antiviral innate immunity may be introduced and multiplexed to yield cell lines with improved LV vector productivity.

Improved intravenous lentiviral gene therapy based on endothelial-specific promoter-driven factor VIII expression for hemophilia A

BACKGROUND

Hemophilia A (HA) is an X-linked monogenic disorder caused by deficiency of the factor VIII (FVIII) gene in the intrinsic coagulation cascade. The current protein replacement therapy (PRT) of HA has many limitations including short term effectiveness, high cost, and life-time treatment requirement. Gene therapy has become a promising treatment for HA. Orthotopic functional FVIII biosynthesis is critical to its coagulation activities.

METHODS

To investigate targeted FVIII expression, we developed a series of advanced lentiviral vectors (LVs) carrying either a universal promoter (EF1α) or a variety of tissue-specific promoters, including endothelial-specific (VEC), endothelial and epithelial-specific (KDR), and megakaryocyte-specific (Gp and ITGA) promoters.

RESULTS

To examine tissue specificity, the expression of a B-domain deleted human F8 (F8BDD) gene was tested in human endothelial and megakaryocytic cell lines. Functional assays demonstrated FVIII activities of LV-VEC-F8BDD and LV-ITGA-F8BDD in the therapeutic range in transduced endothelial and megakaryocytic cells, respectively. In F8 knockout mice (F8 KO mice, F8^null mice), intravenous (iv) injection of LVs illustrated different degrees of phenotypic correction as well as anti-FVIII immune response for the different vectors. The iv delivery of LV-VEC-F8BDD and LV-Gp-F8BDD achieved 80% and 15% therapeutic FVIII activities over 180 days, respectively. Different from the other LV constructs, the LV-VEC-F8BDD displayed a low FVIII inhibitory response in the treated F8^null mice.

CONCLUSIONS

The LV-VEC-F8BDD exhibited high LV packaging and delivery efficiencies, with endothelial specificity and low immunogenicity in the F8^null mice, thus has a great potential for clinical applications.

Discovery of Highly Potent Small Molecule Pan-Coronavirus Fusion Inhibitors

The unprecedented pandemic of COVID-19, caused by a novel coronavirus, SARS-CoV-2, and its highly transmissible variants, led to massive human suffering, death, and economic devastation worldwide. Recently, antibody-evasive SARS-CoV-2 subvariants, BQ and XBB, have been reported. Therefore, the continued development of novel drugs with pan-coronavirus inhibition is critical to treat and prevent infection of COVID-19 and any new pandemics that may emerge. We report the discovery of several highly potent small-molecule inhibitors. One of which, NBCoV63, showed low nM potency against SARS-CoV-2 (IC₅₀: 55 nM), SARS-CoV-1 (IC₅₀: 59 nM), and MERS-CoV (IC₅₀: 75 nM) in pseudovirus-based assays with excellent selectivity indices (SI > 900), suggesting its pan-coronavirus inhibition. NBCoV63 showed equally effective antiviral potency against SARS-CoV-2 mutant (D614G) and several variants of concerns (VOCs) such as B.1.617.2 (Delta), B.1.1.529/BA.1 and BA.4/BA.5 (Omicron), and K417T/E484K/N501Y (Gamma). NBCoV63 also showed similar efficacy profiles to Remdesivir against authentic SARS-CoV-2 (Hong Kong strain) and two of its variants (Delta and Omicron), SARS-CoV-1, and MERS-CoV by plaque reduction in Calu-3 cells. Additionally, we show that NBCoV63 inhibits virus-mediated cell-to-cell fusion in a dose-dependent manner. Furthermore, the absorption, distribution, metabolism, and excretion (ADME) data of NBCoV63 demonstrated drug-like properties.

Intracerebral lentiviral ABCD1 gene therapy in an early disease onset ALD mouse model

X-linked adrenoleukodystrophy (ALD) is a genetic disorder of the ABCD1 gene. We aimed to treat ALD via direct intracerebral injection of lentiviral ABCD1 (LV.ABCD1). Lentiviral vectors (LVs) were injected into the brain of wild type mice to access toxicities and biodistribution. Confocal microscopy illustrated supraphysiological ABCD1 expression surrounding the injection sites, and LVs were also detected in the opposite site of the unilaterally injected brain. In multi-site bilateral injections (4, 6, 8, and 9 sites), LV.ABCD1 transduced most brain regions including the cerebellum. Investigation of neuronal loss, astrogliosis and microglia activation did not detect abnormality. For efficacy evaluation, a novel ALD knockout (KO) mouse model was established by deleting exons 3 to 9 of the ABCD1 gene based on CRISPR/Cas9 gene editing. The KO mice showed behavioral deficit in open-field test (OFT) and reduced locomotor activities in rotarod test at 6 and 7 months of age, respectively. We treated 3-month-old KO mice with bilateral LV.ABCD1 injections into the external capsule and thalamus. ABCD1 expression was detected 15 days later, and the impaired motor ability was gradually alleviated. Our studies established an early onset ALD model and illustrated neurological improvement after LV.ABCD1 intracerebral injection without immunopathological toxicity.

IDO1, FAT10, IFI6, and GILT Are Involved in the Antiretroviral Activity of γ-Interferon and IDO1 Restricts Retrovirus Infection by Autophagy Enhancement

Gamma-interferon (γ-IFN) significantly inhibits infection by replication-defective viral vectors derived from the human immunodeficiency virus type 1 (HIV-1) or murine leukemia virus (MLV) but the underlying mechanism remains unclear. Previously we reported that knockdown of γ-IFN-inducible lysosomal thiolreductase (GILT) abrogates the antiviral activity of γ-IFN in TE671 cells but not in HeLa cells, suggesting that other γ-IFN-inducible host factors are involved in its antiviral activity in HeLa cells. We identified cellular factors, the expression of which are induced by γ-IFN in HeLa cells, using a microarray, and analyzed the effects of 11 γ-IFN-induced factors on retroviral vector infection. Our results showed that the exogenous expression of FAT10, IFI6, or IDO1 significantly inhibits both HIV-1- and MLV-based vector infections. The antiviral activity of γ-IFN was decreased in HeLa cells, in which the function of IDO1, IFI6, FAT10, and GILT were simultaneously inhibited. IDO1 is an enzyme that metabolizes an essential amino acid, tryptophan. However, IDO1 did not restrict retroviral vector infection in Atg3-silencing HeLa cells, in which autophagy did not occur. This study found that IDO1, IFI6, FAT10, and GILT are involved in the antiviral activity of γ-IFN, and IDO1 inhibits retroviral infection by inducing autophagy.

Unique Mode of Antiviral Action of a Marine Alkaloid against Ebola Virus and SARS-CoV-2

Lamellarin α 20-sulfate is a cell-impenetrable marine alkaloid that can suppress infection that is mediated by the envelope glycoprotein of human immunodeficiency virus type 1. We explored the antiviral action and mechanisms of this alkaloid against emerging enveloped RNA viruses that use endocytosis for infection. The alkaloid inhibited the infection of retroviral vectors that had been pseudotyped with the envelope glycoprotein of Ebola virus and SARS-CoV-2. The antiviral effects of lamellarin were independent of the retrovirus Gag-Pol proteins. Interestingly, although heparin and dextran sulfate suppressed the cell attachment of vector particles, lamellarin did not. In silico structural analyses of the trimeric glycoprotein of the Ebola virus disclosed that the principal lamellarin-binding site is confined to a previously unappreciated cavity near the NPC1-binding site and fusion loop, whereas those for heparin and dextran sulfate were dispersed across the attachment and fusion subunits of the glycoproteins. Notably, lamellarin binding to this cavity was augmented under conditions where the pH was 5.0. These results suggest that the final action of the alkaloid against Ebola virus is specific to events following endocytosis, possibly during conformational glycoprotein changes in the acidic environment of endosomes. Our findings highlight the unique biological and physicochemical features of lamellarin α 20-sulfate and should lead to the further use of broadly reactive antivirals to explore the structural mechanisms of virus replication.

Pseudotyped lentiviral vectors: Ready for translation into targeted cancer gene therapy?

Gene therapy holds great promise for curing cancer by editing the deleterious genes of tumor cells, but the lack of vector systems for efficient delivery of genetic material into specific tumor sites in vivo has limited its full therapeutic potential in cancer gene therapy. Over the past two decades, increasing studies have shown that lentiviral vectors (LVs) modified with different glycoproteins from a donating virus, a process referred to as pseudotyping, have altered tropism and display cell-type specificity in transduction, leading to selective tumor cell killing. This feature of LVs together with their ability to enable high efficient gene delivery in dividing and non-dividing mammalian cells in vivo make them to be attractive tools in future cancer gene therapy. This review is intended to summarize the status quo of some typical pseudotypings of LVs and their applications in basic anti-cancer studies across many malignancies. The opportunities of translating pseudotyped LVs into clinic use in cancer therapy have also been discussed.

