Herpes simplex virus type 1 preferentially targets human colon carcinoma: role of extracellular matrix

Elucidating Cancer Subtypes by Using the Relationship between DNA Methylation and Gene Expression

Advancements in the field of next generation sequencing (NGS) have generated vast amounts of data for the same set of subjects. The challenge that arises is how to combine and reconcile results from different omics studies, such as epigenome and transcriptome, to improve the classification of disease subtypes. In this study, we introduce sCClust (sparse canonical correlation analysis with clustering), a technique to combine high-dimensional omics data using sparse canonical correlation analysis (sCCA), such that the correlation between datasets is maximized. This stage is followed by clustering the integrated data in a lower-dimensional space. We apply sCClust to gene expression and DNA methylation data for three cancer genomics datasets from the Cancer Genome Atlas (TCGA) to distinguish between underlying subtypes. We evaluate the identified subtypes using Kaplan-Meier plots and hazard ratio analysis on the three types of cancer-GBM (glioblastoma multiform), lung cancer and colon cancer. Comparison with subtypes identified by both single- and multi-omics studies implies improved clinical association. We also perform pathway over-representation analysis in order to identify up-regulated and down-regulated genes as tentative drug targets. The main goal of the paper is twofold: the integration of epigenomic and transcriptomic datasets followed by elucidating subtypes in the latent space. The significance of this study lies in the enhanced categorization of cancer data, which is crucial to precision medicine.

Oncolytic virotherapy in cancer treatment: challenges and optimization prospects

Oncolytic viruses (OVs) are emerging cancer therapeutics that offer a multifaceted therapeutic platform for the benefits of replicating and lysing tumor cells, being engineered to express transgenes, modulating the tumor microenvironment (TME), and having a tolerable safety profile that does not overlap with other cancer therapeutics. The mechanism of OVs combined with other antitumor agents is based on immune-mediated attack resistance and might benefit patients who fail to achieve durable responses after immune checkpoint inhibitor (ICI) treatment. In this Review, we summarize data on the OV mechanism and limitations of monotherapy, which are currently in the process of combination partner development, especially with ICIs. We discuss some of the hurdles that have limited the preclinical and clinical development of OVs. We also describe the available data and provide guidance for optimizing OVs in clinical practice, as well as a summary of approved and promising novel OVs with clinical indications.

Targeting Persistent Biofilm Infections: Reconsidering the Topography of the Infection Site during Model Selection

The physiology of an organism in the environment reflects its interactions with the diverse physical, chemical, and biological properties of the surface. These principles come into consideration during model selection to study biofilm–host interactions. Biofilms are communities formed by beneficial and pathogenic bacteria, where cells are held together by a structured extracellular matrix. When biofilms are associated with a host, chemical gradients and their origins become highly relevant. Conventional biofilm laboratory models such as multiwall biofilm models and agar plate models poorly mimic these gradients. In contrast, ex vivo models possess the partial capacity to mimic the conditions of tissue-associated biofilm and a biofilm associated with a mineralized surface enriched in inorganic components, such as the human dentin. This review will highlight the progress achieved using these settings for two models of persistent infections: the infection of the lung tissue by Pseudomonas aeruginosa and the infection of the root canal by Enterococcus faecalis. For both models, we conclude that the limitations of the conventional in vitro systems necessitate a complimentary experimentation with clinically relevant ex vivo models during therapeutics development.

Calcium carbonate mineralization is essential for biofilm formation and lung colonization

Biofilms are differentiated microbial communities held together by an extracellular matrix. μCT X-ray revealed structured mineralized areas within biofilms of lung pathogens belonging to two distant phyla - the proteobacteria Pseudomonas aeruginosa and the actinobacteria Mycobacterium abscessus. Furthermore, calcium chelation inhibited the assembly of complex bacterial structures for both organisms with little to no effect on cell growth. The molecular mechanisms promoting calcite scaffold formation were surprisingly conserved between the two pathogens as biofilm development was similarly impaired by genetic and biochemical inhibition of calcium uptake and carbonate accumulation. Moreover, chemical inhibition and mutations targeting mineralization significantly reduced the attachment of P. aeruginosa to the lung, as well as the subsequent damage inflicted by biofilms to lung tissues, and restored their sensitivity to antibiotics. This work offers underexplored druggable targets for antibiotics to combat otherwise untreatable biofilm infections.

