Serologic evidence of frequent human infection with WU and KI polyomaviruses

A cornucopia of human polyomaviruses

During the past 6 years, focused virus hunting has led to the discovery of nine new human polyomaviruses, including Merkel cell polyomavirus, which has been linked to Merkel cell carcinoma, a lethal skin cell cancer. The discovery of so many new and highly divergent human polyomaviruses raises key questions regarding their evolution, tropism, latency, reactivation, immune evasion and contribution to disease. This Review describes the similarities and differences among the new human polyomaviruses and discusses how these viruses might interact with their human host.

From Stockholm to Malawi: recent developments in studying human polyomaviruses

Until a few years ago the polyomavirus family (Polyomaviridae) included a dozen viruses identified in avian and mammalian hosts. Two of these, the JC and BK-polyomaviruses isolated a long time ago, are known to infect humans and cause severe illness in immunocompromised hosts. Since 2007 an unprecedented number of eight novel polyomaviruses were discovered in humans. Among them are the KI- and WU-polyomaviruses identified in respiratory samples, the Merkel cell polyomavirus found in skin carcinomas and the polyomavirus associated with trichodysplasia spinulosa, a skin disease of transplant patients. Another four novel human polyomaviruses were identified, HPyV6, HPyV7, HPyV9 and the Malawi polyomavirus, so far not associated with any disease. In the same period several novel mammalian polyomaviruses were described. This review summarizes the recent developments in studying the novel human polyomaviruses, and touches upon several aspects of polyomavirus virology, pathogenicity, epidemiology and phylogeny.

The rapidly expanding family of human polyomaviruses: recent developments in understanding their life cycle and role in human pathology

Since their discovery in 1971, the polyomaviruses JC (JCPyV) and BK (BKPyV), isolated from patients with progressive multifocal leukoencephalopathy and polyomavirus-associated nephropathy, respectively, remained for decades as the only known members of the Polyomaviridae family of viruses of human origin. Over the past five years, the application of new genomic amplification technologies has facilitated the discovery of several novel human polyomaviruses (HPyVs), bringing the present number to 10. These HPyVs share many fundamental features in common such as genome size and organization. Infection by all HPyVs is widespread in the human population, but they show important differences in their tissue tropism and association with disease. Much remains unknown about these new viruses. In this review, we discuss the problems associated with studying HPyVs, such as the lack of culture systems for the new viruses and the gaps in our basic understanding of their biology. We summarize what is known so far about their distribution, life cycle, tissue tropism, their associated pathologies (if any), and future research directions in the field.

WU and KI polyomaviruses in respiratory samples from allogeneic hematopoietic cell transplant recipients

Routine testing for these viruses in immunocompromised patients is not recommended.

Data are limited regarding 2 new human polyomaviruses, KI polyomavirus (KIPyV) and WU polyomavirus (WUPyV), in immunocompromised patients. We used real-time PCR to test for these and 12 respiratory viruses in 2,732 nasal wash samples collected during the first year after allogeneic hematopoietic cell transplantation from 222 patients. Specimens were collected weekly until day 100; then at least every 3 months. One year after hematopoietic cell transplantation, the cumulative incidence estimate was 26% for KIPyV and 8% for WUPyV. Age <20 years predicted detection of KIPyV (hazard ratio [HR] 4.6) and WUPyV (HR 4.4), and detection of a respiratory virus in the previous 2 weeks predicted KIPyV detection (HR 3.4). Sputum production and wheezing were associated with detection of KIPyV in the past week and WUPyV in the past month. There were no associations with polyomavirus detection and acute graft versus host disease, cytomegalovirus reactivation, neutropenia, lymphopenia, hospitalization, or death.