Discovery of Highly Potent Fusion Inhibitors with Potential Pan-Coronavirus Activity That Effectively Inhibit Major COVID-19 Variants of Concern (VOCs) in Pseudovirus-Based Assays

We report the discovery of several highly potent small molecules with low-nM potency against severe acute respiratory syndrome coronavirus (SARS-CoV; lowest half-maximal inhibitory concentration (IC₅₀: 13 nM), SARS-CoV-2 (IC₅₀: 23 nM), and Middle East respiratory syndrome coronavirus (MERS-CoV; IC₅₀: 76 nM) in pseudovirus-based assays with excellent selectivity index (SI) values (>5000), demonstrating potential pan-coronavirus inhibitory activities. Some compounds showed 100% inhibition against the cytopathic effects (CPE; IC₁₀₀) of an authentic SARS-CoV-2 (US_WA-1/2020) variant at 1.25 µM. The most active inhibitors also potently inhibited variants of concern (VOCs), including the UK (B.1.1.7) and South African (B.1.351) variants and the Delta variant (B.1.617.2) originally identified in India in pseudovirus-based assay. Surface plasmon resonance (SPR) analysis with one potent inhibitor confirmed that it binds to the prefusion SARS-CoV-2 spike protein trimer. These small-molecule inhibitors prevented virus-mediated cell-cell fusion. The absorption, distribution, metabolism, and excretion (ADME) data for one of the most active inhibitors, NBCoV1, demonstrated drug-like properties. An in vivo pharmacokinetics (PK) study of NBCoV1 in rats demonstrated an excellent half-life (t_1/2) of 11.3 h, a mean resident time (MRT) of 14.2 h, and oral bioavailability. We expect these lead inhibitors to facilitate the further development of preclinical and clinical candidates.

Antivirus activity, but not thiolreductase activity, is conserved in interferon-gamma-inducible GILT protein in arthropod

We have previously reported that gamma-interferon inducible lysosomal thiolreductase (GILT) functions as a host defense factor against retroviruses by digesting disulfide bonds on viral envelope proteins. GILT is widely conserved even in plants and fungi as well as animals. The thiolreductase active site of mammalian GILT is composed of a CXXC amino acid motif, whereas the C-terminal cysteine residue is changed to serine in arthropods including shrimps, crabs, and flies. GILT from Penaeus monodon (PmGILT) also has the CXXS motif instead of the CXXC active site. We demonstrate here that a human GILT mutant (GILT C75S) with the CXXS motif and PmGILT significantly inhibit amphotropic murine leukemia virus vector infection in human cells without alterning its expression level and lysosomal localization, showing that the C-terminal cysteine residue of the active site is not required for the antiviral activity. We have reported that human GILT suppresses HIV-1 particle production by digestion of disulfide bonds on CD63. However, GILT C75S mutant and PmGILT did not digest CD63 disulfide bonds, and had no effect on HIV-1 virion production, suggesting that they do not have thiolreductase activity. Taken together, this study found that antiviral activity, but not thiolreductase activity, is conserved in arthropod GILT proteins. This finding provides a new insight that the common function of GILT is antiviral activity in many animals.

Transduction of modified factor VIII gene improves lentiviral gene therapy efficacy for hemophilia A

Hemophilia A (HA) is a bleeding disorder caused by deficiency of the coagulation factor VIII (F8). F8 replacement is standard of care, whereas gene therapy (F8 gene) for HA is an attractive investigational approach. However, the large size of the F8 gene and the immunogenicity of the product present challenges in development of the F8 gene therapy. To resolve these problems, we synthesized a shortened F8 gene (F8-BDD) and cloned it into a lentiviral vector (LV). The F8-BDD produced mainly short cleaved inactive products in LV-transduced cells. To improve F8 functionality, we designed two novel F8-BDD genes, one with an insertion of eight specific N-glycosylation sites (F8-N8) and another which restored all N-glycosylation sites (F8-299) in the B domain. Although the overall protein expression was reduced, high coagulation activity (>100-fold) was detected in the supernatants of LV-F8-N8- and LV-F8-299-transduced cells. Protein analysis of F8 and the procoagulation cofactor, von Willebrand Factor, showed enhanced interaction after restoration of B domain glycosylation using F8-299. HA mouse hematopoietic stem cell transplantation studies illustrated that the bleeding phenotype was corrected after LV-F8-N8 or -299 gene transfer into the hematopoietic stem cells. Importantly, the F8-299 modification markedly reduced immunogenicity of the F8 protein in these HA mice. In conclusion, the modified F8-299 gene could be efficiently packaged into LV and, although with reduced expression, produced highly stable and functional F8 protein that corrected the bleeding phenotype without inhibitory immunogenicity. We anticipate that these results will be beneficial in the development of gene therapies against HA.

Cellular Proteo-Transcriptomic Changes in the Immediate Early-Phase of Lentiviral Transduction

Lentivirus-based vectors derived from human immunodeficiency viruses type 1 and 2 (HIV-1 and 2) are widely used tools in research and may also be utilized in clinical settings. Like their parental virions, they are known to depend on the cellular machinery for successful gene delivery and integration. While most of the studies on cellular proteomic and transcriptomic changes have focused on the late phase of the transduction, studies of those changes in early time-points, especially in the case of HIV-2 based vectors, are widely lacking. Using second generation HIV-1 and 2 vesicular stomatitis virus G protein (VSV-G) pseudotyped lentiviral vectors, we transduced HEK-293T human embryonic kidney cells and carried out transcriptomic profiling at 0 and 2 h time points, with accompanying proteomic analysis at 2 h following transduction. Significant variations were observed in gene expression profile between HIV-1 and HIV-2 transduced samples. Thrombospondin 1 (THBS1), collagens (COL1A2, COL3A1), and eukaryotic translation factors (EIF3CL) in addition to various genes coding for long non-coding RNA (lncRNA) were significantly upregulated 2 h after HIV-2 transduction compared to HIV-1. Label-free quantification mass spectrometry (MS) indicated that seven proteins involved in RNA binding, mRNA transport, and chaperoning were significantly downregulated. The identification of cellular protein targets of lentiviral vectors and their effect on the cellular transcriptome will undoubtedly shed more light on their complex life cycle and may be utilized against infection by their parental lentiviruses. Furthermore, characterizing the early phase of HIV-2 infection may aid in the understanding of its pathomechanism and long incubation period.

An infectious Rous Sarcoma Virus Gag mutant that is defective in nuclear cycling

During retroviral replication, unspliced viral genomic RNA (gRNA) must escape the nucleus for translation into viral proteins and packaging into virions. "Complex" retroviruses such as Human Immunodeficiency Virus (HIV) use cis-acting elements on the unspliced gRNA in conjunction with trans-acting viral proteins to facilitate this escape. "Simple" retroviruses such as Mason-Pfizer Monkey Virus (MPMV) and Murine Leukemia Virus (MLV) exclusively use cis-acting elements on the gRNA in conjunction with host nuclear export proteins for nuclear escape. Uniquely, the simple retrovirus Rous Sarcoma Virus (RSV) has a Gag structural protein that cycles through the nucleus prior to plasma membrane binding. This trafficking has been implicated in facilitating gRNA nuclear export and is thought to be a required mechanism. Previously described mutants that abolish nuclear cycling displayed enhanced plasma membrane binding, enhanced virion release, and a significant loss in genome incorporation resulting in loss of infectivity. Here, we describe a nuclear cycling deficient RSV Gag mutant that has similar plasma membrane binding and genome incorporation to WT virus and surprisingly, is replication competent albeit with a slower rate of spread compared to WT. This mutant suggests that RSV Gag nuclear cycling is not strictly required for RSV replication. Importance While mechanisms for retroviral Gag assembly at the plasma membrane are beginning to be characterized, characterization of intermediate trafficking locales remain elusive. This is in part due to the difficulty of tracking individual proteins from translation to plasma membrane binding. RSV Gag nuclear cycling is a unique phenotype that may provide comparative insight to viral trafficking evolution and may present a model intermediate to cis- and trans-acting mechanisms for gRNA export.

