The small tumor antigen of Merkel cell polyomavirus accomplishes cellular transformation by uniquely localizing to the nucleus despite the absence of a known nuclear localization signal.

BACKGROUND: Merkel Cell Carcinoma (MCC) is an aggressive skin cancer that is three times deadlier than melanoma. In 2008, it was found that 80% of MCC cases are caused by the genomic integration of a novel polyomavirus, Merkel Cell Polyomavirus (MCPyV), and the expression of its small and truncated large tumor antigens (ST and LT-t, respectively). MCPyV belongs to a family of human polyomaviruses; however, it is the only one with a clear association to cancer. METHODS: To investigate the role and mechanisms of various polyomavirus tumor antigens in cellular transformation, Rat-2 and 293A cells were transduced with pLENTI MCPyV LT-t, MCPyV ST, TSPyV ST, HPyV7 ST, or empty pLENTI and assessed through multiple transformation assays, and subcellular fractionations. One-way ANOVA tests were used to assess statistical significance. RESULTS: Soft agar, proliferation, doubling time, glucose uptake, and serum dependence assays confirmed ST to be the dominant transforming protein of MCPyV. Furthermore, it was found that MCPyV ST is uniquely transforming, as the ST antigens of other non-oncogenic human polyomaviruses such as Trichodysplasia Spinulosa-Associated Polyomavirus (TSPyV) and Human Polyomavirus 7 (HPyV7) were not transforming when similarly assessed. Identification of structural dissimilarities between transforming and non-transforming tumor antigens revealed that the uniquely transforming domain(s) of MCPyV ST are likely located within the structurally dissimilar loops of the MCPyV ST unique region. Of all known MCPyV ST cellular interactors, 62% are exclusively or transiently nuclear, suggesting that MCPyV ST localizes to the nucleus despite the absence of a canonical nuclear localization signal. Indeed, subcellular fractionations confirmed that MCPyV ST could achieve nuclear localization through a currently unknown, regulated mechanism independent of its small size, as HPyV7 and TSPyV ST proteins were incapable of nuclear translocation. Although nuclear localization was found to be important for several transforming properties of MCPyV ST, some properties were also performed by a cytoplasmic sequestered MCPyV ST, suggesting that MCPyV ST may perform different transforming functions in individual subcellular compartments. CONCLUSIONS: Together, these data further elucidate the unique differences between MCPyV ST and other polyomavirus ST proteins necessary to understand MCPyV as the only known human oncogenic polyomavirus.

BK Viremia and Viruria Does Not Depend on the Type of Double-J Stent Used During Kidney Transplantation.

OBJECTIVES: BK virus is a major cause of chronic renal allograft failure.Transplant ureteral stent use has been reported as a risk factorfor BK virus infection. Recently, the use of a new type of ureteral stent (Magnetic Black Star) was reported in kidney transplant recipients. The aim ofthis preliminary report was to compare BK virus viremia and viruria occurrence depending on the type of double-J stent (standard versus Magnetic Black Star). MATERIALS AND METHODS: We included all kidney transplants performed in our center from January to December 2022. Each case had double-J stent placement. Indwelling stents were either a 6- or 7-Fr standard double-J stent or a 6-Fr Magnetic Black Star double-J stent. The type of double-J stent was chosen according to the surgeon's preference. A standard BK virus screening protocol was followed during the study period, which consisted of routine polymerase chain reaction examination of plasma and urine samples during monthly follow-ups. RESULTS: We assessed 120 patients without missing data: 92 patients received standard double-J stents and 28 patients received Magnetic Black Star stents. Patients were mostly male in the standard group (70.7%) versus the Magnetic Black Star group (42.9%) (P = .01). ABO- and HLA-incompatible transplant rates were similar in both groups. BK viremia occurrence and BK viruria occurrence were similar between groups at 1 month, 3 months, and 6 months. CONCLUSIONS: This preliminary study showed no differences concerning BKvirus infection depending on the type of double-J stents used during kidney transplant.

