Tumor viruses and cancer biology: Modulating signaling pathways for therapeutic intervention

Recent progress in mRNA cancer vaccines

The research and development of messenger RNA (mRNA) cancer vaccines have gradually overcome numerous challenges through the application of personalized cancer antigens, structural optimization of mRNA, and the development of alternative RNA-based vectors and efficient targeted delivery vectors. Clinical trials are currently underway for various cancer vaccines that encode tumor-associated antigens (TAAs), tumor-specific antigens (TSAs), or immunomodulators. In this paper, we summarize the optimization of mRNA and the emergence of RNA-based expression vectors in cancer vaccines. We begin by reviewing the advancement and utilization of state-of-the-art targeted lipid nanoparticles (LNPs), followed by presenting the primary classifications and clinical applications of mRNA cancer vaccines. Collectively, mRNA vaccines are emerging as a central focus in cancer immunotherapy, offering the potential to address multiple challenges in cancer treatment, either as standalone therapies or in combination with current cancer treatments.

Epigenetic Mechanisms in Latent Epstein-Barr Virus Infection and Associated Cancers

The Epstein-Barr Virus (EBV) is a double-stranded DNA-based human tumor virus that was first isolated in 1964 from lymphoma biopsies. Since its initial discovery, EBV has been identified as a major contributor to numerous cancers and chronic autoimmune disorders. The virus is particularly efficient at infecting B-cells but can also infect epithelial cells, utilizing an array of epigenetic strategies to establish long-term latent infection. The association with histone modifications, alteration of DNA methylation patterns in host and viral genomes, and microRNA targeting of host cell factors are core epigenetic strategies that drive interactions between host and virus, which are necessary for viral persistence and progression of EBV-associated diseases. Therefore, understanding epigenetic regulation and its role in post-entry viral dynamics is an elusive area of EBV research. Here, we present current outlooks of EBV epigenetic regulation as it pertains to viral interactions with its host during latent infection and its propensity to induce tumorigenesis. We review the important epigenetic regulators of EBV latency and explore how the strategies involved during latent infection drive differential epigenetic profiles and host-virus interactions in EBV-associated cancers.

The role of oncolytic virotherapy and viral oncogenes in the cancer stem cells: a review of virus in cancer stem cells

Cancer Stem Cells (CSCs) are the main "seeds" for the initiation, growth, metastasis, and recurrence of tumors. According to many studies, several viral infections, including the human papillomaviruses, hepatitis B virus, Epstein-Barr virus, and hepatitis C virus, promote the aggressiveness of cancer by encouraging the development of CSC features. Therefore, a better method for the targeted elimination of CSCs and knowledge of their regulatory mechanisms in human carcinogenesis may lead to the development of a future tool for the management and treatment of cancer. Oncolytic viruses (OVs), which include the herpes virus, adenovirus, vaccinia, and reovirus, are also a new class of cancer therapeutics that have favorable properties such as selective replication in tumor cells, delivery of numerous eukaryotic transgene payloads, induction of immunogenic cell death and promotion of antitumor immunity, as well as a tolerable safety profile that essentially differs from that of other cancer therapeutics. The effects of viral infection on the development of CSCs and the suppression of CSCs by OV therapy were examined in this paper. The purpose of this review is to investigate the dual role of viruses in CSCs (oncolytic virotherapy and viral oncogenes).

Overexpression of the mitochondrial anti-viral signaling protein, MAVS, in cancers is associated with cell survival and inflammation

Mitochondrial anti-viral signaling protein (MAVS) plays an important role in host defense against viral infection via coordinating the activation of NF-κB and interferon regulatory factors. The mitochondrial-bound form of MAVS is essential for its anti-viral innate immunity. Recently, tumor cells were proposed to mimic a viral infection by activating RNA-sensing pattern recognition receptors. Here, we demonstrate that MAVS is overexpressed in a panel of viral non-infected cancer cell lines and patient-derived tumors, including lung, liver, bladder, and cervical cancers, and we studied its role in cancer. Silencing MAVS expression reduced cell proliferation and the expression and nuclear translocation of proteins associated with transcriptional regulation, inflammation, and immunity. MAVS depletion reduced expression of the inflammasome components and inhibited its activation/assembly. Moreover, MAVS directly interacts with the mitochondrial protein VDAC1, decreasing its conductance, and we identified the VDAC1 binding site in MAVS. Our findings suggest that MAVS depletion, by reducing cancer cell proliferation and inflammation, represents a new target for cancer therapy.

IGF2BP1-An Oncofetal RNA-Binding Protein Fuels Tumor Virus Propagation

The oncofetal RNA-binding protein IGF2BP1 has been reported to be a driver of tumor progression in a multitude of cancer entities. Its main function is the stabilization of target transcripts by shielding these from miRNA-mediated degradation. However, there is growing evidence that several virus species recruit IGF2BP1 to promote their propagation. In particular, tumor-promoting viruses, such as hepatitis B/C and human papillomaviruses, benefit from IGF2BP1. Moreover, recent evidence suggests that non-oncogenic viruses, such as SARS-CoV-2, also take advantage of IGF2BP1. The only virus inhibited by IGF2BP1 reported to date is HIV-1. This review summarizes the current knowledge about the interactions between IGF2BP1 and different virus species. It further recapitulates several findings by presenting analyses from publicly available high-throughput datasets.

Chronic Epstein-Barr virus infection: A potential junction between primary Sjögren's syndrome and lymphoma

Primary Sjögren's syndrome (pSS) is an autoimmune disease that targets exocrine glands, leading to exocrine dysfunction. Due to its propensity to infect epithelial and B cells, Epstein-Barr virus (EBV) is hypothesized to be related with pSS. Through molecular mimicry, the synthesis of specific antigens, and the release of inflammatory cytokines, EBV contributes to the development of pSS. Lymphoma is the most lethal outcome of EBV infection and the development of pSS. As a population-wide virus, EBV has had a significant role in the development of lymphoma in people with pSS. In the review, we will discuss the possible causes of the disease.