Anti-HIV-1 Activity of pepRF1, a Proteolysis-Resistant CXCR4 Antagonist Derived from Dengue Virus Capsid Protein

There is an urgent need for the development of new anti-HIV drugs that can complement existing medicines to be used against resistant strains. Here, we report the anti-HIV-1 peptide pepRF1, a human serum-resistant peptide derived from the Dengue virus capsid protein. In vitro, pepRF1 shows a 50% inhibitory concentration of 1.5 nM with a potential therapeutic window higher than 53 000. This peptide is specific for CXCR4-tropic strains, preventing viral entry into target cells by binding to the viral coreceptor CXCR4, acting as an antagonist of this receptor. pepRF1 is more effective than T20, the only peptide-based HIV-1 entry inhibitor approved, and excels in inhibiting a HIV-1 strain resistant to T20. Potentially, pepRF1 can be used alone or in combination with other anti-HIV drugs. Furthermore, one can also envisage its use as a novel therapeutic strategy for other CXCR4-related diseases.

Stapled Peptides Based on Human Angiotensin-Converting Enzyme 2 (ACE2) Potently Inhibit SARS-CoV-2 Infection In Vitro

SARS-CoV-2 uses human angiotensin-converting enzyme 2 (ACE2) as the primary receptor to enter host cells and initiate the infection. The critical binding region of ACE2 is an ∼30-amino-acid (aa)-long helix. Here, we report the design of four stapled peptides based on the ACE2 helix, which is expected to bind to SARS-CoV-2 and prevent the binding of the virus to the ACE2 receptor and disrupt the infection. All stapled peptides showed high helical contents (50 to 94% helicity). In contrast, the linear control peptide NYBSP-C showed no helicity (19%). We have evaluated the peptides in a pseudovirus-based single-cycle assay in HT1080/ACE2 cells and human lung cell line A549/ACE2, overexpressing ACE2. Three of the four stapled peptides showed potent antiviral activity in HT1080/ACE2 (50% inhibitory concentration [IC₅₀]: 1.9 to 4.1 μM) and A549/ACE2 (IC₅₀: 2.2 to 2.8 μM) cells. The linear peptide NYBSP-C and the double-stapled peptide StRIP16, used as controls, showed no antiviral activity. Most significantly, none of the stapled peptides show any cytotoxicity at the highest dose tested. We also evaluated the antiviral activity of the peptides by infecting Vero E6 cells with the replication-competent authentic SARS-CoV-2 (US_WA-1/2020). NYBSP-1 was the most efficient, preventing the complete formation of cytopathic effects (CPEs) at an IC₁₀₀ of 17.2 μM. NYBSP-2 and NYBSP-4 also prevented the formation of the virus-induced CPE with an IC₁₀₀ of about 33 μM. We determined the proteolytic stability of one of the most active stapled peptides, NYBSP-4, in human plasma, which showed a half-life (T _1/2) of >289 min.IMPORTANCE SARS-CoV-2 is a novel virus with many unknowns. No vaccine or specific therapy is available yet to prevent and treat this deadly virus. Therefore, there is an urgent need to develop novel therapeutics. Structural studies revealed critical interactions between the binding site helix of the ACE2 receptor and SARS-CoV-2 receptor-binding domain (RBD). Therefore, targeting the entry pathway of SARS-CoV-2 is ideal for both prevention and treatment as it blocks the first step of the viral life cycle. We report the design of four double-stapled peptides, three of which showed potent antiviral activity in HT1080/ACE2 cells and human lung carcinoma cells, A549/ACE2. Most significantly, the active stapled peptides with antiviral activity against SARS-CoV-2 showed high α-helicity (60 to 94%). The most active stapled peptide, NYBSP-4, showed substantial resistance to degradation by proteolytic enzymes in human plasma. The lead stapled peptides are expected to pave the way for further optimization of a clinical candidate.

Selective optogenetic stimulation of efferent fibers in the vagus nerve of a large mammal

Background

Electrical stimulation applied to individual organs, peripheral nerves, or specific brain regions has been used to treat a range of medical conditions. In cardiovascular disease, autonomic dysfunction contributes to the disease progression and electrical stimulation of the vagus nerve has been pursued as a treatment for the purpose of restoring the autonomic balance. However, this approach lacks selectivity in activating function- and organ-specific vagal fibers and, despite promising results of many preclinical studies, has so far failed to translate into a clinical treatment of cardiovascular disease.

Objective

Here we report a successful application of optogenetics for selective stimulation of vagal efferent activity in a large animal model (sheep).

Methods and results

Twelve weeks after viral transduction of a subset of vagal motoneurons, strong axonal membrane expression of the excitatory light-sensitive ion channel ChIEF was achieved in the efferent projections innervating thoracic organs and reaching beyond the level of the diaphragm. Blue laser or LED light (>10 mW mm⁻²; 1 ms pulses) applied to the cervical vagus triggered precisely timed, strong bursts of efferent activity with evoked action potentials propagating at speeds of ∼6 m s⁻¹.

Conclusions

These findings demonstrate that in species with a large, multi-fascicled vagus nerve, it is possible to stimulate a specific sub-population of efferent fibers using light at a site remote from the vector delivery, marking an important step towards eventual clinical use of optogenetic technology for autonomic neuromodulation.

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Described is a method of selective efferent vagus nerve stimulation using light.

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Vagal preganglionic neurons are targeted to express light-sensitive channels.

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Specific efferent VNS by light delivery to the cervical vagus is achieved in a large animal model.

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Demonstrates feasibility of using optogenetic technology for autonomic neuromodulation.

Optimized Pseudotyping Conditions for the SARS-COV-2 Spike Glycoprotein

In work with pathogenic viruses, it is useful to have rapid quantitative tests for viral infectivity that can be performed without strict biocontainment restrictions. A common way of accomplishing this is to generate viral pseudoparticles that contain the surface glycoprotein from the pathogenic virus incorporated into a replication-defective viral particle that contains a sensitive reporter system. These pseudoparticles enter cells using the glycoprotein from the pathogenic virus, leading to a readout for infection. Conditions that block entry of the pathogenic virus, such as neutralizing antibodies, will also block entry of the viral pseudoparticles. However, viral glycoproteins often are not readily suited for generating pseudoparticles. Here, we describe a series of modifications that result in the production of relatively high-titer SARS-COV-2 pseudoparticles that are suitable for the detection of neutralizing antibodies from COVID-19 patients.

The severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) Spike glycoprotein is solely responsible for binding to the host cell receptor and facilitating fusion between the viral and host membranes. The ability to generate viral particles pseudotyped with SARS-COV-2 Spike is useful for many types of studies, such as characterization of neutralizing antibodies or development of fusion-inhibiting small molecules. Here, we characterized the use of a codon-optimized SARS-COV-2 Spike glycoprotein for the generation of pseudotyped HIV-1, murine leukemia virus (MLV), and vesicular stomatitis virus (VSV) particles. The full-length Spike protein functioned inefficiently with all three systems but was enhanced over 10-fold by deleting the last 19 amino acids of the cytoplasmic tail. Infection of 293FT target cells was possible only if the cells were engineered to stably express the human angiotensin-converting enzyme 2 (ACE2) receptor, but stably introducing an additional copy of this receptor did not further enhance susceptibility. Stable introduction of the Spike-activating protease TMPRSS2 further enhanced susceptibility to infection by 5- to 10-fold. Replacement of the signal peptide of the Spike protein with an optimal signal peptide did not enhance or reduce infectious particle production. However, modifications D614G and R682Q further enhanced infectious particle production. With all enhancing elements combined, the titer of pseudotyped HIV-1 particles reached almost 10⁶ infectious particles/ml. Finally, HIV-1 particles pseudotyped with SARS-COV-2 Spike were successfully used to detect neutralizing antibodies in plasma from coronavirus disease 2019 (COVID-19) patients, but not in plasma from uninfected individuals.

IMPORTANCE In work with pathogenic viruses, it is useful to have rapid quantitative tests for viral infectivity that can be performed without strict biocontainment restrictions. A common way of accomplishing this is to generate viral pseudoparticles that contain the surface glycoprotein from the pathogenic virus incorporated into a replication-defective viral particle that contains a sensitive reporter system. These pseudoparticles enter cells using the glycoprotein from the pathogenic virus, leading to a readout for infection. Conditions that block entry of the pathogenic virus, such as neutralizing antibodies, will also block entry of the viral pseudoparticles. However, viral glycoproteins often are not readily suited for generating pseudoparticles. Here, we describe a series of modifications that result in the production of relatively high-titer SARS-COV-2 pseudoparticles that are suitable for the detection of neutralizing antibodies from COVID-19 patients.

