BK virus and human cancer: innocent until proven guilty. Semin Cancer Biol. 2009;19:252-260. [PMID: 19505653 DOI: 10.1016/j.semcancer.2009.02.004]

Frequency of BK virus genotypes in patients with colorectal cancer

Background and Objectives

BK polyomavirus infection is prevalent and primarily asymptomatic, except for complications in kidney transplant recipients. Furthermore, its involvement in a tumorigenic family necessitates consideration in various malignancies such as urogenital tumors, prostate cancer, colorectal cancer (CRC), and brain cancer.

Materials and Methods

This investigation encompassed 50 specimens of colorectal adenocarcinoma tumors, 50 adjacent tissues, and 40 urine samples, with patients having a mean age of 61 years ± 12.4 years. The detection of BK virus DNA VP1 gene and genotyping were carried out through nested-PCR and sequencing techniques.

Results

Through the utilization of nested-PCR, BK virus DNA was identified in 15/50 (30%) colorectal tumor samples and 3/50 (6%) adjacent tissues (p-value = 0.008). Additionally, 6/40 (15%) urine samples exhibited positive results for BK virus DNA. Notably, among these findings, 9/15 BK virus positive tumor tissues (60%) and 3/6 BK virus positive urine samples (50%) were confirmed to be positive for BK virus subtype 4 (p-value < 0.001), whereas 2 tumor samples and 3 urine samples were attributed to BK virus type 1b2.

Conclusion

It is imperative to enhance one's understanding of the etiological and risk factors pertaining to cancers. The present findings offer substantiation of a potential correlation between BK virus infection and colorectal cancer. BK virus genotype 4 was found to be dominant among the CRC patients in this study.

Virus Protein-Specific Immune Responses in Selective Depletion of Lymphocyte Populations Using Monoclonal Antibodies in Bolivian Squirrel Monkeys (Saimiri boliviensis boliviensisv)

The increasing use of immune suppressive monoclonal antibodies in the treatment of organ transplant recipients and patients with oncologic, neurological, and autoimmune diseases can lead to serious morbidity and mortality from the reactivation of viral agents that persist in humans. The squirrel monkey polyomaviruses are naturally found in Bolivian squirrel monkeys (SQM) and may be a useful model for the study of polyomavirus-associated pathogenesis and experimental treatment and prevention strategies. Two diverse groups of squirrel monkeys were given, a single dose of an anti-B cell antibody (rituximab) resulting in complete depletion of B cells (CD20+), while an anti-CD8 monoclonal antibody (7 pt-3F9) resulted in a transient depletion of CD8+ lymphocytes compared with control animals (group with no infusion with either of the monoclonal antibodies). The animals remained clinically healthy, with no pathological symptoms suggesting that the intensity and/or duration of immune suppression were inadequate to trigger pathogenic reactivation of the latent polyoma and herpes viruses. We observed a transient reduction in circulating plasma cytokines, IL-2, IFN-γ, and IL-12 reduced JC and BK viral protein-specific proliferative responses in both the CD8 and CD20 depletion groups. This study clearly elucidates the consequences of the use of depletion monoclonal antibodies in immune suppression modalities in the treatment of human malignancies and during transplantation, and SQM acts as a good model in the selection of dosage at which activation of latent viruses is at a minimum, with no pathological consequences.

Are There More Human Cancer Viruses Left to Be Found?

Of the thousands of viruses infecting humans, only seven cause cancer in the general population. Tumor sequencing is now a common cancer medicine procedure, and so it seems likely that more human cancer viruses already would have been found if they exist. Here, we review cancer characteristics that can inform a dedicated search for new cancer viruses, focusing on Kaposi sarcoma herpesvirus and Merkel cell polyomavirus as the most recent examples of successful genomic and transcriptomic searches. We emphasize the importance of epidemiology in determining which cancers to examine and describe approaches to virus discovery. Barriers to virus discovery, such as novel genomes and viral suppression of messenger RNA expression, may exist that prevent virus discovery using existing approaches. Optimally virus hunting should be performed in such a way that if no virus is found, the tumor can be reasonably excluded from having an infectious etiology and new information about the biology of the tumor can be found.

Viruses in glioblastoma: an update on evidence and clinical trials

BACKGROUND

Glioblastoma (GB) is a lethal and aggressive brain tumour. While molecular characteristics of GB is studied extensively, the aetiology of GB remains uncertain. The interest in exploring viruses as a potential contributor to the development of GB stems from the notion that viruses are known to play a key role in pathogenesis of other human cancers such as cervical cancer. Nevertheless, the role of viruses in GB remains controversial.

METHODS

This review delves into the current body of knowledge surrounding the presence of viruses in GB as well as provide updates on clinical trials examining the potential inclusion of antiviral therapies as part of the standard of care protocol.

CONCLUSIONS

The review summarises current evidences and important gaps in our knowledge related to the presence of viruses in GB.

BK polyomavirus infection: more than 50 years and still a threat to kidney transplant recipients

BK polyomavirus (BKPyV) is a ubiquitous human polyomavirus and a major infection after kidney transplantation, primarily due to immunosuppression. BKPyV reactivation can manifest as viruria in 30%-40%, viremia in 10%-20%, and BK polyomavirus-associated nephropathy (BKPyVAN) in 1%-10% of recipients. BKPyVAN is an important cause of kidney graft failure. Although the first case of BKPyV was identified in 1971, progress in its management has been limited. Specifically, there is no safe and effective antiviral agent or vaccine to treat or prevent the infection. Even in the current era, the mainstay approach to BKPyV is a reduction in immunosuppression, which is also limited by safety (risk of de novo donor specific antibody and rejection) and efficacy (graft failure). However, recently BKPyV has been getting more attention in the field, and some new treatment strategies including the utilization of viral-specific T-cell therapy are emerging. Given all these challenges, the primary focus of this article is complications associated with BKPyV, as well as strategies to mitigate negative outcomes.

Possible association between polyomaviruses and gastrointestinal complications: a narrative review

Polyomaviruses are a group of small, double-stranded DNA viruses that are known to be associated with the development of certain human diseases, but there is evidence that these viruses might be associated with gastrointestinal (GI) cancers. Several polyomaviruses have been identified, such as JC polyomavirus (JCPyV), BK polyomavirus (BKPyV) and recently Merkel cell polyomavirus (MCPyV). Although the direct effects of polyomaviruses on transformation of human cells and cancer development are not clearly recognized, their association with certain human diseases including GI cancers has been proposed through several molecular and epidemiological studies. For example, JCPyV and BKPyV have been linked to colorectal cancer, as there is growing evidence of finding viral genomes in cancerous tissues. Nevertheless, the major role of JCPyV, BKPyV and MCPyV in colorectal cancer progression is still under extensive investigation, and further surveys is required to establish a conclusive cause-and-effect relationship. Understanding the role of these viruses in cancer development has significant implications for diagnosis, treatment, and prevention strategies. It seems that proving a causal link between polyomaviruses and GI cancers might provide a novel path for targeted therapies or design and development of specific therapeutic vaccines. In addition, performing research on the possible link can provide insights into the underlying molecular mechanisms of carcinogenesis, potentially leading to the identification of novel biomarkers. This review focuses on polyomaviruses, in particular a recently discovered polyomavirus, MCPyV, and their possible link with human gastrointestinal disorders.

High grade urothelial carcinoma in kidney transplant patients with a history of BK viremia - Just a coincidence?

INTRODUCTION

Kidney transplant recipients (KTR) have a three-to-four-fold increased risk of developing urothelial carcinoma (UC) compared to the general population. BK polyoma virus (BKV) infection is known to affect approximately 15% of KTR. In vitro models support a potential pathogenic role for BKV in the development of UC. We describe a series of UC in kidney transplant recipients.