JAK/STAT Signaling and Cervical Cancer: From the Cell Surface to the Nucleus

The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway constitutes a rapid signaling module from the cell surface to the nucleus, and activates different cellular responses, such as proliferation, survival, migration, invasion, and inflammation. When the JAK/STAT pathway is altered, it contributes to cancer progression and metastasis. STAT proteins play a central role in developing cervical cancer, and inhibiting the JAK/STAT signaling may be necessary to induce tumor cell death. Several cancers show continuous activation of different STATs, including cervical cancer. The constitutive activation of STAT proteins is associated with a poor prognosis and overall survival. The human papillomavirus (HPV) oncoproteins E6 and E7 play an essential role in cervical cancer progression, and they activate the JAK/STAT pathway and other signals that induce proliferation, survival, and migration of cancer cells. Moreover, there is a crosstalk between the JAK/STAT signaling cascade with other signaling pathways, where a plethora of different proteins activate to induce gene transcription and cell responses that contribute to tumor growth. Therefore, inhibition of the JAK/STAT pathway shows promise as a new target in cancer treatment. In this review, we discuss the role of the JAK/STAT pathway components and the role of the HPV oncoproteins associated with cellular malignancy through the JAK/STAT proteins and other signaling pathways to induce tumor growth.

Mechanism of cell cycle regulation and cell proliferation during human viral infection

Over the history of the coevolution of Host viral interaction, viruses have customized the host cellular machinery into their use for viral genome replication, causing effective infection and ultimately aiming for survival. They do so by inducing subversions to the host cellular pathways like cell cycle via dysregulation of important cell cycle checkpoints by viral encoded proteins, arresting the cell cycle machinery, blocking cytokinesis as well as targeting subnuclear bodies, thus ultimately disorienting the cell proliferation. Both DNA and RNA viruses have been active participants in such manipulation resulting in serious outcomes of cancer. They achieve this by employing different mechanisms-Protein-protein interaction, protein-phosphorylation, degradation, redistribution, viral homolog, and viral regulation of APC at different stages of cell cycle events. Several DNA viruses cause the quiescent staged cells to undergo cell cycle which increases nucleotide pools logistically significantly persuading viral replication whereas few other viruses arrest a particular stage of cell cycle. This allows the latter group to sustain the infection which allows them to escape host immune response and support viral multiplication. Mechanical study of signaling such viral mediated pathways could give insight into understanding the etiology of tumorigenesis and progression. Overall this chapter highlights the possible strategies employed by DNA/RNA viral families which impact the normal cell cycle but facilitate viral infected cell replication. Such information could contribute to comprehending viral infection-associated disorders to further depth.

Differential Microbial Signature Associated With Benign Prostatic Hyperplasia and Prostate Cancer

Apart from other risk factors, chronic inflammation is also associated with the onset of Prostate Cancer (PCa), wherein pathogen infection and tissue microbiome dysbiosis are known to play a major role in both inflammatory response and cancer development. However, except for a few studies, the link between microbes and PCa remained poorly understood. To explore the potential microbiome signature associated with PCa in Indian patients, we investigated differential compositions of commensal bacteria among patients with benign prostatic hyperplasia (BPH) and PCa using 16S rRNA amplicon sequencing followed by qPCR analyses using two distinct primer sets. Using two independent cohorts, we show that Prevotella copri, Cupriavidus campinensis, and Propionibacterium acnes represent the three most abundant bacteria in diseased prostate lesions. LEfSe analyses identified that while Cupriavidus taiwanensis and Methylobacterium organophilum are distinctly elevated in PCa samples, Kocuria palustris and Cellvibrio mixtus are significantly enriched in BPH samples. Furthermore, we identify that a number of human tumor viruses, including Epstein-Barr virus (EBV) and hepatitis B virus (HBV), along with two high-risk human papillomaviruses - HPV-16 and HPV-18, are significantly associated with the PCa development and strongly correlated with PCa bacterial signature. The study may thus offer to develop a framework for exploiting this microbial signature for early diagnosis and prognosis of PCa development.

Malignancy: An Adverse Effect of Immunosuppression

Benefits of solid organ transplantation in end stage organ diseases are indisputable. Malignancy is a feared complication of solid organ transplantation and is a leading cause of mortality in patients with organ transplantation. Iatrogenic immunosuppression to prevent graft rejection plays a crucial role in the cancer development in solid organ transplant recipients. Chronic exposure to immunosuppression increases the malignancy burden through deregulation of host immune defense mechanisms and unchecked proliferation of oncogenic viruses and malignancies associated with these viruses. Vigorous screening of candidates undergoing transplant evaluation for malignancies, careful assessment of donors, and vigilant monitoring of transplant recipients are necessary to prevent, detect, and manage this life-threatening complication.

Potential of Naturally Derived Compounds in Telomerase and Telomere Modulation in Skin Senescence and Aging

Proper functioning of cells-their ability to divide, differentiate, and regenerate-is dictated by genomic stability. The main factors contributing to this stability are the telomeric ends that cap chromosomes. Telomere biology and telomerase activity have been of interest to scientists in various medical science fields for years, including the study of both cancer and of senescence and aging. All these processes are accompanied by telomere-length modulation. Maintaining the key levels of telomerase component (hTERT) expression and telomerase activity that provide optimal telomere length as well as some nontelomeric functions represents a promising step in advanced anti-aging strategies, especially in dermocosmetics. Some known naturally derived compounds contribute significantly to telomere and telomerase metabolism. However, before they can be safely used, it is necessary to assess their mechanisms of action and potential side effects. This paper focuses on the metabolic potential of natural compounds to modulate telomerase and telomere biology and thus prevent senescence and skin aging.

Biophysical characterization of structural and conformational changes in methylmethane sulfonate modified DNA leading to the frizzled backbone structure and strand breaks in DNA

Methyl methanesulfonate (MMS) is a highly toxic DNA-alkylating agent that has a potential to damage the structural integrity of DNA. This work employed multiple biophysical and computational methods to report the MMS mediated structural alterations in the DNA (MMS-DNA). Spectroscopic techniques and gel electrophoresis studies revealed MMS induced exposure of chromophoric groups of DNA; methylation mediated anti→syn conformational change, DNA fragmentation and reduced nucleic acid stability. MMS induced single-stranded regions in the DNA were observed in nuclease S1 assay. FT-IR results indicated MMS mediated loss of the assigned peaks for DNA, partial loss of C-O ribose, loss of deoxyribose region, C-O stretching and bending of the C-OH groups of hexose sugar, a progressive shift in the assigned guanine and adenine peaks, loss of thymine peak, base stacking and presence of C-O-H vibrations of glucose and fructose, indicating direct strand breaks in DNA due to backbone loss. Isothermal titration calorimetry showed MMS-DNA interaction as exothermic with moderate affinity. Dynamic light scattering studies pointed towards methylation followed by the generation of single-stranded regions. Electron microscopy pictured the loss of alignment in parallel base pairs and showed the formation of fibrous aggregates in MMS-DNA. Molecular docking found MMS in close contact with the ribose sugar of DNA backbone having non-bonded interactions. Molecular dynamic simulations confirmed that MMS is capable of interacting with DNA at two levels, one at the level of nitrogenous bases and another at the DNA backbone. The study offers insights into the molecular interaction of MMS and DNA.Communicated by Ramaswamy H. Sarma.

