Effect of vitamin D supplementation on clinical outcomes in adult patients with COVID-19: A GRADE-assessed systematic review and meta-analysis of randomized controlled trials.

The COVID-19 pandemic has emerged as a major global health crisis. Vitamin D, a crucial fat-soluble vitamin, has been recommended for COVID-19 patients, though evidence of its effectiveness is inconsistent. This systematic literature review and meta-analysis aimed to evaluate the impact of vitamin D supplementation on COVID-19-related outcomes. A comprehensive search was conducted across PubMed, Scopus, Web of Science, Embase, and Cochrane databases. Primary outcomes included mortality and hospital length of stay, while secondary outcomes encompassed C-reactive protein (CRP), ferritin, D-dimer, hemoglobin (Hb) concentrations, and lymphocyte, neutrophil, and platelet counts. Data analysis was performed using Stata™ Version 14. A total of 16 trials were analyzed. The meta-analysis revealed that vitamin D supplementation significantly reduced hospital length of stay (mean difference = -1.16; 95% confidence interval [CI]: -2.23, -0.09; p = .033) with significant heterogeneity (I2 = 69.2%, p = .002). Subgroup analysis showed a more pronounced reduction in studies with vitamin D dosages ≤10 000 international units (IU) (mean difference = -1.27; 95% CI: -1.96, -0.57; p < .001) and in patients over 60 years old (mean difference = -1.84; 95% CI: -2.53, -1.14; p < .001). Additionally, vitamin D significantly reduced CRP concentrations in older adults (>60 years) (mean difference = -1.13; 95% CI: -2.07, -0.18; p = .019). No significant changes were found in ferritin, D-dimer, Hb concentrations, or in lymphocyte, neutrophil, and platelet counts (p > .05). In conclusion, while vitamin D supplementation did not significantly affect most COVID-19-related biomarkers, however, it reduces the length of hospital stay.

Monkeypox (Mpox) vs. Innate immune responses: Insights into evasion mechanisms and potential therapeutic strategies.

Orthopoxviruses, a group of zoonotic viral infections, have emerged as a significant health emergency and global concern, particularly exemplified by the re-emergence of monkeypox (Mpox). Effectively addressing these viral infections necessitates a comprehensive understanding of the intricate interplay between the viruses and the host's immune response. In this review, we aim to elucidate the multifaceted aspects of innate immunity in the context of orthopoxviruses, with a specific focus on monkeypox virus (MPXV). We provide an in-depth analysis of the roles of key innate immune cells, including natural killer (NK) cells, dendritic cells (DCs), and granulocytes, in the host defense against MPXV. Furthermore, we explore the interferon (IFN) response, highlighting the involvement of toll-like receptors (TLRs) and cytosolic DNA/RNA sensors in detecting and responding to the viral presence. This review also examines the complement system's contribution to the immune response and provides a detailed analysis of the immune evasion strategies employed by MPXV to evade host defenses. Additionally, we discuss current prevention and treatment strategies for Mpox, including pre-exposure (PrEP) and post-exposure (PoEP) prophylaxis, supportive treatments, antivirals, and vaccinia immune globulin (VIG).

Association Between the Level of Vitamin D and COVID-19 Infection in Children and Adolescents: A Systematic Review.

The COVID-19 pandemic has exerted a notable impact on worldwide health across diverse age groups. Although children and adolescents were initially considered less vulnerable, they have also shown susceptibility to the virus, emphasizing the importance of understanding associated risk factors. Epidemiological data reveal an increasing number of COVID-19 cases in this age group. The aim is to conduct a systematic assessment of the association between the level of vitamin D and COVID-19 infection in children and adolescents following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive literature search was performed across various databases up to October 7, 2023. Studies assessing laboratory-confirmed COVID-19 patients, the level of 25-hydroxyvitamin D in serum, and clinical outcomes were encompassed. Quality assessment was performed using the Newcastle-Ottawa Scale. Thirteen studies, conducted across six countries and involving 1,071 pediatric patients, were included. Vitamin D deficiency was prevalent among children and adolescents with COVID-19. Some studies suggested that vitamin D deficiency significantly increased the risk of COVID-19 infection and was linked to disease progression. Furthermore, deficiency in vitamin D demonstrated an association with increased levels of inflammatory markers, reduced lymphocyte counts, and heightened clinical symptoms, including fever and cough. Maintaining adequate vitamin D levels may be a crucial strategy for reducing COVID-19 severity and associated complications in children and adolescents. Nevertheless, there is a requirement for additional high-quality research to establish specific guidelines regarding vitamin D supplementation in this population amid the ongoing COVID-19 pandemic.