Clinicopathologic Spectrum and Outcomes of Infections Diagnosed on Graft Biopsies and Nephrectomy in Live Renal Allograft Recipients: An Institutional Experience.

OBJECTIVES: Modern immunosuppressive regimens have reduced rejection episodes in renal allograft recipients but have increased the risk of opportunistic infections. Infections are considered to be the second leading cause of death after cardiovascular complications in renal allograft recipients. Data on opportunistic infections affecting the allograft itself are scarce. The present study describes the spectrum of renal opportunistic infections and their outcomes diagnosed on renal allograft biopsies and nephrectomy specimens. MATERIALS AND METHODS: Our retrospective observational study was conducted from December 2011 to December 2021. We analyzed infectious episodes diagnosed on renal allograft biopsies or graft nephrectomy specimens. We obtained clinical, epidemiological, and laboratory details for analyses from hospital records. RESULTS: BK virus nephropathy was the most common opportunistic infection affecting the allograft, accounting for 47% of cases, followed by bacterial graft pyelonephritis (25%). Mucormycosis was the most common fungal infection. The diagnosis of infection from day of transplant ranged from 14 days to 39 months. Follow-up periods ranged from 1 to 10 years. Mortality was highest among patients with opportunistic fungal infection (62%), followed by viral infections, and graft failure rate was highest in patients with graft pyelonephritis (50%). Among patients with BK polyomavirus nephropathy, 45% had stable graft function compared with just 33% of patients with bacterial graft pyelonephritis. CONCLUSIONS: BK polyoma virus infection was the most common infection affecting the renal allograft in our study. Although fungal infections caused the highest mortality among our patients, bacterial graft pyelonephritis was responsible for maximum graft failure. Correctly identifying infections on histology is important so that graft and patient life can be prolonged.

Association of BKV viremia and nephropathy with adverse alloimmune outcomes in kidney transplant recipients.

BACKGROUND: Immunosuppression reduction for BK polyoma virus (BKV) must be balanced against risk of adverse alloimmune outcomes. We sought to characterize risk of alloimmune events after BKV within context of HLA-DR/DQ molecular mismatch (mMM) risk score. METHODS: This single-center study evaluated 460 kidney transplant patients on tacrolimus-mycophenolate-prednisone from 2010-2021. BKV status was classified at 6-months post-transplant as "BKV" or "no BKV" in landmark analysis. Primary outcome was T-cell mediated rejection (TCMR). Secondary outcomes included all-cause graft failure (ACGF), death-censored graft failure (DCGF), de novo donor specific antibody (dnDSA), and antibody-mediated rejection (ABMR). Predictors of outcomes were assessed in Cox proportional hazards models including BKV status and alloimmune risk defined by recipient age and molecular mismatch (RAMM) groups. RESULTS: At 6-months post-transplant, 72 patients had BKV and 388 had no BKV. TCMR occurred in 86 recipients, including 27.8% with BKV and 17% with no BKV (p = .05). TCMR risk was increased in recipients with BKV (HR 1.90, (95% CI 1.14, 3.17); p = .01) and high vs. low-risk RAMM group risk (HR 2.26 (95% CI 1.02, 4.98); p = .02) in multivariable analyses; but not HLA serological MM in sensitivity analysis. Recipients with BKV experienced increased dnDSA in univariable analysis, and there was no association with ABMR, DCGF, or ACGF. CONCLUSIONS: Recipients with BKV had increased risk of TCMR independent of induction immunosuppression and conventional alloimmune risk measures. Recipients with high-risk RAMM experienced increased TCMR risk. Future studies on optimizing immunosuppression for BKV should explore nuanced risk stratification and may consider novel measures of alloimmune risk.

Avian Polyomavirus Among Psittacine Birds in Iran: Molecular Detection Rate and Associated Risk Factors.