The role of telomerase and viruses interaction in cancer development, and telomerase-dependent therapeutic approaches

Human telomerase reverse transcriptase (hTERT) is an enzyme that is critically involved in elongating and maintaining telomeres length to control cell life span and replicative potential. Telomerase activity is continuously expressed in human germ-line cells and most cancer cells, whereas it is suppressed in most somatic cells. In normal cells, by reducing telomerase activity and progressively shortening the telomeres, the cells progress to the senescence or apoptosis process. However, in cancer cells, telomere lengths remain constant due to telomerase's reactivation, and cells continue to proliferate and inhibit apoptosis, and ultimately lead to cancer development and human death due to metastasis. Studies demonstrated that several DNA and RNA oncoviruses could interact with telomerase by integrating their genome sequence within the host cell telomeres specifically. Through the activation of the hTERT promoter and lengthening the telomere, these cells contributes to cancer development. Since oncoviruses can activate telomerase and increase hTERT expression, there are several therapeutic strategies based on targeting the telomerase of cancer cells like telomerase-targeted peptide vaccines, hTERT-targeting dendritic cells (DCs), hTERT-targeting gene therapy, and hTERT-targeting CRISPR/Cas9 system that can overcome tumor-mediated toleration mechanisms and specifically apoptosis in cancer cells. This study reviews available data on the molecular structure of telomerase and the role of oncoviruses and telomerase interaction in cancer development and telomerase-dependent therapeutic approaches to conquest the cancer cells.

Long Non-coding RNAs in Gammaherpesvirus Infections: Their Roles in Tumorigenic Mechanisms

Long non-coding RNAs (lncRNAs) regulate gene expression at the epigenetic, transcriptional, or posttranscriptional level by interacting with protein, DNA, and RNA. Emerging evidence suggests that various lncRNAs are abnormally expressed and play indispensable roles in virus-triggered cancers. Besides, a growing number of studies have shown that virus-encoded lncRNAs participate in tumorigenesis. However, the functions of most lncRNAs in tumors caused by oncogenic viruses and their underlying mechanisms remain largely unknown. In this review, we summarize current findings regarding lncRNAs involved in cancers caused by Epstein–Barr virus (EBV) and Kaposi’s sarcoma herpesvirus (KSHV). Additionally, we discuss the contribution of lncRNAs to tumor occurrence, development, invasion, and metastasis; the roles of lncRNAs in key signaling pathways and their potential as biomarkers and therapeutic targets for tumor diagnostics and treatment.

Somatic HLA Class I Loss Is a Widespread Mechanism of Immune Evasion Which Refines the Use of Tumor Mutational Burden as a Biomarker of Checkpoint Inhibitor Response

Neoantigen presentation arises as a result of tumor-specific mutations and is a critical component of immune surveillance that can be abrogated by somatic LOH of the human leukocyte antigen class I (HLA-I) locus. To understand the role of HLA-I LOH in oncogenesis and treatment, we utilized a pan-cancer genomic dataset of 83,644 patient samples, a small subset of which had treatment outcomes with immune checkpoint inhibitors (ICI). HLA-I LOH was common (17%) and unexpectedly had a nonlinear relationship with tumor mutational burden (TMB). HLA-I LOH was frequent at intermediate TMB, yet prevalence decreased above 30 mutations/megabase, suggesting highly mutated tumors require alternate immune evasion mechanisms. In ICI-treated patients with nonsquamous non-small cell lung cancer, HLA-I LOH was a significant negative predictor of overall survival. Survival prediction improved when combined with TMB, suggesting TMB with HLA-I LOH may better identify patients likely to benefit from ICIs. SIGNIFICANCE: This work shows the pan-cancer landscape of HLA-I LOH, revealing an unexpected "Goldilocks" relationship between HLA-I LOH and TMB, and demonstrates HLA-I LOH as a significant negative predictor of outcomes after ICI treatment. These data informed a combined predictor of outcomes after ICI and have implications for tumor vaccine development.This article is highlighted in the In This Issue feature, p. 211.

The interplay between EBV and KSHV viral products and NF-κB pathway in oncogenesis

Among the DNA tumor viruses Epstein-Barr virus (EBV) and Kaposi sarcoma herpesvirus (KSHV), account for a considerable percentage of virus-associated cancers. Deregulation of transcription factors signaling pathways is one of the most significant oncogenic characteristics of EBV and KSHV. NF-κB is a transcription factor that play a remarkable role in oncogenesis because of its function as a master regulator of a spectrum of genes involved in physiological and pathophysiological process. Constitutive activation of NF-κB is a frequent and well-described event in many human malignancies. Compelling evidence represent EBV and KSHV are capable of targeting different components of NF-κB cascade. Here, we summarized recent findings to clarify the precise relationship between dysregulation of NF-κB and EBV and KSHV-related malignancies. This essay also emphasizes on contribution of various viral products in developing cancer through alteration of NF-κB signaling pathway.

The impact of EBV on the epigenetics of gastric carcinoma

EBV is an important human tumor virus and is closely related to the occurrence of a variety of tumors, involving 10% of gastric cancer. In EBV-associated gastric carcinoma (EBVaGC), EBV expresses restrict viral genes including EBV nuclear antigen 1, EBV encoded small RNAs, Bam HI-A rightward transcripts, latent membrane protein 2A and miRNAs. The role of EBV in gastric carcinogenesis has received increasing attention and is considered to be another pathogenic factor in addition to Helicobacter pylori. A typical characteristic of EBVaGC is the extensive methylation of viral and host genome. Combined with other epigenetic mechanisms, EBV infection acts as an epigenetic driver of EBVaGC oncogenesis. In this review we discuss recent findings of EBV effect on host epigenetic alterations in EBVaGC and its role in oncogenic process.

Clinical metagenomics

Clinical metagenomic next-generation sequencing (mNGS), the comprehensive analysis of microbial and host genetic material (DNA and RNA) in samples from patients, is rapidly moving from research to clinical laboratories. This emerging approach is changing how physicians diagnose and treat infectious disease, with applications spanning a wide range of areas, including antimicrobial resistance, the microbiome, human host gene expression (transcriptomics) and oncology. Here, we focus on the challenges of implementing mNGS in the clinical laboratory and address potential solutions for maximizing its impact on patient care and public health.