METHODS

Electronic patient records were searched to identify KTR with UC who had undergone kidney only or simultaneous kidney and pancreas transplantation in a single UK center between 2009 and 2015. Where available, stored pathological samples were retrieved, re-examined and stained for SV40 as a marker of BKV using standard staining protocols for kidney biopsy samples.

RESULTS

Fourteen KTR had developed UC post-transplant. Of these, 10 KTR had a history of BKV infection post-transplant. Six of these 10 KTR developed a rare micropapillary tumor subtype of UC which is typically only found in <1% of UC cases. All six micropapillary tumor samples stained positive for SV40, including samples from metastases. Three tumor samples were available from the four KTR with no history of BKV infection and were not micropapillary subtype and were negative for SV40. Three micropapillary tumors from immunocompetent patients were examined as controls and were negative for SV40.

CONCLUSIONS

These findings would support a pathogenic role for BK virus in the development of rare micropapillary subtype urothelial tumors in the kidney transplant population.

BK Virus Nephropathy in Kidney Transplantation: A State-of-the-Art Review

BK virus maintains a latent infection that is ubiquitous in humans. It has a propensity for reactivation in the setting of a dysfunctional cellular immune response and is frequently encountered in kidney transplant recipients. Screening for the virus has been effective in preventing progression to nephropathy and graft loss. However, it can be a diagnostic and therapeutic challenge. In this in-depth state-of-the-art review, we will discuss the history of the virus, virology, epidemiology, cellular response, pathogenesis, methods of screening and diagnosis, evidence-based treatment strategies, and upcoming therapeutics, along with the issue of re-transplantation in patients.

The Roles of the Virome in Cancer

Viral infections as well as changes in the composition of the intestinal microbiota and virome have been linked to cancer. Moreover, the success of cancer immunotherapy with checkpoint inhibitors has been correlated with the intestinal microbial composition of patients. The transfer of feces-which contain mainly bacteria and their viruses (phages)-from immunotherapy responders to non-responders, known as fecal microbiota transplantation (FMT), has been shown to be able to convert some non-responders to responders. Since phages may also increase the response to immunotherapy, for example by inducing T cells cross-reacting with cancer antigens, modulating phage populations may provide a new avenue to improve immunotherapy responsiveness. In this review, we summarize the current knowledge on the human virome and its links to cancer, and discuss the potential utility of bacteriophages in increasing the responder rate for cancer immunotherapy.

BK Polyomavirus Activates HSF1 Stimulating Human Kidney Hek293 Cell Proliferation

OBJECTIVES

Some DNA viruses, such as BKPyV, are capable of inducing neoplastic transformation in human tissues through still unclear mechanisms. The goal of this study is to investigate the carcinogenic potential of BK polyomavirus (BKPyV) in human embryonic kidney 293 (Hek293) cells, dissecting the molecular mechanism that determines the neoplastic transformation.

MATERIALS AND METHODS

BKPyV, isolated from urine samples of infected patients, was used to infect monolayers of Hek293 cells. Subsequently, intracellular redox changes, GSH/GSSH concentration by HPLC, and reactive oxygen/nitrogen species (ROS/RNS) production were monitored. Moreover, to understand the signaling pathway underlying the neoplastic transformation, the redox-sensitive HFS1-Hsp27 molecular axis was examined using the flavonoid quercetin and polishort hairpin RNA technologies.

RESULTS

The data obtained show that while BKPyV replication is closely linked to the transcription factor p53, the increase in Hek293 cell proliferation is due to the activation of the signaling pathway mediated by HSF1-Hsp27. In fact, its inhibition blocks viral replication and cell growth, respectively.

CONCLUSIONS

The HSF1-Hsp27 signaling pathway is involved in BKPyV infection and cellular replication and its activation, which could be involved in cell transformation.

A "hit-and-run" affair - A possible link for cancer progression in virally driven cancers

BACKGROUND

It is well-known that certain cancers are caused by viruses. However, viral oncogenesis is complex and only a small fraction of the infected people develop cancer. Indeed, a number of environmental factors can contribute to virally infected cells developing cancer hallmarks, promoting tumorigenesis.

SCOPE OF REVIEW

The hit-and-run theory proposes that viruses facilitate the accumulation of mutations and promote genomic instability until the virus becomes dispensable for tumour maintenance. Indeed, several studies have reported viral genome, episome and/or oncogene loss in tumour cells without losing malignant phenotype.

MAJOR CONCLUSIONS

The current evidence supports the clear contribution of certain viruses to develop cancers. Importantly, the evidence supporting the sustained maintenance of malignancy after the loss of viral "presence" is sufficient to support the hit-and-run hypothesis of viral cancer development. Long-term tracking of vaccination outcome over the decades will test this theory.

GENERAL SIGNIFICANCE

If the hit-and-run theory is true, viruses might cause more cancers than previously thought and will have implications in the prevention of many cancers through implementing vaccination programs.

Advances in BK Virus Complications in Organ Transplantation and Beyond

Reactivation of BK virus (BKV) remains a dreaded complication in immunosuppressed states. Conventionally, BKV is known as a cause for BKV-associated nephropathy and allograft dysfunction in kidney transplant recipients. However, emerging studies have shown its negative impact on native kidney function and patient survival in other transplants and its potential role in diseases such as cancer. Because BKV-associated nephropathy is driven by immunosuppression, reduction in the latter is a convenient standard of care. However, this strategy is risk prone due to the development of donor-specific antibodies affecting long-term allograft survival. Despite its pathogenic role, there is a distinct lack of effective anti-BKV therapeutics. This limitation combined with increased morbidity and health care cost of BKV-associated diseases add to the complexity of BKV management. While summarizing recent advances in the pathogenesis of BKV-associated nephropathy and its reactivation in other organ transplants, this review illustrates the limitations of current and emerging therapeutic options and provides a compelling argument for an effective targeted anti-BKV drug.

Fecal, oral, blood and skin virome of laboratory rabbits

Here, we investigated the fecal, oral, blood, and skin virome of 10 laboratory rabbits using a viral metagenomic method. In the oral samples, we detected a novel polyomavirus (RabPyV), and phylogenetic analysis based on the large T antigen, VP1 and VP2 regions indicated that the novel strain might have undergone a recombination event. Recombination analysis based on related genomes confirmed that RabPyV is a multiple recombinant between rodent-like and avian-like polyomaviruses. In fecal samples, three partial or complete genome sequences of viruses belonging to the families Picobirnaviridae, Parvoviridae, Microviridae and Coronaviridae were characterized, and phylogenetic trees were constructed based on the predicted amino acid sequences of viral proteins. This study increases the amount of genetic information on viruses present in laboratory rabbits.

Molecular Mechanisms of Merkel Cell Polyomavirus Transformation and Replication

Viral infection underlies a significant share of the global cancer burden. Merkel cell polyomavirus (MCPyV) is the newest member of the human oncogenic virus family. Its discovery over a decade ago marked the beginning of an exciting era in human tumor virology. Since then, significant evidence has emerged to support the etiologic role of MCPyV in Merkel cell carcinoma (MCC), an extremely lethal form of skin cancer. MCPyV infection is widespread in the general population. MCC diagnoses have tripled over the past 20 years, but effective treatments are currently lacking. In this review, we highlight recent discoveries that have shaped our understanding of MCPyV oncogenic mechanism and host cellular tropism, as well as the molecular events occurring in the viral infectious life cycle. These insights will guide future efforts in developing novel virus-targeted therapeutic strategies for treating the devastating human cancers associated with this new tumorigenic virus.