Avian polyomavirus (APV) infection causes various health problems in psittacine species, including death. The present study was conducted to investigate the prevalence of APV among psittacine birds in Iran. We also aimed to evaluate the impact of age, sex, species, season, and origin of the birds on the prevalence of APV. This study investigated the presence of APV among 1050 individual birds from 7 psittacine species over a 1-year period in Iran, namely, green-cheeked parakeets (Pyrrhura molinae), rosy-faced lovebirds (Agapornis roseicollis), monk parakeets (Myiopsitta monachus), sun conures (Aratinga solstitialis), Senegal parrots (Poicephalus senegalus), cockatiels (Nymphicus hollandicus), and grey parrots (Psittacus erithacus). The overall prevalence of APV in all studied species was 25% (263/1050, 95% confidence interval [CI]: 22.5-27.8). Results of the study showed that age and the season of the year were 2 important determinant factors in the prevalence of APV in psittacine birds. Young psittacine birds <6 months old were 2.94 (95% CI: 1.19-7.27) times more likely to be infected with APV than birds >1 year old, and there was a significant interaction between season and species in the multivariate analysis. In the winter season, rosy-faced lovebirds and green-cheeked parakeets were 15.6 (95% CI: 4.20-57.95) and 4.76 (95% CI: 1.4-16.21) times more likely to be infected with APV than in other seasons, respectively. This is the first report on the detection rate of APV in psittacine birds in Iran.

The association of Torque Teno viral load with CMV and BKV infection in pediatric and adolescent kidney transplant patients.

BACKGROUND: Long-term allograft and patient survival after kidney transplantation (KTX) depends on the balance between over- and under-immunosuppression (IS). High levels of IS predispose to opportunistic infections. Plasma load of Torque Teno Virus (TTV), a non-pathogenic highly prevalent Annellovirus, is associated with its hosts immune status, especially after solid organ transplantation. OBJECTIVES: To investigate the association of plasma TTV load and opportunistic viral infections after pediatric KTX. STUDY DESIGN: This retrospective study includes all pediatric KTX patients followed at the Medical University of Vienna 2014-2020. PCR for Cytomegalovirus (CMV), Epstein-Barr virus (EBV), BK virus (BKV), and TTV was performed every 4-8 weeks at routine follow-up visits. RESULTS: 71 pediatric KTX patients were followed with TTV measurements for a median of 2.7 years. TTV plasma load was associated with CMV DNAemia at the next visit with an OR of 2.37 (95 % CI 1.15-4.87; p = 0.03) after adjustment for time after KTX and recipient age. For a cut-off of 7.68 log10 c/mL TTV a sensitivity of 100 %, a specificity of 61 %, a NPV 100 %, and a PPV of 46 % to detect CMV DNAemia at the next visit was calculated. TTV plasma loads were also associated with BKV DNAuria and BKV DNAemia at the next visit, but not with EBV DNAemia. CONCLUSIONS: This is the first study to analyse associations between TTV plasma loads and opportunistic viral infections in pediatric KTX. We were able to present a TTV cut-off for the prediction of clinically relevant CMV DNAemia that might be useful in clinical care.

Molecular monitoring of viral infections in immunocompromised patients in a large university hospital in Italy: reflections after thirteen years of real-life activity.

PURPOSE: This study aimed to investigate the prevalence and viral reactivations of clinical interest in the immunocompromised patient with particular focus on hematologic and solid organ transplant recipients. METHODS: Molecular screening data of CMV, EBV, JCV and BKV from 2011 to 2023 were analyzed. This extensive time span allowed the access to more than 100,000 samples from over 20,000 patients treated at Policlinico Umberto I. It was possible to temporally investigate patient attendance patterns, average age distribution, seasonality of infections, and positivity rates of the analyzed viruses. RESULTS: Between 2019 and 2022 a significant reduction in organ transplants performed and in the positive molecular detection of EBV, JCV and BKV was observed. Additionally, there has been a noteworthy decrease in CMV reactivations, with a reduction of up to 50% starting in 2019. A remarkable reduction of 39% in the rate of CMV viral reactivation has been also achieved in SOT between 2016 and 2023. CONCLUSION: The years following 2019 were profoundly impacted by the COVID-19 pandemic era. This period resulted in a substantial reduction in healthcare services and hospital visits. Furthermore, the introduction of the drug Letermovir in Italy in 2019 demonstrated remarkable efficacy, evidenced by a reduction in CMV reactivations. Additionally, the adoption of a novel clinical approach centered on personalized therapy facilitated improved management of immunocompromised patients.