Identification of a Four-lncRNA Prognostic Signature for Colon Cancer Based on Genome Instability

LncRNAs (long noncoding RNAs) are closely associated with genome instability. However, the identification of lncRNAs related to the genome instability and their relationship with the prognosis and clinical signature of cancer remains to be explored. In this paper, we analyzed differential lncRNA expression based on the somatic mutation profiles of colon cancer patients from TCGA database and finally identified 153 lncRNAs that are associated with genome instability in colon cancer. Taking four lncRNAs from these 153, we established a genome-instability-related prognostic signature (GIRlncPSig). By applying the GIRlncPSig, we calculated a risk score for each patient, and using their risk scores, we divided them into low- and high-risk groups. We found that the prognosis between the two risk groups was significantly different, and the results were further verified in different independent patient cohorts. Moreover, we observed that the GIRlncPSig was related to somatic mutation rates in colon cancer, indicating that it may be a potential means of measuring genome instability levels in colon cancer. We also revealed that the GIRlncPSig was correlated with BRAF and DPYD mutation rates and that it may be a potential mutation marker for the BRAF and DPYD gene. In summary, we constructed a genome-instability-related lncRNA prognostic signature (GIRlncPSig), which has a significant effect on prognosis prediction and may allow for the discovery of new colon cancer biomarkers.

Virotherapy: Current Trends and Future Prospects for Treatment of Colon and Rectal Malignancies

Colorectal cancer (CRC) is one of the most common malignancies. In recent decades, early diagnosis and conventional therapies have resulted in a significant reduction in mortality. However, late stage metastatic disease still has very limited effective treatment options. There is a growing interest in using viruses to help target therapies to tumour sites. In recent years the evolution of immunotherapy has emphasised the importance of directing the immune system to eliminate tumour cells; we aim to give a state-of-the-art over-view of the diverse viruses that have been investigated as potential oncolytic agents for the treatment of CRC.

Optimizing oncolytic virotherapy in cancer treatment

In the wake of the success of modern immunotherapy, oncolytic viruses (OVs) are currently seen as a potential therapeutic option for patients with cancer who do not respond or fail to achieve durable responses following treatment with immune checkpoint inhibitors. OVs offer a multifaceted therapeutic platform because they preferentially replicate in tumour cells, can be engineered to express transgenes that augment their cytotoxic and immunostimulatory activities, and modulate the tumour microenvironment to optimize immune-mediated tumour eradication, both at locoregional and systemic sites of disease. Lysis of tumour cells releases tumour-specific antigens that trigger both the innate and adaptive immune systems. OVs also represent attractive combination partners with other systemically delivered agents by virtue of their highly favourable safety profiles. Rational combinations of OVs with different immune modifiers and/or antitumour agents, based on mechanisms of tumour resistance to immune-mediated attack, may benefit the large, currently underserved, population of patients who respond poorly to immune checkpoint inhibition.

An oncolytic herpesvirus expressing E-cadherin improves survival in mouse models of glioblastoma

The efficacy of oncolytic herpes simplex virus (oHSV) is limited by rapid viral clearance by innate immune effector cells and poor intratumoral viral spread. We combine two approaches to overcome these barriers: inhibition of natural killer (NK) cells and enhancement of intratumoral viral spread. We engineered an oHSV to express CDH1, encoding E-cadherin, an adherent molecule and a ligand for KLRG1, an inhibitory receptor expressed on NK cells. In vitro, infection with this engineered virus, named OV-CDH1, induced high surface E-cadherin expression on infected glioblastoma (GBM) cells, which typically lack endogenous E-cadherin. Ectopically expressed E-cadherin enhanced the spread of OV-CDH1 by facilitating cell-to-cell infection and viral entry and reduced viral clearance by selectively protecting OV-CDH1-infected cells from KLRG1+ NK cell killing. In vivo, OV-CDH1 treatment substantially prolonged the survival in GBM-bearing mouse models, primarily because of improved viral spread rather than inhibition of NK cell activity. Thus, virus-induced overexpression of E-cadherin may be a generalizable strategy for improving cancer virotherapy.

