Novel Therapeutics for Epstein⁻Barr Virus

Role of Bacterial and Viral Pathogens in Gastric Carcinogenesis

Simple Summary

Stomach cancer is one of the most common cancers in the world, with over one million new cases diagnosed in 2020. Despite recent advances in cancer treatments, gastric cancer remains a serious clinical problem. This disease is tightly linked to gastric infections with Helicobacter pylori bacterium, Epstein–Barr virus, and some other less known pathogens. Here, we discuss how gastric pathogens induce tumorigenic changes in the stomach.

Abstract

Gastric cancer (GC) is one of the deadliest malignancies worldwide. In contrast to many other tumor types, gastric carcinogenesis is tightly linked to infectious events. Infections with Helicobacter pylori (H. pylori) bacterium and Epstein–Barr virus (EBV) are the two most investigated risk factors for GC. These pathogens infect more than half of the world’s population. Fortunately, only a small fraction of infected individuals develops GC, suggesting high complexity of tumorigenic processes in the human stomach. Recent studies suggest that the multifaceted interplay between microbial, environmental, and host genetic factors underlies gastric tumorigenesis. Many aspects of these interactions still remain unclear. In this review, we update on recent discoveries, focusing on the roles of various gastric pathogens and gastric microbiome in tumorigenesis.

Sildenafil prevents HDACi-induced Epstein-Barr virus reactivation through the PKG pathway in NK/T cell lymphoma; potential implications for HDACi-mediated fatal complications

Romidepsin, a histone deacetylase (HDAC) inhibitor, has been approved for the treatment of relapsed and refractory peripheral T-cell lymphoma. However the use of romidepsin reportedly causes potent EBV (Epstein-Barr virus) reactivation leading to severe adverse events in patients with natural killer (NK)/T-cell lymphoma (NKTL). As inhibition of EBV lytic cycle reactivation may help prevent romidepsin-induced adverse events in NKTL, we herein set out to identify a safe and effective drug for inhibiting EBV reactivation and examine its mechanism of inhibition. EBV reactivation was evaluated by qRT-PCR of BZLF1 and BRLF1 mRNA expression, qPCR of EBV DNA, and immunoblotting of viral EA-D protein. High-throughput screening of FDA-approved drugs was performed to identify safe and effective molecules and test their effect on romidepsin-induced EBV reactivation in the EBV-positive NKTL cell lines, SNK6 and NK92MI. We found that phosphodiesterase 5 (PDE5) inhibitors, including sildenafil (Viagra; Pfizer), appeared to be nontoxic and effective inhibitors of romidepsin-induced EBV reactivation. Clinical relevance was investigated by qPCR of EBV in two primary effusion samples of NKTL patients. We also investigated the molecular consequences downstream of sildenafil-induced PDE5 inhibition in NKTL cells. A negative correlation was established between the cGMP/PKG pathway and EBV reactivation in NKTL cells. On a molecular level, PDE5 inhibition downregulates BZLF1 and BRLF1 through cGMP/PKG signaling-induced ZNF overexpression. Co-treatment with romidepsin and sildenafil (inhibiting HDAC and PDE5, respectively) showed a synergistic inhibitory effect on NKTL cells, highlighting PDE5 as an attractive target for future therapy in NKTL.

Drug Discovery of Nucleos(t)ide Antiviral Agents: Dedicated to Prof. Dr. Erik De Clercq on Occasion of His 80th Birthday

