Differential distribution of the JC virus receptor-type sialic acid in normal human tissues

Human B cells and dendritic cells are susceptible and permissive to enterovirus D68 infection

Enterovirus D68 (EV-D68) is predominantly associated with mild respiratory infections, but can also cause severe respiratory disease and extra-respiratory complications, including acute flaccid myelitis. Systemic dissemination of EV-D68 is crucial for the development of extra-respiratory diseases, but it is currently unclear how EV-D68 spreads systemically (viremia). We hypothesize that immune cells contribute to the systemic dissemination of EV-D68, as this is a mechanism commonly used by other enteroviruses. Therefore, we investigated the susceptibility and permissiveness of human primary immune cells for different EV-D68 isolates. In human peripheral blood mononuclear cells inoculated with EV-D68, only B cells were susceptible but virus replication was limited. However, in B cell-rich cultures, such as Epstein-Barr virus-transformed B-lymphoblastoid cell line (BLCL) and primary lentivirus-transduced B cells, which better represent lymphoid B cells, were productively infected. Subsequently, we showed that dendritic cells (DCs), particularly immature DCs, are susceptible and permissive for EV-D68 infection and that they can spread EV-D68 to autologous BLCL. Altogether, our findings suggest that immune cells, especially B cells and DCs, could play an important role in the pathogenesis of EV-D68 infection. Infection of these cells may contribute to systemic dissemination of EV-D68, which is an essential step toward the development of extra-respiratory complications.IMPORTANCEEnterovirus D68 (EV-D68) is an emerging respiratory virus that has caused outbreaks worldwide since 2014. EV-D68 infects primarily respiratory epithelial cells resulting in mild respiratory diseases. However, EV-D68 infection is also associated with extra-respiratory complications, including polio-like paralysis. It is unclear how EV-D68 spreads systemically and infects other organs. We hypothesized that immune cells could play a role in the extra-respiratory spread of EV-D68. We showed that EV-D68 can infect and replicate in specific immune cells, that is, B cells and dendritic cells (DCs), and that virus could be transferred from DCs to B cells. Our data reveal a potential role of immune cells in the pathogenesis of EV-D68 infection. Intervention strategies that prevent EV-D68 infection of immune cells will therefore potentially prevent systemic spread of virus and thereby severe extra-respiratory complications.

Polyomavirus Wakes Up and Chooses Neurovirulence

JC polyomavirus (JCPyV) is a human-specific polyomavirus that establishes a silent lifelong infection in multiple peripheral organs, predominantly those of the urinary tract, of immunocompetent individuals. In immunocompromised settings, however, JCPyV can infiltrate the central nervous system (CNS), where it causes several encephalopathies of high morbidity and mortality. JCPyV-induced progressive multifocal leukoencephalopathy (PML), a devastating demyelinating brain disease, was an AIDS-defining illness before antiretroviral therapy that has "reemerged" as a complication of immunomodulating and chemotherapeutic agents. No effective anti-polyomavirus therapeutics are currently available. How depressed immune status sets the stage for JCPyV resurgence in the urinary tract, how the virus evades pre-existing antiviral antibodies to become viremic, and where/how it enters the CNS are incompletely understood. Addressing these questions requires a tractable animal model of JCPyV CNS infection. Although no animal model can replicate all aspects of any human disease, mouse polyomavirus (MuPyV) in mice and JCPyV in humans share key features of peripheral and CNS infection and antiviral immunity. In this review, we discuss the evidence suggesting how JCPyV migrates from the periphery to the CNS, innate and adaptive immune responses to polyomavirus infection, and how the MuPyV-mouse model provides insights into the pathogenesis of JCPyV CNS disease.

The oncogenic roles of JC polyomavirus in cancer

JC polyomavirus (JCPyV) belongs to the human polyomavirus family. Based on alternative splicing, the early region encodes the large and small T antigens, while the late region encodes the capsid structural proteins (VP1, VP2, and VP3) and the agnoprotein. The regulatory transcription factors for JCPyV include Sp1, TCF-4, DDX1, YB-1, LCP-1, Purα, GF-1, and NF-1. JCPyV enters tonsillar tissue through the intake of raw sewage, inhalation of air droplets, or parent-to-child transmission. It persists quiescently in lymphoid and renal tissues during latency. Both TGF-β1 and TNF-α stimulates JCPyV multiplication, while interferon-γ suppresses the process. The distinct distribution of caspid receptors (α-2, 6-linked sialic acid, non-sialylated glycosaminoglycans, and serotonin) determines the infection capabilities of JCPyV virions, and JCPyV entry is mediated by clathrin-mediated endocytosis. In permissive cells, JCPyV undergoes lytic proliferation and causes progressive multifocal leukoencephalopathy, while its DNA is inserted into genomic DNA and leads to carcinogenesis in non-permissive cells. T antigen targets p53, β-catenin, IRS, Rb, TGF-β1, PI3K/Akt and AMPK signal pathways in cancer cells. Intracranial injection of T antigen into animals results in neural tumors, and transgenic mice develop neural tumors, lens tumor, breast cancer, gastric, Vater’s, colorectal and pancreatic cancers, insulinoma, and hepatocellular carcinoma. Additionally, JCPyV DNA and its encoded products can be detected in the brain tissues of PML patients and brain, oral, esophageal, gastric, colorectal, breast, cervical, pancreatic, and hepatocellular cancer tissues. Therefore, JCPyV might represent an etiological risk factor for carcinogenesis and should be evaluated for early prevention, diagnosis, and treatment of cancers.

Higher detection of JC polyomavirus in colorectal cancerous tissue after pretreatment with topoisomerase I enzyme; colorectal tissue serves as a JCPyV persistence site

BACKGROUND

The JC polyomavirus has been blamed to contribute in colorectal cancer (CRC), however, the topic is still controversial. Varying detection rate of JCPyV genome has been reported mainly due to technical reasons. Here, we provide summative data on the topic, with emphasize on technical issues.

METHODS

Formalin-fixed paraffin-embedded tissue samples from 50 patients with CRC, consisting of tumoral and non-cancerous marginal tissue (totally 100 samples) were included in the study. After DNA extraction, specific JCPyV T-Ag sequences were targeted using Real-time PCR. To unwind the supercoiled JCPyV genome, pretreatment with topoisomerase I, was applied. Immunohistochemical (IHC) staining was performed using an anti-T-Ag monoclonal antibody.

RESULTS

In the first attempts, no samples were found to be positive in Real-time PCR assays. However, JCPyV sequences were found in 60% of CRC tissues and 38% of non-cancerous colorectal mucosa after application of pre-treatment step with topoisomerase I enzyme (P = 0.028). T-Ag protein was found in the nuclear compartment of the stained cells in IHC assays.

CONCLUSIONS

The presence of JCPyV in CRC tissues, as well as T-Ag localization in the nucleolus, where its oncogenic effect takes place, may provide supporting evidence for JCPyV involvement in CRC development. The study highlights the importance of using topoisomerase I to enhance JCPyV genome detection. Also, colorectal tissue is one of the permissive human tissue for JC resistance after preliminary infection.

The Oncogenic Roles of JC Virus T Antigen in Breast Carcinogenesis

Purpose: JC virus (JCV) infects 80–90% of the population and results in progressive multifocal leukoencephalopathy upon immunodeficiency. The study aimed to pathologically clarify the oncogenic roles of T antigen in human breast cancers.