Natural HIV-1 Nef Polymorphisms Impair SERINC5 Downregulation Activity

HIV-1 Nef enhances virion infectivity by counteracting host restriction factor SERINC5; however, the impact of natural Nef polymorphisms on this function is largely unknown. We characterize SERINC5 downregulation activity of 91 primary HIV-1 subtype B nef alleles, including isolates from 45 elite controllers and 46 chronic progressors. Controller-derived Nef clones display lower ability to downregulate SERINC5 (median 80% activity) compared with progressor-derived clones (median 96% activity) (p = 0.0005). We identify 18 Nef polymorphisms associated with differential function, including two CTL escape mutations that contribute to lower SERINC5 downregulation: K94E, driven by HLA-B^∗08, and H116N, driven by the protective allele HLA-B^∗57. HIV-1 strains encoding Nef K94E and/or H116N display lower infectivity and replication capacity in the presence of SERINC5. Our results demonstrate that natural polymorphisms in HIV-1 Nef can impair its ability to internalize SERINC5, indicating that variation in this recently described function may contribute to differences in viral pathogenesis.

Primate lentiviruses require Inositol hexakisphosphate (IP6) or inositol pentakisphosphate (IP5) for the production of viral particles

Inositol hexakisphosphate (IP6) potently stimulates HIV-1 particle assembly in vitro and infectious particle production in vivo. However, knockout cells lacking inositol-pentakisphosphate 2-kinase (IPPK-KO), the enzyme that produces IP6 by phosphorylation of inositol pentakisphosphate (IP5), were still able to produce infectious HIV-1 particles at a greatly reduced rate. HIV-1 in vitro assembly can also be stimulated to a lesser extent with IP5, but until recently, it was not known if IP5 could also function in promoting assembly in vivo. Here we addressed whether there is an absolute requirement for IP6 or IP5 in the production of infectious HIV-1 particles. IPPK-KO cells expressed no detectable IP6 but elevated IP5 levels and displayed a 20-100-fold reduction in infectious particle production, correlating with lost virus release. Transient transfection of an IPPK expression vector stimulated infectious particle production and release in IPPK-KO but not wildtype cells. Several attempts to make IP6/IP5 deficient stable cells were not successful, but transient expression of the enzyme multiple inositol polyphosphate phosphatase-1 (MINPP1) into IPPK-KOs resulted in near ablation of IP6 and IP5. Under these conditions, we found that HIV-1 infectious particle production and virus release were essentially abolished (1000-fold reduction) demonstrating an IP6/IP5 requirement. However, other retroviruses including a Gammaretrovirus, a Betaretrovirus, and two non-primate Lentiviruses displayed only a modest (3-fold) reduction in infectious particle production from IPPK-KOs and were not significantly altered by expression of IPPK or MINPP1. The only other retrovirus found to show a clear IP6/IP5 dependence was the primate (macaque) Lentivirus Simian Immunodeficiency Virus, which displayed similar sensitivity as HIV-1. We were not able to determine if producer cell IP6/IP5 is required at additional steps beyond assembly because viral particles devoid of both molecules could not be generated. Finally, we found that loss of IP6/IP5 in viral target cells had no effect on permissivity to HIV-1 infection.

DNA-induced 2'3'-cGAMP enhances haplotype-specific human STING cleavage by dengue protease

Dengue virus (DENV) antagonizes the DNA sensing cGAS-STING pathway to subvert innate immunity, but how DENV protease-mediated human STING cleavage contributes to DENV pathogenesis remains obscure. Here, we found that STING haplotype frequency varies among different subhuman populations, and different haplotypes respond differently to DENV protease. The cleavage of a DENV protease-sensitive STING can be further enhanced by coculture with neighboring cells producing 2′3′-cGAMP, either by DNA transfection of cGAS or by reactivating Epstein–Barr virus from latent infection. Thus, DENV infection trims down human STING-mediated innate immunity in a haplotype-specific manner. The genetic background of host STING and bystander coinfection of pathogens triggering 2′3′-cGAMP production may be the missing link between STING cleavage and DENV pathogenesis.

The cytosolic DNA sensor cGMP-AMP synthase (cGAS) synthesizes the noncanonical cyclic dinucleotide 2′3′-cGAMP to activate the adaptor protein stimulator of IFN genes (STING), thus awakening host immunity in response to DNA pathogen infection. However, dengue virus (DENV), an RNA virus without a DNA stage in its life cycle, also manipulates cGAS-STING–mediated innate immunity by proteolytic degradation of STING. Here, we found that the sensitivity of STING to DENV protease varied with different human STING haplotypes. Exogenous DNA further enhanced DENV protease’s ability to interact and cleave protease-sensitive STING. DNA-enhanced STING cleavage was reduced in cGAS-knockdown cells and triggered by the cGAS product 2′3′-cGAMP. The source of DNA may not be endogenous mitochondrial DNA but rather exogenous reactivated viral DNA. Cells producing 2′3′-cGAMP by overexpressing cGAS or with DNA virus reactivation enhanced STING cleavage in neighboring cells harboring DENV protease. DENV infection reduced host innate immunity in cells with the protease-sensitive STING haplotype, whose homozygote genotype frequency was found significantly reduced in Taiwanese people with dengue fever. Therefore, the human STING genetic background and DNA pathogen coinfection may be the missing links contributing to DENV pathogenesis.

Combination Vaccination With Tetanus Toxoid and Enhanced Tumor-Cell Based Vaccine Against Cervical Cancer in a Mouse Model

Cervical cancer is the fourth most common cancer in women with an estimated 570,000 new cases in 2018 which constitute about 6. 6% of all cancers in women according to WHO report 2018. Approximately 90% of the 270,000 deaths from cervical cancer in 2015 occurred in low- and middle-income countries. In cervical cancers, which is caused by human papillomavirus (HPV) infection, the expression of HPV 16 E6 and E7 proteins are essential for tumor cell transformation and maintenance of malignancy. Prophylactic vaccines against cervical cancer caused by human papillomavirus have not proven successful. Although virus-like particle-based (VLPs) vaccines have been developed with prophylactic activities to prevent most HPV infections, the therapeutic effect of VLP vaccines has yet to be demonstrated for those who were already infected. A recent study showed that pre-conditioning mice with a potent antigen such as tetanus toxoid significantly improves lymph node homing and efficacy of dendritic cells. Tetanus toxoid has also been used in combination with DNA vaccines designed from tumor based antigens. In the present study, we pre-conditioned mice with tetanus toxoid followed by vaccination with a Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) overexpressing tumor-cell based vaccine (GVAX). We observed that pre-conditioning with tetanus toxoid followed by vaccination with GVAX regressed tumor growth and enhanced the overall survival of the mice. Pre-conditioning with tetanus toxoid enhanced the immune response which was observed by enlarged spleen size, higher proliferation rate of lymphocytes, a higher level of IFN-γ, TNF-α, and IL-4 antigen-specific secretions by the splenocytes. Pre-conditioning with tetanus toxoid increased memory T cell migration into the tumor site and spleen. The antigen-specific cytotoxic T cell lysis percentage was also found to be higher in the group of mice vaccinated with the combination of tetanus toxoid and GVAX. Hence, pre-conditioning with tetanus toxoid prior to vaccination with a tumor-cell based vaccine overexpressing GM-CSF might be an effective strategy for targeting E7-specific HPV-associated cervical malignancy.

Production of Vesicular Stomatitis Virus Glycoprotein-Pseudotyped Lentiviral Vector Is Enhanced by Ezrin Silencing

Human immunodeficiency virus type 1 (HIV-1)-based viral vector is widely used as a biomaterial to transfer a gene of interest into target cells in many biological study fields including gene therapy. Vesicular stomatitis virus glycoprotein (VSV-G)-containing HIV-1 vector much more efficiently transduces various mammalian cells than other viral envelope proteins-containing vectors. Understanding the mechanism would contribute to development of a novel method of efficient HIV-1 vector production. HIV-1 vector is generally constructed by transient transfection of human 293T or African green monkey COS7 cells. It was found in this study that HIV-1 Gag protein is constitutively digested in lysosomes of African green monkey cells. Surprisingly, VSV-G elevated HIV-1 Gag protein levels, suggesting that VSV-G protects Gag protein from the lysosomal degradation. Unphosphorylated ezrin, but not phosphorylated ezrin, was detected in COS7 cells, and ezrin silencing elevated Gag protein levels in the presence of VSV-G. Expression of unphosphorylated ezrin reduced Gag protein amounts. These results indicate that unphosphorylated ezrin proteins inhibit the VSV-G-mediated stabilization of HIV-1 Gag protein. Trafficking of HIV-1 Gag-associated intracellular vesicles may be controlled by ezrin. Finally, this study found that ezrin silencing yields higher amount of VSV-G-pseudotyped HIV-1 vector.