Assessment of Torque Teno Virus (TTV) Frequency in Healthy Blood Donors in the Central Region of Iran, Yazd.

Background: Torque teno virus (TTV) is a globally prevalent virus in humans, yet comprehensive knowledge about its prevalence, predominant transmission routes, and pathogenesis remains limited. This study aimed to assess the frequency of TTV infection among healthy blood donors in Yazd, Iran. Materials and Methods: A total of 236 healthy blood donors, devoid of HIV/HBV/HCV infection markers, participated in the study from 2015 to 2016. Nested Polymerase Chain Reaction (PCR) utilizing a set of oligo primers for the 5΄- UTR region was employed to detect TTV DNA in serum samples. Results: The TTV genome was identified in 161 out of 236 (61.2%) healthy blood donors. The mean age for men and women was 43 and 57 years, respectively. Of the participants, 156 were male, and 107 were female. Donor age exhibited a significant association with virus presence (P=0.007); however, gender did not show a statistically significant association with the frequency of TTV infection in healthy blood donors (P=0.3). Conclusion: The study revealed a notably high frequency of the Torque teno virus in Yazd province, aligning with similar findings globally. Further investigations are warranted to elucidate the clinical implications of the virus in the healthy population.

Efficacy, immunogenicity, and safety of COVID-19 vaccines in individuals with liver cirrhosis: a rapid review and meta-analysis.

The emergence of coronavirus disease 2019 (COVID-19) vaccines has been a remarkable advancement. However, the efficacy, immunogenicity, and safety of these vaccines in individuals with liver cirrhosis require careful evaluation due to their compromised immune status and potential interactions with underlying liver disease. The present study aimed to evaluate the safety and efficacy of COVID-19 vaccines in liver cirrhosis patients. In the present study, we searched international databases, including Google Scholar, PubMed, Scopus, Embase, and Web of Science. The search strategy was carried out by using keywords and MeSH (Medical Subject Headings) terms. STATA ver. 15.0 (Stata Corp., USA) was used to analyze the data statistically. The analysis was performed using the random-effects model. We also used the chi-square test and I2 index to calculate heterogeneity among studies. For evaluating publication bias, Begg's funnel plots and Egger's tests were used. A total of 4,831 liver cirrhosis patients with COVID-19 were examined from 11 studies. The rate of hospitalization in the patients with liver cirrhosis was 17.6% (95% confidence interval [CI], 9%-44%). The rate of fever in the patients with liver cirrhosis was 4.5% (95% CI, 0.9%-8.1%). The rate of positive neutralizing antibodies in the patients with liver cirrhosis was 82.5% (95% CI, 69.8%-95.1%). Also, the rates of seroconversion after the second vaccination in patients with liver cirrhosis and the control group were 96.6% (95% CI, 92.0%-99.0%), and 99.7% (95% CI, 99.0%-100.0%), respectively. COVID-19 vaccines have demonstrated promising efficacy, immunogenicity, and safety profiles in individuals with liver cirrhosis, providing crucial protection against COVID-19-related complications.

The Role of Epstein-Barr Virus (EBV) Infected Gastric Cancer in Increasing microRNA124 (miR-124) Promoter Methylation and Enhancer of Zeste Homolog 2 (EZH2) Gene Expression.

The tumor suppressor microRNAs, miR-21, miR-124, and miR-494, participate in the controlling several cellular processes. To assess target miRNAs promoter methylation levels, we investigated 304 pairs of gastric cancer (GC) tissues and non-tumor tissues. We used a commercial real-time polymerase chain reaction (RT-PCR) for Epstein-Barr virus (EBV) and Helicobacter pylori kit to detect EBV and H. pylori DNA in GC tissues. After finding hypermethylation in the promoter of the miR-124 gene, we evaluated its expression level using quantitative PCR (qPCR). Bioinformatics analysis confirmed miR-124 as a target of enhancer of Zeste homolog 2 (EZH2). Additionally, qPCR confirmed the association between EZH2 and miR-124. EBV and H. pylori DNA were detected in 9.5% and 15.1% of GC patients, respectively. Our findings also revealed significant differences in the miR-124 methylation levels among EBV-infected GC patients, H. pylori infected GC patients, GC patients without EBV and H. pylori infection, and non-tumor tissue. Bioinformatics and qPCR assays suggested an inverse relationship between the expression levels of EZH2 and miR-124 in EBV-infected GC patients. Our data revealed hypermethylation of the miR-124 promoter and significant reduction in its expression in EBV-infected GC tissues. It is possible that miR-124 may target EZH2 by binding to the 3'-UTR of the EZH2 gene, thus potentially contributing to the development of EBV-infected GC.