Methods: Breast cancer, dysplasia, and normal tissues were examined for T antigen of JCV by nested and real-time PCR. The positive rate or copy number of T antigen was compared with clinicopathological parameters of breast cancer. JCV existence was morphologically detected by immunohistochemistry and in situ PCR. T antigen was examined by Western blot using frozen samples of breast cancer and paired normal tissues.

Results: According to nested PCR, the positive rate of breast ductal or lobular carcinoma was lower than that of normal tissue (p < 0.05). T antigen existence was negatively correlated with E-cadherin expression and triple-negative breast cancer (p < 0.05), but positively correlated with lymph node metastasis and estrogen receptor and progestogen receptor expression (p < 0.05). Quantitative PCR showed that JCV copies were gradually decreased from normal, dysplasia to cancer tissues (p < 0.05). JCV T antigen copy number was lower in ductal adenocarcinoma than in normal tissue (p < 0.05), in line with in situ PCR and immunohistochemistry. JCV copies were negatively correlated with tumor size and E-cadherin expression (p < 0.05), but positively correlated with G grading of breast cancer (p < 0.05). Western blot also indicated weaker T antigen expression in breast cancer than normal tissues (p < 0.05).

Conclusion: JCV T antigen might play an important role in breast carcinogenesis. It can be employed as a molecular marker for the differentiation and aggressive behaviors of breast cancer.

The pathogenesis and virulence of enterovirus-D68 infection

In 2014, enterovirus D68 (EV-D68) emerged causing outbreaks of severe respiratory disease in children worldwide. In a subset of patients, EV-D68 infection was associated with the development of central nervous system (CNS) complications, including acute flaccid myelitis (AFM). Since then, the number of reported outbreaks has risen biennially, which emphasizes the need to unravel the systemic pathogenesis in humans. We present here a comprehensive review on the different stages of the pathogenesis of EV-D68 infection – infection in the respiratory tract, systemic dissemination and infection of the CNS – based on observations in humans as well as experimental in vitro and in vivo studies. This review highlights the knowledge gaps on the mechanisms of systemic dissemination, routes of entry into the CNS and mechanisms to induce AFM or other CNS complications, as well as the role of virus and host factors in the pathogenesis of EV-D68.

Possible Oncogenic Viruses Associated with Lung Cancer

Lung cancer is the most common cause of cancer death worldwide. Tobacco smoking is the most predominant etiology for lung cancer. However, only a small percentage of heavy smokers develop lung cancer, which suggests that other cofactors are required for lung carcinogenesis. Viruses have been central to modern cancer research and provide profound insights into cancer causes. Nevertheless, the role of virus in lung cancer is still unclear. In this article, we reviewed the possible oncogenic viruses associated with lung cancer.

Human BK and JC polyomaviruses: Molecular insights and prevalence in Asia

Polyomaviridae family consists of small circular dsDNA viruses. Out of the 14 human polyomaviruses described so far, BKPyV and JCPyV have been studied extensively since their discovery in 1971. Reportedly, both BKPyV and JCPyV are widely distributed across the globe with the frequency of 80-90 % in different populations. The primary infection of these viruses is usually asymptomatic and latent which is activated as a consequence of immunosuppression. Activated BKPyV and JCPyV viruses lead to the development of BK Virus Associated Nephropathy and Progressive Multifocal Leukoencephalopathy, respectively. Immense progress has been made during the last few decades regarding the molecular understanding of polyomaviruses. Epidemiology of polyomaviruses has also been studied extensively. However, most of the epidemiological studies have focused on European and American populations. Therefore, limited data is available regarding the geographical distribution of these potentially oncogenic viruses in Asian countries. In this article, we have presented a compendium of latest advances in the molecular understanding of polyomaviruses and their pathobiology. We also present a comprehensive review of published literature regarding the epidemiology and prevalence of BKPyV and JCPyV in Asian regions. For this purpose, a thorough search of available online resources was performed. As a result, we retrieved 24 studies for BKPyV and 22 studies for JCPyV, that describe their prevalence in Asia. These studies unanimously report high occurrence of both BKPyV and JCPyV in Asian populations. The available data from these studies was categorized into two groups: on the basis of prevalence (low, medium and high) and disease development (healthy and diseased). Altogether, Korean population hasbeen evidenced to possess highest frequency of BKPyV (66.7 %), while JCPyV was found to be most prevalent in Taiwan (88 %). Due to high and ubiquitous distribution of these viruses, frequent studies are required to develop a better understanding regarding the epidemiology and pathobiology of these viruses in Asia.

Human Polyomavirus JCPyV and Its Role in Progressive Multifocal Leukoencephalopathy and Oncogenesis

The human neurotropic virus JCPyV, a member of the Polyomaviridiae family, is the opportunistic infectious agent of Progressive Multifocal Leukoencephalopathy (PML), a fatal disease seen in severe immunosuppressive conditions and, during the last decade, in patients undergoing immunotherapy. JCPyV is a ubiquitous pathogen with up to 85% of the adult population word-wide exhibiting antibodies against it. Early experiments demonstrated that direct inoculation of JCPyV into the brain of different species resulted in the development of brain tumors and other neuroectodermal-derived neoplasias. Later, several reports showed the detection of viral sequences in medulloblastomas and glial tumors, as well as expression of the viral protein T-Antigen. Few oncogenic viruses, however, have caused so much controversy regarding their role in the pathogenesis of brain tumors, but the discovery of new Polyomaviruses that cause Merkel cell carcinomas in humans and brain tumors in racoons, in addition to the role of JCPyV in colon cancer and multiple mechanistic studies have shed much needed light on the role of JCPyV in cancer. The pathways affected by the viral protein T-Antigen include cell cycle regulators, like p53 and pRb, and transcription factors that activate pro-proliferative genes, like c-Myc. In addition, infection with JCPyV causes chromosomal damage and T-Antigen inhibits homologous recombination, and activates anti-apoptotic proteins, such as Survivin. Here we review the different aspects of the biology and physiopathology of JCPyV.

Viral Factors Important for Efficient Replication of Influenza A Viruses in Cells of the Central Nervous System

Central nervous system (CNS) disease is one of the most common extrarespiratory tract complications of influenza A virus infections, and the frequency and severity differ between seasonal, pandemic, and zoonotic influenza viruses. However, little is known about the interaction of these viruses with cells of the CNS. Differences among seasonal, pandemic, and zoonotic influenza viruses in replication efficacy in CNS cells, in vitro, suggest that the presence of an alternative HA cleavage mechanism and ability to attach are important viral factors. Identifying these viral factors and detailed knowledge of the interaction between influenza virus and CNS cells are important to prevent and treat this potentially lethal CNS disease.