Prevalence of JC and BK viruses in Patients with Colorectal Cancer: A Systematic Review and Meta- Analysis

INTRODUCTION

Polyomaviruses including BK virus (BKV) and JC virus (JCV) are widespread in human and have been associated with colorectal cancer (CRC) in some studies. The aim of present systematic review and meta-analysis article is to calculate the pooled prevalence of BKV and JCV in patients with CRC and assessing their association with this malignancy.

MATERIALS AND METHODS

Domestic databases and Sciences Direct, PubMed, ProQuest, Web of Sciences and Scopus were searched for relevant articles up to 2nd  June 2019Two independent reviewers extracted the related data from eligible articles. The pooled prevalence and pooled odds ratio (POR) and their 95% confidence interval (95% CI) were calculated using "metaprop" and "metan" commands in Stata 14. Where I2 statistics were >50%, the random effect model was used.

RESULTS

From 1461 relevant studies, 24 articles were eligible and included in the qualitative while 19 articles included in quantitative analysis. The pooled prevalence based on diagnostic methods varies from 29% using immunohistochemistry to 52% using nested-PCR method. The likelihood of being infected with JCV  was significantly higher in CRC patients compared to healthy (POR: 4.41, 95% CI: 2.13 - 9.13) controls, normal adjacent mucosa (POR: 2.79, 95% CI: 1.3-5.9) and colorectal adenoma (POR: 3.1, 95% CI: 1.5-6.5) but was not significant when non-CRC patients used as control group.

CONCLUSION

The prevalence of JCV in colorectal patients was substantially variable by different methods and targets. The significant association between JCV and CRC that was observed in the present study is not indicative of causation and should be studied more in large-scale prospective designs.

The case for BK polyomavirus as a cause of bladder cancer

In 2014, the International Agency for Research on Cancer judged Merkel cell polyomavirus (MCPyV) to be a probable human carcinogen. BK polyomavirus (BKPyV, a distant cousin of MCPyV) was ruled a possible carcinogen. In this review, we argue that it has recently become reasonable to view both of these viruses as known human carcinogens. In particular, several complementary lines of evidence support a causal role for BKPyV in the development of bladder carcinomas affecting organ transplant patients. The expansion of inexpensive deep sequencing has opened new approaches to investigating the important question of whether BKPyV causes urinary tract cancers in the general population.

The Very Low Frequency of Epstein-Barr JC and BK Viruses DNA in Colorectal Cancer Tissues in Shiraz, Southwest Iran

Viruses including Epstein-Barr virus (EBV), JCV and BKV have been reported to be associated with some cancers. The association of these viruses with colorectal cancers remains controversial. Our objective was to investigate their infections association with adenocarcinoma and adenomatous polyps of the colon. Totally, 210 paraffin-embedded tissue specimens encompassing 70 colorectal adenocarcinoma, 70 colorectal adenomatous and 70 colorectal normal tissues were included. The total DNA was extracted, then qualified samples introduced to polymerase chain reaction (PCR). The EBV, JCV and BKV genome sequences were detected using specific primers by 3 different in-house PCR assays. Out of 210 subjects, 98 cases were female and the rest were male. The mean age of the participants was 52 ± 1.64 years. EBV and JCV DNA was detected just in one (1.42%) out of seventy adenocarcinoma colorectal tissues. All adenomatous polyp and normal colorectal tissues were negative for EBV and JCV DNA sequences. Moreover, all the patients and healthy subjects were negative for BKV DNA sequences. The results suggested that EBV and JCV genomes were not detectable in the colorectal tissue of patients with colorectal cancer in our population. Hence, BKV might not be necessitated for the development of colorectal cancer. The findings merit more investigations.

A virome-wide clonal integration analysis platform for discovering cancer viral etiology

Oncoviral infection is responsible for 12%–15% of cancer in humans. Convergent evidence from epidemiology, pathology, and oncology suggests that new viral etiologies for cancers remain to be discovered. Oncoviral profiles can be obtained from cancer genome sequencing data; however, widespread viral sequence contamination and noncausal viruses complicate the process of identifying genuine oncoviruses. Here, we propose a novel strategy to address these challenges by performing virome-wide screening of early-stage clonal viral integrations. To implement this strategy, we developed VIcaller, a novel platform for identifying viral integrations that are derived from any characterized viruses and shared by a large proportion of tumor cells using whole-genome sequencing (WGS) data. The sensitivity and precision were confirmed with simulated and benchmark cancer data sets. By applying this platform to cancer WGS data sets with proven or speculated viral etiology, we newly identified or confirmed clonal integrations of hepatitis B virus (HBV), human papillomavirus (HPV), Epstein-Barr virus (EBV), and BK Virus (BKV), suggesting the involvement of these viruses in early stages of tumorigenesis in affected tumors, such as HBV in TERT and KMT2B (also known as MLL4) gene loci in liver cancer, HPV and BKV in bladder cancer, and EBV in non-Hodgkin's lymphoma. We also showed the capacity of VIcaller to identify integrations from some uncharacterized viruses. This is the first study to systematically investigate the strategy and method of virome-wide screening of clonal integrations to identify oncoviruses. Searching clonal viral integrations with our platform has the capacity to identify virus-caused cancers and discover cancer viral etiologies.

Viral metagenomics reveals significant viruses in the genital tract of apparently healthy dairy cows

The virome in genital tract secretion samples collected from 80 dairy cattle in Shanghai, China, was characterized. Viruses detected included members of the families Papillomaviridae, Polyomaviridae, Hepeviridae, Parvoviridae, Astroviridae, Picornaviridae, and Picobirnaviridae. A member of a new species within the genus Dyoxipapillomavirus and six circular Rep-encoding single-stranded DNA (ssDNA) (CRESS-DNA) viral genomes were fully sequenced and phylogenetically analyzed. The prevalence of bovine polyomaviruses 1 and 2 was measured by PCR to be 10% (8/80) and 6.25% (5/80), respectively. PCR screening also indicated that the novel papillomavirus ujs-21015 and bovine herpesvirus 6 were present in three and two out of the 80 samples, respectively.

Human polyomaviruses and cancer: an overview

The name of the family Polyomaviridae, derives from the early observation that cells infected with murine polyomavirus induced multiple (poly) tumors (omas) in immunocompromised mice. Subsequent studies showed that many members of this family exhibit the capacity of mediating cell transformation and tumorigenesis in different experimental models. The transformation process mediated by these viruses is driven by viral pleiotropic regulatory proteins called T (tumor) antigens. Similar to other viral oncoproteins T antigens target cellular regulatory factors to favor cell proliferation, immune evasion and downregulation of apoptosis. The first two human polyomaviruses were isolated over 45 years ago. However, recent advances in the DNA sequencing technologies led to the rapid identification of additional twelve new polyomaviruses in different human samples. Many of these viruses establish chronic infections and have been associated with conditions in immunosuppressed individuals, particularly in organ transplant recipients. This has been associated to viral reactivation due to the immunosuppressant therapy applied to these patients. Four polyomaviruses namely, Merkel cell polyomavirus (MCPyV), Trichodysplasia spinulosa polyomavirus (TSPyV), John Cunningham Polyomavirus (JCPyV) and BK polyomavirus (BKPyV) have been associated with the development of specific malignant tumors. However, present evidence only supports the role of MCPyV as a carcinogen to humans. In the present review we present a summarized discussion on the current knowledge concerning the role of MCPyV, TSPyV, JCPyV and BKPyV in human cancers.