Human polyomaviruses in disease and cancer

Today the human polyomavirus (HPyV) family consists of 10 members, BK virus (BKV) and JC virus (JCV) isolated 40 years ago and the more recently identified KI virus (KIPyV), WU virus (WUPyV), Merkel cell polyomavirus (MCPyV), HPyV6, HPyV7, trichodysplasia spinulosa virus (TSPyV), HPyV9 and MWPyV. Serological studies suggest that HPyVs subclinically infect the general population with rates ranging from 35% to 90%. However, significant disease is only observed in patients with impaired immune functions. Thus, BKV has been linked to hemorrhagic cystitis (HC) after allogeneic hematopoietic stem cell transplantation and PyV-associated nephropathy (PyVAN) after kidney transplantation; JCV to progressive multifocal leukoencephalopathy (PML) in HIV-AIDS, hematological diseases and in autoimmune diseases treated with certain lymphocyte-specific antibodies. KIPyV and WUPyV have been found in the respiratory tract, HPyV6 and 7 in the skin, and HPyV9 in serum and skin, and MWPyV in stools and skin, but so far none of these PyVs have been linked to any disease. TSPyV, on the other hand, was identified in trichodysplasia spinulosa, a rare skin disease characterized by virus-induced lytic as well as proliferative tumor-like features that is observed in immune-suppressed transplant patients. In contrast to all the other HPyVs so far, MCPyV is unique in its association with a cancer, Merkel cell carcinoma, which is a rare skin cancer arising in the elderly and chronically immunosuppressed individuals. The discovery of the new HPyVs has revived interest in the Polyomaviridae and their association to human disease and cancer. In this review, we summarize knowledge about this expanding family of human pathogens.

Seroprevalence and cross-reactivity of human polyomavirus 9

Many humans have antibodies against simian lymphotropic polyomavirus (LPyV), but its DNA has not been found in humans. Identification of human polyomavirus 9 (HPyV9) led us to compare the seroprevalence and cross-reactivity of LPyV and HpyV9. Results could indicate that humans who have antibodies against LPyV are infected by HPyV9.

Elucidation and clinical role of emerging viral respiratory tract infections in children

Acute respiratory viral infections (ARVI's) are the most common infectious disease in humans. With the appearance of molecular techniques the recovery of viruses has dramatically increased. Nowadays virologists can quickly discriminate virological families and related viruses from emerging viruses and consequently identify novel viruses. Many new respiratory viruses have been identified in children in the past 15 years. In this review we shortly discuss novel respiratory viruses and their pathogenic role in pediatric respiratory disease. Advantages and drawbacks of the technique and our current knowledge will be discussed. We will conclude this review with a general discussion on the future role of molecular diagnostic virology in the clinic.

Common WU polyomavirus infection in a Beijing population indicated by surveillance for serum IgG antibody against capsid protein VP2

BACKGROUND

WU polyomavirus (WU virus) was identified as a novel polyomavirus in 2007 from specimens of pediatric patients with acute respiratory infection (ARI). A lack of permissive cell lines has limited investigations into WU virus pathogenesis and prevalence.

METHODS

The encoding region of the capsid protein VP2 gene was amplified from a WU virus DNA-positive clinical specimen and expressed as a recombinant Histagged protein in Escherichia coli BL21 (DE3). The expressed VP2 was identified by expected molecular weight and immunoreactivity with anti-His monoclonal antibody in Western blotting assay. Serum samples collected from 455 individuals of all ages in Beijing without symptoms of ARI were tested for IgG antibodies against the affinity-purified recombinant VP2 protein by Western blotting to investigate the prevalence of natural WU virus infection. In addition, serum samples from four ARI pediatric patients, whose nasopharyngeal aspirates were positive for WU virus DNA and negative for all other respiratory-related viruses, were tested for IgM antibody against the recombinant VP2.

RESULTS

Of the 455 serum samples, 238 reacted with the recombinant VP2, yielding an overall positive rate of 52.3% for IgG against VP2 of WU virus. The positive rate was the highest in serum samples from infants and children between 1 to 4 years of age. One of four ARI pediatric patients was positive for IgM against WU virus VP2, implicating WU virus as the causative disease agent.

CONCLUSIONS

The high prevalence of IgG against WU polyomavirus in Beijing-based study population indicates that WU virus infection is common in Beijing. WU virus may be responsible for some pediatric ARI cases, and primary infection of this virus may occur mostly in childhood.

The polyomaviruses WUPyV and KIPyV: a retrospective quantitative analysis in patients undergoing hematopoietic stem cell transplantation

BACKGROUND

The polyomaviruses WUPyV and KIPyV have been detected in various sample types including feces indicating pathogenicity in the gastrointestinal (GI) system. However, quantitative viral load data from other simultaneously collected sample types are missing. As a consequence, primary replication in the GI system cannot be differentiated from swallowed virus from the respiratory tract. Here we present a retrospective quantitative longitudinal analysis in simultaneously harvested specimens from different organ sites of patients undergoing hematopoietic stem cell transplantation (HSCT). This allows the definition of sample types where deoxyribonucleic acid (DNA) detection can be expected and, as a consequence, the identification of their primary replication site.

