Protective anti-gB neutralizing antibodies targeting two vulnerable sites for EBV-cell membrane fusion.

Epstein-Barr virus (EBV) infects more than 90% of the world's adult population and accounts for a significant cancer burden of epithelial and B cell origins. Glycoprotein B (gB) is the primary fusogen essential for EBV entry into host cells. Here, we isolated two EBV gB-specific neutralizing antibodies, 3A3 and 3A5; both effectively neutralized the dual-tropic EBV infection of B and epithelial cells. In humanized mice, both antibodies showed effective protection from EBV-induced lymphoproliferative disorders. Cryoelectron microscopy analyses identified that 3A3 and 3A5 bind to nonoverlapping sites on domains D-II and D-IV, respectively. Structure-based mutagenesis revealed that 3A3 and 3A5 inhibit membrane fusion through different mechanisms involving the interference with gB-cell interaction and gB activation. Importantly, the 3A3 and 3A5 epitopes are major targets of protective gB-specific neutralizing antibodies elicited by natural EBV infection in humans, providing potential targets for antiviral therapies and vaccines.

T cell epitope screening of Epstein-Barr virus fusion protein gB.

Glycoprotein B (gB) is an essential fusion protein for the Epstein-Barr virus (EBV) infection of both B cells and epithelial cells and is thus a promising target antigen for a prophylactic vaccine to prevent or reduce EBV-associated disease. T cell responses play key roles in the control of persistent EBV infection and in the efficacy of a vaccine. However, to date, T cell responses to gB have been characterized for only a limited number of human leukocyte antigen (HLA) alleles. Here, we screened gB T cell epitopes in 23 healthy EBV carriers and ten patients with nasopharyngeal cancer (NPC) using a peptide library spanning the entire gB sequence. We identified twelve novel epitopes in the context of seven new HLA restrictions that are common in Asian populations. Two epitopes, gB214-223 and gB840-849, restricted by HLA-B*58:01 and B*38:02, respectively, elicited specific CD8+ T cell responses to inhibit EBV-driven B cell transformation. Interestingly, gB-specific CD8+ T cells were more frequent in healthy viral carriers with EBV reactivation than in those without EBV reactivation, indicating that EBV reactivation in vivo stimulates both humoral (VCA-gp125-IgA) and cellular responses to gB. We further found that most gB epitopes are conserved among different EBV strains. Our study broadens the diversity and HLA restrictions of gB epitopes and suggests that gB is a common target of T cell responses in healthy viral carriers with EBV reactivation. In particular, the precisely mapped and conserved gB epitopes provide valuable information for prophylactic vaccine development.ImportanceT cells are crucial for the control of persistent EBV infection and the development of EBV-associated diseases. The EBV gB protein is essential for virus entry into B cells and epithelial cells and is thus a target antigen for vaccine development. Understanding T cell responses to gB is important for subunit vaccine design. Herein, we comprehensively characterized T cell responses to full-length gB. Our results expand the available gB epitopes and HLA restrictions, particularly those common in Asian populations. Furthermore, we showed that gB-specific CD8+ T cells inhibit B cell transformation ex vivo and that gB-specific CD8+ T cell responses in vivo may be associated with intermittent EBV reactivation in asymptomatic viral carriers. These gB epitopes are highly conserved among geographically separated EBV strains. Precisely mapped and conserved T cell epitopes may contribute to immune monitoring and to the development of a gB subunit vaccine.

IL-4 Inhibits the Biogenesis of an Epigenetically Suppressive PIWI-Interacting RNA To Upregulate CD1a Molecules on Monocytes/Dendritic Cells.

The discovery of PIWI-interacting RNAs (piRNAs) revealed the complexity of the RNA world. Although piRNAs were first deemed to be germline specific, substantial evidence shows their various roles in somatic cells; however, their function in highly differentiated immune cells remains elusive. In this study, by initially screening with a small RNA deep-sequencing analysis, we found that a piRNA, tRNA-Glu-derived piRNA [td-piR(Glu)], was expressed much more abundantly in human monocytes than in dendritic cells. By regulating the polymerase III activity, IL-4 potently decreased the biogenesis of tRNA-Glu and, subsequently, td-piR(Glu). Further, we revealed that the td-piR(Glu)/PIWIL4 complex recruited SETDB1, SUV39H1, and heterochromatin protein 1ß to the CD1A promoter region and facilitated H3K9 methylation. As a result, the transcription of CD1A was significantly inhibited. Collectively, we demonstrated that a piRNA acted as the signal molecule for a cytokine to regulate the expression of an important membrane protein for lipid Ag presentation.

An Lnc RNA (GAS5)/SnoRNA-derived piRNA induces activation of TRAIL gene by site-specifically recruiting MLL/COMPASS-like complexes.