Evaluation of hematological parameters alterations in different waves of COVID-19 pandemic: A cross-sectional study.

BACKGROUND: The occurrence of variations in routine hematological parameters is closely associated with disease progression, the development of severe illness, and the mortality rate among COVID-19 patients. This study aimed to investigate hematological parameters in COVID-19 hospitalized patients from the 1st to the 5th waves of the current pandemic. METHODS: This cross-sectional study included a total of 1501 hospitalized patients with laboratory-confirmed COVID-19 based on WHO criteria, who were admitted to Shahid Sadoughi Hospital (SSH) in Yazd, Iran, from February 2020 to September 2021. Throughout, we encountered five COVID-19 surge waves. In each wave, we randomly selected approximately 300 patients and categorized them based on infection severity during their hospitalization, including partial recovery, full recovery, and death. Finally, hematological parameters were compared based on age, gender, pandemic waves, and outcomes using the Mann-Whitney U and Kruskal-Wallis tests. RESULTS: The mean age of patients (n = 1501) was 61.1±21.88, with 816 (54.3%) of them being men. The highest mortality in this study was related to the third wave of COVID-19 with 21.3%. There was a significant difference in all of the hematological parameters, except PDW, PLT, and RDW-CV, among pandemic waves of COVID-19 in our population. The highest rise in the levels of MCV and RDW-CV occurred in the 1st wave, in the 2nd wave for lymphocyte count, MCHC, PLT count, and RDW-SD, in the 3rd wave for WBC, RBC, neutrophil count, MCH, and PDW, and in the 4th wave for Hb, Hct, and ESR (p < 0.01). The median level of Hct, Hb, RBC, and ESR parameters were significantly higher, while the mean level of lymphocyte and were lower in men than in women (p < 0.001). Also, the mean neutrophil in deceased patients significantly was higher than in those with full recovered or partial recovery (p < 0.001). CONCLUSION: The findings of our study unveiled notable variations in hematological parameters across different pandemic waves, gender, and clinical outcomes. These findings indicate that the behavior of different strains of the COVID-19 may differ across various stages of the pandemic.

Higher Risk of Chronic Hepatitis E Virus Infection in Patients with Human Immunodeficiency Virus-1: An Iranian Cross-sectional Study.

Background & Objective: Occurrence of Hepatitis E Virus (HEV) infection may be common in Human Immunodeficiency Virus (HIV-1) patients and may lead to chronic infection as well as cirrhosis. We intended to determine the incidence of HEV infection among HIV-1 patients compared to individuals without HIV-1 infection. Methods: In our cross-sectional study, 87 HIV-1-positive patients were compared to 93 healthy individuals in Kerman, Iran. Plasma and peripheral blood mononuclear cells (PBMCs) were obtained from all the participants. Plasma samples were evaluated for HEV IgM and IgG using the ELISA kit. Then, reverse transcriptase-nested polymerase chain reaction (RT-nested PCR) was used in RNA extractions from PBMCs to check for the presence of HEV RNA. Results: Among the subjects examined in our study, 61 (70.1%) and 71 (77.4%) out of patients with HIV-1 infection and healthy individuals were male, respectively. The average ages of patients with HIV-1 and the control group were 40.2 years and 39.9 years, respectively. No discernible differences were found between the two groups based on IgM and IgG seropositivity against the HEV. However, HEV-RNA was found in 8% of patients with HIV-1 and 1.1% of HIV-1-negative individuals (P=0.03). There was also an association between the HEV genome and anti-HEV and anti-HCV antibodies in HIV-1-positive patients (P=0.02 and P=0.014, respectively). Conclusion: HEV infection may be more common in HIV-1 patients and may develop a chronic infection in immunocompromised individuals. Molecular-based HEV diagnostic tests, including RT-PCR assays, should be performed in HIV-1 patients with unknown impaired liver function tests.

Beyond skin deep: shedding light on the neuropsychiatric consequences of Monkeypox (Mpox).