FINDINGS

Viral DNA loads from 37 patients undergoing HSCT were quantified in respiratory tract secretions (RTS), stool and urine samples as well as in leukocytes (n = 449). Leukocyte-associated virus could not be found. WUPyV was found in feces, RTS and urine samples of an infant, while KIPyV was repeatedly detected in RTS and stool samples of 4 adult patients.RTS and stool samples were matched to determine the viral load difference showing a mean difference of 2.3 log copies/ml (p < 0.001).

CONCLUSIONS

The data collected in this study suggest that virus detection in the GI tract results from swallowed virus from the respiratory tract (RT). We conclude that shedding from the RT should be ruled out before viral DNA detection in the feces can be correlated to GI symptoms.

Novel human polyomaviruses in pregnancy: higher prevalence of BKPyV, but no WUPyV, KIPyV and HPyV9

BACKGROUND

Immunosuppression due to pregnancy may lead to higher susceptibility to infections and reactivation of latent infections, such as BK polyomavirus (BKPyV). There is lack of information about the prevalence of novel human polyomavirus 9 (HPyV9), WU (WUPyV) and KI (KIPyV) during pregnancy.

OBJECTIVES

To study whether pregnancy results in higher prevalence of HPyV9, WUPyV, KIPyV and their correlation with BKPyV.

STUDY DESIGN

Plasma, urine and throat swab samples from 100 pregnant and 100 non pregnant women were screened for the presence of WUPyV, KIPyV, HPyV9 and BKPyV by PCR.

RESULTS

No WUPyV DNA was detected in plasma, urine and respiratory samples from pregnant and non pregnant women. KIPyV DNA was found in two plasma samples from non pregnant women (2%) and not detected in other samples from neither pregnant nor non pregnant women. HPyV9 DNA was determined in all sample types of pregnant and non pregnant women, respectively. There were no significant differences between pregnant and non pregnant women in HPyV9 DNA frequencies for plasma (2% vs. 6%), urine (3% vs. 2%) and respiratory samples (2% vs. 2%). Prevalence of BKPyV in urine samples was significantly higher (p=0.039) in pregnant women (13%) then in non pregnant women (4%); co infection with KIPyV and/or HPyV9 was not detected.

CONCLUSIONS

In contrast with BKPyV, infection with WUPyV, KIPyV and HPyV9 was not detected more frequently during pregnancy. To the best of our knowledge HPyV9 was detected first in respiratory samples in our study.

Seroepidemiology of WU polyomavirus among children exposed perinatally to HIV-1

WU polyomavirus (WUPyV), a new member of the genus wukipolyomavirus in the family Polyomaviridae, has been detected in serum and tissues of individuals infected with HIV. However, the epidemiology of WUPyV among children exposed perinatally to HIV-1 is unknown. To investigate the epidemiology of WUPyV in children exposed to and infected perinatally with HIV, serum samples from 150 children exposed to HIV and 114 children infected with HIV were screened for IgG antibodies to WUPyV. A subset was screened for IgM antibodies to WUPyV. Both antibody detection assays were performed using a recombinant WUPyV VP1-based ELISA. The overall seroprevalence of WUPyV IgG was 76.3% in children infected with HIV and 62% in children exposed perinatally to HIV. In the group of children infected with HIV, the prevalence of WUPyV IgG antibody reached its peak in 2-3 year olds (90.9%). In children 0-5 months of age, IgG seroprevalence was lower in those children exposed to HIV compared to children infected with HIV (43.1% vs.75%, P = 0.047). However, the seroprevalence of WUPyV IgM antibody was higher in children exposed to HIV compared to infants infected with HIV (27.4% vs. 8.3%, P = 0.044). WUPyV infection is acquired in early childhood in the majority of children born to mothers infected with HIV. The implication of this infection and the specific clinical syndrome that it produces, if any, remain to be defined.