More than just oncogenes: mechanisms of tumorigenesis by human viruses

Most humans are infected with at least one of the known human cancer viruses during their lifetimes. While the initial infection with these viruses does not cause major disease, infected cells can acquire cancer hallmarks, particularly upon immunosuppression or exposure to co-carcinogenic stimuli. Even though cancer formation represents a rare outcome of a viral infection, approximately one out of eight human cancers has a viral etiology. Viral cancers present unique opportunities for prophylaxis, diagnosis, and therapy, as demonstrated by the success of HBV and HPV vaccines and HCV antivirals in decreasing the incidence of tumors that are caused by these viruses. Here we review common characteristics and mechanisms of action of the human oncogenic viruses.

The Paris System for Reporting Urinary Cytology: early review of the literature reveals successes and rare shortcomings

The Paris System for Reporting Urinary Cytology (TPS) provides recommendations for the diagnosis of urinary tract cytology (UTC) specimens and has found acceptance on an international level. Since the official release of TPS in 2016, numerous research studies have been published analyzing its impact. This review summarizes the studies published since the release of TPS, highlighting areas in which TPS has performed well and other areas in which TPS may need improvement.

Role of BK human polyomavirus in cancer

Human polyomaviruses (HPyV), which are small DNA viruses classified into the polyomaviridae family, are widely distributed in human populations. Thirteen distinct HPyVs have been described to date. Some of these viruses have been found in human tumors, suggesting an etiological relationship with cancer. In particular, convincing evidence of an oncogenic role has emerged for a specific HPyV, the Merkel cell polyomavirus (MCPyV). This HPyV has been linked to rare skin cancer, Merkel cell carcinoma (MCC). This finding may be just the tip of the iceberg, as HPyV infections are ubiquitous in humans. Many authors have conjectured that additional associations between HPyV infections and neoplastic diseases will likely be discovered. In 2012, the International Agency for Research on Cancer (IARC) evaluated the carcinogenicity of the BK virus (BKPyV), reporting that BKPyV is “possibly carcinogenic to humans.” This review explores the BKPyV infection from a historical point of view, including biological aspects related to viral entry, tropism, epidemiology and mechanisms potentially involved in BKPyV-mediated human carcinogenesis. In order to clarify the role of this virus in human cancer, more epidemiological and basic research is strongly warranted.

Co-infection with human polyomavirus BK enhances gene expression and replication of human adenovirus

Immunocompromised patients are susceptible to multiple viral infections. Relevant interactions between co-infecting viruses might result from viral regulatory genes which trans-activate or repress the expression of host cell genes as well as the genes of any co-infecting virus. The aim of the current study was to show that the replication of human adenovirus 5 is enhanced by co-infection with BK polyomavirus and is associated with increased expression of proteins including early region 4 open reading frame 1 and both the large tumor antigen and small tumor antigen. Clinical samples of whole blood and urine from 156 hematopoietic stem cell transplant recipients were tested. We also inoculated adenocarcinomic human alveolar basal epithelial cells with both human adenovirus 5 and BK polyomavirus to evaluate if co-infection of viruses affected their replication. Data showed that adenovirus load was significantly higher in the plasma (mean 7.5 x 10³ ± 8.5 x 10² copies/ml) and urine (mean 1.9 x 10³ ± 8.0 x 10² copies/ml) of samples from patients with co-infections, in comparison to samples from patients with isolated adenovirus infection. In vitro co-infection led to an increased (8.6 times) expression of the adenovirus early region 4 open reading frame gene 48 hours post-inoculation. The expression of the early region 4 open reading frame gene positively correlated with the expression of BK polyomavirus large tumor antigen (r = 0.90, p < 0.0001) and small tumor antigen (r = 0.83, p < 0.001) genes. The enhanced expression of the early region 4 open reading frame gene due to co-infection with BK polyomavirus was associated with enhanced adenovirus, but not BK polyomavirus, replication. The current study provides evidence that co-infection of adenovirus and BK polyomavirus contributes to enhanced adenovirus replication. Data obtained from this study may have significant importance in the clinical setting.

BK virus-associated collecting duct carcinoma of the renal allograft in a kidney-pancreas allograft recipient

BK polyomavirus (BKV) nephropathy is a major concern in renal transplantation. Its main consequence is graft loss, which occurs in more than 50% of the cases. De novo renal cell carcinoma in renal allograft is a very rare event. Most of these tumors are papillary or clear cell carcinomas. We report herein the first case of collecting duct carcinoma of the renal allograft in a kidney-pancreas allograft adult recipient. Collecting duct carcinoma occurs long after the cure of a BKV nephropathy. At this time, BKV viremia and viruria were negative as well as the immunostaining for SV40 in the non-tumor kidney. The viral oncoprotein Tag persists only in the tumor cells. To preserve pancreas graft function, we maintained immunosuppression levels. After a 9-months follow-up, the evolution was free from clinical and radiological progression. The oncogenic role of BKV remains controversial in human cancers. However, strong experimental data have shown an association between BKV infection and urologic neoplasms. Further works might precise the exact role of polyomaviruses in renal carcinogenesis. In the meantime, clinical vigilance for early diagnostic of these tumors is mandatory after BKV nephropathy.

Treatment for presumed BK polyomavirus nephropathy and risk of urinary tract cancers among kidney transplant recipients in the United States

Recent case series describe detection of BK polyomavirus (BKV) in urinary tract cancers in kidney transplant recipients, suggesting that BKV could contribute to the development of these cancers. We assessed risk for urinary tract cancers in kidney recipients with or without treatment for presumed BKV nephropathy (tBKVN) using data from the United States Transplant Cancer Match Study (2003-2013). Among 55 697 included recipients, 2015 (3.6%) were reported with tBKVN. Relative to the general population, incidence was similarly elevated (approximately 4.5-fold) for kidney cancer in recipients with or without tBKVN, and incidence was not increased in either group for prostate cancer. In contrast, for invasive bladder cancer, incidence was more strongly elevated in recipients with versus without tBKVN (standardized incidence ratios 4.5 vs. 1.7; N = 48 cases), corresponding to an incidence rate ratio (IRR) of 2.9 (95% confidence interval [CI] 1.0-8.2), adjusted for sex, age, transplant year, and use of polyclonal antibody induction. As a result, recipients with tBKVN had borderline increased incidence for all urothelial cancers combined (renal pelvis, ureter, and bladder cancers: adjusted IRR 2.2, 95% CI 0.9-5.4; N = 89 cases). Together with reports describing BKV detection in tumor tissues, these results support an association between BKV and urothelial carcinogenesis among kidney transplant recipients.

A novel polyomavirus from the nasal cavity of a giant panda (Ailuropoda melanoleuca)

Background

Polyomaviruses infect a wide variety of mammalian and avian hosts with a broad spectrum of outcomes including asymptomatic infection, acute systemic disease, and tumor induction.

Methods

Viral metagenomics and general PCR methods were used to detected viral nucleic acid in the samples from a diseased and healthy giant pandas.

Results

A novel polyomavirus, the giant panda polyomavirus 1 (GPPyV1) from the nasal cavity of a dead giant panda (Ailuropoda melanoleuca) was characterized. The GPPyV1 genome is 5144 bp in size and reveals five putative open-reading frames coding for the classic small and large T antigens in the early region, and the VP1, VP2 and VP3 capsid proteins in the late region. Phylogenetic analyses of the large T antigen of the GPPyV1 indicated GPPyV1 belonged to a putative new species within genus Deltapolyomavirus, clustering with four human polyomavirus species. The GPPyV1 VP1 and VP2 clustered with genus Alphapolyomavirus. Our epidemiologic study indicated that this novel polyomavirus was also detected in nasal swabs and fecal samples collected from captive healthy giant pandas.