This review is attempted in view of World Health Organization (WHO) warning on Monkeypox virus (Mpox) to summarize the available data regarding the potential effect on central nervous system (CNS), its complications, and diagnostic methods. We combed various international databases (including Scopus, PubMed, Web of Science, and Google Scholar) for articles mentioning Mpox infection, orthopox infection, and the central nervous system that were published between the years 2000 and 2022. Further evidence was evaluated from relevant studies published in the literature. There is emerging evidence of central nervous system neurological involvement. In addition to encephalopathy, which is one of the most serious neurological complications of Mpox, the most common complications of Mpox infection are headache, weakness, myalgia, anorexia, and altered consciousness. Anxiety and depression have also been identified as the most common psychiatric symptoms in these patients.

A comprehensive review of highly pathogenic avian influenza (HPAI) H5N1: An imminent threat at doorstep.

Avian influenza viruses (AIVs) are globally challenging due to widespread circulation and high mortality rates. Highly pathogenic avian influenza (HPAI) strains like H5N1 have caused significant outbreaks in birds. Since 2003 to 14 July 2023, the World Health Organization (WHO) has documented 878 cases of HPAI H5N1 infection in humans and 458 (52.16%) fatalities in 23 countries. Recent outbreaks in wild birds, domestic birds, sea lions, minks, and etc., and the occurrence of genetic variations among HPAI H5N1 strains raise concerns about potential transmission and public health risks. This paper aims to provide a comprehensive overview of the current understanding and new insights into HPAI H5N1. It begins with an introduction to the significance of studying this virus and highlighting the need for updated knowledge. The origin and evaluation of HPAI H5N1 are examined, shedding light on its emergence, and spread across different geographic regions. The genome organization and structural biology of the H5N1 virus are explored, providing insights into its molecular composition and key structural features. This manuscript also delves into the phylogeny, evolution, mutational trends, reservoirs, and transmission routes of HPAI H5N1. The immune response against HPAI H5N1 and its implications for vaccine development are analyzed, along with an exploration of the pathogenesis and clinical manifestations of HPAI H5N1 in human cases. Furthermore, diagnostic tools and preventive and therapeutic strategies are discussed, highlighting the current approaches and potential future directions for better management of the potential pandemic.

Monkeypox virus diagnosis and laboratory testing.

The multi-country outbreak of monkeypox virus (MPXV) infection, while the coronavirus disease 2019 pandemic is still an ongoing issue, has caused a new challenge. The re-emergence of MPXV and the rising incidence in non-endemic countries is turning into an upcoming threat to global health. Hence, rapid identification of the virus with appropriate methodology with the lowest false results plays a critical role in estimating the global extent of the crisis and providing preventive measures. This review summarised the main applicable strategies for primary detection and confirmation of MPXV and highlighted available data in biosafety, requirements, standard operating procedures, specimen collection, transportation and storage of clinical samples, and waste disposal of the viral agent. Also, various assays including molecular techniques, immunoassays, histopathological methods, electron microscopy, genomic sequencing, and cell culture have been illustrated. Moreover, we reflected on current knowledge of the advantages and disadvantages of each approach.

Detection of High-Risk Human Papillomavirus DNA in Invasive Ductal Carcinoma Specimens.

BACKGROUND: According to several studies, there is an association between human papillomavirus (HPV) and breast cancer. Therefore, detection and genotyping of HPV seem important. The present study aimed to investigate the presence of HPV DNA in breast tissues  by analyzing the L1 gene. MATERIALS AND METHODS: This case-control study was conducted on 63 formalin-fixed paraffin-embedded (FFPE) tissues of invasive ductal carcinoma (IDC) as the case group and 32 FFPE tissues of fibroadenoma as the control group. HPV DNA was detected using the polymerase chain reaction assay. Positive samples were then subjected to genotyping. All statistical analyses were performed in SPSS version 22.0. RESULTS: The patients' age ranged from 15 to 92 years, with a mean age of 43.54±16.36 years. HPV DNA was detected in 17/95 (17.89%) samples, including 9/32 (28.12%) fibroadenoma samples and 8/63 (12.69%) IDC samples. No significant difference was observed regarding the presence of HPV DNA between the IDC and fibroadenoma tissues (P=0.08). However, a significant difference was found in the detection of high-risk HPV (HR-HPV) between the case and control groups (P=0.03). In the case group, 87.5% of the detected viruses (7/8 samples) were HR-HPV, while in the control group, 22.22% of positive samples (2/9 samples) were HR-HPV (P=0.03). Based on the results, HR-HPV and low-risk HPV genotypes were detected in 53% (9/17) and 47% (8/17) of positive samples, respectively. CONCLUSION: In this study, 12.69% of IDC samples were positive for HPV genomes, and HR-HPV was detected in 87.5% of these samples. The present results suggest the important role of HR-HPV in the development of breast cancer.