Viral infections of the lower respiratory tract

Lower respiratory tract infections (LRTIs) are a global burden to public health and are frequently caused by respiratory viruses. Advances in molecular diagnostic techniques have allowed the identification of previously undetected viral pathogens and have improved our understanding of respiratory virus infections. Here we review the epidemiological and clinical characteristics of recently identified viruses including human metapneumovirus, human coronaviruses NL63 and HKU1, human rhinovirus C, bocavirus, WU and KI polyomaviruses, and parechovirus. The roles of these viruses in LRTIs in children and adults are discussed.

Seroprevalence of human polyomavirus 9 and cross-reactivity to African green monkey-derived lymphotropic polyomavirus

Human polyomavirus 9 (HPyV9) was discovered recently in immunocompromised patients and shown to be genetically closely related to B-lymphotropic polyomavirus (LPyV). No serological data are available for HPyV9, but human antibodies against LPyV have been reported previously. To investigate the seroepidemiology of HPyV9 and the sero-cross-reactivity between HPyV9 and LPyV, a capsomer-based IgG ELISA was established using the major capsid protein VP1 of HPyV9 and LPyV. VP1 of an avian polyomavirus was used as control. For HPyV9, a seroprevalence of 47 % was determined in healthy adults and adolescents (n = 328) and 20 % in a group of children (n =101). In both groups, the seroreactivities for LPyV were less frequent and the ELISA titres of LPyV were lower. Of the HPyV9-reactive sera, 47 % reacted also with LPyV, and the titres for both PyVs correlated. Sera from African green monkeys, the natural hosts of LPyV, reacted also with both HPyV9 and LPyV, but here the HPyV9 titres were lower. This potential sero-cross-reactivity between HPyV9 and LPyV was confirmed by competition assays, and it was hypothesized that the reactivity of human sera against LPyV may generally be due to cross-reactivity between HPyV9 and LPyV. The HPyV9 seroprevalence of liver transplant recipients and patients with neurological dysfunctions did not differ from that of age-matched controls, but a significantly higher seroprevalence was determined in renal and haematopoietic stem-cell transplant recipients, indicating that certain immunocompromised patient groups may be at a higher risk for primary infection with or for reactivation of HPyV9.

Seroprevalence of trichodysplasia spinulosa-associated polyomavirus

We identified a new polyomavirus in skin lesions from a patient with trichodysplasia spinulosa (TS). Apart from TS being an extremely rare disease, little is known of its epidemiology. On the basis of knowledge regarding other polyomaviruses, we anticipated that infections with trichodysplasia spinulosa-associated polyomavirus (TSV) occur frequently and become symptomatic only in immunocompromised patients. To investigate this hypothesis, we developed and used a Luminex-based TSV viral protein 1 immunoassay, excluded cross-reactivity with phylogenetically related Merkel cell polyomavirus, and measured TSV seroreactivity. Highest reactivity was found in a TS patient. In 528 healthy persons in the Netherlands, a wide range of seroreactivities was measured and resulted in an overall TSV seroprevalence of 70% (range 10% in small children to 80% in adults). In 80 renal transplant patients, seroprevalence was 89%. Infection with the new TSV polyomavirus is common and occurs primarily at a young age.

Efficient propagation of archetype BK and JC polyomaviruses

BKPyV and JCPyV are closely related, ubiquitous human pathogens that cause disease in immunocompromised patients. The DNA sequence of the regulatory regions distinguishes two forms of these viruses, designated archetype and rearranged. Although cell culture systems exist for rearranged BKPyV and JCPyV, currently there is no robust cell culture system to study the archetype viruses. Large T antigen (TAg) is a virally encoded protein required to initiate viral DNA synthesis. Because archetype virus produces undetectable levels of TAg, we hypothesized that TAg overexpression would stimulate archetype virus replication. Efficient propagation of the archetype forms of BKPyV and JCPyV was observed in 293TT cells, human embryonic kidney cells overexpressing SV40 TAg. Importantly, the archetypal structure of the regulatory region was maintained during viral growth. Significant replication was not observed for Merkel cell, KI, or WU polyomaviruses. 293TT cells provide a means of propagating archetype BKPyV and JCPyV for detailed study.