Nucleoside and nucleotide analogues are essential antivirals in the treatment of infectious diseases such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), herpes simplex virus (HSV), varicella-zoster virus (VZV), and human cytomegalovirus (HCMV). To celebrate the 80th birthday of Prof. Dr. Erik De Clercq on 28 March 2021, this review provides an overview of his contributions to eight approved nucleos(t)ide drugs: (i) three adenosine nucleotide analogues, namely tenofovir disoproxil fumarate (Viread^®) and tenofovir alafenamide (Vemlidy^®) against HIV and HBV infections and adefovir dipivoxil (Hepsera^®) against HBV infections; (ii) two thymidine nucleoside analogues, namely brivudine (Zostex^®) against HSV-1 and VZV infections and stavudine (Zerit^®) against HIV infections; (iii) two guanosine analogues, namely valacyclovir (Valtrex^®, Zelitrex^®) against HSV and VZV and rabacfosadine (Tanovea^®-CA1) for the treatment of lymphoma in dogs; and (iv) one cytidine nucleotide analogue, namely cidofovir (Vistide^®) for the treatment of HCMV retinitis in AIDS patients. Although adefovir dipivoxil, stavudine, and cidofovir are virtually discontinued for clinical use, tenofovir disoproxil fumarate and tenofovir alafenamide remain the most important antivirals against HIV and HBV infections worldwide. Overall, the broad-spectrum antiviral potential of nucleos(t)ide analogues supports their development to treat or prevent current and emerging infectious diseases worldwide.

As Evidence-Based Tumorigenic Role of Epstein-Barr Virus miR-BART1-3p in Neurological Tumors

INTRODUCTION

Central nervous system tumors are a diverse group of tumors that account for 2% of all adult cancers and 17% of childhood malignancies. Several internal and external risk factors are involved in the development of this cancer such as viral infections. The aim of this study was to the determination of the EBV infection frequency and the expression level of miR-122 and miR-BART in CNS tumors samples.

METHODS

One hundred and thirty-eight  fresh tissue sample (106 case and 32 control) was collected from CNS specimens. The presence of Epstein-Barr virus (EBV) DNA was examined by PCR assay and the expression level of miR-122 and miR-BART were evaluated by using real-time PCR assay in CNS tissue samples.

RESULTS

EBV DNA was detected in 17% (18 of 106) of tumors tissue samples and 6.4% (2 of 32) of control samples. according to results, there was a significant relationship between the presence of EBV-DNA with CNS tumors. Additionally, the expression level of miR-122 was significantly downregulated in the EBV-positive sample compared to that of the EBV-negative sample. Also, the level of EBV-BART1-3p expression was significantly higher in EBV-positive tumors samples than EBV-positive normal samples.

CONCLUSION

The results of this study suggest that the EBV could change the condition of cancer cells by altering the expression of miR-122 and EBV-BART1-3p and maybe contribute to the development of cancer cells. However, the role of viral infections in CNS cancer requires further studies. <br />.

Frequent co-reactivation of Epstein-Barr virus in patients with cytomegalovirus viremia under immunosuppressive therapy and/or chemotherapy

Objective

Co-reactivation of cytomegalovirus (CMV) and Epstein–Barr virus (EBV) occurs in iatrogenically immunosuppressed patients, but the clinical relevance of this is unknown. We aimed to determine the frequency of EBV reactivation in patients with CMV viremia and to explore its clinical significance.

Methods

Serum or plasma CMV and EBV DNA was detected by quantitative real-time PCR in 82 patients who received immunosuppressive therapy and/or chemotherapy and underwent CMV antigenemia tests.

Results

CMV DNA was positive in 55 patients, with EBV reactivation being found in 29 of these (52.7%). EBV co-reactivation was significantly associated with aging (>64 years vs. ≤64 years, odds ratio 4.07, 95% confidence interval 1.06–15.6). When older patients were divided into two groups according to age, EBV co-reactivation occurred more frequently in early-old patients (aged 65–74 years) than in late-old patients (aged ≥75 years) (100.0% vs. 53.3%, respectively). Steroid pulse treatment was administered significantly more often in the early-old group than in those aged ≤64 years and ≥75 years (72.7% vs 27.6% vs 14.3%, respectively).

Conclusions

Co-reactivation of EBV in patients with CMV viremia highlighted early-old patients and may reflect treatment intensity as well as immunosenescence.