PIWI-interacting RNA (piRNA) silences the transposons in germlines or induces epigenetic modifications in the invertebrates. However, its function in the mammalian somatic cells remains unknown. Here we demonstrate that a piRNA derived from Growth Arrest Specific 5, a tumor-suppressive long non-coding RNA, potently upregulates the transcription of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a proapoptotic protein, by inducing H3K4 methylation/H3K27 demethylation. Interestingly, the PIWIL1/4 proteins, which bind with this piRNA, directly interact with WDR5, resulting in a site-specific recruitment of the hCOMPASS-like complexes containing at least MLL3 and UTX (KDM6A). We have indicated a novel pathway for piRNAs to specially activate gene expression. Given that MLL3 or UTX are frequently mutated in various tumors, the piRNA/MLL3/UTX complex mediates the induction of TRAIL, and consequently leads to the inhibition of tumor growth.

Cancer diagnosis and treatment platform based on manganese-based nanomaterials.

Cancer is a leading cause of death worldwide, and the development of new diagnostic and treatment methods is crucial. Manganese-based nanomaterials (MnNMs) have emerged as a focal point in the field of cancer diagnosis and treatment due to their multifunctional properties. These nanomaterials have been extensively explored as contrast agents for various imaging technologies such as magnetic resonance imaging (MRI), photoacoustic imaging (PAI), and near-infrared fluorescence imaging (NIR-FL). The use of these nanomaterials has significantly enhanced the contrast for precise tumor detection and localization. Moreover, MnNMs have shown responsiveness to the tumor microenvironment (TME), enabling innovative approaches to cancer treatment. This review provides an overview of the latest developments of MnNMs and their potential applications in tumor diagnosis and therapy. Finally, potential challenges and prospects of MnNMs in clinical applications are discussed. We believe that this review would serve as a valuable resource for guiding further research on the application of manganese nanomaterials in cancer diagnosis and treatment, addressing the current limitations, and proposing future research directions.

RIG-I is an intracellular checkpoint that limits CD8+ T-cell antitumour immunity.

Retinoic acid-inducible gene I (RIG-I) is a pattern recognition receptor involved in innate immunity, but its role in adaptive immunity, specifically in the context of CD8+ T-cell antitumour immunity, remains unclear. Here, we demonstrate that RIG-I is upregulated in tumour-infiltrating CD8+ T cells, where it functions as an intracellular checkpoint to negatively regulate CD8+ T-cell function and limit antitumour immunity. Mechanistically, the upregulation of RIG-I in CD8+ T cells is induced by activated T cells, and directly inhibits the AKT/glycolysis signalling pathway. In addition, knocking out RIG-I enhances the efficacy of adoptively transferred T cells against solid tumours, and inhibiting RIG-I enhances the response to PD-1 blockade. Overall, our study identifies RIG-I as an intracellular checkpoint and a potential target for alleviating inhibitory constraints on T cells in cancer immunotherapy, either alone or in combination with an immune checkpoint inhibitor.

EBV-Upregulated B7-H3 Inhibits NK cell-Mediated Antitumor Function and Contributes to Nasopharyngeal Carcinoma Progression.

Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV)-associated epithelial malignancy characterized by the presence of prominent infiltration of lymphocytes, including natural killer (NK) cells. Although NK cells can directly target EBV-infected tumor cells without restriction by the MHC, EBV-positive (EBV+) NPC cells often develop resistance mechanisms that allow them to evade immune surveillance by NK cells. Elucidating the mechanisms involved in EBV-induced NK-cell dysfunction will contribute to the design of novel NK cell-based immunotherapies to treat NPC. Herein, we confirmed that the cytotoxic function of NK cells was impaired in EBV+ NPC tissues and found that EBV infection-induced expression of B7-H3 in NPC negatively correlated with NK-cell function. The inhibitory effect of EBV+ tumor expression of B7-H3 on NK-cell function was clarified in vitro and in vivo. Mechanistically, activation of the PI3K/AKT/mTOR signaling pathway via EBV latent membrane protein 1 (LMP1) was responsible for EBV infection-induced upregulation of B7-H3 expression. In an NPC xenograft mouse model with adoptive transfer of primary NK cells, deletion of B7-H3 on tumor cells in combination with anti-PD-L1 treatment restored NK cell-mediated antitumor activity and significantly improved the antitumor efficacy of NK cells. On the basis of our findings, we conclude that EBV infection can inhibit NK cell-mediated antitumor function by inducing upregulation of B7-H3 expression and provide a rationale for NK cell-based immunotherapies in combination of PD-L1 blockade and overcoming the immunosuppression of B7-H3 to treat EBV-associated NPC.