Human polyomaviruses in skin diseases

Polyomaviruses are a family of small, nonenveloped viruses with a circular double-stranded DNA genome of ∼5,000 base pairs protected by an icosahedral protein structure. So far, members of this family have been identified in birds and mammals. Until 2006, BK virus (BKV), JC virus (JCV), and simian virus 40 (SV40) were the only polyomaviruses known to circulate in the human population. Their occurrence in individuals was mainly confirmed by PCR and the presence of virus-specific antibodies. Using the same methods, lymphotropic polyomavirus, originally isolated in monkeys, was recently shown to be present in healthy individuals although with much lower incidence than BKV, JCV, and SV40. The use of advanced high-throughput sequencing and improved rolling circle amplification techniques have identified the novel human polyomaviruses KI, WU, Merkel cell polyomavirus, HPyV6, HPyV7, trichodysplasia spinulosa-associated polyomavirus, and HPyV9. The skin tropism of human polyomaviruses and their dermatopathologic potentials are the focus of this paper.

[Merkel cell carcinoma revisited: a new example of viro-induced human tumour]

Merkel cell carcinoma (MCC) is a neuroendocrine carcinoma of the skin of poor outcome. A new type of virus, isolated in 2008, was found to be strongly associated with CCM. This virus, belonging to the family of polyomavirus, was called MCPyV for Merkel Carcinoma Polyomavirus. Recent data favour a causative role of MCPyV in oncogenesis. MCC represents thus a new model for the understanding of the mechanisms of oncogenesis. The distinct molecular viral signature in every case of MCC represents an original tool for the follow-up of the disease. New therapeutic perspectives are to be drawn using this model.

WU polyomavirus infection among children in South China

This study aimed at investigating the prevalence and clinical characteristics of children with respiratory infection by WU polyomavirus (WUPyV) in Southern China. Nasopharyngeal aspirate samples were collected from 771 children with acute respiratory tract infection admitted to hospital and 82 samples from healthy subjects for routine examination at the outpatient service at the Second Affiliated Hospital of Shantou University, Medical College from July 2008 to June 2009. WUPyV was detected by the polymerase chain reaction (PCR) and DNA sequencing. All WUPyV-positive specimens were characterized further for nine viruses causing common respiratory infections, including influenza A and B, respiratory syncytial virus (RSV), parainfluenza virus (PIV) 1 and 3, human metapneumovirus, human bocavirus, adenovirus, and rhinovirus by PCR or real time (RT)-PCR. Fifteen out of 771 specimens from patients with acute respiratory tract infection, but none from healthy subjects, were positive for WUPyV and the positivity rate was 2%. Patients with WUPyV infection were between 2 and 48 months of age, and nine of the patients were male while six female. Four out of 15 patients were co-infected with RSV, one with adenovirus or rhinovirus, respectively. Patients with WUPyV infection displayed predominantly cough, moderate fever, and wheezing, and were diagnosed with pneumonia (n = 8), bronchiolitis (n = 4), upper respiratory tract infections (n = 2) and bronchitis (n = 1). One patient developed encephalitis. Therefore, WUPyV infection can cause acute respiratory tract infection with atypical symptoms, including severe complications, in children.

Infrequent detection of KI, WU and MC polyomaviruses in immunosuppressed individuals with or without progressive multifocal leukoencephalopathy

Conflicting prevalence of newly identified KI(KIPyV), WU(WUPyV) and Merkel Cell Carcinoma(MCPyV) polyomaviruses have been reported in progressive multifocal leukoencephalopathy(PML) patient samples, ranging from 0 to 14.3%. We analyzed the prevalence of these polyomaviruses in cerebrospinal fluid(CSF), peripheral blood mononuclear cells(PBMC), and bone marrow samples from PML patients, immunosuppressed individuals with or without HIV, and multiple sclerosis(MS) patients. Distinct PCR tests for KIPyV, WUPyV and MCPyV DNA performed in two independent laboratories detected low levels of MCPyV DNA only in 1/269 samples. The infrequent detections of these viruses in multiple samples from immunosuppressed individuals including those with PML suggest that their reactivation mechanisms may be different from that of JC polyomavirus (JCPyV) and that they do not play a role in the pathogenesis of PML.