Upregulation of Interleukin-6 in HPV-Positive Breast Cancer Patients.

BACKGROUND: Interleukin-6 (IL-6) is a well-known proinflammatory cytokine with tumor promoting capacity in various forms of malignancies including breast cancer (BC). Data highlighted the substantial role of HPV in the pathogenesis of BC. Compelling evidence suggests the contribution of HPV in carcinogenesis through triggering inflammatory cytokines such as IL-6. OBJECTIVE: Here, we assessed the correlation between the presence of HPV infection and the status of IL-6 expression and serum level in BC. METHODS: 72 tissue specimens including tumoral (Case; n=36) and their adjacent normal tissues (Control; n=36) were used. Nested-PCR and Real-Time PCR were employed to identify HPV DNA and assess the expression of IL-6, respectively. In addition, 72 sera samples from BC patients (n=36) and an age-matched healthy control group (n=36) were taken to measure the IL-6 serum level by ELISA. RESULTS: Overall, the HPV DNA was detected in 19.4% (14/72) of samples. 33.33% (12/36) of cases and 5.5% (2/36) of the controls were found to be positive for HPV (P=0.003). The overexpression of IL-6 was observed in HPV+ samples compared to HPV- samples (P=0.05). However, the concentration of IL-6 serum level was remarkably different between patients and normal controls (P=0.0001. Intriguingly, IL-6 serum level was connected to the advanced clinical stage (III/IV), high grade (II/III), metastasis and, ER+ status of patients. CONCLUSIONS: Our finding indicated that the overexpression of the IL-6 may be connected to HPV infection in BC. Furthermore, the results reinforced the clinical significance and prognostic value of the serum IL-6 in BC patients.

MiRNA-218 Is Frequently Downregulated in Malignant Breast Tumors: A Footprint of Epstein-Barr Virus Infection.

BACKGROUND & OBJECTIVE: The role of Epstein-Barr Virus in development of breast cancer is frequently studied. In this regard, miRNAs are among the contributing elements in the molecular pathophysiology of EBV-related diseases. In addition, a growing number of host miRNAs are believed to be implicated in pathogenesis of breast cancer. MiR-218 is a tumor suppressive miRNA that is subjected to dysregulation in various EBV-associated cancers. We aimed to investigate the frequency of EBV and its relationship with expression status of tumor suppressive miR-218 in breast cancer and adjacent normal tissue. METHODS: A total number of 51 fresh malignant breast cancer tissues (cases) and their adjacent normal tissues (controls) were collected. Nested-PCR and RT-qPCR were set to identify EBV frequency and miR-218 expression in cases and controls, respectively. RESULTS: Out of all samples, 6.8% (7/102) comprising 11.6% (6/51) in malignant tissues and 1.9% (1/51) in normal control tissues were positive for EBV (P<0.05). Quantitative data showed that miR-218 was significantly downregulated in malignant tissues compared to control tissues (P<0.0001). In addition, reduced expression of miR-218 was associated with adverse clinical outcomes, metastasis, and higher grades of malignancy. Given the presence of EBV, lower expression of miR-218 was observed in breast cancer group in comparison with normal group (P<0.05). CONCLUSION: Our results raise the possibility of the relation between EBV infection and miR-218 downregulation in breast cancer and propose further investigations in this regard.

Molecular and Serological Prevalence of HCMV in Iranian Patients with Breast Cancer.

BACKGROUND: Human cytomegalovirus (HCMV) is prevalent viral infection involved in several human cancers including breast cancer. The presence of HCMV genome in breast cancer tissue and footprint of viral last exposure patient's serum are considered as important factor in the process of breast cancer development. OBJECTIVES: This study aimed to investigate molecular and serological epidemiology of HCMV in patients with breast cancer in Iran for first time. METHODS: In our case-control study, 98 samples of breast tissue, including 49 cancerous (case) and 49 adjacent non-cancerous tissue were collected (control). In addition, we collected sera samples from all patients (n=49) and healthy individual (n=49). Seroprevalence of HCMV was assessed by Enzyme-linked immunosorbent assay (ELISA) and detection of HCMV genome was performed using Nested-PCR method. RESULTS: HCMV genome found in 16.3% (8/49) of cases tissue and 2% (1/49) of controls tissue. In patients group, the levels of anti-CMV IgG and IgM were 93.9% and 2% compared to 69.4% and 4.1% in healthy individuals, respectively. There was a statistically difference between the anti-CMV IgG in patients and healthy control (p= 0.002). We found 75% of (6/8) HCMV genome positive PCR samples were also positive for their anti-CMV IgG in cases which was statistically significant (p= 0.01).  Conclusions: Our result showed significant presence of HCMV genome and anti-CMV IgG in patients, supporting the role of HCMV in breast cancer.
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The role of viruses in adenocarcinoma development.