Establishment of COS-BK cells persistently infected with archetype BK polyomavirus.

BK polyomavirus (BKPyV) was the first human polyomavirus to be isolated from an immunosuppressed kidney transplant recipient in 1971. BKPyV reactivation causes BKPyV-associated nephropathy and hemorrhagic cystitis. However, the mechanisms underlying BKPyV replication remain unclear. In the present study, we performed the long-term cultivation of COS-7 cells transfected with archetype KOM-5 DNA, which were designated as COS-BK cells. BKPyV derived from COS-BK cells was characterized by analyzing the amount of the virus based on hemagglutination, viral replication, and the production of viral protein 1 (VP1). Immunostaining showed that VP1-positive cells accounted for a small percentage of COS-BK cells. The nucleotide sequences encompassing the origin of the DNA replication of BKPyV derived from COS-BK cells were generated from KOM-5 by the deletion of an 8-bp sequence, which did not involve T antigen binding sites. BKPyV replicated most efficiently in COS-BK cells in DMEM containing 2% fetal bovine serum. These results indicate that COS-BK cells are a suitable culture system for studying the persistent infection of archetype BKPyV.

LT and SOX9 expression are associated with gene sets that distinguish Merkel cell polyomavirus (MCPyV)-positive and MCPyV-negative Merkel cell carcinoma.

BACKGROUND: Merkel cell carcinoma (MCC) is an aggressive malignant neuroendocrine tumour. There are two subsets of MCC, one related to Merkel cell polyomavirus (MCPyV) and the other to ultraviolet radiation (UVR). MCPyV-positive and MCPyV-negative MCCs have been considered to be different tumours, as the former harbour few DNA mutations and are not related to UVR, and the latter usually arise in sun-exposed areas and may be found in conjunction with other keratinocytic tumours, mostly squamous cell carcinomas. Two viral oncoproteins, large T antigen (LT; coded by MCPyV_gp3) and small T antigen (sT; coded by MCPyV_gp4), promote different carcinogenic pathways. OBJECTIVES: To determine which genes are differentially expressed in MCPyV-positive and MCPyV-negative MCC; to describe the mutational burden and the most frequently mutated genes in both MCC subtypes; and to identify the clinical and molecular factors that may be related to patient survival. METHODS: Ninety-two patients with a diagnosis of MCC were identified from the medical databases of participating centres. To study gene expression, a customized panel of 172 genes was developed. Gene expression profiling was performed with nCounter technology. For mutational studies, a customized panel of 26 genes was designed. Somatic single nucleotide variants (SNVs) were identified following the GATK Best Practices workflow for somatic mutations. RESULTS: The expression of LT enabled the series to be divided into two groups (LT positive, n = 55; LT negative, n = 37). Genes differentially expressed in LT-negative patients were related to epithelial differentiation, especially SOX9, or proliferation and the cell cycle (MYC, CDK6), among others. Congruently, LT displayed lower expression in SOX9-positive patients, and differentially expressed genes in SOX9-positive patients were related to epithelial/squamous differentiation. In LT-positive patients, the mean SNV frequency was 4.3; in LT-negative patients it was 10 (P = 0.03). On multivariate survival analysis, the expression of SNAI1 [hazard ratio (HR) 1.046, 95% confidence interval (CI) 1.007-1.086; P = 0.02] and CDK6 (HR 1.049, 95% CI 1.020-1.080; P = 0.001) were identified as risk factors. CONCLUSIONS: Tumours with weak LT expression tend to co-express genes related to squamous differentiation and the cell cycle, and to have a higher mutational burden. These findings are congruent with those of earlier studies.