Expression and serological characterization of polyomavirus WUPyV and KIPyV structural proteins

The polyomaviruses WUPyV and KIPyV were recently discovered. We expressed their structural proteins VP1, VP2, and VP3, and the corresponding proteins of BKV and JCV, for immunoblotting of IgG antibodies from 115 wheezing young children and 25 asymptomatic adults. Furthermore, nasopharyngeal aspirates (NPA) and sera from the children were examined by PCR for viral DNA. The overlapping minor proteins VP2 and VP3 of WUPyV and KIPyV were more reactive in immunoblots than the major protein VP1; of 100 NPA PCR-negative wheezing children aged < or = 4 y, 31 (31%) and 31 (31%) were positive for WUPyV and KIPyV VP2/VP3, compared to only 3 (3%) and 5 (5%) for VP1, respectively. For comparison, the respective WUPyV and KIPyV IgG seroprevalences as determined by immunofluorescence assay (IFA) with nondenatured VP1 were 80% and 54%, respectively, among 50 NPA PCR-negative children aged < or = 2 y. This difference shows the importance of conformational VP1 antigenicity. Of the 25 adults, 52% and 68% were IgG-positive in immunoblots for VP2/VP3 of WUPyV and KIPyV, and 8% and 12% were for VP1, respectively. Of the 192 NPA samples studied by PCR, 7 (3.6%) were positive for WUPyV, and 3 (1.5%) were positive for KIPyV DNA. Unlike the NPA samples, none of the corresponding 443 sera contained WUPyV or KIPyV DNA. Together with the high VP2/VP3 IgG prevalence, this points to a paucity or brevity of KIPyV and WUPyV viremias among immunocompetent children. Our results indicate the significance of protein conformation in immunoreactivity of VP1, and show the antigenic importance of the WUPyV and KIPyV minor proteins VP2 and VP3. The high and rapidly increasing IgG prevalence rates observed in this study for WUPyV and KIPyV support the notion that these novel polyomaviruses are widespread and are acquired early in childhood.

Serological evidence of Merkel cell polyomavirus primary infections in childhood

BACKGROUND

Merkel cell polyomavirus (MCPyV) was identified newly (2008) and is believed to be an etiologic factor of Merkel cell carcinoma (MCC). Recent molecular and serological data suggest that MCPyV infection is common in the general population.

OBJECTIVES

The aim of this study was to investigate the age of primary exposure to MCPyV.

STUDY DESIGN

A MCPyV-IgG EIA was developed using the MCPyV major capsid protein VP1 expressed and self-assembled into virus-like particles (VLPs) in insect cells. The assay was used to detect serum IgG antibodies in two groups of children. Group 1 comprised paired and 5-8 year follow-up sera from 217 children (3-13 years) with acute lower respiratory tract infection. Group 2 comprised sera from 158 children (1-4 years) with otitis media; 86 children underwent adenoidectomy and 72 did not, whereafter follow-up sera were obtained 3 years later.

RESULT

The prevalence of MCPyV-IgG was 9% at 1-4 years, and increased to 35% at 4-13 years among subjects from Group 1, with a 33% seroconversion rate during 5-8 years. Among Group 2, the seroconversion rate was 16% during 3 years. The IgG prevalence at 4-7 years as well as the IgG levels showed an apparent gender difference, with male preponderance prevailing among the children without adenoidectomy.

CONCLUSION

MCPyV primary infections occur ubiquitously in childhood, and the first exposure takes place at young age. The serology showed no evidence for a causative role of MCPyV in lower respiratory tract infection manifesting as acute wheezing, but was compatible with the notion of MCPyV persistence in tonsils.

Newly discovered KI, WU, and Merkel cell polyomaviruses: no evidence of mother-to-fetus transmission

Background

Three* human polyomaviruses have been discovered recently, KIPyV, WUPyV and MCPyV. These viruses appear to circulate ubiquitously; however, their clinical significance beyond Merkel cell carcinoma is almost completely unknown. In particular, nothing is known about their preponderance in vertical transmission. The aim of this study was to investigate the frequency of fetal infections by these viruses. We sought the three by PCR, and MCPyV also by real-time quantitative PCR (qPCR), from 535 fetal autopsy samples (heart, liver, placenta) from intrauterine fetal deaths (IUFDs) (N = 169), miscarriages (120) or induced abortions (246). We also measured the MCPyV IgG antibodies in the corresponding maternal sera (N = 462) mostly from the first trimester.