Cancer is a leading public health issue that accounts for million deaths around the world every year. Human cancers contain over 100 types, which are categorized into different groups. Adenocarcinoma is one of those categories of cancer that begins from the glans and involves various tissues such as lung, esophagus, pancreas, prostate and colorectal. A range of risk factors has been identified for the development and progression of adenocarcinomas. One of these risk factors are viruses that serves special mechanisms to affect important host cell factors and tumorigenic pathways, contributing in development and promotion of adenocarcinomas. Here, we summarized the main viruses and their mechanisms implicated in the course of various adenocarcinomas development.

Detection of human herpes viruses 1-5 in miscarriage: A case-control study.

BACKGROUND: Miscarriage is the spontaneous pregnancy loss before 24 wk of gestation. The incidence rate of miscarriage over the past few decades has shown steady or even growing trends. Viral intrauterine infections are one of the probable etiological causes of miscarriage. Previous evidence have shown that human herpes viruses (HHVs) could be considered as the potential reasons for intrauterine infections and adverse pregnancy outcomes. OBJECTIVE: This case-control study aimed to detect HHV1-5 DNAs in placental tissues and assess their association with miscarriage during the first 24 wk of pregnancy in spontaneous and therapeutic abortions. MATERIALS AND METHODS: Placental tissues from 83 women with spontaneous abortions during the first and the second trimesters of pregnancy and 81 women with therapeutic abortion during the same gestational age were collected. The DNA extraction was performed by the phenol/chloroform method. A part of the DNA polymerase gene of HHVs was amplified with multiplex nested-polymerase chain reaction. The polymerase chain reaction products were subjected to sequencing. RESULTS: The results showed the presence of human cytomegalovirus genome in the placenta of both spontaneous (8.4%) and therapeutic (4.9%) abortions. No statistically significant differences were found between these two groups. The other investigated viruses were not detected here. CONCLUSION: In conclusion, like some other studies, no correlation was detected between the HHVs placental infections and the increased risk of spontaneous abortions. In order to find the actual role of HHVs infections in miscarriage, further investigations should be performed on a larger sample size in different areas.

Molecular detection of HHV1-5, AAV and HPV in semen specimens and their impact on male fertility.

Viral infections have been considered as possible destructive factors that influence male fertility. The aim of this study was to determine the prevalence of human herpes viruses 1-5 (HHV1-5), adeno associated virus (AAV) and human papilloma virus (HPV) in semen and whether these influence semen quality. DNA extraction was performed using phenol-chloroform protocol, then three different nested-PCRs were done to detect HHV1-5, AAV and HPV DNAs in the semen samples. Of 145 samples, 66 (45.5%) were positive at least for one of the viruses. The genome detection rate of HSV1/2, VZV, EBV, HCMV, AAV and HPV were zero, 2.8%, zero, 1.4%, 27.6% and 19.3%, respectively. Of 66 positive samples for these viruses, 6 (4.1% of all samples) were positive for two viruses simultaneously. Here no association was found between variations in semen parameters related to fertility and detection of VZV, HCMV, AAV and HPV DNA in semen samples. It should be noted that the prevalence of different viruses in semen, and their relevance to male infertility, differs significantly due to the genome extraction and amplification methods or due to a real variation between study populations and geographical regions.

DNA methyltransferases in virus-associated cancers.

Human tumor viruses are either casually linked or contribute in the development of human cancers. Viruses can stimulate oncogenesis through affecting diverse biological pathways in human cells. Growing data have demonstrated frequent involvement of one of the most characteristic parts of cellular epigenetic machinery, DNA methylation, in the oncogenesis. DNA methylation of cellular genes is catalyzed by DNA methyltransferases (DNMTs) as a key effector enzyme in this process. Dysregulation of DNMTs can cause aberrant gene methylation in promoter of cancer-related genes including tumor suppressor genes, resulting in gene silencing. In this regard, the role of tumor viruses is remarkable. Here, in this review, we used published information to elucidate whether tumor viruses are able to manipulate DNMT regulation, and if so, what are its consequences in the process of oncogenesis. This essay also aims to shed light on which cellular pathways have been engaged by viruses to induce DNMTs.