Conclusion

A novel polyomavirus was detected in giant pandas and its complete genome was characterized, which may cause latency infection in giant pandas.

Detection of oncogenic viruses in water environments by a Luminex-based multiplex platform for high throughput screening of infectious agents

Recent studies documented the detection of viruses strongly associated with human cancer in urban sewages and other water environments worldwide. The aim of this study was to estimate the occurrence of human oncogenic viruses in environmental samples (sewage, river, marine, and pool/spa water) using highly sensitive and specific multiplex bead-based assays (Luminex technology). A total of 33 samples were analysed for 140 oncogenic viral agents, including mucosal and cutaneous human papillomaviruses (HPVs), human polyomaviruses (HPyV), human herpesviruses (HHV) and mouse mammary tumour virus (MMTV). Eighty-eight percent of the samples tested positive for at least one viral pathogen and the simultaneous presence of more than one virus was frequent (mean number of positivities/sample = 3.03). A total of 30 different Alpha, Beta and Gamma HPVs were detected, including mucosal and cutaneous types. The high-risk type HPV16 was the most frequently detected virus, identified in 73% of the samples. Of the 12 HPyVs tested, only two (BKPyV and MCPyV) were detected. At least one of these two was present in 48% of the samples. MMTV was detected in 21% of the samples, while herpesviruses - HHV-6 and HHV-1 - were detected in two samples (6%). The present study is the first to provide a comprehensive picture of the occurrence of oncogenic viruses belonging to different families and species in diverse water environments, and the first to successfully use, in environmental samples, a Luminex-based multiplex platform for high throughput screening of infectious agents. Our findings, showing that oncogenic viruses are ubiquitous in water environments, pave the way for future studies on the fate of these pathogens in water environments as well as on their potential for transmission via the waterborne route.

Polyomavirus Replication and Smoking Are Independent Risk Factors for Bladder Cancer After Renal Transplantation

BACKGROUND

Solid organ transplant recipients are at increased risk for developing malignancies. Polyomaviruses (PV) have been historically associated with experimental tumor development and recently described in association with renourinary malignancies in transplant patients. The aim of this study was to investigate the relationship between PV replication and smoking, and the development of malignant neoplasms in kidney transplant recipients.

METHODS

A retrospective case-control study was conducted for PV replication in all kidney biopsies and urine cytologies performed between 1998 and 2014 from kidney transplant recipients at the University of Maryland Medical Center. Polyomavirus-positive patients (n = 943) were defined as having any of the following: a kidney biopsy with PV associated nephropathy, any urine cytology demonstrating "decoy" cells, and/or significant polyomavirus BK viremia. Polyomavirus-negative matched patients (n = 943) were defined as lacking any evidence of PV replication. The incidence of malignancy (excluding nonmelanoma skin tumors) was determined in these 1886 patients and correlated with demographic data and history of smoking.

RESULTS

There was a 7.9% incidence of malignant tumors after a mean posttransplant follow-up of 7.9 ± 5.4 years. Among all cancer subtypes, only bladder carcinoma was significantly associated with PV replication. By multivariate analysis, only PV replication and smoking independently increased the risk of bladder cancer, relative risk, 11.7 (P = 0.0013) and 5.6 (P = 0.0053), respectively.

CONCLUSIONS

The findings in the current study indicate that kidney transplant recipients with PV replication and smoking are at particular risk to develop bladder carcinomas and support the need for long-term cancer surveillance in these patients.

BK polyomavirus: a review of the virology, pathogenesis, clinical and laboratory features, and treatment

BK polyomavirus (BKPyV) is a non-enveloped, circular dsDNA virus with a genome of approximately 5100 base pairs. It can be divided into four major genotypes, but the effects of different genotypes on clinical disease are uncertain. Primary BKPyV infection is generally acquired asymptomatically in childhood. It establishes low-level persistence in many tissues, particularly the genitourinary tract. Reactivation can lead to severe disease including BKPyV-associated nephropathy confirmed by renal biopsy, hemorrhagic cystitis and meningoencephalitis. Nucleic acid amplification testing of blood and urine is the main diagnostic and prognostic test for BKPyV infection. The treatment of BKPyV infection has concentrated on reduction in immunosuppressive therapy. Recent studies suggest that antiviral drugs have demonstrated only modest benefit, but adoptive T-cell therapies offer potential advances.

Specific and quantitative detection of Human polyomaviruses BKPyV and JCPyV in the healthy Pakistani population

BACKGROUND

The BK Polyomavirus (BKPyV) and JC polyomavirus (JCPyV) infections are widespread in human population and have been associated with severe kidney and brain disorders, respectively. The viruses remain latent primarily in reno-urinary tract, reactivating only in case of a compromised immune system. The seroepidemiology and molecular prevalence of BKPyV and JCPyV have been widely studied both in healthy and immunocompromised patients worldwide. However, data regarding the prevalence of these viruses in the immunocompetent or apparently healthy Pakistani population is lacking. Herein, we present the first ever report on quantitative prevalence of BKPyV and JCPyV in the peripheral blood of a randomly selected cohort of healthy Pakistani population.

METHODS

A total of 266 whole blood samples were examined. The subjects were divided into three age groups: ≤ 25 years (young), 26-50 years (middle) and ≥ 51 years (elder). Absolute real time PCR assay was designed to quantify the BKPyV and JCPyV viral copy numbers in the range of 106 to 100 copies/mL.

RESULTS

Overall, BKPyV was detected in 27.1% (72/266) individuals while JCPyV in 11.6% (31/266) indicating significant difference (p < 0.005) in the distribution of these two viruses. The prevalence of BKPyV significantly decreased from 51% (49/96) in young age group to 8.2% (7/85) in eldest age group. Whereas, JCPyV positivity rate slightly increased from 8.3% (8/96) in young age group to 11.8% (10/85) in elder age group. The median viral load was calculated as 6.2 log and 3.38 log copies/mL of blood for BKPyV and JCPyV, respectively. Notably, no significant difference in viral load of either of the subtypes was found between different age groups.

CONCLUSION

The current study provides an important baseline data on the prevalence and viral load of circulating BKPyV and JCPyV in Pakistani population. The prevalence and viral load of BKPyV was comparatively higher than JCPyV. The prevalence of BKPyV significantly decreased with increase in age while JCPyV positivity rate slightly increased with increasing age. Viral load of both BKPyV and JCPyV was not correlated with the individual ages.

Archetype and Rearranged Non-coding Control Regions in Urothelial Bladder Carcinoma of Immunocompetent Individuals

BACKGROUND

Polyomaviruses (PyVs) are potential transforming viruses. Despite their involvement in human tumours still being debated, there is evidence to suggest a role for PyVs in bladder carcinoma (BC). Therefore, a possible association between PyVs and BC was investigated.

MATERIALS AND METHODS

Urine, blood and fresh bladder tissue specimens were collected from 29 patients with BC. PyV prevalence, non-coding control region (NCCR) organization and genotypic analysis were assessed.

RESULTS

Data showed a significant prevalence of John Cunningham (JC) PyV in BC tissues and in urine with respect to BKPyV, while simian virus 40 was not revealed. A BKPyV rearranged NCCR sequence was isolated, whereas a JCPyV archetypal structure was consistently retained. A prevalence of European genotypes was observed.

CONCLUSION

Our data would suggest a JCPyV involvement in cancer progression and a BKPyV association with BC pathogenesis in immunocompetent patients. However, further work is necessary to better understand the exact role of PyVs in urothelial carcinogenesis.