Silver nanoparticles selectively induce human oncogenic γ-herpesvirus-related cancer cell death through reactivating viral lytic replication

Silver nanoparticle (nAg), which is one of the most common manufactured nanomaterials, has a wide range of biomedical applications. The human oncogenic γ-herpesviruses, Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr Virus (EBV), are etiologically linked to many malignancies. Currently, there are no efficient or specific treatments for these types of tumors, and most patients die because of resistance to conventional cytotoxic chemotherapy. Despite nAg having antitumor and antiviral activities, its effects on oncogenic herpesvirus-related cancer cells remain largely unknown. Here, we reveal that nAg presents higher cytotoxicity against KSHV- or EBV-latently infected cells via reactivating viral lytic replication, which relies on the induction of reactive oxygen species (ROS) generation and autophagy. Moreover, nAg blocks KSHV primary infection by directly destroying virion particles, as well as effectively inhibits colony formation and moderately represses the growth of KSHV-associated tumors in xenograft mouse model. Taken together, these results demonstrate the therapeutic potential of nAg for use in the antiviral infection and treatment of oncogenic herpesvirus-related cancers.

Changes in apoptosis, proliferation and T lymphocyte subtype on thymic cells of SPF chickens infected with reticuloendotheliosis virus

Reticuloendotheliosis virus (REV), an avian retrovirus is able to infect a variety of birds and can cause immunosuppression. The aim of this study was to investigate the relationship of thymic lymphocytes apoptosis, proliferation and T cell subtype with immunosuppression. In this study, a hundred and twenty one-day old SPF chickens were randomly divided into control groups (group C) and a REV infection groups (group I). The chickens of group I received intraperitoneal injections of REV with 10^4.62/0.1 ml TCID₅₀. On day 14, 21, 28 and 35 post-inoculation, the chickens of C group and I group were sacrificed by cardiac puncture blood collection, and the thymic lymphocytes was sterile collected. The proliferation ability of lymphocytes was tested by Cell Counting Kit-8. Flow cytometry was performed to detect apoptosis, cell cycle stage and the change in T cell subtype. The RNA genome copy numbers of REV virus were detected using real-time PCR. Real-time PCR and western blotting were performed to analyze the expression of CyclinD1 and Bcl-2. Our results showed that REV genome copy number steadily declined, the proliferation potential of thymic lymphocytes was inhibited, lymphocytes apoptosed, the ratio of CD4+/CD8+ decreased and the expression of CyclinD1 and Bcl-2 were firstly inhibited, then rapidly recovered. Thus, immunosuppression lead by REV is closely related to the change of T cell subtype, apoptosis, and proliferation of thymic lymphocytes.

Comparative analysis of glutathione transferase genetic polymorphism, Helicobacter pylori and Epstein-Barr virus between the tumor area and the proximal and distal resection margins of gastric cancer

OBJECTIVE

to compare the polymorphism of the Glutathione S-transferase theta 1 (GSTT1) and Glutathione S-transferase mu 1 (GSTM1) genes from the tumor area with the proximal and distal margins of stomach specimens resected from patients with gastric cancer, and to investigate the presence of Epstein-Barr virus (EBV) DNA and Helicobacter pylori.

METHODS

we prospectively collected tissue specimens from the tumor area and from the proximal and distal resection margins of the stomachs of ten patients with gastric adenocarcinoma who underwent gastrectomy with D2 lymphadenectomy, and submitted these specimens to DNA extraction. We compared the tumor area with the proximal and distal margins of the resected stomachs for polymorphism of GSTT1 and GSTM1 genes and investigated the presence of EBV-DNA and H. pylori. We used the p53 exon 5 gene as an internal control of the multiplex PCR reaction.

RESULTS

in one patient, we detected null GSTT1 and GSTM1 genotypes in the tumor area, in contrast to the presence of both genes in the proximal and distal margins. We found EBV-DNA and H. pylori in the tumor area and also in the proximal and distal margins. In another patient, the proximal margin was negative for GSTT1, and EBV-DNA was negative in the distal margin. In three patients, EBV-DNA was negative only in the distal margin.

CONCLUSION

this is the first report where different genotypes, EBV-DNA and H. pylori infection were observed in the same patient, indicating a probable deletion of these genes in response to tumor progression and intratumoral heterogeneity.

Deregulation of the Notch pathway as a common road in viral carcinogenesis

The Notch pathway is a conserved signaling pathway and a form of direct cell-cell communication related to many biological processes during development and adulthood. Deregulation of the Notch pathway is involved in many diseases, including cancer. Almost 20% of all cancer cases have an infectious etiology, with viruses responsible for at least 1.5 million new cancer cases per year. Seven groups of viruses have been classified as oncogenic: hepatitis B and C viruses (HBV and HCV respectively), Epstein-Barr virus (EBV), Kaposi sarcoma-associated herpesvirus (KSHV), human T lymphotropic virus (HTLV-1), human papillomavirus (HPV), and Merkel cell polyomavirus (MCPyV). These viruses share the ability to manipulate a variety of cell pathways that are critical in proliferation and differentiation, leading to malignant transformation. Viral proteins interact directly or indirectly with different members of the Notch pathway, altering their normal function. This review focuses exclusively on the direct interactions of viral oncoproteins with Notch elements, providing a deeper understanding of the dual behavior of the Notch pathway as activator or suppressor of neoplasia in virus-related cancers.

Epigenetic Regulation of Tumor Suppressors by Helicobacter pylori Enhances EBV-Induced Proliferation of Gastric Epithelial Cells

Helicobacter pylori and Epstein-Barr virus (EBV) are two well-known contributors to cancer and can establish lifelong persistent infection in the host. This leads to chronic inflammation, which also contributes to development of cancer. Association with H. pylori increases the risk of gastric carcinoma, and coexistence with EBV enhances proliferation of infected cells. Further, H. pylori-EBV coinfection causes chronic inflammation in pediatric patients. We have established an H. pylori-EBV coinfection model system using human gastric epithelial cells. We showed that H. pylori infection can increase the oncogenic phenotype of EBV-infected cells and that the cytotoxin-associated gene (CagA) protein encoded by H. pylori stimulated EBV-mediated cell proliferation in this coinfection model system. This led to increased expression of DNA methyl transferases (DNMTs), which reprogrammed cellular transcriptional profiles, including those of tumor suppressor genes (TSGs), through hypermethylation. These findings provide new insights into a molecular mechanism whereby cooperativity between two oncogenic agents leads to enhanced oncogenic activity of gastric cancer cells.IMPORTANCE We have studied the cooperativity between H. pylori and EBV, two known oncogenic agents. This led to an enhanced oncogenic phenotype in gastric epithelial cells. We now demonstrate that EBV-driven epigenetic modifications are enhanced in the presence of H. pylori, more specifically, in the presence of its CagA secretory antigen. This results in increased proliferation of the infected gastric cells. Our findings now elucidate a molecular mechanism whereby expression of cellular DNA methyl transferases is induced influencing infection by EBV. Hypermethylation of the regulatory genomic regions of tumor suppressor genes results in their silencing. This drastically affects the expression of cell cycle, apoptosis, and DNA repair genes, which dysregulates their associated processes, and promotion of the oncogenic phenotype.