Immunotherapeutic approaches in EBV-associated nasopharyngeal carcinoma.

Epstein-Barr virus (EBV) was the first tumor virus in humans. Nasopharyngeal carcinoma (NPC) accounts for approximately 60% of the 200,000 new tumor cases caused by EBV infection worldwide each year. NPC has an insidious onset and is highly malignant, with more than 70% of patients having intermediate to advanced disease at the time of initial diagnosis, and is strongly implicated in epithelial cancers as well as malignant lymphoid and natural killer/T cell lymphomas. Over 90% of patients with confirmed undifferentiated NPC are infected with EBV. In recent decades, much progress has been made in understanding the molecular mechanisms of NPC and developing therapeutic approaches. Radiotherapy and chemotherapy are the main treatment options for NPC; however, they have a limited efficacy in patients with locally advanced or distant metastatic tumors. Tumor immunotherapy, including vaccination, adoptive cell therapy, and immune checkpoint blockade, represents a promising therapeutic approach for NPC. Significant breakthroughs have recently been made in the application of immunotherapy for patients with recurrent or metastatic NPC (RM-NPC), indicating a broad prospect for NPC immunotherapy. Here, we review important research findings regarding immunotherapy for NPC patients and provide insights for future research.

EBV Infection in Epithelial Malignancies Induces Resistance to Antitumor Natural Killer Cells via F3-Mediated Platelet Aggregation.

Nasopharyngeal carcinoma (NPC) and Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) are two major EBV-associated epithelial malignancies, both of which are characterized by the infiltration of a large number of lymphocytes, including natural killer (NK) cells. Although NK cells can prevent the development of EBV-associated epithelial malignancies, EBV-infected tumor cells often develop resistance to surveillance by NK cells. Elucidating the interactions between NK cells and EBV-infected tumor cells will facilitate the development of more effective NK-mediated therapies for treating EBV-associated malignancies. Here we investigated the cytotoxic function of NK cells in EBV-associated epithelial malignancies and discovered that EBV infection-induced upregulation of F3 expression correlates with NK-cell dysfunction in NPC and EBVaGC. The subsequent inhibitory effect of F3-mediated platelet aggregation on NK-cell function was verified in vitro and in vivo. Mechanistically, EBV latent membrane protein 2A (LMP2A) mediated upregulation of F3 through the PI3K/AKT signaling pathway. In an NPC xenograft mouse model, inhibition of F3 restored the antitumor function of NK cells and showed therapeutic efficacy when administered with NK-cell transfer. On the basis of these findings, EBV infection induces F3-mediated platelet aggregation that inhibits the antitumor function of NK cells, providing a rationale for developing and combining NK-cell-based therapies with F3 inhibitors to treat EBV-associated epithelial malignancies. SIGNIFICANCE: This study reveals a mechanism by which EBV-associated epithelial malignancies escape NK-cell-mediated immune surveillance, providing a new target for improving NK-cell immunotherapy.

Adaptive mutation F772S-enhanced p7-NS4A cooperation facilitates the assembly and release of hepatitis C virus and is associated with lipid droplet enlargement.

Hepatitis C virus (HCV) infection is a major cause of chronic hepatitis and liver cancer worldwide. Adaptive mutations play important roles in the development of the HCV replicon and its infectious clones. We and others have previously identified the p7 mutation F772S and the co-presence of NS4A mutations in infectious HCV full-length clones and chimeric recombinants. However, the underlying mechanism of F772S function remains incompletely understood. Here, we investigated the functional role of F772S using an efficient JFH1-based reporter virus with Core-NS2 from genotype 2a strain J6, and we designated J6-p7/JFH1-4A according to the strain origin of the p7 and NS4A sequences. We found that replacing JFH1-4A with J6-4A (wild-type or mutated NS4A) or genotype 2b J8-4A severely attenuated the viability of J6-p7/JFH1-4A. However, passage-recovered viruses that contained J6-p7 all acquired F772S. Introduction of F772S efficiently rescued the viral spread and infectivity titers of J6-p7/J6-4A, which reached the levels of the original J6-p7/JFH1-4A and led to a concomitant increase in RNA replication, assembly and release of viruses with J6-specific p7 and NS4A. These data suggest that an isolate-specific cooperation existed between p7 and NS4A. NS4A exchange- or substitution-mediated viral attenuation was attributed to the RNA sequence, and no p7-NS4A protein interaction was detected. Moreover, we found that F772S-enhanced p7-NS4A cooperation was associated with the enlargement of intracellular lipid droplets. This study therefore provides new insights into the mechanisms of adaptive mutations and facilitates studies on the HCV life cycle and virus-host interaction.

Development of an Infectious Cell Culture System for Hepatitis C Virus Genotype 6a Clinical Isolate Using a Novel Strategy and Its Sensitivity to Direct-Acting Antivirals.