Structures of immature EIAV Gag lattices reveal a conserved role for IP6 in lentivirus assembly

Retrovirus assembly is driven by the multidomain structural protein Gag. Interactions between the capsid domains (CA) of Gag result in Gag multimerization, leading to an immature virus particle that is formed by a protein lattice based on dimeric, trimeric, and hexameric protein contacts. Among retroviruses the inter- and intra-hexamer contacts differ, especially in the N-terminal sub-domain of CA (CANTD). For HIV-1 the cellular molecule inositol hexakisphosphate (IP6) interacts with and stabilizes the immature hexamer, and is required for production of infectious virus particles. We have used in vitro assembly, cryo-electron tomography and subtomogram averaging, atomistic molecular dynamics simulations and mutational analyses to study the HIV-related lentivirus equine infectious anemia virus (EIAV). In particular, we sought to understand the structural conservation of the immature lentivirus lattice and the role of IP6 in EIAV assembly. Similar to HIV-1, IP6 strongly promoted in vitro assembly of EIAV Gag proteins into virus-like particles (VLPs), which took three morphologically highly distinct forms: narrow tubes, wide tubes, and spheres. Structural characterization of these VLPs to sub-4Å resolution unexpectedly showed that all three morphologies are based on an immature lattice with preserved key structural components, highlighting the structural versatility of CA to form immature assemblies. A direct comparison between EIAV and HIV revealed that both lentiviruses maintain similar immature interfaces, which are established by both conserved and non-conserved residues. In both EIAV and HIV-1, IP6 regulates immature assembly via conserved lysine residues within the CACTD and SP. Lastly, we demonstrate that IP6 stimulates in vitro assembly of immature particles of several other retroviruses in the lentivirus genus, suggesting a conserved role for IP6 in lentiviral assembly.

Histone deacetylase 1 interacts with HIV-1 Integrase and modulates viral replication

Background

HIV-1 hijacks the cellular machinery for its own replication through protein-protein interactions between viral and host cell factors. One strategy against HIV-1 infection is thus to target these key protein complexes. As the integration of reverse transcribed viral cDNA into a host cell chromosome is an essential step in the HIV-1 life cycle, catalyzed by the viral integrase and other important host factors, we aimed at identifying new integrase binding partners through a novel approach.

Methods

A LTR-derived biotinylated DNA fragment complexed with the integrase on magnetic beads was incubated with extracts from integrase-expressing 293 T cells. Liquid chromatography-mass spectrometry/mass spectrometry and co-immunoprecipitation/pull-down experiments were used for the identification of binding partners. Transfections of histone deacetylase 1 (HDAC1) expression vectors and/or specific siRNA were conducted in HeLa-CD4 and 293 T cells followed by infection with fully infectious NL4–3 and luciferase-expressing pseudotyped viruses or by proviral DNA transfection. Fully infectious and pseudotyped viruses produced from HDAC1-silenced 293 T cells were tested for their infectivity toward HeLa-CD4 cells, T cell lines and primary CD4+ T cells. Late RT species and integrated viral DNA were quantified by qPCR and infectivity was measured by luciferase activity and p24 ELISA assay. Results were analyzed by the Student’s t-test.

Results

Using our integrase-LTR bait approach, we successfully identified new potential integrase-binding partners, including HDAC1. We further confirmed that HDAC1 interacted with the HIV-1 integrase in co-immunoprecipitation and pull-down experiments. HDAC1 knockdown in infected HeLa cells was shown to interfere with an early preintegration step of the HIV-1 replication cycle, which possibly involves reverse transcription. We also observed that, while HDAC1 overexpression inhibited HIV-1 expression after integration, HDAC1 knockdown had no effect on this step. In virus producer cells, HDAC1 knockdown had a limited impact on virus infectivity in either cell lines or primary CD4+ T cells.

Conclusions

Our results show that HDAC1 interacts with the HIV-1 integrase and affects virus replication before and after integration. Overall, HDAC1 appears to facilitate HIV-1 replication with a major effect on a preintegration step, which likely occurs at the reverse transcription step.

Primary HIV-1 Strains Use Nef To Downmodulate HLA-E Surface Expression

Human immunodeficiency virus type 1 (HIV-1) has evolved elaborate ways to evade immune cell recognition, including downregulation of classical HLA class I (HLA-I) from the surfaces of infected cells. Recent evidence identified HLA-E, a nonclassical HLA-I, as an important part of the antiviral immune response to HIV-1. Changes in HLA-E surface levels and peptide presentation can prompt both CD8+ T-cell and natural killer (NK) cell responses to viral infections. Previous studies reported unchanged or increased HLA-E levels on HIV-1-infected cells. Here, we examined HLA-E surface levels following infection of CD4+ T cells with primary HIV-1 strains and observed that a subset downregulated HLA-E. Two primary strains of HIV-1 that induced the strongest reduction in surface HLA-E expression were chosen for further testing. Expression of single Nef or Vpu proteins in a T-cell line, as well as tail swap experiments exchanging the cytoplasmic tail of HLA-A2 with that of HLA-E, demonstrated that Nef modulated HLA-E surface levels and targeted the cytoplasmic tail of HLA-E. Furthermore, infection of primary CD4+ T cells with HIV-1 mutants showed that a lack of functional Nef (and Vpu to some extent) impaired HLA-E downmodulation. Taken together, the results of this study demonstrate for the first time that HIV-1 can downregulate HLA-E surface levels on infected primary CD4+ T cells, potentially rendering them less vulnerable to CD8+ T-cell recognition but at increased risk of NKG2A+ NK cell killing.IMPORTANCE For almost two decades, it was thought that HIV-1 selectively downregulated the highly expressed HLA-I molecules HLA-A and HLA-B from the cell surface in order to evade cytotoxic-T-cell recognition, while leaving HLA-C and HLA-E molecules unaltered. It was stipulated that HIV-1 infection thereby maintained inhibition of NK cells via inhibitory receptors that bind HLA-C and HLA-E. This concept was recently revised when a study showed that primary HIV-1 strains reduce HLA-C surface levels, whereas the cell line-adapted HIV-1 strain NL4-3 lacks this ability. Here, we demonstrate that infection with distinct primary HIV-1 strains results in significant downregulation of surface HLA-E levels. Given the increasing evidence for HLA-E as an important modulator of CD8+ T-cell and NKG2A+ NK cell functions, this finding has substantial implications for future immunomodulatory approaches aimed at harnessing cytotoxic cellular immunity against HIV.

The Spirocyclic Imine from a Marine Benthic Dinoflagellate, Portimine, Is a Potent Anti-Human Immunodeficiency Virus Type 1 Therapeutic Lead Compound

In this study, we aimed to find chemicals from lower sea animals with defensive effects against human immunodeficiency virus type 1 (HIV-1). A library of marine natural products consisting of 80 compounds was screened for activity against HIV-1 infection using a luciferase-encoding HIV-1 vector. We identified five compounds that decreased luciferase activity in the vector-inoculated cells. In particular, portimine, isolated from the benthic dinoflagellate Vulcanodinium rugosum, exhibited significant anti-HIV-1 activity. Portimine inhibited viral infection with an 50% inhibitory concentration (IC₅₀) value of 4.1 nM and had no cytotoxic effect on the host cells at concentrations less than 200 nM. Portimine also inhibited vesicular stomatitis virus glycoprotein (VSV-G)-pseudotyped HIV-1 vector infection. This result suggested that portimine mainly targeted HIV-1 Gag or Pol protein. To analyse which replication steps portimine affects, luciferase sequences were amplified by semi-quantitative PCR in total DNA. This analysis revealed that portimine inhibits HIV-1 vector infection before or at the reverse transcription step. Portimine has also been shown to have a direct effect on reverse transcriptase using an in vitro reverse transcriptase assay. Portimine efficiently inhibited HIV-1 replication and is a potent lead compound for developing novel therapeutic drugs against HIV-1-induced diseases.

Testicular endothelial cells promote self-renewal of spermatogonial stem cells in rats†

Spermatogonial stem cells (SSCs) are the basis of spermatogenesis in male due to their capability to multiply in numbers by self-renewal and subsequent meiotic processes. However, as SSCs are present in a very small proportion in the testis, in vitro proliferation of undifferentiated SSCs will facilitate the study of germ cell biology. In this study, we investigated the effectiveness of various cell lines as a feeder layer for rat SSCs. Germ cells enriched for SSCs were cultured on feeder layers including SIM mouse embryo-derived thioguanine and ouabain-resistant cells, C166 cells, and mouse and rat testicular endothelial cells (TECs) and their stem cell potential for generating donor-derived colonies and offspring was assessed by transplantation into recipient testes. Rat germ cells cultured on TECs showed increased mRNA and protein levels of undifferentiated spermatogonial markers. Rat SSCs derived from these germ cells underwent spermatogenesis and generated offspring when transplanted into recipients. Collectively, TECs can serve as an effective feeder layer that enhances the proliferative and self-renewal capacity of cultured rat SSCs while preserving their stemness properties.