The role of soluble mediators in the clinical course of EBV infection and B cell homeostasis after kidney transplantation

Epstein-Barr virus (EBV) reactivation can lead to serious complications in kidney transplant patients, including post-transplant lymphoproliferative disorder (PTLD). Here, we have assessed the impact of EBV on B cell homeostasis at cellular and humoral level. In a multicenter study monitoring 540 kidney transplant patients during the first post-transplant year, EBV reactivation was detected in 109 patients. Thirteen soluble factors and B cell counts were analyzed in an EBV⁺ sub-cohort (N = 54) before, at peak and after EBV clearance and compared to a control group (N = 50). The B cell activating factor (BAFF) was significantly elevated among EBV⁺ patients. No additional soluble factors were associated with EBV. Importantly, in vitro experiments confirmed the proliferative effect of BAFF on EBV-infected B cells, simultaneously promoting EBV production. In contrast, elevated levels of BAFF in EBV⁺ patients did not lead to B cell expansion in vivo. Moreover, diminished positive inter-correlations of soluble factors and alterations of the bi-directional interplay between B cell and soluble factors were observed in EBV⁺ patients at peak and after clearance. Our data suggest that such alterations may counteract the proliferative effect of BAFF, preventing B cell expansion. The role of these alterations in lymphoma development should be analyzed in future studies.

An Autopsy Case of an Elderly Patient with Classic Hodgkin Lymphoma Presenting with a Plethora of Clinical Symptoms and Signs

BACKGROUND Hodgkin lymphoma (HL) is a potentially curable disease with favorable outcomes. However, elderly patients with HL usually have more adverse prognostic factors and hence a much worse prognosis than younger patients. CASE REPORT The patient was a woman in her 80s. She reported high fever, anorexia, and a weight loss of 8 kg within 5 months. She had been on treatment for diabetes mellitus and hypertension. She had undergone percutaneous coronary intervention and pacemaker implantation to treat acute coronary syndrome and sinus arrhythmia, respectively. Blood tests showed elevation of alkaline phosphatase, C-reactive protein, leukocyte count, CA 19-9, and carcinoembryonic antigen. Computed tomography did not show tumors in the liver, and cholangitis and sepsis were suspected. Aspartate transaminase, alanine aminotransferase, and total bilirubin gradually increased through the course of the patient's hospital stay. Despite treatment, her condition deteriorated and she died 22 days after hospital admission. At autopsy, we found stage IV HL with lymph node swelling on both sides of the diaphragm, as well as diffusely disseminated nodules in the liver and spleen. CONCLUSIONS Our patient had several poor prognostic factors including B symptoms, comorbidity, advanced stage, Epstein-Barr virus infection, and expression of programmed death-ligand 1 and interleukin-6, all of which were closely connected with her advanced age. Her age and comorbidities may have been the most adverse prognostic factors for her illness. An effective HL screening method for elderly individuals should be developed to ameliorate poor prognosis and adverse outcomes.

Evaluation of T-activated proteins as recall antigens to monitor Epstein-Barr virus and human cytomegalovirus-specific T cells in a clinical trial setting

BACKGROUND

Pools of overlapping synthetic peptides are routinely used for ex vivo monitoring of antigen-specific T-cell responses. However, it is rather unlikely that these peptides match those resulting from naturally processed antigens. T-activated proteins have been described as immunogenic and more natural stimulants, since they have to pass through antigen processing and comprise activation of all clinically relevant effector cell populations.

METHODS

We performed comparative analysis of numbers and cytokine expression pattern of CD4 and CD8 T cells after stimulation with recombinant, urea-formulated T-activated EBV-BZLF1, -EBNA3A, and HCMV-IE1, and -pp65 proteins or corresponding overlapping peptide pools. Freshly isolated and cryopreserved PBMC of 30 EBV- and 19 HCMV-seropositive and seven EBV- and HCMV-seronegative subjects were stimulated ex vivo and analysed for IFN-γ, TNF and IL-2 production by flow cytometry-based intracellular cytokine staining.