Herpes Simplex Virus 1 Infection Promotes the Growth of a Subpopulation of Tumor Cells in Three-Dimensional Uveal Melanoma Cultures

Cancer cells are exposed to HSV-1 during oncolytic virotherapy with the intention of killing tumor cells. Our observations reported here suggest that potential dangers of HSV-1 oncolytic therapy include promotion of growth of some tumor cells. Furthermore, our findings raise the possibility that HSV-1 infection of neoplastic cells during natural infections or vaccinations may promote the growth of tumors. Our study indicates that HSV-1 infection of 3D tumor cell cultures provides an experimental platform in which mechanisms of HSV-1-mediated promotion of tumor cell growth can be effectively studied.

Herpes simplex virus 1 (HSV-1)-mediated oncolytic therapy is an emerging cancer treatment modality with potential effectiveness against a variety of malignancies. To better understand the interaction of HSV-1 with neoplastic cells, we inoculated three-dimensional (3D) cultures of human uveal melanoma cells with HSV-1. 3D melanoma cultures were established by placing tumor cells on the surface of a Matrigel matrix, which was followed by the growth of tumor cells on the matrix surface and invasion of the Matrigel matrix by some tumor cells to form multicellular tumor spheroids within the matrix. When established 3D melanoma cultures were inoculated with HSV-1 by placing virus on the surface of cultures, virus infection caused extensive death of melanoma cells growing on the surface of the 3D matrix and significantly decreased the number of tumor cell spheroids within the matrix. However, HSV-1 infection did not lead to a complete destruction of tumor cells in the 3D cultures during a 17-day observation period and, surprisingly, HSV-1 infection promoted the growth of some melanoma cells within the matrix as determined by the significantly increased size of residual viable multicellular tumor spheroids in virus-inoculated 3D cultures at 17 days after virus inoculation. Acyclovir treatment inhibited HSV-1-induced tumor cell killing but did not block the virus infection-induced increase in spheroid size. These findings suggest that although HSV-1 oncolytic virotherapy may cause extensive tumor cell killing, it may also be associated with the unintended promotion of the growth of some tumor cells.

IMPORTANCE Cancer cells are exposed to HSV-1 during oncolytic virotherapy with the intention of killing tumor cells. Our observations reported here suggest that potential dangers of HSV-1 oncolytic therapy include promotion of growth of some tumor cells. Furthermore, our findings raise the possibility that HSV-1 infection of neoplastic cells during natural infections or vaccinations may promote the growth of tumors. Our study indicates that HSV-1 infection of 3D tumor cell cultures provides an experimental platform in which mechanisms of HSV-1-mediated promotion of tumor cell growth can be effectively studied.

A biosafety level 2 virology lab for biotechnology undergraduates

Medical, industrial, and basic research relies heavily on the use of viruses and vectors. Therefore, it is important that bioscience undergraduates learn the practicalities of handling viruses. Teaching practical virology in a student laboratory setup presents safety challenges, however. The aim of this article is to describe the design and implementation of a virology laboratory, with emphasis on student safety, for biotechnology undergraduates. Cell culture techniques, animal virus infection, quantification, and identification are taught at a biosafety level 2 for a diverse group of undergraduates ranging from 20 to 50 students per group. © 2017 by The International Union of Biochemistry and Molecular Biology, 45(6):537-543, 2017.

Concomitant herpes simplex virus colitis and hepatitis in a man with ulcerative colitis: Case report and review of the literature

BACKGROUND

Herpesvirus infections often complicate the clinical course of patients with inflammatory bowel disease; however, invasive disease due to herpes simplex virus is distinctly uncommon.

METHODS

We present a case of herpes simplex virus colitis and hepatitis, review all the previously published cases of herpes simplex virus colitis, and discuss common clinical features and outcomes. We also discuss the epidemiology, clinical manifestations, diagnosis, and management of herpes simplex virus infections, focusing specifically on patients with inflammatory bowel disease.