Role of Pattern Recognition Receptors in KSHV Infection

Kaposi’s sarcoma-associated herpesvirus or Human herpesvirus-8 (KSHV/HHV-8), an oncogenic human herpesvirus and the leading cause of cancer in HIV-infected individuals, is a major public health concern with recurring reports of epidemics on a global level. The early detection of KSHV virus and subsequent activation of the antiviral immune response by the host’s immune system are crucial to prevent KSHV infection. The host’s immune system is an evolutionary conserved system that provides the most important line of defense against invading microbial pathogens, including viruses. Viruses are initially detected by the cells of the host innate immune system, which evoke concerted antiviral responses via the secretion of interferons (IFNs) and inflammatory cytokines/chemokines for elimination of the invaders. Type I IFN and cytokine gene expression are regulated by multiple intracellular signaling pathways that are activated by germline-encoded host sensors, i.e., pattern recognition receptors (PRRs) that recognize a conserved set of ligands, known as ‘pathogen-associated molecular patterns (PAMPs)’. On the contrary, persistent and dysregulated signaling of PRRs promotes numerous tumor-causing inflammatory events in various human cancers. Being an integral component of the mammalian innate immune response and due to their constitutive activation in tumor cells, targeting PRRs appears to be an effective strategy for tumor prevention and/or treatment. Cellular PRRs are known to respond to KSHV infection, and KSHV has been shown to be armed with an array of strategies to selectively inhibit cellular PRR-based immune sensing to its benefit. In particular, KSHV has acquired specific immunomodulatory genes to effectively subvert PRR responses during the early stages of primary infection, lytic reactivation and latency, for a successful establishment of a life-long persistent infection. The current review aims to comprehensively summarize the latest advances in our knowledge of role of PRRs in KSHV infections.

The Immunology of Melanoma

The relatively high DNA mutational burden in melanoma allows for the creation of potentially "foreign," immune-stimulating neoantigens, and leads to its exceptional immunogenicity. Brisk tumor-infiltrating lymphocytes, a marker of immune editing, confer improved overall survival in melanoma, possibly due to reduced sentinel lymph node spread. Meanwhile, T-cell-stimulating drugs, so-called T-cell checkpoint inhibitors, which reverse peripheral tolerance-dependent tumor escape, have demonstrated unparalleled clinical success in metastatic melanoma. Markers to predict response to immunotherapy are currently imperfect, and the subject of intense research, which will guide the future of ancillary pathologic testing in this setting.

Therapeutic Strategies against Epstein-Barr Virus-Associated Cancers Using Proteasome Inhibitors

Epstein-Barr virus (EBV) is closely associated with several lymphomas (endemic Burkitt lymphoma, Hodgkin lymphoma and nasal NK/T-cell lymphoma) and epithelial cancers (nasopharyngeal carcinoma and gastric carcinoma). To maintain its persistence in the host cells, the virus manipulates the ubiquitin-proteasome system to regulate viral lytic reactivation, modify cell cycle checkpoints, prevent apoptosis and evade immune surveillance. In this review, we aim to provide an overview of the mechanisms by which the virus manipulates the ubiquitin-proteasome system in EBV-associated lymphoid and epithelial malignancies, to evaluate the efficacy of proteasome inhibitors on the treatment of these cancers and discuss potential novel viral-targeted treatment strategies against the EBV-associated cancers.

An EBV recombinant deleted for residues 130-159 in EBNA3C can deregulate p53/Mdm2 and Cyclin D1/CDK6 which results in apoptosis and reduced cell proliferation

Epstein-Barr virus (EBV), a gamma herpes virus is associated with B-cell malignancies. EBNA-3C is critical for in vitro primary B-cell transformation. Interestingly, the N terminal domain of EBNA3C which contains residues 130–159, interacts with various cellular proteins, such as p53, Mdm2, CyclinD1/Cdk6 complex, and E2F1. In the current reverse genetics study, we deleted the residues 130-159 aa within EBNA3C open reading frame (ORF) by BACmid recombinant engineering methodology. Our experiments demonstrated that deletion of the 130-159 aa showed a reduction in cell proliferation. Also, this recombinant virus showed with higher infectivity of human peripheral blood mononuclear cells (PBMCs) compared to wild type EBV. PBMCs- infected with recombinant EBV deleted for 130-159 residues have differential expression patterns for the p53/Mdm2, CyclinD1/Cdk6 and pRb/E2F1 pathways compared to wild type EBV-infected PBMCs. PBMCs infected with recombinant virus showed increased apoptotic cell death which further resulted in activation of polymerase 1 (PARP1), an important contributor to apoptotic signaling. Interestingly, cells infected with this recombinant virus showed a dramatic decrease in chromosomal instability, indicated by the presence of increased multinucleation and micronucleation. In addition infection with recombinant virus have increased cells in G0/G1 phase and decreased cells in S-G2M phase when compared to wild type infected cells. Thus, these differences in signaling activities due to 29 amino acid residues of EBNA3C is of particular significance in deregulation of cell proliferation in EBV-infected cells.

Sero-Prevalence of Bloodborne Tumor Viruses (HCV, HBV, HTLV-I and KSHV Infections) and Related Risk Factors among Prisoners in Razavi Khorasan Province, Iran, in 2008

BACKGROUND

Prisoners are at high risk of blood borne and sexually transmitted infections due to their high involvement in risky behaviors. In this descriptive/cross-sectional study, the prevalence, sero-prevalence, and risk factors for bloodborne tumor viruses including HTLV-I, HBV, HCV, and KSHV were evaluated among inmates of two central prisons in the northeast of Iran.

METHODS

Blood samples of 1114 inmates were analyzed for the presence of anti HTLV-I, KSHV, and HCV antibodies and HBsAg by ELISA. PCR tests were performed to confirm the presence of these viruses in plasma and identify the current infections.