Urothelial carcinoma of donor origin in a kidney transplant patient

Background

Malignancy after transplantation is an uncommon multifactorial occurrence. Immunosuppression to prevent graft rejection is described as a major risk factor in malignancy development in the post-transplant state. Donor-derived malignancy is a rare reported complication. Herein, we review our patient history and discuss diagnostic strategies and the implications of immunosuppression for donor-derived malignancy.

Case presentation

This is a 69-year-old man with post-renal-transplant urothelial carcinoma determined to be of donor origin. His course was complicated by BK virus at six years post-transplant; urothelial carcinoma was identified nine years post-transplant. Cystectomy was performed, but because of immunosuppression and underlying chronic kidney disease, the patient was considered ineligible for adjuvant chemotherapy. Two years after resection, screening MRI demonstrated retroperitoneal lymphadenopathy and a right upper pole mass in the transplanted kidney. Urine cytology confirmed the presence of malignant cells; FISH showed 2-8 copies of the X chromosome and no Y chromosome consistent with female origin of the malignant cells. CT-guided renal mass and paraaortic lymph node biopsies demonstrated that about 50 % of cells had an XY complement, while the remainder showed a XX genotype by chromosomal SNP microarray analysis. Immunosuppression was discontinued and the donor kidney removed. X/Y FISH of the urothelial carcinoma identified in the explanted kidney confirmed that the malignant cells were of female donor origin. Follow-up at 3, 6 and 12 months after discontinuation of immunosuppression and surgery demonstrated normalization of the lymphadenopathy and absence of new lesions.

Conclusions

Immunosuppression is a major risk factor for development of malignancy in transplant recipients. Donor-derived malignancy can arise and current molecular studies allow an accurate diagnosis. Withdrawal of immunosuppression and surgical resection of the transplant kidney proved an effective treatment in our case.

BK nephropathy in the native kidneys of patients with organ transplants: Clinical spectrum of BK infection

Nephropathy secondary to BK virus, a member of the Papoviridae family of viruses, has been recognized for some time as an important cause of allograft dysfunction in renal transplant recipients. In recent times, BK nephropathy (BKN) of the native kidneys has being increasingly recognized as a cause of chronic kidney disease in patients with solid organ transplants, bone marrow transplants and in patients with other clinical entities associated with immunosuppression. In such patients renal dysfunction is often attributed to other factors including nephrotoxicity of medications used to prevent rejection of the transplanted organs. Renal biopsy is required for the diagnosis of BKN. Quantitation of the BK viral load in blood and urine are surrogate diagnostic methods. The treatment of BKN is based on reduction of the immunosuppressive medications. Several compounds have shown antiviral activity, but have not consistently shown to have beneficial effects in BKN. In addition to BKN, BK viral infection can cause severe urinary bladder cystitis, ureteritis and urinary tract obstruction as well as manifestations in other organ systems including the central nervous system, the respiratory system, the gastrointestinal system and the hematopoietic system. BK viral infection has also been implicated in tumorigenesis. The spectrum of clinical manifestations from BK infection and infection from other members of the Papoviridae family is widening. Prevention and treatment of BK infection and infections from other Papovaviruses are subjects of intense research.

No Evidence of Human Polyomavirus 9, WU and KI DNA in Kidney and Urinary Bladder Tumour Tissue Samples

BACKGROUND/AIMS

The oncogenic potential of human polyomaviruses (HPyVs) has been proposed, but so far only Merkel cell carcinoma polyomavirus seems to be associated with a human tumour. The role of BK polyomavirus (BKPyV) in human tumourigenesis remains controversial. BKPyV establishes persistent infection in the urinary tract, and renal and bladder neoplasms have been studied extensively, but conflicting prevalence data are reported. KI, WU and HPyV9 were detected in urine samples suggesting that these viruses may also infect the urinary tract, but their presence in urinary tract tumours has not been studied. The aim of this work was to examine the prevalence of KIPyV, WUPyV, HPyV9 and BKPyV by PCR in renal and bladder neoplasms.

METHODS

A total of 190 formalin-fixed paraffin-embedded renal neoplasms, bladder cancer and kidney biopsy samples were analysed for the presence of BKPyV, KIPyV, WUPyV and HPyV9 DNA by real-time and nested PCR.

RESULTS

Amplifiable DNA was extracted from all the samples, but none of the studied viruses were detected in benign renal neoplasia (0/23), malignant renal tumours (0/89) or bladder cancer (0/76).

CONCLUSION

Our study did not find any evidence that BKPyV, KIPyV, WUPyV or HPyV9 are associated with bladder and renal tumours.

Anion homeostasis is important for non-lytic release of BK polyomavirus from infected cells

BK polyomavirus (BKPyV) is a member of a family of potentially oncogenic viruses, whose reactivation can cause severe pathological conditions in transplant patients, leading to graft rejection. As with many non-enveloped viruses, it is assumed that virus release occurs through lysis of the host cell. We now show the first evidence for a non-lytic release pathway for BKPyV and that this pathway can be blocked by the anion channel inhibitor DIDS. Our data show a dose-dependent effect of DIDS on the release of BKPyV virions. We also observed an accumulation of viral capsids in large LAMP-1-positive acidic organelles within the cytoplasm of cells upon DIDS treatment, suggesting potential late endosome or lysosome-related compartments are involved in non-lytic BKPyV release. These data highlight a novel mechanism by which polyomaviruses can be released from infected cells in an active and non-lytic manner, and that anion homeostasis regulation is important in this pathway.

Antibody response to BK polyomavirus as a prognostic biomarker and potential therapeutic target in prostate cancer

Infectious agents, including the BK polyomavirus (BKPyV), have been proposed as important inflammatory pathogens in prostate cancer. Here, we evaluated whether the preoperative antibody response to BKPyV large T antigen (LTag) and viral capsid protein 1 (VP1) was associated with the risk of biochemical recurrence in 226 patients undergoing radical prostatectomy for primary prostate cancer. Essentially, the multivariate Cox regression analysis revealed that preoperative seropositivity to BKPyV LTag significantly reduced the risk of biochemical recurrence, independently of established predictors of biochemical recurrence such as tumor stage, Gleason score and surgical margin status. The predictive accuracy of the regression model was denotatively increased by the inclusion of the BKPyV LTag serostatus. In contrast, the VP1 serostatus was of no prognostic value. Finally, the BKPyV LTag serostatus was associated with a peculiar cytokine gene expression profile upon assessment of the cellular immune response elicited by LTag. Taken together, our findings suggest that the BKPyV LTag serology may serve as a prognostic factor in prostate cancer. If validated in additional studies, this biomarker may allow for better treatment decisions after radical prostatectomy. Finally, the favorable outcome of LTag seropositive patients may provide a potential opportunity for novel therapeutic approaches targeting a viral antigen.

Survey for human polyomaviruses in cancer

Over the past 8 years, the discovery of 11 new human polyomaviruses (HPyVs) has revived interest in this DNA tumor virus family. Although HPyV infection is widespread and largely asymptomatic, one of these HPyVs, Merkel cell polyomavirus (MCV), is a bona fide human tumor virus. JC virus (JCV), BK virus, HPyV7, and trichodysplasia-spinulosa virus (TSV) can cause nonneoplastic diseases in the setting of immunosuppression. Few specific reagents are available to study the biology of the newly discovered HPyVs. We developed a pan-HPyV-screening method using a cocktail of 3 antibodies that, when combined, recognize T antigen proteins of all HPyVs. We validated detection characteristics of the antibody cocktail by immunoblotting and immunohistochemistry and screened 1,184 cases, including well-defined diseases and tumor tissue microarrays. This assay robustly detected MCV, TSV, JCV, and HPyV7 in etiologically related diseases. We further identified WU polyomavirus in a case of chronic lymphocytic lymphoma-associated bronchitis. Except for scattered, incidentally infected cells in 5% of lung squamous cell carcinomas and colon adenocarcinomas, a broad panel of tumor tissues was largely negative for infection by any HPyV. This method eliminates known HPyVs as suspected causes of cancers investigated in this study. Pan-HPyV survey can be applied to identify diseases associated with recently discovered polyomaviruses.