Central nervous system (CNS) disease is one of the most common extrarespiratory tract complications of influenza A virus infections. Remarkably, zoonotic H5N1 virus infections are more frequently associated with CNS disease than seasonal or pandemic influenza viruses. Little is known about the interaction between influenza A viruses and cells of the CNS; therefore, it is currently unknown which viral factors are important for efficient replication. Here, we determined the replication kinetics of a seasonal, pandemic, zoonotic, and lab-adapted influenza A virus in human neuron-like (SK-N-SH) and astrocyte-like (U87-MG) cells and primary mouse cortex neurons. In general, highly pathogenic avian influenza (HPAI) H5N1 virus replicated most efficiently in all cells, which was associated with efficient attachment and infection. Seasonal H3N2 and to a lesser extent pandemic H1N1 virus replicated in a trypsin-dependent manner in SK-N-SH but not in U87-MG cells. In the absence of trypsin, only HPAI H5N1 and WSN viruses replicated. Removal of the multibasic cleavage site (MBCS) from HPAI H5N1 virus attenuated, but did not abrogate, replication. Taken together, our results showed that the MBCS and, to a lesser extent, the ability to attach are important determinants for efficient replication of HPAI H5N1 virus in cells of the CNS. This suggests that both an alternative hemagglutinin (HA) cleavage mechanism and preference for α-2,3-linked sialic acids allowing efficient attachment contribute to the ability of influenza A viruses to replicate efficiently in cells of the CNS. This study further improves our knowledge on potential viral factors important for the neurotropic potential of influenza A viruses.

IMPORTANCE Central nervous system (CNS) disease is one of the most common extrarespiratory tract complications of influenza A virus infections, and the frequency and severity differ between seasonal, pandemic, and zoonotic influenza viruses. However, little is known about the interaction of these viruses with cells of the CNS. Differences among seasonal, pandemic, and zoonotic influenza viruses in replication efficacy in CNS cells, in vitro, suggest that the presence of an alternative HA cleavage mechanism and ability to attach are important viral factors. Identifying these viral factors and detailed knowledge of the interaction between influenza virus and CNS cells are important to prevent and treat this potentially lethal CNS disease.

Plant-made virus-like particle vaccines bearing the hemagglutinin of either seasonal (H1) or avian (H5) influenza have distinct patterns of interaction with human immune cells in vitro

INTRODUCTION

The recent emergence of avian influenza strains has fuelled concern about pandemic preparedness since vaccines targeting these viruses are often poorly immunogenic. Weak antibody responses to vaccines have been seen across multiple platforms including plant-made VLPs. To better understand these differences, we compared the in vitro responses of human immune cells exposed to plant-made virus-like particle (VLP) vaccines targeting H1N1 (H1-VLP) and H5N1 (H5-VLP).

METHODS

Peripheral blood mononuclear cells (PBMC) from healthy adults were stimulated ex vivo with 2-5µg/mL VLPs bearing the hemagglutinin (HA) of either H1N1 (A/California/7/2009) or H5N1 (A/Indonesia/5/05). VLP-immune cell interactions were characterized by confocal microscopy and flow cytometry 30min after stimulation with dialkylaminostyryl dye-labeled (DiD) VLP. Expression of CD69 and pro-inflammatory cytokines were used to assess innate immune activation 6h after stimulation.

RESULTS

H1- and H5-VLPs rapidly associated with all subsets of human PBMC but exhibited unique binding preferences and frequencies. The H1-VLP bound to 88.7±1.6% of the CD19⁺ B cells compared to only 21.9±1.8% bound by the H5-VLP. At 6h in culture, CD69 expression on B cells was increased in response to H1-VLP but not H5-VLP (22.79±3.42% vs. 6.15±0.82% respectively: p<0.0001). Both VLPs were rapidly internalized by CD14⁺ monocytes resulting in the induction of pro-inflammatory cytokines (i.e.: IL-8, IL-1β, TNFα and IL-6). However, a higher concentration of the H5-VLP was required to induce a comparable response and the pattern of cytokine production differed between VLP vaccines.

CONCLUSIONS

Plant-made VLP vaccines bearing H1 or H5 rapidly elicit immune activation and cytokine production in human PBMC. Differences in the VLP-immune cell interactions suggest that features of the HA proteins themselves, such as receptor specificity, influence innate immune responses. Although not generally considered for inactivated vaccines, the distribution and characteristics of influenza receptor(s) on the immune cells themselves may contribute to both the strength and pattern of the immune response generated.

Nasal Infection of Enterovirus D68 Leading to Lower Respiratory Tract Pathogenesis in Ferrets (Mustela putorius furo)

Data from EV-D68-infected patients demonstrate that pathological changes in the lower respiratory tract are principally characterized by severe respiratory illness in children and acute flaccid myelitis. However, lack of a suitable animal model for EV-D68 infection has limited the study on the pathogenesis of this critical pathogen, and the development of a vaccine. Ferrets have been widely used to evaluate respiratory virus infections. In the current study, we used EV-D68-infected ferrets as a potential animal to identify impersonal indices, involving clinical features and histopathological changes in the upper and lower respiratory tract (URT and LRT). The research results demonstrate that the EV-D68 virus leads to minimal clinical symptoms in ferrets. According to the viral load detection in the feces, nasal, and respiratory tracts, the infection and shedding of EV-D68 in the ferret model was confirmed, and these results were supported by the EV-D68 VP1 immunofluorescence confocal imaging with α2,6-linked sialic acid (SA) in lung tissues. Furthermore, we detected the inflammatory cytokine/chemokine expression level, which implied high expression levels of interleukin (IL)-1a, IL-8, IL-5, IL-12, IL-13, and IL-17a in the lungs. These data indicate that systemic observation of responses following infection with EV-D68 in ferrets could be used as a model for EV-D68 infection and pathogenesis.

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.

Polyomavirus Nephropathy in Kidney Transplantation

Polyomavirus nephropathy has become an important complication in kidney transplantation, with a prevalence of 1% to 8%. Unfortunately, the risk factors for polyomavirus nephropathy and renal allograft loss are not well defined. The definitive diagnosis is made through assessment of a kidney transplant biopsy. Recently, noninvasive urine and serum markers have been used to assist in polyomavirus nephropathy diagnosis and monitoring. Primary treatment is immunosuppression reduction, but must be balanced with the risks of rejection. No antiviral treatments for polyomavirus nephropathy have been approved by the Food and Drug Administration. Although cidofovir has shown in vitro activity against murine polyomaviruses, and has been effective in some patients, it is associated with significant nephrotoxicity. Graft loss due to polyomavirus nephropathy should not be a contraindication to retransplantation; however, experience is limited. This review presents potential risk factors, screening, diagnostic and monitoring methods, therapeutic management, and retransplantation experience for polyomavirus nephropathy.

Gene Therapy for Human Lung Adenocarcinoma Using a Suicide Gene Driven by a Lung-Specific Promoter Delivered by JC Virus-Like Particles

Lung adenocarcinoma, the most commonly diagnosed type of lung cancer, has a poor prognosis even with combined surgery, chemotherapy, or molecular targeted therapies. Most patients are diagnosed with an in-operable advanced or metastatic disease, both pointing to the necessity of developing effective therapies for lung adenocarcinoma. Surfactant protein B (SP-B) has been found to be overexpressed in lung adenocarcinoma. In addition, it has also been demonstrated that human lung adenocarcinoma cells are susceptible to the JC polyomavirus (JCPyV) infection. Therefore, we designed that the JCPyV virus-like particle (VLP) packaged with an SP-B promoter-driven thymidine kinase suicide gene (pSPB-tk) for possible gene therapy of human lung adenocarcinoma. Plasmids expressing the GFP (pSPB-gfp) or thymidine kinase gene (pSPB-tk) under the control of the human SP-B promoter were constructed. The promoter's tissue specificity was tested by transfection of pSPB-gfp into A549, CH27, and H460 human lung carcinoma cells and non-lung cells. The JCPyV VLP's gene transfer efficiency and the selective cytotoxicity of pSPB-tk combined with ganciclovir (GCV) were tested in vitro and in a xenograft mouse model. In the current study, we found that SP-B promoter-driven GFP was specifically expressed in human lung adenocarcinoma (A549) and large cell carcinoma (H460) cells. JCPyV VLPs were able to deliver a GFP reporter gene into A549 cells for expression. Selective cytotoxicity was observed in A549 but not non-lung cells that were transfected with pSPB-tk or infected with pSPB-tk-carrying JCPyV VLPs. In mice injected with pSPB-tk-carrying JCPyV VLPs through the tail vein and treated with ganciclovir (GCV), a potent 80% inhibition of growth of human lung adenocarcinoma nodules resulted. The JCPyV VLPs combined with the use of SP-B promoter demonstrates effectiveness as a potential gene therapy against human lung adenocarcinoma.