Sequence Determinants in Gammaretroviral Env Cytoplasmic Tails Dictate Virus-Specific Pseudotyping Compatibility

Viruses can incorporate foreign glycoproteins to form infectious particles through a process known as pseudotyping. However, not all glycoproteins are compatible with all viruses. Despite the fact that viral pseudotyping is widely used, what makes a virus/glycoprotein pair compatible is poorly understood. To study this, we chose to analyze a gammaretroviral glycoprotein (Env) whose compatibility with different viruses could be modulated through small changes in its cytoplasmic tail (CT). One form of this glycoprotein is compatible with murine leukemia virus (MLV) particles but incompatible with human immunodeficiency virus type 1 (HIV-1) particles, while the second is compatible with HIV-1 particles but not with MLV particles. To decipher the factors affecting virus-specific Env incompatibility, we characterized Env incorporation, maturation, cell-to-cell fusogenicity, and virus-to-cell fusogenicity of each Env. The HIV-1 particle incompatibility correlated with less efficient cleavage of the R peptide by HIV-1 protease. However, the MLV particle incompatibility was more nuanced. MLV incompatibility appeared to be caused by lack of incorporation into particles, yet incorporation could be restored by further truncating the CT or by using a chimeric MLV Gag protein containing the HIV-1 MA without fully restoring infectivity. The MLV particle incompatibility appeared to be caused in part by fusogenic repression in MLV particles through an unknown mechanism. This study demonstrates that the Env CT can dictate functionality of Env within particles in a virus-specific manner.IMPORTANCE Viruses utilize viral glycoproteins to efficiently enter target cells during infection. How viruses acquire viral glycoproteins has been studied to understand the pathogenesis of viruses and develop safer and more efficient viral vectors for gene therapies. The CTs of viral glycoproteins have been shown to regulate various stages of glycoprotein biogenesis, but a gap still remains in understanding the molecular mechanism of glycoprotein acquisition and functionality regarding the CT. Here, we studied the mechanism of how specific mutations in the CT of a gammaretroviral envelope glycoprotein distinctly affect infectivity of two different viruses. Different mutations caused failure of glycoproteins to function in a virus-specific manner due to distinct fusion defects, suggesting that there are virus-specific characteristics affecting glycoprotein functionality.

Effect of Multiple Vaccinations with Tumor Cell-Based Vaccine with Codon-Modified GM-CSF on Tumor Growth in a Mouse Model

Ectopic expression of codon-modified granulocyte-macrophage colony-stimulating factor (cGM-CSF) in TC-1 cells (TC-1/cGM-CSF), a model cell line for human papillomavirus (HPV)-infected cervical cancer cells, increased the expression level of GM-CSF and improved the efficacy of tumor cell-based vaccines in a cervical cancer mouse model. The number of vaccine doses required to induce a long-term immune response in a cervical cancer mouse model is poorly understood. Here, we investigated one, three, and five doses of the irradiated TC-1/cGM-CSF vaccine to determine which dose was effective in inducing a greater immune response and the suppression of tumors. Our findings showed that three doses of irradiated TC-1/cGM-CSF vaccine elicited slower tumor growth rates and enhanced survival rates compared with one dose or five doses of irradiated TC-1/cGM-CSF vaccine. Consistently, mice vaccinated with three doses of irradiated TC-1/cGM-CSF vaccine exhibited stronger interferon gamma (IFN-γ) production in HPV E7-specific CD8⁺ T cells and CD4⁺ T cells. A higher percentage of natural killer cells and interferon-producing killer dendritic cells (IKDCs) appeared in the splenocytes of the mice vaccinated with three doses of irradiated TC-1/cGM-CSF vaccine compared with those of the mice vaccinated with one dose or five doses of irradiated TC-1/cGM-CSF vaccine. Our findings demonstrate that single or multiple vaccinations, such as five doses, with irradiated TC-1/cGM-CSF vaccine suppressed the immune response, whereas three doses of irradiated TC-1/cGM-CSF vaccine elicited a greater immune response and subsequent tumor suppression.

Genotypic and Mechanistic Characterization of Subtype-Specific HIV Adaptation to Host Cellular Immunity

The extent to which viral genetic context influences HIV adaptation to human leukocyte antigen (HLA) class I-restricted immune pressures remains incompletely understood. The Ugandan HIV epidemic, where major pandemic group M subtypes A1 and D cocirculate in a single host population, provides an opportunity to investigate this question. We characterized plasma HIV RNA gag, pol, and nef sequences, along with host HLA genotypes, in 464 antiretroviral-naive individuals chronically infected with HIV subtype A1 or D. Using phylogenetically informed statistical approaches, we identified HLA-associated polymorphisms and formally compared their strengths of selection between viral subtypes. A substantial number (32%) of HLA-associated polymorphisms identified in subtype A1 and/or D had previously been reported in subtype B, C, and/or circulating recombinant form 01_AE (CRF01_AE), confirming the shared nature of many HLA-driven escape pathways regardless of viral genetic context. Nevertheless, 34% of the identified HLA-associated polymorphisms were significantly differentially selected between subtypes A1 and D. Experimental investigation of select examples of subtype-specific escape revealed distinct underlying mechanisms with important implications for vaccine design: whereas some were attributable to subtype-specific sequence variation that influenced epitope-HLA binding, others were attributable to differential mutational barriers to immune escape. Overall, our results confirm that HIV genetic context is a key modulator of viral adaptation to host cellular immunity and highlight the power of combined bioinformatic and mechanistic studies, paired with knowledge of epitope immunogenicity, to identify appropriate viral regions for inclusion in subtype-specific and universal HIV vaccine strategies.IMPORTANCE The identification of HIV polymorphisms reproducibly selected under pressure by specific HLA alleles and the elucidation of their impact on viral function can help identify immunogenic viral regions where immune escape incurs a fitness cost. However, our knowledge of HLA-driven escape pathways and their functional costs is largely limited to HIV subtype B and, to a lesser extent, subtype C. Our study represents the first characterization of HLA-driven adaptation pathways in HIV subtypes A1 and D, which dominate in East Africa, and the first statistically rigorous characterization of differential HLA-driven escape across viral subtypes. The results support a considerable impact of viral genetic context on HIV adaptation to host HLA, where HIV subtype-specific sequence variation influences both epitope-HLA binding and the fitness costs of escape. Integrated bioinformatic and mechanistic characterization of these and other instances of differential escape could aid rational cytotoxic T-lymphocyte-based vaccine immunogen selection for both subtype-specific and universal HIV vaccines.

Role of Ezrin Phosphorylation in HIV-1 Replication

Host-cell expression of the ezrin protein is required for CXCR4 (X4)-tropic HIV-1 infection. Ezrin function is regulated by phosphorylation at threonine-567. This study investigates the role of ezrin phosphorylation in HIV-1 infection and virion release. We analyzed the effects of ezrin mutations involving substitution of threonine-567 by alanine (EZ-TA), a constitutively inactive mutant, or by aspartic acid (EZ-TD), which mimics phosphorylated threonine. We also investigated the effects of ezrin silencing on HIV-1 virion release using a specific siRNA. We observed that X4-tropic HIV-1 vector infection was inhibited by expression of the EZ-TA mutant but increased by expression of the EZ-TD mutant, suggesting that ezrin phosphorylation in target cells is required for efficient HIV-1 entry. Expression of a dominant-negative mutant of ezrin (EZ-N) and ezrin silencing in HIV-1 vector-producing cells significantly reduced the infectivity of released virions without affecting virion production. This result indicates that endogenous ezrin expression is required for virion infectivity. The EZ-TD but not the EZ-TA inhibited virion release from HIV-1 vector-producing cells. Taken together, these findings suggest that ezrin phosphorylation in target cells is required for efficient HIV-1 entry but inhibits virion release from HIV-1 vector-producing cells.

Inositol phosphates are assembly co-factors for HIV-1

A short, 14-amino-acid segment called SP1, located in the Gag structural protein1, has a critical role during the formation of the HIV-1 virus particle. During virus assembly, the SP1 peptide and seven preceding residues fold into a six-helix bundle, which holds together the Gag hexamer and facilitates the formation of a curved immature hexagonal lattice underneath the viral membrane2,3. Upon completion of assembly and budding, proteolytic cleavage of Gag leads to virus maturation, in which the immature lattice is broken down; the liberated CA domain of Gag then re-assembles into the mature conical capsid that encloses the viral genome and associated enzymes. Folding and proteolysis of the six-helix bundle are crucial rate-limiting steps of both Gag assembly and disassembly, and the six-helix bundle is an established target of HIV-1 inhibitors4,5. Here, using a combination of structural and functional analyses, we show that inositol hexakisphosphate (InsP6, also known as IP6) facilitates the formation of the six-helix bundle and assembly of the immature HIV-1 Gag lattice. IP6 makes ionic contacts with two rings of lysine residues at the centre of the Gag hexamer. Proteolytic cleavage then unmasks an alternative binding site, where IP6 interaction promotes the assembly of the mature capsid lattice. These studies identify IP6 as a naturally occurring small molecule that promotes both assembly and maturation of HIV-1.