Hepatitis C virus (HCV) is classified into seven major genotypes, and genotype 6 is commonly prevalent in Asia, thus reverse genetic system representing genotype 6 isolates in prevalence is required. Here, we developed an infectious clone for a Chinese HCV 6a isolate (CH6a) using a novel strategy. We determined CH6a consensus sequence from patient serum and assembled a CH6a full-length (CH6aFL) cDNA using overlapped PCR product-derived clones that shared the highest homology with the consensus. CH6aFL was non-infectious in hepatoma Huh7.5 cells. Next, we constructed recombinants containing Core-NS5A or 5'UTR-NS5A from CH6a and the remaining sequences from JFH1 (genotype 2a), and both were engineered with 7 mutations identified previously. However, they replicated inefficiently without virus spread in Huh7.5 cells. Addition of adaptive mutations from CH6a Core-NS2 recombinant, with JFH1 5'UTR and NS3-3'UTR, enhanced the viability of Core-NS5A recombinant and acquired replication-enhancing mutations. Combination of 22 mutations in CH6a recombinant with JFH1 5'UTR and 3'UTR (CH6aORF) enabled virus replication and recovered additional four mutations. Adding these four mutations, we generated two efficient recombinants containing 26 mutations (26m), CH6aORF_26m and CH6aFL_26m (designated "CH6acc"), releasing HCV of 104.3-104.5 focus-forming units (FFU)/ml in Huh7.5.1-VISI-mCherry and Huh7.5 cells. Seven newly identified mutations were important for HCV replication, assembly, and release. The CH6aORF_26m virus was inhibited in a dose- and genotype-dependent manner by direct-acting-antivirals targeting NS3/4A, NS5A, and NS5B. The CH6acc enriches the toolbox of HCV culture systems, and the strategy and mutations applied here will facilitate the culture development of other HCV isolates and related viruses.

Cavernous hemangiomas of the temporalis muscle with prominent formation of phleboliths: Case report and review of the literature.

RATIONALE: Hemangiomas are benign tumors characterized by an abnormal proliferation of blood vessels, most often occur in the skin and subcutaneous tissue, intramuscular hemangioma, a distinctive type of hemangioma within the skeletal muscle, account for <1% of all hemangiomas, temporalis muscle is a very uncommon site, cavernous hemangioma of the temporalis muscle with prominent formation of phleboliths is rare reported. PATIENT CONCERNS: A 62-year-old man presented with a slowly increased mass in his right temporal fossa. DIAGNOSES: Computed tomography (CT) scan showed the lesion across the zygomatic arch, with many calcified nodules differ in sizes and no erosion to the bone, magnetic resonance imaging (MRI) showed an oval lesion with hypointense and isointense on T2-weighted imaging within the temporal muscle, and preoperation diagnosis was hemangioma. INTERVENTIONS: The tumor was resected under general anesthesia. OUTCOMES: The mass was excised completely, and the histopathology examination confirmed the diagnosis of cavernous hemangioma with prominent formation of phleboliths. The patient recovered very well without dysfunctions. LESSONS: Cavernous hemangioma should be suspected when mass occurs in this region. CT and MRI are important for the early diagnosis of tumor, and resection the tumor completely is recommended.

A recombinant chimeric protein specifically induces mutant KRAS degradation and potently inhibits pancreatic tumor growth.

Pancreatic cancer is one of the most lethal human diseases, with an all-stage 5-year survival rate below 5%. To date, no effective and specific therapy is available for this disease. Mutations in KRAS are frequently reported in pancreatic and many other cancers; thus, KRAS is an attractive therapeutic target. Our objective was to specifically eliminate mutant KRAS and induce cell death of tumors expressing this mutant protein. We thus constructed several chimeric proteins by connecting the C-terminal domains of several adaptor proteins of E3 ubiquitin ligases such as CBL, CHIP, E6AP, and VHL, as well as VIF encoded by human immunodeficiency virus type 1 (HIV-1), to the Ras binding domain (RBD) of Raf. Although all of these chimeric proteins caused the degradation of mutant KRAS and the death of KRAS-mutant-tumor cell lines, the RBD-VIF with a protein transduction domain (PTD), named PTD-RBD-VIF, had the strongest tumor-killing effect. Intraperitoneally administered recombinant PTD-RBD-VIF potently inhibited the growth of xenografted KRAS-mutant pancreatic cancer cells. Our findings indicate that recombinant PTD-RBD-VIF, a chimeric protein with a combined cellular-viral origin, could be further developed for the treatment of various tumors harboring mutant or over-activated KRAS, especially for cases presenting with pancreatic cancer recurrence after surgery.