RESULTS

T-activated proteins showed a high specificity of 100% (EBV-BZLF1, HCMV-IE1, and -pp65) and 86% (EBV-EBNA3A), and a high T-cell stimulatory capacity of 73-95% and 67-95% using freshly isolated and cryopreserved PBMC, respectively. The overall CD4 T-cell response rates in both cohorts were comparable after stimulation with either T-activated protein or peptide pools with the exception of lower numbers of CD8 T cells detected after stimulation with T-activated EBV-EBNA3A- (p = 0.038) and HCMV-pp65- (p = 0.0006). Overall, the number of detectable antigen-specific T cells varied strongly between individuals. Cytokine expression patterns in response to T-activated protein and peptide pool-based stimulation were similar for CD4, but significantly different for CD8 T-cell responses.

CONCLUSION

EBV and HCMV-derived T-activated proteins represent innovative, highly specific recall antigens suitable for use in immunological endpoint assays to evaluate success or failure in immunotherapy clinical trials (e.g. to assess the risk of EBV and/or HCMV reactivation after allogenic hematopoietic stem cell transplantation). T-activated proteins could be of particular importance, if an impaired antigen processing (e.g. in a post-transplant setting) must be taken into account.

Epstein-Barr virus retinitis in an immunocompromised child: A case report

INTRODUCTION

The Epstein-Barr virus is a rare causative pathogen identified in the posterior segment. The majority of cases were presented with a serious condition of acute retinal necrosis, and most of these eyes had poor outcomes. The clinical features and effective treatment options for this condition are still unclear.Case description: A 10-year-old boy with leukaemia and receiving immunosuppressive regimen presented with decreasing visual acuity to counting fingers in his left eye for 2 weeks. Fundus examination revealed disc swelling, retinitis, retinal exudates and haemorrhages. Aqueous polymerase chain reaction was positive for Epstein-Barr virus DNA but negative for cytomegalovirus, herpes simplex virus and varicella zoster virus DNA. Systemic acyclovir and intravitreal ganciclovir injection were administered. Seven months later, retinitis resolved with remnant retinal fibrosis, and visual acuity improved to 20/500.

CONCLUSION

Epstein-Barr virus is rarely identified as a sole pathogen in retinitis. Peripapillary predilection might be another type of presenting feature apart from the more-commonly reported peripheral acute retinal necrosis.

Construction of Epstein-Bar virus cocktail peptide fused with Fcγ of IgG: as a potential delivery system for vaccine development

Epstein–Barr virus (EBV) associated with several diseases such as contagious mononucleosis chronic active EBV infection, and diverse sorts of malignant tumors. Therefore, using applicable vaccines could be advantageous for public health. Yet, the vaccine has been unavailable to protect from EBV so far. In the current study, to develop a multi-peptide vaccine for EBV and assess its expression in Pichia pastoris yeast system, three immunodominant sequences in glycoprotein (gp) 85, gp350 and latent membrane protein 1 (LMP1) were chosen. To construct fusion peptide, -GGGGS- liker was applied. After cloning the fusion peptide in the pPICZαA expression vector, this recombinant vector processed and transfected into Pichia pastoris host cells. The expression of high level of EBV fusion peptide was confirmed by dot blot and SDS-PAGE procedures. The Pichia pastoris is capable of supporting EBV fusion peptide expression. The application of this fusion peptide as a peptide vaccine to fight EBV is suggested.