Inhibitory Effects of HIV-2 Vpx on Replication of HIV-1

Human immunodeficiency virus type 1 (HIV-1) and HIV-2 share a striking genomic resemblance; however, variability in the genetic sequence accounts for the presence of unique accessory genes, such as the viral protein X (vpx) gene in HIV-2. Dual infection with both viruses has long been described in the literature, yet the molecular mechanism of how dually infected patients tend to do better than those who are monoinfected with HIV-1 has not yet been explored. We hypothesized that in addition to extracellular mechanisms, an HIV-2 accessory gene is the culprit, and interference at the viral accessory/regulatory protein level is perhaps responsible for the attenuated pathogenicity of HIV-1 observed in dually infected patients. Following simulation of dual infection in cell culture experiments, we found that pretransduction of cells with HIV-2 significantly protects against HIV-1 transduction. Importantly, we have found that this dampening of the infectivity of HIV-1 was a result of interviral interference carried out by viral protein X of HIV-2, resulting in a severe hindrance to the replication dynamics of HIV-1, influencing both its early and late phases of the viral life cycle. Our findings shed light on potential intracellular interactions between the two viruses and broaden our understanding of the observed clinical spectrum in dually infected patients, highlighting HIV-2 Vpx as a potential candidate worth exploring in the fight against HIV-1.IMPORTANCE Dual infection with human immunodeficiency virus types 1 and 2 is relatively common in areas of endemicity. For as-yet-unclarified reasons, patients who are dually infected were shown to have lower viral loads and generally a lower rate of progression to AIDS than those who are monoinfected. We aimed to explore dual infection in cell culture, to elucidate possible mechanisms by which HIV-2 may be able to exert such an effect. Our results indicate that on the cellular level, pretransduction of cells with HIV-2 significantly protects against HIV-1 transduction, which was found to be a result of interviral interference carried out by viral protein X of HIV-2. These findings broaden our knowledge of interviral interactions on the cellular level and may provide an explanation for the decreased pathogenicity of HIV-1 in dually infected patients, highlighting HIV-2 Vpx as a potential candidate worth exploring in the fight against HIV.

Distinct chromatin functional states correlate with HIV latency reactivation in infected primary CD4+ T cells

Human immunodeficiency virus (HIV) infection is currently incurable, due to the persistence of latently infected cells. The 'shock and kill' approach to a cure proposes to eliminate this reservoir via transcriptional activation of latent proviruses, enabling direct or indirect killing of infected cells. Currently available latency-reversing agents (LRAs) have however proven ineffective. To understand why, we used a novel HIV reporter strain in primary CD4+ T cells and determined which latently infected cells are reactivatable by current candidate LRAs. Remarkably, none of these agents reactivated more than 5% of cells carrying a latent provirus. Sequencing analysis of reactivatable vs. non-reactivatable populations revealed that the integration sites were distinguishable in terms of chromatin functional states. Our findings challenge the feasibility of 'shock and kill', and suggest the need to explore other strategies to control the latent HIV reservoir.

Current and future perspectives of functional metabolomics in disease studies-A review

Functional metabolomics is a new concept, which studies the functions of metabolites and related enzymes focused on metabolomics. It overcomes the shortcomings of traditional discovery metabolomics of mainly relying on literatures for biological interpretation. Functional metabolomics has many advantages. Firstly, the functional roles of metabolites and related metabolic enzymes are focused. Secondly, the in vivo and in vitro experiments are conducted to validate the metabolomics findings, therefore, increasing the reliability of metabolomics study and producing the new knowledge. Thirdly, functional metabolomics can be used by biologists to investigate functions of metabolites, and related genes and proteins. In this review, we summarize the analytical, biological and clinical platforms used in functional metabolomics studies. Recent progresses of functional metabolomics in cancer, metabolic diseases and biological phenotyping are reviewed, and future development is also predicted. Because of the tremendous advantages of functional metabolomics, it will have a bright future.

Distinct functions for the membrane-proximal ectodomain region (MPER) of HIV-1 gp41 in cell-free and cell-cell viral transmission and cell-cell fusion

HIV-1 is spread by cell-free virions and by cell-cell viral transfer. We asked whether the structure and function of a broad neutralizing antibody (bNAb) epitope, the membrane-proximal ectodomain region (MPER) of the viral gp41 transmembrane glycoprotein, differ in cell-free and cell-cell-transmitted viruses and whether this difference could be related to Ab neutralization sensitivity. Whereas cell-free viruses bearing W666A and I675A substitutions in the MPER lacked infectivity, cell-associated mutant viruses were able to initiate robust spreading infection. Infectivity was restored to cell-free viruses by additional substitutions in the cytoplasmic tail (CT) of gp41 known to disrupt interactions with the viral matrix protein. We observed contrasting effects on cell-free virus infectivity when W666A was introduced to two transmitted/founder isolates, but both mutants could still mediate cell-cell spread. Domain swapping indicated that the disparate W666A phenotypes of the cell-free transmitted/founder viruses are controlled by sequences in variable regions 1, 2, and 4 of gp120. The sequential passaging of an MPER mutant (W672A) in peripheral blood mononuclear cells enabled selection of viral revertants with loss-of-glycan suppressor mutations in variable region 1, suggesting a functional interaction between variable region 1 and the MPER. An MPER-directed bNAb neutralized cell-free virus but not cell-cell viral spread. Our results suggest that the MPER of cell-cell-transmitted virions has a malleable structure that tolerates mutagenic disruption but is not accessible to bNAbs. In cell-free virions, interactions mediated by the CT impose an alternative MPER structure that is less tolerant of mutagenic alteration and is efficiently targeted by bNAbs.

Inhibition of NF-κB-dependent HIV-1 replication by the marine natural product bengamide A

HIV-1 inhibitors that act by mechanisms distinct from existing antiretrovirals can provide novel insights into viral replication and potentially inform development of new therapeutics. Using a multi-cycle HIV-1 replication assay, we screened 252 pure compounds derived from marine invertebrates and microorganisms and identified 6 (actinomycin Z₂, bastadin 6, bengamide A, haliclonacyclamine A + B, keramamine C, neopetrosiamide B) that inhibited HIV-1 with 50% effective concentrations (EC₅₀s) of 3.8 μM or less. The most potent inhibitor, bengamide A, blocked HIV-1 in a T cell line with an EC₅₀ of 0.015 μM and in peripheral blood mononuclear cells with an EC₅₀ of 0.032 μM. Bengamide A was previously described to inhibit NF-κB signaling. Consistent with this mechanism, bengamide A suppressed reporter expression from an NF-κB-driven minimal promoter and an HIV-1 long terminal repeat (LTR) with conserved NF-κB response elements, but lacked activity against an LTR construct with mutation of these elements. In single-cycle HIV-1 infection assays, bengamide A also suppressed viral protein expression when viruses encoded an intact LTR but exhibited minimal activity against those with mutated NF-κB elements. Finally, bengamide A did not inhibit viral DNA accumulation, indicating that it likely acts downstream of this step in HIV-1 replication. Our study identifies multiple new antiviral compounds including an unusually potent inhibitor of HIV-1 gene expression.

Gamma-interferon-inducible, lysosome/endosome-localized thiolreductase, GILT, has anti-retroviral activity and its expression is counteracted by HIV-1

The mechanism by which type II interferon (IFN) inhibits virus replications remains to be identified. Murine leukemia virus (MLV) replication was significantly restricted by γ-IFN, but not human immunodeficiency virus type 1 (HIV-1) replication. Because MLV enters host cells via endosomes, we speculated that certain cellular factors among γ-IFN-induced, endosome-localized proteins inhibit MLV replication. We found that γ-IFN-inducible lysosomal thiolreductase (GILT) significantly restricts HIV-1 replication as well as MLV replication by its thiolreductase activity. GILT silencing enhanced replication-defective HIV-1 vector infection and virion production in γ-IFN-treated cells, although γ-IFN did not inhibit HIV-1 replication. This result showed that GILT is required for the anti-viral activity of γ-IFN. Interestingly, GILT protein level was increased by γ-IFN in uninfected cells and env-deleted HIV-1-infected cells, but not in full-length HIV-1-infected cells. γ-IFN-induced transcription from the γ-IFN-activation sequence was attenuated by the HIV-1 Env protein. These results suggested that the γ-IFN cannot restrict HIV-1 replication due to the inhibition of γ-IFN signaling by HIV-1 Env. Finally, we found that 4,4′-dithiodipyridine (4-PDS), which inhibits S-S bond formation at acidic pH, significantly suppresses HIV-1 vector infection and virion production, like GILT. In conclusion, this study showed that GILT functions as a host restriction factor against the retroviruses, and a GILT mimic, 4-PDS, is the leading compound for the development of novel concept of anti-viral agents.