RESULTS

The sero-prevalence of HCV, HBV, HTLV-I, and KSHV was 24.5%, 4.2%, 3.4%, and 3.2% and the prevalence of HCV, HBV, HTLV-I, and KSHV was 19.1%, 2.1%, 2%, and 3%, respectively. HCV infection was significantly associated with history of imprisonment, tobacco consumption, alcohol consumption, intravenous drug use, length of imprisonment, and type of crime committed. Thirty one (2.8%) prisoners had HCV-KSHV co-infection, 16 (1.5%) had HCV-HTLV-I co-infection, and 14 (1.3%) had HBV-HCV co-infection. Triple co-infection was observed in seven cases and one case had four infections concomitantly.

CONCLUSIONS

This epidemiological study indicated different rates and transmission risks for these viruses. HCV was the most contagious viral infection and HTLV-I was the weakest in the prisoners. Apart from KSHV infection which its prevalence was as twice as in the general population, the prevalence of HBV and HTLV-I in prisoners was nearly in ranges of the general population.

Epigenetic Impact on EBV Associated B-Cell Lymphomagenesis

Epigenetic modifications leading to either transcriptional repression or activation, play an indispensable role in the development of human cancers. Epidemiological study revealed that approximately 20% of all human cancers are associated with tumor viruses. Epstein-Barr virus (EBV), the first human tumor virus, demonstrates frequent epigenetic alterations on both viral and host genomes in associated cancers—both of epithelial and lymphoid origin. The cell type-dependent different EBV latent gene expression patterns appear to be determined by the cellular epigenetic machinery and similarly viral oncoproteins recruit epigenetic regulators in order to deregulate the cellular gene expression profile resulting in several human cancers. This review elucidates the epigenetic consequences of EBV–host interactions during development of multiple EBV-induced B-cell lymphomas, which may lead to the discovery of novel therapeutic interventions against EBV-associated B-cell lymphomas by alteration of reversible patho-epigenetic markings.

Oncogenic Role of Tumor Viruses in Humans

Viruses are the intracellular pathogens that reproduce only in the living cell and manipulate the cellular machinery to produce more viruses. Viral replications can affect cellular genes of the host in multiple cancerous ways. Approximately, 20% of all human oncogenesis is caused by cancer-causing viruses known as oncoviruses. Viral infection causes chronic inflammation leading to cell death, uncontrollable proliferation, and modulated expression of some of the regulatory proteins. Oncogenesis is a multistep phenomenon in which normal host cells are transformed into cancerous cells on the basis of host genetic variability. Oncogenic viruses encode genes that cause viral replication and transformation of the host cells to produce viral proteins and protein complexes. The phenomenon from basic viral infection to tumorigenesis is lengthy due to the involvement of factors like immunity complications, cellular mutations, and exposure to other cancerous agents. The viruses that are involved in human cancer development are Hepatitis B virus (HBV), Hepatitis C virus (HCV), Epstein-Barr virus (EBV), Human papilloma virus (HPV), Kaposi's sarcoma herpes virus (KSHV), and Human T lymphotrophic virus 1 (HTLV-1). This review article summarizes advanced knowledge related to human oncogenic viruses and the molecular mechanisms that lead to tumorigenesis in humans.

Key Characteristics of Carcinogens as a Basis for Organizing Data on Mechanisms of Carcinogenesis

BACKGROUND

A recent review by the International Agency for Research on Cancer (IARC) updated the assessments of the > 100 agents classified as Group 1, carcinogenic to humans (IARC Monographs Volume 100, parts A-F). This exercise was complicated by the absence of a broadly accepted, systematic method for evaluating mechanistic data to support conclusions regarding human hazard from exposure to carcinogens.

OBJECTIVES AND METHODS

IARC therefore convened two workshops in which an international Working Group of experts identified 10 key characteristics, one or more of which are commonly exhibited by established human carcinogens.

DISCUSSION

These characteristics provide the basis for an objective approach to identifying and organizing results from pertinent mechanistic studies. The 10 characteristics are the abilities of an agent to 1) act as an electrophile either directly or after metabolic activation; 2) be genotoxic; 3) alter DNA repair or cause genomic instability; 4) induce epigenetic alterations; 5) induce oxidative stress; 6) induce chronic inflammation; 7) be immunosuppressive; 8) modulate receptor-mediated effects; 9) cause immortalization; and 10) alter cell proliferation, cell death, or nutrient supply.

CONCLUSION

We describe the use of the 10 key characteristics to conduct a systematic literature search focused on relevant end points and construct a graphical representation of the identified mechanistic information. Next, we use benzene and polychlorinated biphenyls as examples to illustrate how this approach may work in practice. The approach described is similar in many respects to those currently being implemented by the U.S. EPA's Integrated Risk Information System Program and the U.S. National Toxicology Program.

CITATION

Smith MT, Guyton KZ, Gibbons CF, Fritz JM, Portier CJ, Rusyn I, DeMarini DM, Caldwell JC, Kavlock RJ, Lambert P, Hecht SS, Bucher JR, Stewart BW, Baan R, Cogliano VJ, Straif K. 2016. Key characteristics of carcinogens as a basis for organizing data on mechanisms of carcinogenesis. Environ Health Perspect 124:713-721; http://dx.doi.org/10.1289/ehp.1509912.

The Modulation of Apoptotic Pathways by Gammaherpesviruses

Apoptosis or programmed cell death is a tightly regulated process fundamental for cellular development and elimination of damaged or infected cells during the maintenance of cellular homeostasis. It is also an important cellular defense mechanism against viral invasion. In many instances, abnormal regulation of apoptosis has been associated with a number of diseases, including cancer development. Following infection of host cells, persistent and oncogenic viruses such as the members of the Gammaherpesvirus family employ a number of different mechanisms to avoid the host cell’s “burglar” alarm and to alter the extrinsic and intrinsic apoptotic pathways by either deregulating the expressions of cellular signaling genes or by encoding the viral homologs of cellular genes. In this review, we summarize the recent findings on how gammaherpesviruses inhibit cellular apoptosis via virus-encoded proteins by mediating modification of numerous signal transduction pathways. We also list the key viral anti-apoptotic proteins that could be exploited as effective targets for novel antiviral therapies in order to stimulate apoptosis in different types of cancer cells.