Merkel cell carcinoma (MCC) is an aggressive form of skin tumour. There are two subtypes of MCC: one of them is related to a virus called Merkel cell polyomavirus (MCPyV); the other one is related to persistent exposure to sunlight. The aim of this research was to find differences between these subtypes in their molecular behaviour (the genes that are expressed and the mutations that may be found). To do this, we carried out two studies, one to investigate gene expression (the process cells use to convert the instructions in our DNA into a functional product such as a protein) and one to look at gene mutations (changes in the DNA sequence). We found that the tumours that were not related to MCPyV expressed genes related to epithelial differentiation (the process by which unspecialized cells gain features characteristics of epithelial cells, which, among other things, make up the outer surface of the body), which means that the origin of both MCC subtypes may be different. We also found that MCPyV-related tumours had fewer mutations. Our findings are important because they help us to understand the biology of the MCC subtypes and could help with the development of new treatments for people diagnosed with skin tumours.

Regulation of Transcriptional Activity of Merkel Cell Polyomavirus Large T-Antigen by PKA-Mediated Phosphorylation.

Merkel cell polyomavirus (MCPyV) is the major cause of Merkel cell carcinoma (MCC), an aggressive skin cancer. MCPyV large T-antigen (LTag) and small T-antigen (sTag) are the main oncoproteins involved in MCPyV-induced MCC. A hallmark of MCPyV-positive MCC cells is the expression of a C-terminal truncated LTag. Protein kinase A (PKA) plays a fundamental role in a variety of biological processes, including transcription by phosphorylating and thereby regulating the activity of transcription factors. As MCPyV LTag has been shown to be phosphorylated and acts as a transcription factor for the viral early and late promoter, we investigated whether LTag can be phosphorylayted by PKA, and whether this affects the transcript activity of LTag. Using a phosphorylation prediction algorithm, serine 191, 203, and 265 were identified as putative phosphorylation sites for PKA. Mass spectrometry of in vitro PKA-phosphorylated peptides confirmed phosphorylation of S203 and S265, but not S191. Full-length LTag inhibited early and late promoter activity of MCPyV, whereas the truncated MKL2 LTag variant stimulated both promoters. Single non-phosphorylable, as well as phosphomimicking mutations did not alter the inhibitory effect of full-length LTag. However, the non-phosphorylable mutations abrogated transactivation of the MCPyV promoters by MKL2 LTag, whereas phosphomimicking substitutions restored the ability of MKL2 LTag to activate the promoters. Triple LTag and MKL2 LTag mutants had the same effect as the single mutants. Activation of the PKA signaling pathway did not enhance MCPyV promoter activity, nor did it affect LTag expression levels in MCPyV-positive Merkel cell carcinoma (MCC) cells. Our results show that phosphorylation of truncated LTag stimulates viral promoter activity, which may contribute to higher levels of the viral oncoproteins LTag and sTag. Interfering with PKA-induced LTag phosphorylation/activity may be a therapeutic strategy to treat MCPyV-positive MCC patients.

Merkel Cell Polyomavirus and their Association with the Pathogenesis of Cervical Squamous Cell Carcinomas and Adenocarcinomas: A Review Article.