Bacterially derived synthetic mimetics of mammalian oligomannose prime antibody responses that neutralize HIV infectivity

Oligomannose-type glycans are among the major targets on the gp120 component of the HIV envelope protein (Env) for broadly neutralizing antibodies (bnAbs). However, attempts to elicit oligomannose-specific nAbs by immunizing with natural or synthetic oligomannose have so far not been successful, possibly due to B cell tolerance checkpoints. Here we design and synthesize oligomannose mimetics, based on the unique chemical structure of a recently identified bacterial lipooligosaccharide, to appear foreign to the immune system. One of these mimetics is bound avidly by members of a family of oligomannose-specific bnAbs and their putative common germline precursor when presented as a glycoconjugate. The crystal structure of one of the mimetics bound to a member of this bnAb family confirms the antigenic resemblance. Lastly, immunization of human-antibody transgenic animals with a lead mimetic evokes nAbs with specificities approaching those of existing bnAbs. These results provide evidence for utilizing antigenic mimicry to elicit oligomannose-specific bnAbs to HIV-1.

Detection of Replication Competent Lentivirus Using a qPCR Assay for VSV-G

Lentiviral vectors are a common tool used to introduce new and corrected genes into cell therapy products for treatment of human diseases. Although lentiviral vectors are ideal for delivery and stable integration of genes of interest into the host cell genome, they potentially pose risks to human health, such as integration-mediated transformation and generation of a replication competent lentivirus (RCL) capable of infecting non-target cells. In consideration of the latter risk, all cell-based products modified by lentiviral vectors and intended for patient use must be tested for RCL prior to treatment of the patient. Current Food and Drug Administration (FDA) guidelines recommend use of cell-based assays to this end, which can take up to 6 weeks for results. However, qPCR-based assays are a quick alternative for rapid assessment of RCL in products intended for fresh infusion. We describe here the development and qualification of a qPCR assay based on detection of envelope gene sequences (vesicular stomatitis virus G glycoprotein [VSV-G]) for RCL in accordance with Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines. Our results demonstrate the sensitivity, linearity, specificity, and reproducibility of detection of VSV-G sequences, with a low false-positive rate. These procedures are currently being used in our phase 1 clinical investigations.

Absence of Replication-Competent Lentivirus in the Clinic: Analysis of Infused T Cell Products

Exposure to replication-competent lentivirus (RCL) is a theoretical safety concern for individuals treated with lentiviral gene therapy. For certain ex vivo gene therapy applications, including cancer immunotherapy trials, RCL detection assays are used to screen the vector product as well as the vector-transduced cells. In this study, we reviewed T cell products screened for RCL using methodology developed in the National Gene Vector Biorepository. All trials utilized third-generation lentiviral vectors produced by transient transfection. Samples from 26 clinical trials totaling 460 transduced cell products from 375 subjects were evaluated. All cell products were negative for RCL. A total of 296 of the clinical trial participants were screened for RCL at least 1 month after infusion of the cell product. No research subject has shown evidence of RCL infection. These findings provide further evidence attesting to the safety of third-generation lentiviral vectors and that testing T cell products for RCL does not provide added value to screening the lentiviral vector product.

Rab3a-Bound CD63 Is Degraded and Rab3a-Free CD63 Is Incorporated into HIV-1 Particles

CD63, a member of the tetraspanin family, is involved in virion production by human immunodeficiency virus type 1 (HIV-1), but its mechanism is unknown. In this study, we showed that a small GTP-binding protein, Rab3a, interacts with CD63. When Rab3a was exogenously expressed, the amounts of CD63 decreased in cells. The Rab3a-mediated reduction of CD63 was suppressed by lysosomal and proteasomal inhibitors. The amount of CD63 was increased by reducing the endogenous Rab3a level using a specific shRNA. These results indicate that Rab3a binds to CD63 to induce the degradation of CD63. Rab3a is thought to be involved in exocytosis, but we found that another function of Rab3a affects the fate of CD63 in lysosomes. CD63 interacted with Rab3a and was incorporated into HIV-1 particles. However, Rab3a was not detected in HIV-1 virions, thereby indicating that Rab3a-free CD63, but not Rab3a-bound CD63, is incorporated into HIV-1 particles. Overexpression or silencing of Rab3a moderately reduced HIV-1 virion formation. Overexpression of Rab3a decreased CD63 levels, but did not affect the incorporation of CD63 into HIV-1 particles. This study showed that Rab3a binds to CD63 to induce the degradation of CD63, and only Rab3a-free CD63 is incorporated into HIV-1 particles.

Lentiviral Transfer of the LacZ Gene into Human Endothelial Cells and Human Bone Marrow Mesenchymal Stem Cells

Because one of the attractive characteristics of human immunodeficiency virus type 1 (HIV-1)-based lentiviral vectors is that it can infect even nondividing cells, a lentivirus-mediated gene delivery system is currently being paid a great deal of attention as an innovative tool for gene transfer into target cells. The purpose of the work was to investigate the efficacy of lentiviral transfer of the LacZ gene into human umbilical vein endothelial cells (HUVECs) and human bone marrow mesenchymal stem cells (HMSCs) in vitro. For the present study, a vesicular stomatitis virus G-protein (VSV-G)-pseudotyped lentiviral vector encoding the E. coli LacZ gene tagged with nuclear localization signal (NLS) was generated in 293T cells by means of the three-plasmid system. The resulting lentiviral vector, LtV-NLS/LacZ, was allowed to infect HUVECs and HMSCs. Approximately 70% of HUVECs were positive for LacZ expression and 50% of HMSCs showed LacZ activity. There was no significant difference in transduction efficacy between early and late-passage phases in both cells. LtV-NLS/LacZ-transduced HUVECs showed gene expression of endothelial markers including CD34 and flt-1 and KDR/flk-1 of vascular endothelial growth factor (VEGF) receptors and had angiogenic potential as efficiently as primarily cultured HUVECs in a Matrigel assay. These findings provide evidence that lentiviral vectors are efficient tools for gene transfer and expression in human endothelial cells and stem cells that could be useful for tissue engineering.

NFκB-Pim-1-Eomesodermin axis is critical for maintaining CD8 T-cell memory quality

T-cell memory is critical for long-term immunity. However, the factors involved in maintaining the persistence, function, and phenotype of the memory pool are undefined. Eomesodermin (Eomes) is required for the establishment of the memory pool. Here, we show that in T cells transitioning to memory, the expression of high levels of Eomes is not constitutive but rather requires a continuum of cell-intrinsic NFκB signaling. Failure to maintain NFκB signals after the peak of the response led to impaired Eomes expression and a defect in the maintenance of CD8 T-cell memory. Strikingly, we found that antigen receptor [T-cell receptor (TCR)] signaling regulates this process through expression of the NFκB-dependent kinase proviral integration site for Moloney murine leukemia virus-1 (PIM-1), which in turn regulates NFκB and Eomes. T cells defective in TCR-dependent NFκB signaling were impaired in late expression of Pim-1, Eomes, and CD8 memory. These defects were rescued when TCR-dependent NFκB signaling was restored. We also found that NFκB-Pim-1 signals were required at memory to maintain memory CD8 T-cell longevity, effector function, and Eomes expression. Hence, an NFκB-Pim-1-Eomes axis regulates Eomes levels to maintain memory fitness.

Expression of CHODL in hepatocellular carcinoma affects invasion and migration of liver cancer cells

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-associated death. Due to rapid progression and metastasis, the long-term survival remains poor for most patients. Thus, it is important to discover and develop novel preventive strategies and therapeutic approaches for HCC. Recent data show that chondrolectin (CHODL) is commonly overexpressed in the majority of lung cancers, indicating a possible correlation between CHODL and metastasis of lung cancer cells. Our investigation shows that the expression of CHODL is significantly decreased in HCC clinical samples and in HCC cell lines. Overexpression of CHODL in SMMC7721 cells with a lentiviral vector increased SMMC7721 cell migration and invasion. Our findings establish for the first time an association between human CHODL and HCC metastasis.