RESULTS

A 43-year-old man with ulcerative colitis, previously controlled with an oral 5-aminosalicylic agent, developed symptoms of a colitis flare that did not respond to treatment with systemic corticosteroid therapy. One week later he developed orolabial ulcers and progressive hepatic dysfunction, with markedly elevated transaminases and coagulopathy. He underwent emergent total colectomy when imaging suggested bowel micro-perforation. Pathology from both the colon and liver was consistent with herpes simplex virus infection, and a viral culture of his orolabial lesions and a serum polymerase chain reaction assay also identified herpes simplex virus. He was treated with systemic antiviral therapy and made a complete recovery.

CONCLUSIONS

Disseminated herpes simplex virus infection with concomitant involvement of the colon and liver has been reported only 3 times in the published literature, and to our knowledge this is the first such case in a patient with inflammatory bowel disease. The risk of invasive herpes simplex virus infections increases with some, but not all immunomodulatory therapies. Optimal management of herpes simplex virus in patients with inflammatory bowel disease includes targeted prophylactic therapy for patients with evidence of latent infection, and timely initiation of antiviral therapy for those patients suspected to have invasive disease.

The Transcription and Translation Landscapes during Human Cytomegalovirus Infection Reveal Novel Host-Pathogen Interactions

Viruses are by definition fully dependent on the cellular translation machinery, and develop diverse mechanisms to co-opt this machinery for their own benefit. Unlike many viruses, human cytomegalovirus (HCMV) does suppress the host translation machinery, and the extent to which translation machinery contributes to the overall pattern of viral replication and pathogenesis remains elusive. Here, we combine RNA sequencing and ribosomal profiling analyses to systematically address this question. By simultaneously examining the changes in transcription and translation along HCMV infection, we uncover extensive transcriptional control that dominates the response to infection, but also diverse and dynamic translational regulation for subsets of host genes. We were also able to show that, at late time points in infection, translation of viral mRNAs is higher than that of cellular mRNAs. Lastly, integration of our translation measurements with recent measurements of protein abundance enabled comprehensive identification of dozens of host proteins that are targeted for degradation during HCMV infection. Since targeted degradation indicates a strong biological importance, this approach should be applicable for discovering central host functions during viral infection. Our work provides a framework for studying the contribution of transcription, translation and degradation during infection with any virus.

Viruses are fully dependent on the cellular translation machinery, and develop diverse mechanisms to co-opt it for their own benefit. However, fundamental questions such as: what is the effect that infection has on the spectrum of host mRNAs that are being translated, and whether, and to what extent, a virus possesses mechanisms to commandeer the translation machinery are still hard to address. Here we show that by simultaneously examining the changes in transcription and translation along Human cytomegalovirus (HCMV) infection, we can uncover extensive transcriptional regulation, but also diverse and dynamic translational control. We were also able to show that, at late time points in infection, translation of viral mRNAs is higher than that of cellular mRNAs. Lastly, we take advantage of our measurements of translation (protein synthesis rate) and integrate these with mass spectrometry measurements (protein abundance). This integration allowed us to unbiasedly reveal dozens of cellular proteins that are being degraded during HCMV infection. Since targeted degradation indicates a strong biological importance, this approach should be applicable for discovering central host functions during viral infection. Our work provides a framework for studying the contribution of transcription, translation and degradation during infection with any virus.

Therapeutic potential of oncolytic Newcastle disease virus: a critical review

Newcastle disease virus (NDV) features a natural preference for replication in many tumor cells compared with normal cells. The observed antitumor effect of NDV appears to be a result of both selective killing of tumor cells and induction of immune responses. Genetic manipulations to change viral tropism and arming the virus with genes encoding for cytokines improved the oncolytic capacity of NDV. Several intracellular proteins in tumor cells, including antiapoptotic proteins (Livin) and oncogenic proteins (H-Ras), are relevant for the oncolytic activity of NDV. Defects in the interferon system, found in some tumor cells, also contribute to the oncolytic selectivity of NDV. Notwithstanding, NDV displays effective oncolytic activity in many tumor types, despite having intact interferon signaling. Taken together, several cellular systems appear to dictate the selective oncolytic activity of NDV. Some barriers, such as neutralizing antibodies elicited during NDV treatment and the extracellular matrix in tumor tissue appear to interfere with spread of NDV and reduce oncolysis. To further understand the oncolytic activity of NDV, we compared two NDV strains, ie, an attenuated virus (NDV-HUJ) and a pathogenic virus (NDV-MTH-68/H). Significant differences in amino acid sequence were noted in several viral proteins, including the fusion precursor (F0) glycoprotein, an important determinant of replication and pathogenicity. However, no difference in the oncolytic activity of the two strains was noted using human tumor tissues maintained as organ cultures or in mouse tumor models. To optimize virotherapy in clinical trials, we describe here a unique organ culture methodology, using a biopsy taken from a patient’s tumor before treatment for ex vivo infection with NDV to determine the oncolytic potential on an individual basis. In conclusion, oncolytic NDV is an excellent candidate for cancer therapy, but more knowledge is needed to ensure success in clinical trials.