Co-prevalence of Epstein-Barr virus and high-risk human papillomaviruses in Syrian women with breast cancer

ABSTRAT We recently performed 2 studies viewing the presence of Epstein-Barr virus (EBV) and high-risk human papillomaviruses (HPVs) types 16, 18, 31, 33 and 35 in human breast cancer in the Syrian population. Herein, we report that EBV and high-risk HPVs are co-present in breast cancer in Syrian women. Therefore, and based on our previous studies and present data, we reveal that 35 (32%) of 108 cancer samples are positive for both EBV and high-risk HPVs and their co-presence is associated with high grade invasive ductal carcinomas (IDCs) with at least one positive lymph nodes, in comparison with EBV and high-risk HPVs-positive samples, which are low to intermediate grade IDCs, respectively. Future studies are needed to confirm the co-presence and the cooperation effect of these onco-viruses in human breast carcinogenesis and metastasis.

Role of EBNA-3 Family Proteins in EBV Associated B-cell Lymphomagenesis

Epstein-Barr virus (EBV) is highly ubiquitous in human population and establishes a lifelong asymptomatic infection within the infected host unless the immune system is compromised. Following initial infection in the oropharyngeal epithelial cells, EBV primarily infects naive B-lymphocytes and develops a number of B-cell lymphomas particularly in immune-deficient individuals. In vitro, EBV can also infect and subsequently transform quiescent B-lymphocytes into continuously proliferating lymphoblastoid cell lines (LCLs) resembling EBV-induced lymphoproliferative disorders in which a subset of latent transcripts are detected. Genetic studies revealed that EBNA-3 family comprising of three adjacent genes in the viral genome-EBNA-3A and -3C, but not -3B, are critical for B-cell transformation. Nevertheless, all three proteins appear to significantly contribute to maintain the overall proliferation and viability of transformed cells, suggesting a critical role in lymphoma development. Apart from functioning as important viral transcriptional regulators, EBNA-3 proteins associate with many cellular proteins in different signaling networks, providing a suitable platform for lifelong survival of the virus and concurrent lymphoma development in the infected host. The chapter describes the function of each these EBV nuclear antigen 3 proteins employed by the virus as a means to understand viral pathogenesis of several EBV-associated B-cell malignancies.

An overview of new biomolecular pathways in pathogen-related cancers

Cancer molecular pathways are combinations of metabolic processes deregulated in neoplastic cells. Besides pathways specific to tissues from which cancers originate, common neoplastic traits are present among most tumors. Hanahan and Weinberg have described the most critical 'hallmarks' shared by many cancer types. In recent years, cancer stem cell specific properties and pathways have also been identified. Other altered pathways are peculiar of cancer type and cancer stage, even in different cancer stem cell types. In pathogen-related tumors, the alteration of inflammatory and immunologic response along with impairment of cell cycle control represents key molecular events of tumor progression. This article summarizes the recent discoveries of new altered pathways in cancer and their importance in cancer diagnosis and tailored therapies.

Kat3 coactivators in somatic stem cells and cancer stem cells: biological roles, evolution, and pharmacologic manipulation

Long-lived somatic stem cells regenerate adult tissues throughout our lifetime. However, with aging, there is a significant deterioration in the function of stem and progenitor cells, which contribute to diseases of aging. The decision for a long-lived somatic stem cell to become activated and subsequently to undergo either a symmetric or an asymmetric division is a critical cellular decision process. The decision to preferentially divide symmetrically or asymmetrically may be the major fundamental intrinsic difference between normal somatic stem cells and cancer stem cells. Based upon work done primarily in our laboratory over the past 15 years, this article provides a perspective on the critical role of somatic stem cells in aging. In particular, we discuss the importance of symmetric versus asymmetric divisions in somatic stem cells and the role of the differential usage of the highly similar Kat3 coactivators, CREB-binding protein (CBP) and p300, in stem cells. We describe and propose a more complete model for the biological mechanism and roles of these two coactivators, their evolution, and unique roles and importance in stem cell biology. Finally, we discuss the potential to pharmacologically manipulate Kat3 coactivator interactions in endogenous stem cells (both normal and cancer stem cells) to potentially ameliorate the aging process and common diseases of aging.

Biology and pathogenesis of cytomegalovirus in periodontal disease

Human periodontitis is associated with a wide range of bacteria and viruses and with complex innate and adaptive immune responses. Porphyromonas gingivalis, Tannerella forsythia, Aggregatibacter actinomycetemcomitans, Treponema denticola, cytomegalovirus and other herpesviruses are major suspected pathogens of periodontitis, and a combined herpesvirus–bacterial periodontal infection can potentially explain major clinical features of the disease. Cytomegalovirus infects periodontal macrophages and T‐cells and elicits a release of interleukin‐1β and tumor necrosis factor‐α. These proinflammatory cytokines play an important role in the host defense against the virus, but they also have the potential to induce alveolar bone resorption and loss of periodontal ligament. Gingival fibroblasts infected with cytomegalovirus also exhibit diminished collagen production and release of an increased level of matrix metalloproteinases. This article reviews innate and adaptive immunity to cytomegalovirus and suggests that immune responses towards cytomegalovirus can play roles in controlling, as well as in exacerbating, destructive periodontal disease.

Epigenetic silencing of tumor suppressor genes during in vitro Epstein-Barr virus infection

DNA-methylation at CpG islands is one of the prevalent epigenetic alterations regulating gene-expression patterns in mammalian cells. Hypo- or hypermethylation-mediated oncogene activation, or tumor suppressor gene (TSG) silencing mechanisms, widely contribute to the development of multiple human cancers. Furthermore, oncogenic viruses, including Epstein-Barr virus (EBV)-associated human cancers, were also shown to be influenced by epigenetic modifications on the viral and cellular genomes in the infected cells. We investigated EBV infection of resting B lymphocytes, which leads to continuously proliferating lymphoblastoid cell lines through examination of the expression pattern of a comprehensive panel of TSGs and the epigenetic modifications, particularly methylation of their regulatory sequences. EBV infection of primary B lymphocytes resulted in global transcriptional repression of TSGs through engagement of hypermethylation. Therefore, CpG methylation profiles of TSGs may be used as a prognostic marker as well as development of potential therapeutic strategies for controlling acute infection and EBV-associated B-cell lymphomas.

