Functional Domains of the Early Proteins and Experimental and Epidemiological Studies Suggest a Role for the Novel Human Polyomaviruses in Cancer

JC Polyomavirus in Prostate Cancer-Friend or Foe?

Background/Objectives: Recently, many researchers have evaluated various viruses, including polyomaviruses (JCV, BKV) and EBV, as potential factors playing a role in the development and/or progression of prostate cancer (PCa), one of the most common cancers in men. Therefore, we aimed to assess the frequency of the JCPyV DNA in tissue collected from PCa patients. Methods: We detected the presence of viral DNA (PCR) in 49.6% of clinical samples, including 71.9% with single EBV infection and 28.1% with EBV/JCV co-infection. We did not detect BKV or a single JCV infection. Therefore, we compared patients with EBV mono-infection with EBV/JCV co-infected patients in the context of risk group, Gleason score, and TNM classification. Results: Our results showed differences in clinicopathological features between single EBV infection and EBV/JCV co-infection. In the group of patients with single EBV infection, most patients were classified as medium/high risk, while in the group with EBV/JCV co-infection, most patients were classified as low risk. Conclusions: Among patients with single EBV infection, a more advanced stage of cancer was observed than in EBV/JCV co-infection. Moreover, the level of anti-EBVCA and anti-EBNA antibodies as well as EBV load was higher in the case of single infection compared to EBV/JCV co-infection. Higher antibody levels were detected in more advanced tumor stages in single EBV infection. Does JCV only "reside" in prostate cells or is it a co-factor in EBV infection? In light of these studies, there is a need to clarify the role of JCV virus in the development and/or progression of prostate cancer.

Merkel Cell Polyomavirus (MCPyV) and Its Possible Role in Head and Neck Cancers

Despite significant progress in its prevention, diagnosis, and treatment, head and neck cancer (HNC) remains a major global health issue due to its multifactorial pathogenesis. Indeed, HNCs have been found to be associated with different environmental and lifestyle factors, as well as with infection with oncogenic viruses. To date, seven viruses are recognized for their tumorigenic properties and have been proposed as implicated in HNC development, including Merkel Cell Polyomavirus (MCPyV). MCPyV is well recognized as the major etiological agent of Merkel cell carcinoma (MCC), a rare but rapidly metastasizing skin neoplasm. Specifically, in almost 80% of MCC cases, viral genome integration occurs, and a truncated form of Large T Antigen (tLT) is expressed. Although MCC is a rare cancer, MCPyV is a ubiquitous virus, widely distributed among the human population. Therefore, a plausible role of the virus has been proposed, even for other tumors. The current review provides an overview of the available data describing the presence of MCPyV in non-MCC tumors, such as HNCs, with the aim of elucidating the potential contribution of MCPyV to oral cancer. Understanding the role of viral infections in the etiology of cancer opens up the opportunity for developing preventive measures and targeted therapies that effectively address HNC progression while reducing treatment-related side effects.

Polyomaviruses and the risk of breast cancer: a systematic review and meta-analysis

BACKGROUND

Breast cancer is a major global health problem worldwide, affecting more than 2.25 million women annually. The disease is influenced by various factors, including some viruses, gender, age, and family history. This study aimed to conducting a comprehensive systematic review and meta-analysis of existing studies on the polyomaviruses in breast cancer.

METHODS

This systematic review and meta-analysis aimed to provide an evidence-based analysis of the relationship between polyomaviruses and breast cancer. The global online databases were used to identify relevant studies published from 2000 to July 2024. The quality of each article was assessed using the Newcastle-Ottawa Scale (NOS) checklist. Data analysis was performed using STATA software, and standard errors of prevalence were calculated using the binomial distribution formula. Heterogeneity of study results was evaluated using the I-square and Q index, while publication bias was examined using the Begg's test. A random effects model was used to determine prevalence rates, and a forest plot diagram was used to present results with 95% confidence intervals. The Trim and Fill test was applied to estimate publication bias, and sensitivity analysis was performed to assess the influence of individual studies on the overall estimate.

RESULTS

Nine studies met the inclusion and exclusion criteria for this analysis. In this study, the prevalence of BKV, JCV, HPyV7, KIV, WUV, SV40, and TSV in breast cancer patients was found to be 0%. By combining the results of these studies, the prevalence of PyV, MCV, and HPyV6 in breast cancer patients was 11%, 4%, and 1%, respectively.

CONCLUSION

The meta-analysis presented here provides an exhaustive overview of the current literature on the prevalence of polyomaviruses in breast cancer patients. Findings indicate a potentially stronger association between PyV and breast cancer than other human polyomaviruses.

Novel polyomavirus in the endangered garden dormouse Eliomys quercinus

BACKGROUND

The garden dormouse (Eliomys quercinus) has experienced a significant population decline across Europe in recent decades. While habitat loss and climate change are often cited as primary factors, pathogen exposure, either to novel or to previously known, may play a role in such a decline. This study aimed to investigate the presence of polyomaviruses in garden dormice, given that these viruses are highly prevalent and can cause disease, particularly in immunocompromised individuals.