The oncogenic role of JC virus T antigen in lens tumors without cell specificity of alternative splicing of its intron

JC virus (JCV), a ubiquitous polyoma virus that commonly infects the human, is identified as the etiologic agent for progressive multifocal leukoencephalopathy and some malignancies. To clarify the oncogenic role of JCV T antigen, we established two transgenic mice of T antigen using either α-crystallin A (αAT) or cytokeratin 19(KT) promoter. Lens tumors were found in high-copy αAT mice with the immunopositivity of T antigen, p53, β-catenin and N-cadherin. Enlarged eyeballs were observed and tumor invaded into the brain by magnetic resonance imaging and hematoxylin-and-eosin staining. The overall survival time of homozygous mice was shorter than that of hemizygous mice (p<0.01), the latter than wild-type mice (p<0.01). The spontaneous salivary tumor and hepatocellular carcinoma were seen in αAT5 transgenic mice with no positivity of T antigen. KT7 mice suffered from lung tumor although JCV T antigen was strongly expressed in gastric epithelial cells. The alternative splicing of T antigen intron was detectable in the lens tumor of αAT mice, gastric mucosa of KT mice, and various cells transfected with pEGFP-N1-T antigen. It was suggested that JCV T antigen might induce carcinogenesis at a manner of cell specificity, which is not linked to alternative splicing of its intron. Both spontaneous lens and lung tumor models provide good tools to investigate the oncogenic role of JCV T antigen.

JC polyomavirus attachment, entry, and trafficking: unlocking the keys to a fatal infection

The human JC polyomavirus (JCPyV) causes a lifelong persistent infection in the reno-urinary tract in the majority of the adult population worldwide. In healthy individuals, infection is asymptomatic, while in immunocompromised individuals, the virus can spread to the central nervous system and cause a fatal demyelinating disease known as progressive multifocal leukoencephalopathy (PML). There are currently very few treatment options for this rapidly progressing and devastating disease. Understanding the basic biology of JCPyV-host cell interactions is critical for the development of therapeutic strategies to prevent or treat PML. Research in our laboratory has focused on gaining a detailed mechanistic understanding of the initial steps in the JCPyV life cycle in order to define how JCPyV selectively targets cells in the kidney and brain. JCPyV requires sialic acids to attach to host cells and initiate infection, and JCPyV demonstrates specificity for the oligosaccharide lactoseries tetrasaccharide c (LSTc) with an α2,6-linked sialic acid. Following viral attachment, JCPyV entry is facilitated by the 5-hydroxytryptamine (5-HT)2 family of serotonin receptors via clathrin-dependent endocytosis. JCPyV then undergoes retrograde transport to the endoplasmic reticulum (ER) where viral disassembly begins. A novel retrograde transport inhibitor termed Retro-2(cycl) prevents trafficking of JCPyV to the ER and inhibits both initial virus infection and infectious spread in cell culture. Understanding the molecular mechanisms by which JCPyV establishes infection will open up new avenues for the prevention or treatment of virus-induced disease.

The human JC polyomavirus (JCPyV): virological background and clinical implications

JC polyomavirus (JCPyV) was the first of now 12 PyVs detected in humans, when in 1964, PyV particles were revealed by electron microscopy in progressive multifocal leukoencephalopathy (PML) tissues. JCPyV infection is common in 35-70% of the general population, and the virus thereafter persists in the renourinary tract. One third of healthy adults asymptomatically shed JCPyV at approximately 50,000 copies/mL urine. PML is rare having an incidence of <0.3 per 100,000 person years in the general population. This increased to 2.4 per 1000 person years in HIV-AIDS patients without combination antiretroviral therapy (cART). Recently, PML emerged in multiple sclerosis patients treated with natalizumab to 2.13 cases per 1000 patients. Natalizumab blocks α4-integrin-dependent lymphocyte homing to the brain suggesting that not the overall cellular immunodeficiency but local failure of brain immune surveillance is a pivotal factor for PML. Recovering JCPyV-specific immune control, e.g., by starting cART or discontinuing natalizumab, significantly improves PML survival, but is challenged by the immune reconstitution inflammatory syndrome. Important steps of PML pathogenesis are undefined, and antiviral therapies are lacking. New clues might come from molecular and functional profiling of JCPyV and PML pathology and comparison with other replicative pathologies such as granule cell neuronopathy and (meningo-)encephalitis, and non-replicative JCPyV pathology possibly contributing to some malignancies. Given the increasing number of immunologically vulnerable patients, a critical reappraisal of JCPyV infection, replication and disease seems warranted.

Progressive multifocal leukoencephalopathy-associated mutations in the JC polyomavirus capsid disrupt lactoseries tetrasaccharide c binding

The human JC polyomavirus (JCPyV) is the causative agent of the fatal, demyelinating disease progressive multifocal leukoencephalopathy (PML). The Mad-1 prototype strain of JCPyV uses the glycan lactoseries tetrasaccharide c (LSTc) and serotonin receptor 5-HT_2A to attach to and enter into host cells, respectively. Specific residues in the viral capsid protein VP1 are responsible for direct interactions with the α2,6-linked sialic acid of LSTc. Viral isolates from individuals with PML often contain mutations in the sialic acid-binding pocket of VP1 that are hypothesized to arise from positive selection. We reconstituted these mutations in the Mad-1 strain of JCPyV and found that they were not capable of growth. The mutations were then introduced into recombinant VP1 and reconstituted as pentamers in order to conduct binding studies and structural analyses. VP1 pentamers carrying PML-associated mutations were not capable of binding to permissive cells. High-resolution structure determination revealed that these pentamers are well folded but no longer bind to LSTc due to steric clashes in the sialic acid-binding site. Reconstitution of the mutations into JCPyV pseudoviruses allowed us to directly quantify the infectivity of the mutants in several cell lines. The JCPyV pseudoviruses with PML-associated mutations were not infectious, nor were they able to engage sialic acid as measured by hemagglutination of human red blood cells. These results demonstrate that viruses from PML patients with single point mutations in VP1 disrupt binding to sialic acid motifs and render these viruses noninfectious.

Infection with human JC polyomavirus (JCPyV) is common and asymptomatic in healthy individuals, but during immunosuppression, JCPyV can spread from the kidney to the central nervous system (CNS) and cause a fatal, demyelinating disease, progressive multifocal leukoencephalopathy (PML). Individuals infected with HIV, those who have AIDS, or those receiving immunomodulatory therapies for autoimmune diseases are at serious risk for PML. Recent reports have demonstrated that viral isolates from PML patients often have distinct changes within the major capsid protein. Our structural-functional approach highlights that these mutations result in abolished engagement of the carbohydrate receptor motif LSTc that is necessary for infection. Viruses with PML-associated mutations are not infectious in glial cells, suggesting that they may play an alternative role in PML pathogenesis.