Results

No sample showed KIPyV or WUPyV DNA. Interestingly, one placenta was reproducibly PCR positive for MCPyV. Among the 462 corresponding pregnant women, 212 (45.9%) were MCPyV IgG seropositive.

Conclusions

Our data suggest that none of the three emerging polyomaviruses often cause miscarriages or IUFDs, nor are they transmitted to fetuses. Yet, more than half the expectant mothers were susceptible to infection by the MCPyV.

Distinct merkel cell polyomavirus molecular features in tumour and non tumour specimens from patients with merkel cell carcinoma

Merkel Cell Polyomavirus (MCPyV) is associated with Merkel Cell carcinoma (MCC), a rare, aggressive skin cancer with neuroendocrine features. The causal role of MCPyV is highly suggested by monoclonal integration of its genome and expression of the viral large T (LT) antigen in MCC cells. We investigated and characterized MCPyV molecular features in MCC, respiratory, urine and blood samples from 33 patients by quantitative PCR, sequencing and detection of integrated viral DNA. We examined associations between either MCPyV viral load in primary MCC or MCPyV DNAemia and survival. Results were interpreted with respect to the viral molecular signature in each compartment. Patients with MCC containing more than 1 viral genome copy per cell had a longer period in complete remission than patients with less than 1 copy per cell (34 vs 10 months, P = 0.037). Peripheral blood mononuclear cells (PBMC) contained MCPyV more frequently in patients sampled with disease than in patients in complete remission (60% vs 11%, P = 0.00083). Moreover, the detection of MCPyV in at least one PBMC sample during follow-up was associated with a shorter overall survival (P = 0.003). Sequencing of viral DNA from MCC and non MCC samples characterized common single nucleotide polymorphisms defining 8 patient specific strains. However, specific molecular signatures truncating MCPyV LT were observed in 8/12 MCC cases but not in respiratory and urinary samples from 15 patients. New integration sites were identified in 4 MCC cases. Finally, mutated-integrated forms of MCPyV were detected in PBMC of two patients with disseminated MCC disease, indicating circulation of metastatic cells. We conclude that MCPyV molecular features in primary MCC tumour and PBMC may help to predict the course of the disease.

Merkel cell polyomavirus (MCPyV) is a recently discovered virus highly associated with a rare skin cancer, Merkel cell carcinoma (MCC). The causal role of MCPyV in cancer is suggested by integration of viral sequences into the cell genome and by a specific molecular signature. We looked for and compared molecular species of MCPyV in tumour and non tumour samples of 33 MCC patients. We showed that a tumour viral load greater than 1 copy per cell was associated with a better outcome, and that detection of the virus in blood but not in urine correlated with a shorter overall survival. A tumour–specific molecular signature was found in the blood of two patients with metastatic disease, but did not occur in their respiratory nor urine samples. We propose that molecular analysis of MCPyV in tumour and blood be used as a biomarker of infection and cancer progression in MCC patients.

Glycyrrhizin inhibits highly pathogenic H5N1 influenza A virus-induced pro-inflammatory cytokine and chemokine expression in human macrophages

Hypercytokinaemia is thought to contribute to highly pathogenic H5N1 influenza A virus disease. Glycyrrhizin is known to exert immunomodulatory and anti-inflammatory effects and therefore a candidate drug for the control of H5N1-induced pro-inflammatory gene expression. Here, the effects of an approved parenteral glycyrrhizin preparation were investigated on H5N1 virus replication, H5N1-induced pro-inflammatory responses, and H5N1-induced apoptosis in human monocyte-derived macrophages. Glycyrrhizin 100 μg/ml, a therapeutically achievable concentration, impaired H5N1-induced production of CXCL10, interleukin 6, and CCL5 and inhibited H5N1-induced apoptosis but did not interfere with H5N1 replication. Global inhibition of immune responses may result in the loss of control of virus replication by cytotoxic immune cells including natural killer cells and cytotoxic CD8(+) T-lymphocytes. Notably, glycyrrhizin concentrations that inhibited H5N1-induced pro-inflammatory gene expression did not affect cytolytic activity of natural killer cells. Since H5N1-induced hypercytokinaemia is considered to play an important role within H5N1 pathogenesis, glycyrrhizin may complement the arsenal of potential drugs for the treatment of H5N1 disease.