METHODS

The carcasses of garden dormice (n = 89) were collected throughout Germany. Kidney samples were tested for the presence of polyomavirus DNA using nested degenerate and specific diagnostic PCRs. Seroprevalence was assessed from chest cavity fluid samples through an enzyme-linked immunosorbent assay using polyomavirus VP1 virus-like particles produced in yeast.

RESULTS

A new polyomavirus, related to chimpanzee (Pan troglodytes) polyomaviruses 4 and 5 and human Merkel cell polyomavirus, was identified in the garden dormouse. Two 5,380 bp-length complete viral genomes were sequenced from dormice kidney samples (sequences PQ246041 and PQ246042). Genes encoding the putative structural proteins VP1, VP2, and VP3, as well as the Large, Middle, and small T antigens, containing conserved functional domains were identified. Polyomavirus DNA was detected in 2 of 74 dormice (2.7%, 95% confidence interval: 0-6.4%) through PCR, while 12 of 69 animals (17.4%, 95% confidence interval: 8.4-26.3%) tested positive for polyomavirus-specific antibodies.

CONCLUSIONS

In conclusion, here we describe a novel polyomavirus in the garden dormouse with molecular and serological detection. Pairwise sequence comparison and phylogenetic analysis suggest that this novel virus may represent a novel species within the genus Alphapolyomavirus. Future work should examine if this virus is garden dormouse-specific and whether it is associated with disease in dormice.

Human Oncogenic Viruses: Characteristics and Prevention Strategies-Lessons Learned from Human Papillomaviruses

Approximately 12% of human cancers worldwide are associated with infectious agents, which are classified by the International Agency for Research on Cancer (IARC) as Group 1 within the agents that are carcinogenic to humans. Most of these agents are viruses. Group 1 oncogenic viruses include hepatitis C virus, hepatitis B virus (HBV), human T-cell lymphotropic virus type 1, Epstein-Barr virus, Kaposi sarcoma-associated herpesvirus, human immunodeficiency virus-1 and high-risk human papillomaviruses (HPVs). In addition, some human polyomaviruses are suspected of inducing cancer prevalently in hosts with impaired immune responses. Merkel cell polyomavirus has been associated with Merkel cell carcinoma and included by the IARC in Group 2A (i.e., probably carcinogenic to humans). Linking viruses to human cancers has allowed for the development of diagnostic, prophylactic and therapeutic measures. Vaccination significantly reduced tumours induced by two oncogenic viruses as follows: HBV and HPV. Herein, we focus on mucosal alpha HPVs, which are responsible for the highest number of cancer cases due to tumour viruses and against which effective prevention strategies have been developed to reduce the global burden of HPV-related cancers.

Development of a novel multi‑epitope vaccine against the pathogenic human polyomavirus V6/7 using reverse vaccinology

BACKGROUND

Human polyomaviruses contribute to human oncogenesis through persistent infections, but currently there is no effective preventive measure against the malignancies caused by this virus. Therefore, the development of a safe and effective vaccine against HPyV is of high priority.

METHODS

First, the proteomes of 2 polyomavirus species (HPyV6 and HPyV7) were downloaded from the NCBI database for the selection of the target proteins. The epitope identification process focused on selecting proteins that were crucial, associated with virulence, present on the surface, antigenic, non-toxic, and non-homologous with the human proteome. Then, the immunoinformatic methods were used to identify cytotoxic T-lymphocyte (CTL), helper T-lymphocyte (HTL), and B-cell epitopes from the target antigens, which could be used to create epitope-based vaccine. The physicochemical features of the designed vaccine were predicted through various online servers. The binding pattern and stability between the vaccine candidate and Toll-like receptors were analyzed through molecular docking and molecular dynamics (MD) simulation, while the immunogenicity of the designed vaccines was assessed using immune simulation.

RESULTS

Online tools were utilized to forecast the most optimal epitope from the immunogenic targets, including LTAg, VP1, and VP1 antigens of HPyV6 and HPyV7. A multi-epitope vaccine was developed by combining 10 CTL, 7 HTL, and 6 LBL epitopes with suitable linkers and adjuvant. The vaccine displayed 98.35% of the world's population coverage. The 3D model of the vaccine structure revealed that the majority of residues (87.7%) were located in favored regions of the Ramachandran plot. The evaluation of molecular docking and MD simulation revealed that the constructed vaccine exhibits a strong binding (-1414.0 kcal/mol) towards the host's TLR4. Moreover, the vaccine-TLR complexes remained stable throughout the dynamic conditions present in the natural environment. The immune simulation results demonstrated that the vaccine design had the capacity to elicit robust immune responses in the host.