Structure-function analysis of the human JC polyomavirus establishes the LSTc pentasaccharide as a functional receptor motif

The human JC polyomavirus (JCV) causes a fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML), in immunocompromised individuals. Current treatment options for PML are inadequate. Sialylated oligosaccharides and the serotonin receptor are known to be necessary for JCV entry, but the molecular interactions underlying JCV attachment remain unknown. Using glycan array screening and viral infectivity assays, we identify a linear sialylated pentasaccharide with the sequence NeuNAc-α2,6-Gal-β1,4-GlcNAc-β1,3-Gal-β1,4-Glc (LSTc) present on host glycoproteins and glycolipids as a specific JCV recognition motif. The crystal structure of the JCV capsid protein VP1 was solved alone and in complex with LSTc. It reveals extensive interactions with the terminal sialic acid of the LSTc motif and specific recognition of an extended conformation of LSTc. Mutations in the JCV oligosaccharide-binding sites abolish cell attachment, viral spread, and infectivity, further validating the importance of this interaction. Our findings provide a powerful platform for the development of antiviral compounds.

Progressive multifocal leukoencephalopathy and promyelocytic leukemia nuclear bodies: a review of clinical, neuropathological, and virological aspects of JC virus-induced demyelinating disease

Progressive multifocal leukoencephalopathy is a fatal viral-induced demyelinating disease that was once rare but has become more prevalent today. Over the past decades, much has been learned about the disease from molecular study of the etiological agent of the disease, JC virus. Recently, promyelocytic leukemia nuclear bodies (PML-NBs), punctuate structures for important nuclear functions in eukaryotic cells, were identified as an intranuclear target of JC virus infection. Neuropathologically, JC virus-infected glial cells display diffuse amphophilic viral inclusions by hematoxylin–eosin staining (full inclusions), a diagnostic hallmark of this disease. Recent results using immunohistochemistry, however, revealed the presence of punctate viral inclusions preferentially located along the inner nuclear periphery (dot-shaped inclusions). Dot-shaped inclusions reflect the accumulation of viral progeny at PML-NBs, which may be disrupted after viral replication. Structural changes to PML-NBs have been reported for a variety of human diseases, including cancers and neurodegenerative disorders. Thus, PML-NBs may provide clues to the further pathogenesis of JC virus-induced demyelinating disease. Here, we review what we have learned since the disease entity establishment, including a look at recent progress in understanding the relationship between JC virus, etiology and PML-NBs.

Pandemic influenza A (H1N1) virus infection and avian influenza A (H5N1) virus infection: a comparative analysis

The 2009 H1N1 and H5N1 influenza viruses are newly (re-) emerged influenza A viruses (2009 A(H1N1) and A(H5N1), respectively) that have recently posed tremendous health threats in many regions worldwide. With the 2009 outbreak of H1N1 influenza A, the world witnessed the first influenza pandemic of the 21st century. The disease has rapidly spread across the entire globe, and has resulted in hundreds of thousands of cases with confirmed infection. Although characterized by high transmissibility, the virulence and fatality of the 2009 A(H1N1) influenza virus have thus far remained relatively low. The reverse holds true for A(H5N1) influenza; at a fatality rate that exceeds 60%, it is known to cause severe damage to the human respiratory system, but is not presently capable of efficient transmission from human to human. Apart from the clear differences between the two types of influenza, there are some significant similarities that warrant attention. In particular, the more severe and fatal 2009 A(H1N1) influenza cases have shown symptoms similar to those reported in cases of A(H5N1) influenza. Histopathological findings for these cases, to the extent available, also appear to have similarities for both diseases in terms of damage and severity. Here we review important recent publications in this area, and we discuss some of the key commonalities and contrasts between the two influenza A types in terms of their biology, origins, clinical features, pathology and pathogenesis, and receptors and transmissibility.

Fatal progressive multifocal leukoencephalopathy in a patient with non-Hodgkin lymphoma treated with rituximab

We report a case of progressive multifocal leukoencephalopathy (PML) in a woman with non-Hodgkin lymphoma treated with chemotherapy in combination with rituximab. She presented with rapid deterioration of vision and subsequently cognitive decline. Magnetic resonance imaging (MRI) of the brain raised the suspicion of PML. The first PCR analysis of the cerebrospinal fluid (CSF) was negative, but a second sample was positive for JC virus DNA. Anti-viral treatment was ineffective and the patient died 7 months after debut of symptoms. Our case emphasizes the importance of the awareness of PML in patients with progressive neurological symptoms treated with antilymphocytic drugs and that consecutive CSF analyses may be needed to detect the JC virus.

Avian influenza H5N1 virus induces cytopathy and proinflammatory cytokine responses in human astrocytic and neuronal cell lines

It has previously been reported that the avian H5N1 type of influenza A virus can be detected in neurons and astrocytes of human brains in autopsy cases. However, the underlying neuropathogenicity remains unexplored. In this study, we used differentiated human astrocytic and neuronal cell lines as models to examine the effect of H5N1 influenza A viral infection on the viral growth kinetics and immune responses of the infected cells. We found that the influenza virus receptors, sialic acid-alpha2,3-galactose and sialic acid-alpha2,6-galactose, were expressed on differentiated human astrocytic and neuronal cells. Both types of cells could be infected with H5N1 influenza A viruses, but progeny viruses were only produced from infected astrocytic cells but not neuronal cells. Moreover, increased expression of interleukin (IL)-6 and/or tumor necrosis factor alpha (TNF-alpha) mRNA was detected in both astrocytic and neuronal cells at 6 and 24 h post-infection. To examine the biological consequences of such enhanced cytokine expression, differentiated astrocytic and neuronal cells were directly treated with these two cytokines. TNF-alpha treatment induced apoptosis, as well as proinflammatory cytokine, chemokine and inflammatory responses in differentiated astrocytic and neuronal cells. Taken together, our findings reveal that avian influenza H5N1 viruses can infect human astrocytic and neuronal cells, resulting in the induction of direct cellular damage and proinflammatory cytokine cascades. Our observations suggest that avian influenza H5N1 infection can trigger profound CNS injury, which may play an important role in the influenza viral pathogenesis.

Adaptive mutations in the JC virus protein capsid are associated with progressive multifocal leukoencephalopathy (PML)

PML is a progressive and mostly fatal demyelinating disease caused by JC virus infection and destruction of infected oligodendrocytes in multiple brain foci of susceptible individuals. While JC virus is highly prevalent in the human population, PML is a rare disease that exclusively afflicts only a small percentage of immunocompromised individuals including those affected by HIV (AIDS) or immunosuppressive drugs. Viral- and/or host-specific factors, and not simply immune status, must be at play to account for the very large discrepancy between viral prevalence and low disease incidence. Here, we show that several amino acids on the surface of the JC virus capsid protein VP1 display accelerated evolution in viral sequences isolated from PML patients but not in sequences isolated from healthy subjects. We provide strong evidence that at least some of these mutations are involved in binding of sialic acid, a known receptor for the JC virus. Using statistical methods of molecular evolution, we performed a comprehensive analysis of JC virus VP1 sequences isolated from 55 PML patients and 253 sequences isolated from the urine of healthy individuals and found that a subset of amino acids found exclusively among PML VP1 sequences is acquired via adaptive evolution. By modeling of the 3-D structure of the JC virus capsid, we showed that these residues are located within the sialic acid binding site, a JC virus receptor for cell infection. Finally, we go on to demonstrate the involvement of some of these sites in receptor binding by demonstrating a profound reduction in hemagglutination properties of viral-like particles made of the VP1 protein carrying these mutations. Collectively, these results suggest that a more virulent PML causing phenotype of JC virus is acquired via adaptive evolution that changes viral specificity for its cellular receptor(s).