BK Polyomavirus Infection and Renourinary Tumorigenesis

BK polyomavirus (BKPyV) infection represents a major problem in transplantation, particularly for renal recipients developing polyomavirus-associated nephropathy (PyVAN). The possibility that BKPyV may also be oncogenic is not routinely considered. Twenty high-grade renourinary tumors expressing polyomavirus large T antigen in the entirety of the neoplasm in 19 cases, including the metastases in six, have been reported in transplant recipients with a history of PyVAN or evidence of BKPyV infection. Morphological and phenotypical features consistent with inactivation of the tumor suppressors pRB and p53 were found in the bladder tumors, suggesting a carcinogenesis mechanism involving the BKPyV large tumor oncoprotein/antigen. The pathogenesis of these tumors is unclear, but given the generally long interval between transplantation and tumor development, the risk for neoplasms after BKPyV infections may well be multifactorial. Other elements potentially implicated include exposure to additional exogenous carcinogens, further viral mutations, and cell genomic instability secondary to viral integration, as occurs with the Merkel cell PyV-associated carcinoma. The still scarce but increasingly reported association between longstanding PyVAN and renourinary neoplasms requires a concerted effort from the transplant community to better understand, diagnose, and treat the putative association between the BKPyV and these neoplasms.

Herpes and polyoma family viruses in thyroid cancer

Thyroid cancer is considered the most common malignancy that affects the endocrine system. Generally, thyroid cancer derives from follicular epithelial cells, and thyroid cancer is divided into well-differentiated papillary (80% of cases) and follicular (15% of cases) carcinoma. Follicular thyroid cancer is further divided into the conventional and oncocytic (Hürthle cell) type, poorly differentiated carcinoma and anaplastic carcinoma. Both poorly differentiated and anaplastic carcinoma can arise either de novo, or secondarily from papillary and follicular thyroid cancer. The incidence of thyroid cancer has significantly increased for both males and females of all ages, particularly for females between 55–64 years of age, from 1999 through 2008. The increased rates refer to tumors of all stages, though they were mostly noted in localized disease. Recently, viruses have been implicated in the direct regulation of epithelial-mesenchymal transition (EMT) and the development of metastases. More specifically, Epstein-Barr virus (EBV) proteins may potentially lead to the development of metastasis through the regulation of the metastasis suppressor, Nm23, and the control of Twist expression. The significant enhancement of the metastatic potential, through the induction of angiogenesis and changes to the tumor microenvironment, subsequent to viral infection, has been documented, while EMT also contributes to cancer cell permissiveness to viruses. A number of viruses have been identified to be associated with carcinogenesis, and these include lymphotropic herpesviruses, namely EBV and Kaposi's sarcoma-associated herpesvirus [KSHV, also known as human herpesvirus type 8 (HHV8)]; two hepatitis viruses, hepatitis B virus (HBV) and hepatitis C virus (HCV); human papillomaviruses (HPVs); human T cell lymphoma virus (HTLV); and a new polyomavirus, Merkel cell polyomavirus identified in 2008. In this review, we examined the association between thyroid cancer and two oncogenic virus families, the herpes and polyoma family viruses, and we discuss their potential role as causative agents in thyroid carcinogenesis.

Polyomavirus BK and prostate cancer: a complex interaction of potential clinical relevance

Several studies associating BK polyomavirus (BKPyV) and prostate cancer (PCa) suggested that this virus may exert its oncogenic activity at early stages of cancer development. The BKPyV oncogene, the large T antigen (LTag), has frequently been detected in areas of proliferative inflammatory atrophy, which is considered a precursor lesion leading to prostatic intraepithelial neoplasia and overt PCa. In a recently updated systematic review, the presence of BKPyV was significantly higher in PCa tissues than in healthy control tissues, providing an indication for a link between BKPyV infection and cancer risk. In addition, recent original investigations highlighted an association between expression of the virus and the clinical course of PCa. For example, by studying immune responses elicited against BKPyV LTag, a significant association between LTag positive cancer lesions and a peculiar regulatory profiling has been observed in PCa patients with evidence of disease recurrence after surgical radical prostatectomy. Lastly, a study carried out in a larger cohort of patients undergoing radical prostatectomy revealed the IgG response against LTag as an independent predictor of disease recurrence. Although a full picture of the mechanisms potentially responsible for the involvement of BKPyV in PCa is not available yet, continuing work on this topic should help to refine the potential role of BKPyV in PCa patients, perhaps revealing unsuspected associations with the clinical course of this disease.

The role of Merkel cell polyomavirus and other human polyomaviruses in emerging hallmarks of cancer

Polyomaviruses are non-enveloped, dsDNA viruses that are common in mammals, including humans. All polyomaviruses encode the large T-antigen and small t-antigen proteins that share conserved functional domains, comprising binding motifs for the tumor suppressors pRb and p53, and for protein phosphatase 2A, respectively. At present, 13 different human polyomaviruses are known, and for some of them their large T-antigen and small t-antigen have been shown to possess oncogenic properties in cell culture and animal models, while similar functions are assumed for the large T- and small t-antigen of other human polyomaviruses. However, so far the Merkel cell polyomavirus seems to be the only human polyomavirus associated with cancer. The large T- and small t-antigen exert their tumorigenic effects through classical hallmarks of cancer: inhibiting tumor suppressors, activating tumor promoters, preventing apoptosis, inducing angiogenesis and stimulating metastasis. This review elaborates on the putative roles of human polyomaviruses in some of the emerging hallmarks of cancer. The reciprocal interactions between human polyomaviruses and the immune system response are discussed, a plausible role of polyomavirus-encoded and polyomavirus-induced microRNA in cancer is described, and the effect of polyomaviruses on energy homeostasis and exosomes is explored. Therapeutic strategies against these emerging hallmarks of cancer are also suggested.

Investigation of BK virus, Epstein-Barr virus and human papillomavirus sequences in postoperative thyroid gland specimens

BACKGROUND

Although recent evidence has implicated viruses in the regulation of epithelial-to-mesenchymal transition and tumor progression, little is known regarding viral infections in thyroid malignancies. Thus the aim of this study was to detect sequences of 3 potentially oncogenic viruses - BK virus (BKV), Epstein-Barr virus (EBV) and human papillomavirus (HPV) - in a series of postoperative thyroid gland specimens.

METHODS

Thirty patients with thyroid nodules who underwent surgery for thyroid disease within a 3-year period were enrolled. Both nodular and adjacent normal thyroid tissue was surgically excised from each patient. Viral gene sequences of BKV (VP1), EBV (LMP1, EBNA2 and EBER1) and HPV were amplified by PCR. The PCR results were confirmed by direct sequencing analysis.

RESULTS

VP1 gene sequences were detected in 60% (18/30) of thyroid cancer or multinodular hyperplasia lesions compared with in 43.3% (13/30) of adjacent normal thyroid tissue specimens. Fifteen of thirty (50%) of thyroid cancer or multinodular hyperplasia samples revealed LMP1 sequences compared with 46.7% (14/30) of corresponding normal thyroid tissues. EBNA2 gene sequences were detected in 90% (27/30) of thyroid cancer or multinodular hyperplasia samples, compared with 90% (27/30) of adjacent normal thyroid tissue specimens. All samples were negative for EBER1 sequences, while HPV DNA was not detected in either nodular or normal thyroid tissue.