Background: This review aims to determine the potential role of Merkel Cell Polyomavirus (MCPyV) in the pathogenesis of cervical squamous cell carcinomas and adenocarcinomas. Methods: A PRISMA systematic search appraisal was conducted. The Scopus, Web of Science, PubMed, EMBASE, Google Scholar, and MEDLINE databases for publications in English were searched up to September 2022 for all relevant articles. All articles that have outlined the contributions of the MCPyV to cervical squamous cell carcinomas and adenocarcinomas were included. Results: The six databases produced 6806 articles. Only six articles met the inclusion criteria and were included. The protocol of this review was submitted and registered with the PROSPERO (Code no. CRD42022369197). The total sample size across the articles was 1135; the age of the participants ranged between 18 and 75 years. In addition, the included articles were conducted between 2012 to 2016. All included articles have a cross-sectional design.Furthermore, different kinds of samples were collected in the reviewed articles, namely cervical tissue biopsies, cervical smears, formalin-fixed paraffin-embedded resection specimens, and cervical adenocarcinomas. Moreover, five articles showed no statistically significant association between the MCPyV and cervical squamous cell carcinomas and adenocarcinomas. In contrast, one article revealed a positive association between MCPyV and cervical squamous cell carcinomas and adenocarcinomas. Conclusions: MCPyV could not be associated with the pathogenesis of cervical squamous cell carcinomas and adenocarcinomas. Further attention should be given to examining this association, and further studies with a large sample size are recommended to confirm these findings.

Lyon IARC Polyomavirus Displays Transforming Activities in Primary Human Cells.

Several studies reported the presence of a recently discovered polyomavirus (PyV), Lyon IARC PyV (LIPyV), in human and domestic animal specimens. LIPyV has some structural similarities to well-established animal and human oncogenic PyVs, such as raccoon PyV and Merkel cell PyV (MCPyV), respectively. In this study, we demonstrate that LIPyV early proteins immortalize human foreskin keratinocytes. LIPyV LT binds pRb, accordingly cell cycle checkpoints are altered in primary human fibroblasts and keratinocytes expressing LIPyV early genes. Mutation of the pRb binding site in LT strongly affected the ability of LIPyV ER to induced HFK immortalization. LIPyV LT also binds p53 and alters p53 functions activated by cellular stresses. Finally, LIPyV early proteins activate telomerase reverse transcriptase (hTERT) gene expression, via accumulation of the Sp1 transcription factor. Sp1 recruitment to the hTERT promoter is controlled by its phosphorylation, which is mediated by ERK1 and CDK2. Together, these data highlight the transforming properties of LIPyV in in vitro experimental models, supporting its possible oncogenic nature. IMPORTANCE Lyon IARC PyV is a recently discovered polyomavirus that shows some structural similarities to well-established animal and human oncogenic PyVs, such as raccoon PyV and Merkel cell PyV, respectively. Here, we show the capability of LIPyV to efficiently promote cellular transformation of primary human cells, suggesting a possible oncogenic role of this virus in domestic animals and/or humans. Our study identified a novel virus-mediated mechanism of activation of telomerase reverse transcriptase gene expression, via accumulation of the Sp1 transcription factor. In addition, because the persistence of infection is a key event in virus-mediated carcinogenesis, it will be important to determine whether LIPyV can deregulate immune-related pathways, similarly to the well-established oncogenic viruses.

BK Polyomavirus Requires the Mismatch Repair Pathway for DNA Damage Response Activation.

BK polyomavirus (PyV) infects the genitourinary tract of >90% of the adult population. Immunosuppression increases the risk of viral reactivation, making BKPyV a leading cause of graft failure in kidney transplant recipients. Polyomaviruses have a small double-stranded DNA (dsDNA) genome that requires host replication machinery to amplify the viral genome. Specifically, polyomaviruses promote S phase entry and delay S phase exit by activating the DNA damage response (DDR) pathway via an uncharacterized mechanism requiring viral replication. BKPyV infection elevates expression of MutSα, a mismatch repair (MMR) pathway protein complex that senses and repairs DNA mismatches and can activate the DDR. Thus, we investigated the role of the MMR pathway by silencing the MutSα component, Msh6, in BKPyV-infected primary cells. This resulted in severe DNA damage that correlated with weak DNA damage response activation and a failure to arrest the cell cycle to prevent mitotic entry during infection. Furthermore, silencing Msh6 expression resulted in significantly fewer infectious viral particles due to significantly lower levels of VP2, a minor capsid protein important for trafficking during subsequent infections. Since viral assembly occurs in the nucleus, our findings are consistent with a model in which entry into mitosis disrupts viral assembly due to nuclear envelope breakdown, which disperses VP2 throughout the cell, reducing its availability for encapsidation into viral particles. Thus, the MMR pathway may be required to activate the ATR (ATM-Rad3-related) pathway during infection to maintain a favorable environment for both viral replication and assembly. IMPORTANCE Since there are no therapeutics that target BKPyV reactivation in organ transplant patients, it is currently treated by decreasing immunosuppression to allow the natural immune system to fight the viral infection. Antivirals would significantly improve patient outcomes since reducing immunosuppression carries the risk of graft failure. PyVs activate the DDR, for which there are several promising inhibitors. However, a better understanding of how PyVs activate the DDR and what role the DDR plays during infection is needed. Here, we show that a component of the mismatch repair pathway is required for DDR activation during PyV infection. These findings show that the mismatch repair pathway is important for DDR activation during PyV infection and that inhibiting the DDR reduces viral titers by generating less infectious virions that lack the minor capsid protein VP2, which is important for viral trafficking.