JC virus is a highly prevalent human polyomavirus. Infection with this virus is generally benign and asymptomatic despite viral persistence in the kidney of many people. However, in immunocompromised individuals, very rarely, the infection can progress to become a potentially deadly brain disease called Progressive Multifocal Leukoencephalopathy (PML). The discrepancy between very high viral prevalence and low incidence of PML suggests that there could be some unique viral characteristics that regulate the progression from the asymptomatic infection to the PML. Identification of such factors will help us to understand the basis of PML development and hopefully will lead to the creation of new diagnostic and treatment tools for managing PML. In this work, we demonstrate that the part of the viral surface protein that is thought to be responsible for viral interaction with cellular receptors and infection acquires specific mutations that appear to be critical for the development of PML. These mutations are found more frequently than by simple chance and therefore are thought to be “positively selected.” Based on these results, we hypothesize that the specific mutations in the viral VP1 protein that we have identified are critical for the evolution of JC virus to the version associated with PML.

Treatment options for AIDS patients with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a demyelinating viral disease produced by the John Cunningham (JC) virus, which is ubiquitously distributed. Up to 80% of adults seroconvert to JC virus. Classically, PML is a life-threatening AIDS-defining disease of the CNS, usually occurring in severely immunocompromised individuals. Until now, and despite several therapeutic attempts, there is no specific treatment for PML. Soon after the widespread use of combination antiretroviral therapy (CART), several studies showed prolonged survival for patients with AIDS-associated PML who were treated with CART. The outcome of PML in patients receiving CART is unpredictable at disease onset. Prognostic markers are needed. The JC virus DNA detection in cerebrospinal fluid by nucleic acid amplification techniques and the CD4+ cell count are the most promising parameters. Higher levels of CD4+ cell counts were independently associated with an improved survival in different clinical observations. A summary of the main current knowledge about AIDS-related PML is presented. The most effective strategy is to optimize CART to completely suppress HIV-1 viral load and allow the best CD4+ T-cell immune recovery. Nowadays, AIDS-related PML is no longer an ultimately fatal disease. A substantial number of HIV-1-infected patients with this condition can improve with CART.

High JC virus load in tongue carcinomas may be a risk factor for tongue tumorigenesis

The John Cunningham virus (JCV) asymptomatically infects a large proportion (approximately 90%) of the population worldwide but may be activated in immunodeficient patients, resulting in progressive multifocal leukoencephalopathy. Recent reports demonstrated its oncogenic role in malignancies. In this paper, the presence of JCV-targeting T antigen was investigated in tongue carcinoma (TC, n = 39), dysplastic tongue epithelium (DTE, n = 15) and glossitis (n = 15) using real-time polymerase chain reaction (PCR) and in situ PCR and immunohistochemistry, and JCV copies were analyzed with the clinicopathological parameters of TCs. The results demonstrated that glossitis and DTEs had significantly lower copies of JCV (410.5 +/- 44.3 and 658.3 +/- 53.3 copies/mug DNA respectively) than TCs (981.5 +/- 14.0, p < 0.05). When they were divided into three groups with 0-200 copies/mug DNA (low), 201-1,000 (moderate) and more than 1001 (high), TCs showed 3 (7.6%) in the low group, 21 (53.8%) in the moderate group and 15 (38.4%) in the high group and glossitis showed 11 (73.3%) in the low group, 0 (0%) in the moderate group and 4 (26.6%) in the high group. The DTEs occupied an intermediate position between them (p < 0.001). In situ PCR demonstrated that the nuclei of TC and DTE cells are sporadically T-antigen positive but not in nasal turbinate epithelial cells. Immunohistochemistry for T-antigen protein revealed four positive cases only in TCs. The existence of JCV T-antigen DNA was not associated with the clinicopathological variables of TCs. In conclusion, the presence of JCV may be a risk factor of tongue carcinogenesis.

Detection of the JC virus genome in lung cancers: possible role of the T-antigen in lung oncogenesis

The JC virus (JCV) infects a large proportion of the population worldwide and 80% to 90% of adults are seropositive and it may be activated in immunodeficient patients, resulting in progressive multifocal leukoencephalopathy. Recent reports described the possibility of its oncogenetic role in several malignancies. To clarify whether JCV might have a potential role in the genesis of lung cancers, we investigated the presence of its genome in 62 tumors, along with 23 samples of normal lung tissue, targeting the T-antigen, VP, and Agnoprotein by nested polymerase chain reaction/Southern blotting followed by direct DNA sequencing. Immunohistochemistry was performed to assess links between p53 and beta-catenin in lung cancers and the presence of T-antigen. The T-antigen was detected in 25 of 62 lung cancers but only 4 of 23 normal lung samples (P=0.048). In total, the JCV genome was present in 33 of the lung cancers and 10 of the normal samples. Furthermore, T-antigen was found in cancer cells in metastatic lymph nodes in 3 of 4 cases (P=0.042) and was more frequently detected in adenocarcinomas than in squamous cell carcinomas (P=0.038). Immunohistochemistry showed significant correlations between T-antigen and p53 (P=0.022) and also nuclear detection of beta-catenin (P=0.021). It is concluded that the JCV genome might be present in cancer cells in approximately half of all Japanese lung cancer cases, and that the T-antigen may play a role in oncogenesis of lung cancers through inactivation of p53 and dysregulation of the Wnt signaling pathway.

Avian influenza receptor expression in H5N1-infected and noninfected human tissues

Avian and human influenza viruses preferentially bind to alpha-2,3-linked and alpha-2,6-linked sialic acids, respectively. Until today, the distributions of these two receptor types had never been investigated in H5N1-infected human tissue samples. Here, the expression of avian (AIV-Rs) and human influenza receptors (HuIV-Rs) is studied in various organs (upper and lower respiratory tracts, brain, placenta, liver, kidney, heart, intestines, and spleen) of two H5N1 cases and 14 control cases. Histochemical stains using biotinylated Maackia amurensis lectin II and Sambucus nigra agglutinin were performed to localize AIV-Rs and HuIV-Rs, respectively. Immunohistochemical stainings were performed to identify the receptor-bearing cells. AIV-Rs were detected on type II pneumocytes; a limited number of epithelial cells of the upper respiratory tract; and the bronchi, bronchioli, and trachea; as well as on Kupffer cells, glomerular cells, splenic T cells, and neurons in the brain and intestines. HuIV-Rs were abundantly present in the respiratory tract and lungs. They were also detected on Hofbauer cells, glomerular cells, splenic B cells, and in the liver. Moreover, endothelial cells of all organs examined expressed both receptor types. In conclusion, the distribution pattern of AIV-Rs is partially inconsistent with the pattern of infected cells as detected in previous studies, which suggests there may be other receptors or mechanisms involved in H5N1 infection. In addition, the diffuse presence of receptors on endothelial cells may account for the multiple organ involvement in H5N1 influenza. Finally, the relative lack of AIV-Rs in the upper airway may be a one of the factors preventing efficient human-to-human transmission of H5N1 influenza.