Design and development of a robotized system coupled to µCT imaging for intratumoral drug evaluation in a HCC mouse model

Hepatocellular carcinoma (HCC) is one of the most common cancer related deaths worldwide. One of the main challenges in cancer treatment is drug delivery to target cancer cells specifically. Preclinical evaluation of intratumoral drugs in orthotopic liver cancer mouse models is difficult, as percutaneous injection hardly can be precisely performed manually. In the present study we have characterized a hepatoma model developing a single tumor nodule by implantation of Hep55.1C cells in the liver of syngeneic C57BL/6J mice. Tumor evolution was followed up by µCT imaging, and at the histological and molecular levels. This orthotopic, poorly differentiated mouse HCC model expressing fibrosis, inflammation and cancer markers was used to assess the efficacy of drugs. We took advantage of the high precision of a previously developed robotized system for automated, image-guided intratumoral needle insertion, to administer every week in the tumor of the Hep55.1C mouse model. A significant tumor growth inhibition was observed using our robotized system, whereas manual intraperitoneal administration had no effect, by comparison to untreated control mice.

A new antiviral screening method that simultaneously detects viral replication, cell viability, and cell toxicity

Viruses cause a variety of illnesses in humans, yet only a few antiviral drugs have been developed; thus, new antiviral drugs are urgently needed. Plants could be a good source of antiviral drugs, they do not have mobility and can only defend themselves by producing compounds against pathogens such as viruses in their own fix environment. These compounds may have the potential to inhibit animal and human viruses as well. In this study, a fast and reliable method for screening plant extracts for specific antiviral activity against Herpes simplex virus type-1 (HSV-1) was developed. This method distinguishes between host cell death due to infectivity and multiplicity of the virus versus toxicity of the plant extract. Extracts from 80 plant and plant organs were screened using this approach. Six plant extracts showed potential to exert specific HSV-1 growth inhibition activity. In two cases, different organs from the same plant showed similar active results. With this method it is possible to screen a large number of extracts in a rapid and accurate way to detect antiviral substances against HSV-I and other viruses.

Armed therapeutic viruses - a disruptive therapy on the horizon of cancer immunotherapy

For the past 150 years cancer immunotherapy has been largely a theoretical hope that recently has begun to show potential as a highly impactful treatment for various cancers. In particular, the identification and targeting of immune checkpoints have given rise to exciting data suggesting that this strategy has the potential to activate sustained antitumor immunity. It is likely that this approach, like other anti-cancer strategies before it, will benefit from co-administration with an additional therapeutic and that it is this combination therapy that may generate the greatest clinical outcome for the patient. In this regard, oncolytic viruses are a therapeutic moiety that is well suited to deliver and augment these immune-modulating therapies in a highly targeted and economically advantageous way over current treatment. In this review, we discuss the blockade of immune checkpoints, how oncolytic viruses complement and extend these therapies, and speculate on how this combination will uniquely impact the future of cancer immunotherapy.

Different modes of herpes simplex virus type 1 spread in brain and skin tissues

Herpes simplex virus type 1 (HSV-1) initially infects the skin and subsequently spreads to the nervous system. To investigate and compare HSV-1 mode of propagation in the two clinically relevant tissues, we have established ex vivo infection models, using native tissues of mouse and human skin, as well as mouse brain, maintained in organ cultures. HSV-1, which is naturally restricted to the human, infects and spreads in the mouse and human skin tissues in a similar fashion, thus validating the mouse model. The spread of HSV-1 in the skin was concentric to form typical plaques of limited size, predominantly of cytopathic cells. By contrast, HSV-1 spread in the brain tissue was directed along specific neuronal networks with no apparent cytopathic effect. Two additional differences were noted following infection of the skin and brain tissues. First, only a negligible amount of extracellular progeny virus was produced of the infected brain tissues, while substantial quantity of infectious progeny virus was released to the media of the infected skin. Second, antibodies against HSV-1, added following the infection, effectively restricted viral spread in the skin but have no effect on viral spread in the brain tissue. Taken together, these results reveal that HSV-1 spread within the brain tissue mostly by direct transfer from cell to cell, while in the skin the progeny extracellular virus predominates, thus facilitating the infection to new individuals.