Molecular Epidemiology and Variation of the BK Polyomavirus in the Population of Central and Eastern Europe Based on the Example of Poland.

The BK polyomavirus (BKPyV) is a widespread pathogen in humans. Polymorphism of the region encoding the VP1 protein of BKPyV provides the basis for classifying the virus into types and subtypes, whose frequency varies depending on geographic location. The aim of our study was to determine the frequency of BKPyV in the Polish population and to assess its variation by analysing polymorphism in the typing region. The study was conducted on 168 healthy, Polish volunteers, whose blood (plasma) and urine were sampled. The virus was detected using PCR, products, sequenced and subjected to bioinformatic analysis. In addition, viral load was assessed by qPCR. The presence of the genetic material of the BK virus was noted in 61/168 urine samples but in none of the plasma sample. Sequencing and phylogenetic analysis confirmed that the BKPyV isolates were of types I and IV, dominant in Europe (63.93% and 36.07%, respectively). All isolates from genotype I belonged to subtype Ib-2, showing polymorphism at position 1809 with a frequency of 61.54% (G1809A) and 38.46% (G1809C). To the best of our knowledge, this is the first study of this magnitude on the genetic variation of BKPyV among healthy volunteers in Poland.

Prevalence of MCPyV, HPyV6, HPyV7 and TSPyV in Actinic Keratosis Biopsy Specimens.

To date, 14 human polyomaviruses (HPyVs) have been identified using high-throughput technologies. Among them, MCPyV, HPyV6, HPyV7 and TSPyV present a skin tropism, but a causal role in skin diseases has been established only for MCPyV as a causative agent of Merkel cell carcinoma (MCC) and TSPyV as an etiological agent of Trichodysplasia Spinulosa (TS). In the search for a possible role for cutaneous HPyVs in the development of skin malignant lesions, we investigated the prevalence of MCPyV, HPyV6, HPyV7 and TSPyV in actinic keratosis (AK), a premalignant skin lesion that has the potential to progress towards a squamous cell carcinoma (SCC). One skin lesion and one non-lesion skin from nine affected individuals were analyzed by qualitative PCR. MCPyV was detected in 9 out of 9 lesion biopsies and 6 out of 8 non-lesion biopsies. HPyV6 was detected only in healthy skin, while HPyV7 and TSPyV were not detected in any skin sample. These findings argue against a possible role of cutaneous HPyVs in AK. However, considering the small sample size analyzed, a definitive conclusion cannot be drawn. Longitudinal studies on large cohorts are warranted.

Merkel cell polyomavirus is a passenger virus in both poroma and porocarcinoma.