BK virus nephropathy and kidney transplantation

Nephropathy from BK virus (BKV) infection is an evolving challenge in kidney transplant recipients. It is the consequence of modern potent immunosuppression aimed at reducing acute rejection and improving allograft survival. Untreated BKV infections lead to kidney allograft dysfunction or loss. Decreased immunosuppression is the principle treatment but predisposes to acute and chronic rejection. Screening protocols for early detection and prevention of symptomatic BKV nephropathy have improved outcomes. Although no approved antiviral drug is available, leflunomide, cidofovir, quinolones, and intravenous Ig have been used. Retransplantation after BKV nephropathy has been successful.

Virus receptors and tropism

Polyomaviruses are small, tumorigenic, nonenveloped viruses that infect several different species. Interaction of these viruses with cell surface receptors represents the initial step during infection of host cells. This interaction can be a major determinant of viral host and tissue tropism. This chapter reviews what is currently known about the cellular receptors for each of five polyomavirus family members: Mouse polyomavirus (PyV), JC virus (JCV), BK virus (BKV), Lymphotropic papovavirus (LPV) and Simian virus 40 (SV40). These polyomaviruses serve to illustrate the enormous diversity of virus-cell surface interactions and allow us to closely evaluate the role of receptors in their life cycles. The contribution of other factors such as transcriptional regulators and signaling pathways are also summarized.

Identification of a third human polyomavirus

We have previously reported on a system for large-scale molecular virus screening of clinical samples. As part of an effort to systematically search for unrecognized human pathogens, the technology was applied for virus screening of human respiratory tract samples. This resulted in the identification of a previously unknown polyomavirus provisionally named KI polyomavirus. The virus is phylogenetically related to other primate polyomaviruses in the early region of the genome but has very little homology (<30% amino acid identity) to known polyomaviruses in the late region. The virus was found by PCR in 6 (1%) of 637 nasopharyngeal aspirates and in 1 (0.5%) of 192 fecal samples but was not detected in sets of urine and blood samples. Since polyomaviruses have oncogenic potential and may produce severe disease in immunosuppressed individuals, continued searching for the virus in different medical contexts is important. This finding further illustrates how unbiased screening of respiratory tract samples can be used for the discovery of diverse virus types.

JC [corrected] virus detection in human tissue specimens

AIM

To clarify the advantages and disadvantages of different detection methods for Jamestown Canyon virus (JCV) in human tissue specimens.

METHODS

Specimens of lung and gastric carcinomas, and normal lung tissue, gastric mucosa, and tonsil were examined for T-antigen, VP and agnoprotein of JCV by nested PCR, Southern blotting and sequencing. JCV load targeting T-antigen was evaluated by real-time PCR, and JCV existence morphologically by immunohistochemistry, in-situ hybridisation (ISH) and PCR. For these experiments, the JCI cell line (JCV cultured neuroblastoma cell line) was employed as positive control.

RESULTS

In lung and gastric carcinomas, T-antigen, VP and agnoprotein of JCV could be detected by nested PCR whose products were confirmed by Southern blots and sequencing. With real-time PCR, frozen samples of gastric carcinomas gave better detection of JCV than their corresponding paraffin-embedded tissues (p<0.05). The positive rate of JCV was high in lung carcinoma, compared with normal lung tissue (p<0.05). It was the same for JCV copies in gastric carcinoma (p<0.05). Only the positive control exhibited JCV in the nucleus by ISH and immunohistochemistry. In-situ PCR showed that JCV genomic DNA was located in the nucleus of the carcinoma cell, some alveolar epithelial cells, and tonsil lymphocytes. In ISH and PCR, NBT/BCIP colouring was stronger than Fuchsin.

CONCLUSIONS

Nested PCR whose amplicons should be confirmed by Southern blot and sequencing was a comparatively sensitive approach to detect JCV genomic DNA in human non-neural tissues. Real-time PCR might be employed to quantify copy number of JCV. In-situ PCR was a good method to observe the JCV location in cells, given appropriate modulation of amplification cycles. Combinations of various approaches will be adopted to explore the oncogenic roles of JCV in malignancies.

Oncogenic role of JC virus in lung cancer

The JC virus (JCV) infects a large proportion of the population world wide and can cause progressive multifocal leucoencephalopathy in the context of immunodeficiency. Recent reports provide evidence that it may also be oncogenic. Here, JCV was examined by targeting its T-antigen in lung carcinomas (n=103) and normal lung tissues (n=18) by nested-PCR followed by Southern blot, real-time PCR, immunohistochemistry, in situ hybridization and in situ PCR. Additionally, expression of Ki-67, caspase-3, beta-catenin, p53, and Rb was analysed by immunohistochemistry on tissue microarrays of lung carcinomas. Copy numbers of JCV were compared with clinicopathological features. Normal lung tissue was positive significantly less frequently, and contained a lower copy number of JCV than lung carcinomas (p<0.05), and copies were lower in lung adenocarcinomas than in squamous, small or large cell carcinomas (p<0.05). In situ PCR and immunolabelling revealed JCV positivity in the nuclei of lung carcinoma cells. The JCV copy number correlated closely with sex, and expression of Ki-67 and membrane beta-catenin (p<0.05), but not with age, tumour size, pleural invasion, lymph node metastasis, expression of caspase-3, cytoplasmic beta-catenin, p53 or Rb, prognosis, smoking or cancer family history (p>0.05). Age and UICC staging were independent prognostic factors for lung carcinoma patients. These data suggest that JCV may be involved in lung carcinogenesis, especially in tumour types other than adenocarcinoma. Lung carcinomas with higher JCV copy numbers display high proliferation and down-regulation of cell adhesion mediated by membrane beta-catenin.

The role of sialic acid in human polyomavirus infections

JC virus (JCV) and BK virus (BKV) are human polyomaviruses that infect approximately 85% of the population worldwide [1,2]. JCV is the underlying cause of the fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML), a condition resulting from JCV induced lytic destruction of myelin producing oligodendrocytes in the brain [3]. BKV infection of kidneys in renal transplant recipients results in a gradual loss of graft function known as polyomavirus associated nephropathy (PVN) [4]. Following the identification of these viruses as the etiological agents of disease, there has been greater interest in understanding the basic biology of these human pathogens [5,6]. Recent advances in the field have shown that viral entry of both JCV and BKV is dependent on the ability to interact with sialic acid. This review focuses on what is known about the human polyomaviruses and the role that sialic acid plays in determining viral tropism.