Increased Resistance of Breast, Prostate, and Embryonic Carcinoma Cells against Herpes Simplex Virus in Three-Dimensional Cultures

In previous studies we found that uveal melanoma cells grown in extracellular matrix (ECM)-containing three-dimensional (3D) cultures have increased resistance against herpes simplex virus type 1 (HSV-1)-mediated destruction relative to cells cultured without ECM. Using additional tumor cell types including MB-231 human breast cancer cells, PC-3 human prostate cancer cells, and P19 mouse embryonal carcinoma cells, we show here that tumor cell lines other than melanoma are also more resistant to HSV-1-mediated destruction in 3D cultures than cells grown in 2D. We also demonstrate here that one mechanism responsible for the increased resistance of tumor cells to HSV-1 infection in 3D cultures is an ECM-mediated inhibition of virus replication following virus entry into cells. These findings confirm and extend previous observations related to the role of the ECM in tumor resistance against HSV-1 and may lead to improved strategies of oncolytic virotherapy.

Efficiency of cell-free and cell-associated virus in mucosal transmission of human immunodeficiency virus type 1 and simian immunodeficiency virus

Effective strategies are needed to block mucosal transmission of human immunodeficiency virus type 1 (HIV-1). Here, we address a crucial question in HIV-1 pathogenesis: whether infected donor mononuclear cells or cell-free virus plays the more important role in initiating mucosal infection by HIV-1. This distinction is critical, as effective strategies for blocking cell-free and cell-associated virus transmission may be different. We describe a novel ex vivo model system that utilizes sealed human colonic mucosa explants and demonstrate in both the ex vivo model and in vivo using the rectal challenge model in rhesus monkeys that HIV-1-infected lymphocytes can transmit infection across the mucosa more efficiently than cell-free virus. These findings may have significant implications for our understanding of the pathogenesis of mucosal transmission of HIV-1 and for the development of strategies to prevent HIV-1 transmission.

Mechanisms of foot-and-mouth disease virus tropism inferred from differential tissue gene expression

Foot-and-mouth disease virus (FMDV) targets specific tissues for primary infection, secondary high-titer replication (e.g. foot and mouth where it causes typical vesicular lesions) and long-term persistence at some primary replication sites. Although integrin αVβ6 receptor has been identified as primary FMDV receptors in animals, their tissue distribution alone fails to explain these highly selective tropism-driven events. Thus, other molecular mechanisms must play roles in determining this tissue specificity. We hypothesized that differences in certain biological activities due to differential gene expression determine FMDV tropism and applied whole genome gene expression profiling to identify genes differentially expressed between FMDV-targeted and non-targeted tissues in terms of supporting primary infection, secondary replication including vesicular lesions, and persistence. Using statistical and bioinformatic tools to analyze the differential gene expression, we identified mechanisms that could explain FMDV tissue tropism based on its association with differential expression of integrin αVβ6 heterodimeric receptor (FMDV receptor), fibronectin (ligand of the receptor), IL-1 cytokines, death receptors and the ligands, and multiple genes in the biological pathways involved in extracellular matrix turnover and interferon signaling found in this study. Our results together with reported findings indicate that differences in (1) FMDV receptor availability and accessibility, (2) type I interferon-inducible immune response, and (3) ability to clear virus infected cells via death receptor signaling play roles in determining FMDV tissue tropism and the additional increase of high extracellular matrix turnover induced by FMDV infection, likely via triggering the signaling of highly expressed IL-1 cytokines, play a key role in the pathogenesis of vesicular lesions.