CONCLUSION

The multi-parametric analysis revealed that the designed vaccine is capable of inducing sustained immunity against the selected polyomaviruses, although further in-vivo investigations are needed to verify its effectiveness.

miRNAs driving diagnosis, prognosis and progression in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive form of skin malignancy with a high recurrence commonly within two to three years of initial diagnosis. The incidence of MCC has nearly doubled in the past few decades. Options for diagnosing, assessing, and treating MCC are limited. MicroRNAs (miRNAs) are a class of small, non-coding RNA molecules that play an important role in controlling many different aspects of cell biology. Many miRNAs are aberrantly expressed in distinct types of cancer, with some serving as tumor suppressors and others as oncomiRs. Therefore, the future holds great promise for the utilization of miRNAs in enhancing diagnostic, prognostic, and therapeutic approaches for MCC. Accordingly, the goal of this article is to compile, summarize, and discuss the latest research on miRNAs in MCC, highlighting their potential clinical utility as diagnostic and prognostic biomarkers.

Immunological evidence of an early seroconversion to oncogenic Merkel cell polyomavirus in healthy children and young adults

Oncogenic Merkel cell polyomavirus (MCPyV) provokes a widespread and asymptomatic infection in humans. Herein, sera from healthy children and young adults (HC, n = 344) aged 0-20 years old were evaluated for anti-MCPyV immunoglobulin G (IgG) and IgM antibodies employing a recently developed immunoassay. Serum MCPyV IgG data from healthy subjects (HS, n = 510) and elderlies (ES, n = 226), aged 21-65/66-100 years old, from our previous studies, were included. The anti-MCPyV IgG and IgM rates in HC sera were 40.7% and 29.7%, respectively. A lower prevalence of anti-MCPyV IgGs was found in HC aged 0-5 years old (13%) compared to 6-10 (52.3%), 11-15 (60.5%) and 16-20 years old (61.6%) cohorts. Age-stratified HCs exhibited similar anti-MCPyV IgM rates (27.9%-32.9%). Serological profiles indicated that anti-MCPyV IgGs and IgMs had low optical densities (ODs) during the first years of life, while IgM ODs appeared to decrease throughout young adulthood. A lower anti-MCPyV IgGs rate was found in HC (40.7%) than HS (61.8%) and ES (63.7%). Upon the 5-years range age-stratification, a lower anti-MCPyV IgGs rate was found in the younger HC cohort aged 0-5 years old compared to the remaining older HC/HS/ES cohorts (52.3%-72%). The younger HC cohort exhibited the lowest anti-MCPyV IgG ODs than the older cohorts. Low anti-MCPyV IgMs rates and ODs were found in the 21-25 (17.5%) and 26-30 (7.7%) years old cohorts. Our data indicate that, upon an early-in-life seroconversion, the seropositivity for oncogenic MCPyV peaks in late childhood/young adulthood and remains at high prevalence and relatively stable throughout life.

Merkel Cell Polyomavirus: Infection, Genome, Transcripts and Its Role in Development of Merkel Cell Carcinoma

The best characterized polyomavirus family member, i.e., simian virus 40 (SV40), can cause different tumors in hamsters and can transform murine and human cells in vitro. Hence, the SV40 contamination of millions of polio vaccine doses administered from 1955-1963 raised fears that this may cause increased tumor incidence in the vaccinated population. This is, however, not the case. Indeed, up to now, the only polyomavirus family member known to be the most important cause of a specific human tumor entity is Merkel cell polyomavirus (MCPyV) in Merkel cell carcinoma (MCC). MCC is a highly deadly form of skin cancer for which the cellular origin is still uncertain, and which appears as two clinically very similar but molecularly highly different variants. While approximately 80% of cases are found to be associated with MCPyV the remaining MCCs carry a high mutational load. Here, we present an overview of the multitude of molecular functions described for the MCPyV encoded oncoproteins and non-coding RNAs, present the available MCC mouse models and discuss the increasing evidence that both, virus-negative and -positive MCC constitute epithelial tumors.

MicroRNA dysregulations in Merkel cell carcinoma: Molecular mechanisms and clinical applications

Merkel cell carcinoma (MCC) is an aggressive skin malignancy with two distinct etiologies. The first, which accounts for the highest proportion, is caused by Merkel cell polyomavirus (MCPyV), a DNA tumor virus. A second, UV-induced, MCC form has also been identified. Few MCC diagnostic, prognostic, and therapeutic options are available. MicroRNAs (miRNAs) are small noncoding RNA molecules, which play a key role in regulating various physiologic cellular functions including cell cycling, proliferation, differentiation, and apoptosis. Numerous miRNAs are dysregulated in cancer, by acting as either tumor suppressors or oncomiRs. The aim of this review is to collect, summarize, and discuss recent findings on miRNAs whose dysregulation has been assumed to play a role in MCC. The potential clinical application of miRNAs as diagnostic and prognostic biomarkers in MCC is also described. In the future, miRNAs will potentially gain clinical significance for the improvement of MCC diagnostic, prognostic, and therapeutic options.