Seroprevalence of Epstein-Barr virus among children and adults in Tehran, Iran

Epstein–Barr virus (EBV) as a herpes virus can be associated with numerous infections and cancers. The virus is known to cause infectious mononucleosis. There is no accurate estimation of the seroprevalence of EBV in Tehran, so this study aimed to estimate the seroprevalence of EBV among children and adults in Tehran, Iran. This descriptive–analytical study was conducted from 2015 to 2019 in Tehran province. In this study, 1220 people were selected by cross-sectional sampling, and blood samples and demographic data were collected by questionnaire. An anti-EBV-VCA ELISA kit was used to determine the seroprevalence of IgG against viral capsid antigen (VCA) among children and adults. In this study, most of the participants were in the age range of 20–29 years (349 individuals). The results of the ELISA test showed that the highest number of positive cases were in people over 40 years (94.8%), 30–39 years (92.5%) and 20–29 years were (92.1%), respectively. On the other hand, the seroprevalence of EBV infection in boys and girls up to 3 years was about 50%, and in adults, up to 40 years, it was about 95% (p < 0.001). The results of this study showed that in Tehran, the seroprevalence of VCA-IgG varied from 70% in primary school children to more than 90% in adults up to 40 years, indicating a broad spread of the virus. The results also indicate that the seroprevalence of EBV is high among men and women in Tehran.

Viral miRNAs as Active Players and Participants in Tumorigenesis

The theory that viruses play a role in human cancers is now supported by scientific evidence. In fact, around 12% of human cancers, a leading cause of morbidity and mortality in some regions, are attributed to viral infections. However, the molecular mechanism remains complex to decipher. In recent decades, the uncovering of cellular miRNAs, with their invaluable potential as diagnostic and prognostic biomarkers, has increased the number of studies being conducted regarding human cancer diagnosis. Viruses develop clever mechanisms to succeed in the maintenance of the viral life cycle, and some viruses, especially herpesviruses, encode for miRNA, v-miRNAs. Through this viral miRNA, the viruses are able to manipulate cellular and viral gene expression, driving carcinogenesis and escaping the host innate or adaptive immune system. In this review, we have discussed the main viral miRNAs and virally influenced cellular pathways, and their capability to drive carcinogenesis.

Dipyridamole as a new drug to prevent Epstein-Barr virus reactivation

Epstein-Barr virus (EBV) is a widely distributed gamma-herpesvirus that has been associated with various cancers mainly from lymphocytic and epithelial origin. Although EBV-mediated oncogenesis has been associated with viral oncogenes expressed during latency, a growing set of evidence suggested that antiviral treatments directed against EBV lytic phase may contribute to prevent some forms of cancers, including EBV-positive Post-Transplant Lymphoproliferative Diseases. It is shown here that dipyridamole (DIP), a safe drug with favorable and broad pharmacological properties, inhibits EBV reactivation from B-cell lines. DIP repressed immediate early and early genes expression mostly through its ability to inhibit nucleoside uptake. Considering its wide clinical use, DIP repurposing could shortly be evaluated, alone or in combination with other antivirals, to treat EBV-related diseases where lytic replication plays a deleterious role.

The Function and Therapeutic Potential of Epstein-Barr Virus-Encoded MicroRNAs in Cancer

Epstein-Barr virus (EBV) is a ubiquitous human γ-herpesvirus that infects over 90% of the global population. EBV is considered a contributory factor in a variety of malignancies including nasopharyngeal carcinoma, gastric carcinoma, Burkitt lymphoma, and Hodgkin’s lymphoma. Notably, EBV was the first virus found to encode microRNAs (miRNAs). Increasing evidence indicates that EBV-encoded miRNAs contribute to the carcinogenesis and development of EBV-associated malignancies. EBV miRNAs have been shown to inhibit the expression of genes involved in cell proliferation, apoptosis, invasion, and immune signaling pathways. Therefore, EBV miRNAs perform a significant function in the complex host-virus interaction and EBV-driven carcinogenesis. However, the integrated mechanisms underlying the roles of EBV miRNAs in carcinogenesis remain to be further explored. In this review, we describe recent advances regarding the involvement of EBV miRNAs in the pathogenesis of EBV-associated malignancies and discuss their potential utility as cancer biomarkers. An in-depth investigation into the pro-carcinogenic role of EBV miRNAs will expand our knowledge of the biological processes associated with virus-driven tumors and contribute to the development of novel therapeutic strategies for the treatment of EBV-associated malignancies.