Extracellular matrix constituents interfere with Newcastle disease virus spread in solid tissue and diminish its potential oncolytic activity

Advanced melanoma cells, characterized by resistance to chemotherapy, have been shown to be highly sensitive to oncolysis by Newcastle disease virus (NDV). In the present study, we investigated the capacity of NDV to specifically infect and spread into solid tissues of human melanoma and lung carcinoma, in vivo and ex vivo. For this purpose a new model of SCID-beige mice implanted with human melanoma was developed. Surprisingly, the replication competent NDV-MTH and the attenuated, single-cycle replication NDV-HUJ strains, demonstrated a similar oncolytic activity in the melanoma-implanted mice. Further, ex vivo analysis, using organ cultures derived from the melanoma tissues indicated a limited spread of the two NDV strains in the tissue. Extracellular matrix (ECM) molecules, notably heparin sulfate and collagen, were found to limit viral spread in the tissue. This observation was validated with yet another solid tumour of human lung carcinoma. Taken together, the results indicate that the ECM acts as a barrier to virus spread within solid tumour tissues and that this restriction must be overcome to achieve effective oncolysis with NDV.

Modeling of human cytomegalovirus maternal-fetal transmission in a novel decidual organ culture

Human cytomegalovirus (HCMV) is the leading cause of congenital infection, associated with severe birth defects and intrauterine growth retardation. The mechanism of HCMV transmission via the maternal-fetal interface is largely unknown, and there are no animal models for HCMV. The initial stages of infection are believed to occur in the maternal decidua. Here we employed a novel decidual organ culture, using both clinically derived and laboratory-derived viral strains, for the ex vivo modeling of HCMV transmission in the maternal-fetal interface. Viral spread in the tissue was demonstrated by the progression of infected-cell foci, with a 1.3- to 2-log increase in HCMV DNA and RNA levels between days 2 and 9 postinfection, the expression of immediate-early and late proteins, the appearance of typical histopathological features of natural infection, and dose-dependent inhibition of infection by ganciclovir and acyclovir. HCMV infected a wide range of cells in the decidua, including invasive cytotrophoblasts, macrophages, and endothelial, decidual, and dendritic cells. Cell-to-cell viral spread was revealed by focal extension of infected-cell clusters, inability to recover infectious extracellular virus, and high relative proportions (88 to 93%) of cell-associated viral DNA. Intriguingly, neutralizing HCMV hyperimmune globulins exhibited inhibitory activity against viral spread in the decidua even when added at 24 h postinfection-providing a mechanistic basis for their clinical use in prenatal prevention. The ex vivo-infected decidual cultures offer unique insight into patterns of viral tropism and spread, defining initial stages of congenital HCMV transmission, and can facilitate evaluation of the effects of new antiviral interventions within the maternal-fetal interface milieu.

Restrictions that control herpes simplex virus type 1 infection in mouse brain ex vivo

Elucidating the cellular and molecular factors governing herpes simplex virus type 1 (HSV-1) neurotropism is a prerequisite for understanding HSV-1 encephalitis and for targeting HSV-1-derived vectors for gene transfer to the brain. Earlier we had described an ex vivo system of mouse brain slices and demonstrated a selective and unique infection pattern, mostly around the ventricles. Here, we examined tissue factors controlling HSV-1 infection of brain slices. We demonstrated that heparan sulphate, while an important factor, does not determine the infection pattern. Hyaluronic acid, but not collagen, appears to enhance HSV-1 brain infection. To investigate whether tissue distribution of viral receptors determines the infection pattern, we examined transcription of herpes virus entry mediator and nectin-1 receptor genes in infected and uninfected brain regions. Both the infected and the uninfected regions express the receptors. We also explored the influence of intra-cellular factors. HSV-1 does not preferentially infect proliferating cells in the brain slices, despite its predilection to the ventricular zones. To delineate the step at which the HSV-1 infection cascade is restricted, mRNA was isolated following tissue infection, and transcription of the immediate-early and late viral genes was evaluated. The results indicated that HSV-1 genes are not expressed in regions that do not express a viral reporter gene. Therefore, we conclude that tissue resistance to infection is associated with a block at or prior to the immediate-early mRNA synthesis. Taken together, using the ex vivo system of organotypic culture we describe here extra-cellular and intra-cellular restriction levels of HSV-1 brain infection.