BACKGROUND: Merkel cell polyomavirus (MCPyV) has been studied in several malignant and nonmalignant tissues. However, only in Merkel cell carcinoma (MCC) has the connection to tumorigenesis been established. Previously, eccrine porocarcinoma samples were shown to express MCPyV in the majority of samples. We aimed to examine MCPyV in porocarcinoma and poroma samples using MCC as the reference material. METHODS: We analyzed 17 porocarcinoma and 50 poroma samples for the presence of MCPyV using LT antigen immunostaining and DNA detection methods. In addition, 180 MCC samples served as controls. RESULTS: MCPyV LT antigen immunostaining was detected in 10% of poroma and 18% of porocarcinoma samples; on the other hand, it was present in 65% of MCC samples. MCPyV DNA was detected in only 10% of poroma and porocarcinoma samples compared with 96% of MCC samples. The viral DNA copy number in all MCPyV DNA-positive MCCs was at least 25 times higher than that in porocarcinoma or poroma samples with the highest MCPyV DNA-to-PTPRG ratio. CONCLUSIONS: The low number of viral DNA copies in poroma and porocarcinoma samples, together with the negative LT expression of MCPyV DNA-positive tumors, indicates that MCPyV is simply a passenger virus rather than an oncogenic driver of porocarcinoma.

Prevalence of Merkel Cell Polyomavirus (MCPyV) in the Oral Cavity Biopsies in Northern Iran.

OBJECTIVE: Infection with human tumor viruses is one of the hypothesized causes of cancer. The current investigation aimed to explore the presence and quantitative analysis of a new human tumor virus, Merkel cell polyomavirus (MCPyV) in tissue samples of 114 patients with oral cavity lesions including oral squamous cell carcinoma (OSCC), oral lichen planus (OLP), Dysplasia and oral irritation fibroma (OIF) in Northern Iran. METHODS: From 114 formalin fixed paraffin embedded samples; 35 with SCC, 29 with OLP, 14 with dysplasia and 36 with OIF were cut, deparaffinized and DNA was extracted. Quantitative detection of MCPyV large T antigen was performed by absolute quantitative Real-Time PCR. RESULT: MCPyV DNA was detected in 30.6% (n: 11/36) of IF, 24.1% (n; 7/29) of OLP, 21.4% (n:3/14) of dysplasia and 20% (n;7/35) of OSCC samples. The mean MCPyV DNA copy number was 2.32×10-2 ± 3.97 ×10-2, 2.02×10-2 (SD=3.13×10-2), 2.69×10-4 (SD=2.51×10-4), and 2.56×10-4 (SD=6.73×10-4) per cell in OSCC, dysplasia and both of OLP and OIF samples, respectively (P=0.76). CONCLUSION: This study provides the first data from Iran regarding the presence of MCPyV genome in oral cavity lesions and oral cancer. These results also emphasize that MCPyV has an active role in the occurrence of oral lesions and progression to cancer. Further studies should be carried out to clarify the role of MCPyV in oral cavity lesions.

Database and Statistical Analyses of Transcription Factor Binding Sites in the Non-Coding Control Region of JC Virus.

JC virus (JCV), as an archetype, establishes a lifelong latent or persistent infection in many healthy individuals. In immunocompromised patients, prototype JCV with variable mutations in the non-coding control region (NCCR) causes progressive multifocal leukoencephalopathy (PML), a severe demyelinating disease. This study was conducted to create a database of NCCR sequences annotated with transcription factor binding sites (TFBSs) and statistically analyze the mutational pattern of the JCV NCCR. JCV NCCRs were extracted from >1000 sequences registered in GenBank, and TFBSs within each NCCR were identified by computer simulation, followed by examination of their prevalence, multiplicity, and location by statistical analyses. In the NCCRs of the prototype JCV, the limited types of TFBSs, which are mainly present in regions D through F of archetype JCV, were significantly reduced. By contrast, modeling count data revealed that several TFBSs located in regions C and E tended to overlap in the prototype NCCRs. Based on data from the BioGPS database, genes encoding transcription factors that bind to these TFBSs were expressed not only in the brain but also in the peripheral sites. The database and NCCR patterns obtained in this study could be a suitable platform for analyzing JCV mutations and pathogenicity.