CONCLUSIONS

This study suggests that BKV and EBV "infection" is an early event, occurring within normal tissue. Our findings do not show a clear role for the viruses examined, instead they suggest an "endemicity" pattern rather than a causal effect.

Mobile elements and viral integrations prompt considerations for bacterial DNA integration as a novel carcinogen

Insertional mutagenesis has been repeatedly demonstrated in cancer genomes and has a role in oncogenesis. Mobile genetic elements can induce cancer development by random insertion into cancer related genes or by inducing translocations. L1s are typically implicated in cancers of an epithelial cell origin, while Alu elements have been implicated in leukemia as well as epithelial cell cancers. Likewise, viral infections have a significant role in cancer development predominantly through integration into the human genome and mutating or deregulating cancer related genes. Human papilloma virus is the best-known example of viral integrations contributing to carcinogenesis. However, hepatitis B virus, Epstein-Barr virus, and Merkel cell polyomavirus also integrate into the human genome and disrupt cancer related genes. Thus far, the role of microbes in cancer has primarily been attributed to mutations induced through chronic inflammation or toxins, as is the case with Helicobacter pylori and enterotoxigenic Bacteroides fragilis. We hypothesize that like mobile elements and viral DNA, bacterial and parasitic DNA may also integrate into the human somatic genome and be oncogenic. Until recently it was believed that bacterial DNA could not integrate into the human genome, but new evidence demonstrates that bacterial insertional mutagenesis may occur in cancer cells. Although this work does not show causation between bacterial insertions and cancer, it prompts more research in this area. Promising new sequencing technologies may reduce the risk of artifactual chimeric sequences, thus diminishing some of the challenges of identifying novel insertions in the somatic human genome.

Are human polyomaviruses co-factors for cancers induced by other oncoviruses?

Presently, 12 human polyomaviruses are known: BK polyomavirus (BKPyV), JCPyV, KIPyV, WUPyV, Merkel cell polyomavirus (MCPyV), HPyV6, HPyV7, Trichodysplasia spinulosa-associated polyomavirus, HPyV9, HPyV10, STLPyV and HPyV12. In addition, the non-human primate polyomavirus simian virus 40 (SV40) seems to circulate in the human population. MCPyV was first described in 2008 and is now accepted to be an etiological factor in about 80% of the rare but aggressive skin cancer Merkel cell carcinoma. SV40, BKPyV and JCPyV or part of their genomes can transform cells, including human cells, and induce tumours in animal models. Moreover, DNA and RNA sequences and proteins of these three viruses have been discovered in tumour tissue. Despite these observations, their role in cancer remains controversial. So far, an association between cancer and the other human polyomaviruses is lacking. Because human polyomavirus DNA has been found in a broad spectrum of cell types, simultaneous dwelling with other oncogenic viruses is possible. Co-infecting human polyomaviruses may therefore act as a co-factor in the development of cancer, including those induced by other oncoviruses. Reviewing studies that report co-infection with human polyomaviruses and other tumour viruses in cancer tissue fail to detect a clear link between co-infection and cancer. Directions for future studies to elaborate on a possible auxiliary role of human polyomaviruses in cancer are suggested, and the mechanisms by which human polyomaviruses may synergize with other viruses in oncogenic transformation are discussed.

The landscape of viral expression and host gene fusion and adaptation in human cancer

Viruses cause 10–15% of all human cancers. Massively parallel sequencing has recently proved effective for uncovering novel viruses and virus–tumour associations, but this approach has not yet been applied to comprehensive patient cohorts. Here we screen a diverse landscape of human cancer, encompassing 4,433 tumours and 19 cancer types, for known and novel expressed viruses based on >700 billion transcriptome sequencing reads from The Cancer Genome Atlas Research Network. The resulting map confirms and extends current knowledge. We observe recurrent fusion events, including human papillomavirus insertions in RAD51B and ERBB2. Patterns of coadaptation between host and viral gene expression give clues to papillomavirus oncogene function. Importantly, our analysis argues strongly against viral aetiology in several cancers where this has frequently been proposed. We provide a virus–tumour map of unprecedented scale that constitutes a reference for future studies of tumour-associated viruses using transcriptome sequencing data.

Viruses contribute to the pathogenesis of certain cancers. Using massively parallel sequencing data from The Cancer Genome Atlas to analyse viral expression in 19 tumour types, Tang et al. both confirm and reject previously described viral associations and present new information on viral integration and host interaction.

Polyomavirus BK and prostate cancer: an unworthy scientific effort?

The Polyomavirus BK (BKV) has been proposed to be one of the possible co-factors in the genesis of prostate cancer (PCa) but, so far, the only convincing suggestion is the hypothesis of a “hit and run” carcinogenic mechanism induced by the virus at early stages of this disease. To support this hypothesis we conducted an updated systematic review on previous studies regarding the association between BKV and PCa, in order to interpret the contrasting results and to explore whether there might be a significant virus-disease link. This updated analysis provides evidence for a significant link between BKV expression and PCa development, particularly between the BKV infection and the cancer risk. Forthcoming scientific efforts that take cue from this study might overcome the atavistic and fruitless debate regarding the BKV-PCa association.

Polyomavirus miRNAs: the beginning

Polyomaviruses are small, double stranded DNA viruses that replicate in the nucleus of the infected cell. Since 2005, clear evidence for miRNAs has been presented for a subset of the members of this viral family, each of which express a single miRNA. All the miRNAs share in common the ability to regulate expression of the major viral regulatory protein, large T antigen. Growing evidence suggests that the major role of the miRNA is to control viral replication. In vitro studies suggesting an immmunomodulatory role for the miRNA have not been supported by in vivo infections. Very little is known about cellular targets of the viral miRNAs, however. Thus, much remains to be learned about these interesting non-coding RNAs.

BK polyomavirus genotypes represent distinct serotypes with distinct entry tropism

BK polyomavirus (BKV) causes significant urinary tract pathogenesis in immunosuppressed individuals, including kidney and bone marrow transplant recipients. It is currently unclear whether BKV-neutralizing antibodies can moderate or prevent BKV disease. We developed reporter pseudoviruses based on seven divergent BKV isolates and performed neutralization assays on sera from healthy human subjects. The results demonstrate that BKV genotypes I, II, III, and IV are fully distinct serotypes. While nearly all healthy subjects had BKV genotype I-neutralizing antibodies, a majority of subjects did not detectably neutralize genotype III or IV. Surprisingly, BKV subgenotypes Ib1 and Ib2 can behave as fully distinct serotypes. This difference is governed by as few as two residues adjacent to the cellular glycan receptor-binding site on the virion surface. Serological analysis of mice given virus-like particle (VLP)-based BKV vaccines confirmed these findings. Mice administered a multivalent VLP vaccine showed high-titer serum antibody responses that potently cross-neutralized all tested BKV genotypes. Interestingly, each of the neutralization serotypes bound a distinct spectrum of cell surface receptors, suggesting a possible connection between escape from recognition by neutralizing antibodies and cellular attachment mechanisms. The finding implies that different BKV genotypes have different cellular tropisms and pathogenic potentials in vivo. Individuals who are infected with one BKV serotype may remain humorally vulnerable to other BKV serotypes after implementation of T cell immunosuppression. Thus, prevaccinating organ transplant recipients with a multivalent BKV VLP vaccine might reduce the risk of developing posttransplant BKV disease.