Nanoparticle Drug Delivery Systems Designed to Improve Cancer Vaccines and Immunotherapy

Recent studies have demonstrated great therapeutic potential of educating and unleashing our own immune system for cancer treatment. However, there are still major challenges in cancer immunotherapy, including poor immunogenicity of cancer vaccines, off-target side effects of immunotherapeutics, as well as suboptimal outcomes of adoptive T cell transfer-based therapies. Nanomaterials with defined physico-biochemical properties are versatile drug delivery platforms that may address these key technical challenges facing cancer vaccines and immunotherapy. Nanoparticle systems have been shown to improve targeted delivery of tumor antigens and therapeutics against immune checkpoint molecules, amplify immune activation via the use of new stimuli-responsive or immunostimulatory materials, and augment the efficacy of adoptive cell therapies. Here, we review the current state-of-the-art in nanoparticle-based strategies designed to potentiate cancer immunotherapies, including cancer vaccines with subunit antigens (e.g., oncoproteins, mutated neo-antigens, DNA and mRNA antigens) and whole-cell tumor antigens, dendritic cell-based vaccines, artificial antigen-presenting cells, and immunotherapeutics based on immunogenic cell death, immune checkpoint blockade, and adoptive T-cell therapy.

Identification of Pathogen Signatures in Prostate Cancer Using RNA-seq

Infections of the prostate by bacteria, human papillomaviruses, polyomaviruses, xenotropic murine leukemia virus (MLV)-related gammaretroviruses, human cytomegaloviruses and other members of the herpesvirus family have been widely researched. However, many studies have yielded conflicting and controversial results. In this study, we systematically investigated the transcriptomes of human prostate samples for the unique genomic signatures of these pathogens using RNA-seq data from both western and Chinese patients. Human and nonhuman RNA-seq reads were mapped onto human and pathogen reference genomes respectively using alignment tools Bowtie and BLAT. Pathogen infections and integrations were analyzed in adherence with the standards from published studies. Among the nine pathogens (Propionibacterium acnes, HPV, HCMV, XMRV, BKV, JCV, SV40, EBV, and HBV) we analyzed, Propionibacterium acnes genes were detected in all prostate tumor samples and all adjacent samples, but not in prostate samples from healthy individuals. SV40, HCMV, EBV and low-risk HPVs transcripts were detected in one tumor sample and two adjacent samples from Chinese prostate cancer patients, but not in any samples of western prostate cancer patients; XMRV, BKV and JCV sequences were not identified in our work; HBV, as a negative control, was absent from any samples. Moreover, no pathogen integration was identified in our study. While further validation is required, our analysis provides evidence of Propionibacterium acnes infections in human prostate tumors. Noted differences in viral infections across ethnicity remain to be confirmed with other large prostate cancer data sets. The effects of bacterial and viral infections and their contributions to prostate cancer pathogenesis will require continuous research on associated pathogens.

Nasopharyngeal carcinoma progression is mediated by EBER-triggered inflammation via the RIG-I pathway

EBERs (EBER1 and EBER2) are suggested to be involved in cellular transformation and tumor growth. Cytoplasmic pattern recognition receptor-RIG-I, which is characterized by the recognition of viral dsRNAs, could efficiently trigger the downstream pathways of innate immunity. Although some previous reports have shown that EBERs and RIG-I associate with hematological malignancies, the role of EBERs-RIG-I signaling in solid tumors remains to be clarified. Here we demonstrate that EBER mediation of the inflammatory response via RIG-I contributes to NPC development in vitro and in vivo. We first verified that the expression level of RIG-I was associated with EBER transcription in a dose-dependent manner in NPC cells and specimens from NPC patients. Furthermore, pro-inflammatory cytokine transcription and release were sharply reduced after RIG-I knockdown compared with the control shRNA group in the presence of EBERs, accompanied by an attenuation of the NF-κB and MAPK signaling pathways. Consequently, the tumor burden was greatly alleviated in the RIG-I knockdown group in a xenograft model. In addition, macrophage colony-stimulating factor (M-CSF) and monocyte chemoattractant protein (MCP-1), which promote the maturation and attraction of tumor-associated macrophages, were stimulated upon the introduction of EBERs, and this upregulation conceivably led to the tumor-promoting subset transition of the macrophages. Taken together, our results reveal that EBERs could promote NPC progression through RIG-I-mediated cancer-related inflammation.

Oncogenic Virus Infections in the General Population and End-stage Renal Disease Patients With Special Emphasis on Kaposi's Sarcoma Associated Herpes Virus (KSHV) in Northeast of Iran

BACKGROUND

Globally, almost 20% of cancers are related to infectious agents that can be prevented. Oncogenicity refers to viruses that may cause cancers, more importantly in immunocompromised subjects such as transplant and hemodialysis patients. Therefore, epidemiological studies are the first line for understanding the importance of these agents in public health, particularly, in mobile populations, tourism and pilgrimage regions.

OBJECTIVES

Oncogenic viral infections, such as hepatitis B virus (HBV), hepatitis C virus (HCV) and Epstein-barr virus (EBV) are the most common viral agents in immunocompromised patients. Furthermore, human T lymphocyte virus type I (HTLV-I), due to endemicity in Khorasan Razavi province located northeast of Iran as a pilgrimage region, and Kaposi's sarcoma associated herpes virus (KSHV), as an oncogenic herpesvirus in immunocompromised subjects have been investigated among the general population and those with end-stage renal diseases (ESRD).

PATIENTS AND METHODS

A cross-sectional study was carried out among 1227 randomly selected individuals; 25 donors and 195 patients with ESRD, including 60 kidney transplant recipients and 135 dialysis patients from the Khorasan Razavi province, Iran. Serological tests were carried out using commercial enzyme-immunoassay kits. To confirm positive serology tests, the extracted viral DNA or RNA was examined for the presence of KSHV, HTLV-I and HCV by conventional PCR.

RESULTS

The prevalence of KSHV infection in the general population was 1.71% (21/1227); 2.60% (10/384) males and 1.30% (11/843) females. In kidney transplants, viral infections occurred in 23.3% of subjects; including EBV, HTLV-I and HBV-HCV co-infection in 8.3%, 3.3% and 1.7%, respectively. In patients on hemodialysis, viral infections were present in 29.6% including EBV, HTLV-I and HBV-HCV co-infection in 2.2%, 5.9% and 16.3%, respectively. Seroprevalence of KSHV in patients with kidney transplants was 1.7% and in patients on dialysis was 3.0%. Furthermore, KSHV and HTLV-I genome was detected in 25% and 100% of seropositive subjects, respectively.

CONCLUSIONS

In conclusion, this study demonstrated that these tumor virus infections including HTLV-I, KSHV and particularly hepatitis viruses (HBV plus HCV) are prevalent in the general population and in patients on hemodialysis, which might be an important health concern in this region due to the mobile population.