Amino acid change 335 E to K affects the sialic-acid-binding and neuraminidase activities of Urabe AM9 mumps virus hemagglutinin-neuraminidase glycoprotein

A mutation coding for the amino acid change E335 to K is frequently found in the hemagglutinin-neuraminidase (HN) gene of Urabe AM9 mumps viruses isolated during post-vaccination meningitis cases. To identify if this mutation modifies the biological activities of the HN glycoprotein, two variants of Urabe AM9 vaccine differing at amino acid 335 (HN-E335 and HN-K335) were isolated and their receptor-binding specificity was determined by means of competence assays. Pre-incubation of the viruses with sialic acids inhibited both syncytia formation in Vero cells and replication in SH-SY5Y cells. Thus, HN-K335 showed higher affinity towards sialylalpha2,6lactose, whereas HN-G335 preferred sialylalpha2,3lactose. These results are relevant because a high expression of sialylalpha2,6lactose in nerve cells was confirmed by means of Sambucus nigra lectin-cytochemistry. In addition, kinetics assays showed that HN-K335 and HN-E335 also differ in their hydrolysis rate (Vmax values of 37.5 vs. 3.5 nmol min-1mg-1, respectively). Therefore, HN-K335 variant presented a neuraminidase activity level 11-fold higher than that of HN-E335 variant. In conclusion, the mutation affects the receptor-binding and neuraminidase activities of Urabe AM9 mumps virus variants.

The polyomavirus, JCV and its involvement in human disease

The human neurotropic polyomavirus, JC virus (JCV), is the etiologic agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system that occurs mainly in immunosuppressed patients. JCV has also been found to be associated with human tumors of the brain and other organs. In this chapter, we describe JC virus and its role in human diseases.

Involvement of periodontopathic anaerobes in aspiration pneumonia

Increasing evidence has linked the anaerobic bacteria forming periodontopathic biofilms with aspiration pneumonia in elderly persons. In experiments designed to eliminate the potent respiratory pathogens forming biofilms in the oral cavity, we have shown that the mechanical and chemical oral cleansing using povidone-iodine effectively reduced the detection rates and numbers of methicillin-sensitive Staphylococcus species, Streptococcus pneumoniae, and Haemophilus influenzae in patients scheduled to undergo oral surgery requiring endotracheal intubation. We confirmed the pathogenicity of periodontopathic anaerobic bacteria for aspiration pneumonia in an experimental mouse model. Based upon the finding of the coexistence of Porphyromonas gingivalis with Treponema denticola in chronic periodontitis lesions, we innoculated a mixed culture of P. gingivalis and T. denticola into the mouse trachea; the resulting infection induced inflammatory cytokine production and caused pneumonia. In another series of investigations, professional oral health care (POHC), mainly cleansing administered by dental hygienists once a week for 24 months to elderly persons requiring daily care, resulted in the reduction of the number of total anaerobes, Candida albicans, and Staphylococcus species and in the number of cases of fatal aspiration pneumonia. We also found that the POHC treatment of elderly persons for 6 months in the winter season reduced the salivary levels of protease, trypsin-like activity, and neuraminidase and also decreased the frequency of influenza cases.

Finding new tricks for old drugs: an efficient route for public-sector drug discovery

With the annotation of the human genome approaching completion, public-sector researchers - spurred in part by various National Institutes of Health Roadmap Initiatives - have become increasingly engaged in drug discovery and development efforts. Although large and diverse chemical libraries of 'drug-like' compounds can be readily screened to yield chemically novel scaffolds, transforming these 'chemical probes' into drugs is a daunting endeavour. A more efficient approach involves screening libraries of approved and off-patent medications; both phenotypic- and molecular target-based screening of 'old drugs' can readily yield compounds that could be immediately used in clinical trials. Using case studies, we describe how this approach has rapidly identified candidate medications suitable for clinical trials in disorders such as progressive multifocal leukoencephalopathy and amyotrophic lateral sclerosis. This approach has also led to the discovery of the molecular targets responsible for serious drug side effects, thereby allowing efficient 'counter-screening' to avoid these side effects.

Enterovirus 70 binds to different glycoconjugates containing alpha2,3-linked sialic acid on different cell lines

Enterovirus 70 (EV70), the causative agent of acute hemorrhagic conjunctivitis, exhibits a restricted tropism for conjunctival and corneal cells in vivo but infects a wide spectrum of mammalian cells in culture. Previously, we demonstrated that human CD55 is a receptor for EV70 on HeLa cells but that EV70 also binds to sialic acid-containing receptors on a variety of other human cell lines. Virus recognition of sialic acid attached to underlying glycans by a particular glycosidic linkage may contribute to host range, tissue tropism, and pathogenesis. Therefore, we tested the possibility that EV70 binds to alpha2,3-linked sialic acid, like other viruses associated with ocular infections. Through the use of linkage-specific sialidases, sialyltransferases, and lectins, we show that EV70 recognizes alpha2,3-linked sialic acid on human corneal epithelial cells and on U-937 cells. Virus attachment to both cell lines is CD55 independent and sensitive to benzyl N-acetyl-alpha-D-galactosaminide, an inhibitor of O-linked glycosylation. Virus binding to corneal cells, but not U-937 cells, is inhibited by proteinase K, but not by phosphatidylinositol-specific phospholipase C treatment. These results are consistent with the idea that a major EV70 receptor on corneal epithelial cells is an O-glycosylated, non-glycosyl phosphatidylinositol-anchored membrane glycoprotein containing alpha2,3-linked sialic acid, while sialylated receptors on U-937 cells are not proteinaceous.

Inhibition of simian virus 40 large tumor antigen expression in human fetal glial cells by an antisense oligodeoxynucleotide delivered by the JC virus-like particle

Human JC virus (JCV) is a neurotropic virus, and the etiological agent of progressive multifocal leukoencephalopathy (PML), a fatal neurological disease. Because of its natural infection tropism, it is possible to use the JCV capsid as a gene-transducing vector for therapeutic purposes in neurological disorders. In the current study, a recombinant JCV virus-like particle (VLP) was generated and purified from yeast. VLP was able to accommodate and protect DNA molecules of up to approximately 2000 bp in length. VLP was able to package and deliver an antisense oligodeoxynucleotide (AS-ODN) against simian virus 40 (SV40) large tumor antigen (LT) into SV40-transformed human fetal glial (SVG) cells in order to inhibit expression of the oncoprotein. Subsequently, apoptosis of VLP-AS-ODN-treated cells was demonstrated after the blocking of LT expression. In addition, JCV VLP was able to deliver ODN into human astrocytoma, neuroblastoma, and glioblastoma cells with high efficiency. In vivo delivery of ODN into a human neuroblastoma tumor nodule by VLP was also demonstrated. These findings suggest that JCV VLP is a gene delivery vector with potential therapeutic use for human neurological disorders.

Establishment of an immunoscreening system using recombinant VP1 protein for the isolation of a monoclonal antibody that blocks JC virus infection

Polyomavirus JC (JCV) infection causes the fatal human demyelinating disease, progressive multifocal leukoencephalopathy. Although the initial interaction of JCV with host cells occurs through direct binding of the major viral capsid protein (VP1) with cell-surface molecules possessing sialic acid, these molecules have not yet been identified. In order to isolate monoclonal antibodies which inhibit attachment of JCV, we established an immunoscreening system using virus-like particles consisting of the VP1. Using this system, among monoclonal antibodies against the cell membrane fraction from JCV-permissive human neuroblastoma IMR-32 cells, we isolated a monoclonal antibody designated as 24D2 that specifically inhibited attachment and infection of JCV to IMR-32 cells. The antibody 24D2 recognized a single molecule of around 60 kDa in molecular weight in the IMR-32 membrane fraction. Immunohistochemical staining with 24D2 demonstrated immunoreactivity in the cell membrane of JCV-permissive cell lines and glial cells of the human brain. These results suggested that the molecule recognized by 24D2 plays a role in JCV infection, and that it might participate as a receptor or a co-receptor in JCV attachment and entry into the cells.