The emerging role of viruses in the treatment of solid tumours

There is increasing optimism for the use of non-pathogenic viruses in the treatment of many cancers. Initial interest in oncolytic virotherapy was based on the observation of an occasional clinical resolution of a lymphoma after a systemic viral infection. In many cancers, by comparison with normal tissues, the competency of the cellular anti-viral mechanism is impaired, thus creating an exploitable difference between the tumour and normal cells, as an unimpeded viral proliferation in cancer cells is eventually cytocidal. In addition to their oncolytic capability, these particular viruses may be engineered to facilitate gene delivery to tumour cells to produce therapeutic effects such as cytokine secretion and anti -tumour immune responses prior to the eventual cytolysis. There is now promising clinical experience with these viral strategies, particularly as part of multimodal studies, and already several clinical trials are in progress. The limitations of standard cancer chemotherapies, including their lack of specificity with consequent collateral toxicity and the development of cross-resistance, do not appear to apply to viral-based therapies. Furthermore, virotherapy frequently restores chemoradiosensitivity to resistant tumours and has also demonstrated efficacy against cancers that historically have a dismal prognosis. While there is cause for optimism, through continued improvements in the efficiency and safety of systemic delivery, through the emergence of alternative viral agents and through favourable clinical experiences, clinical trials as part of multimodal protocols will be necessary to define clinical utility. Significant progress has been made and this is now a major research area with an increasing annual bibliography.

A common neuronal response to alphaherpesvirus infection

Alphaherpesviruses are a subfamily of the Herpesviridae that can invade the nervous system and establish either lytic or latent infections. The establishment of latent infection can occur only in neurons, indicating a unique virus-host interaction in these cells. Here, we compare results from seven microarray studies that focused on the host response of either neural tissue or isolated neurons to alphaherpesvirus infection. These studies utilized either herpes simplex virus type 1 or pseudorabies virus as the infectious agent. From these data, we have found common host responses spanning a variety of infection models in different species, with different herpesvirus strains, and during all phases of infection including lytic, latent, and reactivation. The repeated observation of transcriptional effects on these genes and gene families indicates their likely importance in host defenses or the viral infectious process. We discuss the possible role of these different genes and genes families in alphaherpesvirus infection.

A single-amino-acid substitution in herpes simplex virus 1 envelope glycoprotein B at a site required for binding to the paired immunoglobulin-like type 2 receptor alpha (PILRalpha) abrogates PILRalpha-dependent viral entry and reduces pathogenesis

Paired immunoglobulin-like type 2 receptor α (PILRα) is a herpes simplex virus 1 (HSV-1) entry receptor that associates with O-glycans on HSV-1 envelope glycoprotein B (gB). Two threonine residues (Thr-53 and Thr-480) in gB, which are required for the addition of the principal gB O-glycans, are essential for binding to soluble PILRα. However, the role of the two threonines in PILRα-dependent viral entry remains to be elucidated. Therefore, we constructed a recombinant HSV-1 carrying an alanine replacement of gB Thr-53 alone (gB-T53A) or of both gB Thr-53 and Thr-480 (gB-T53/480A) and demonstrated that these mutations abrogated viral entry in CHO cells expressing PILRα. In contrast, the mutations had no effect on viral entry in CHO cells expressing known host cell receptors for HSV-1 gD, viral entry in HL60 cells expressing myelin-associated glycoprotein (MAG) (another HSV-1 gB receptor), viral attachment to heparan sulfate, and viral replication in PILRα-negative cells. These results support the hypothesis that gB Thr-53 and Thr-480 as well as gB O-glycosylation, probably at these sites, are critical for PILRα-dependent viral entry. Interestingly, following corneal inoculation in mice, the gB-T53A and gB-T53/480A mutations significantly reduced viral replication in the cornea, the development of herpes stroma keratitis, and neuroinvasiveness. The abilities of HSV-1 to enter cells in a PILRα-dependent manner and to acquire specific carbohydrates on gB are therefore linked to an increase in viral replication and virulence in the experimental murine model.

Analysis of genetically engineered oncolytic herpes simplex viruses in human prostate cancer organotypic cultures

Oncolytic herpes simplex viruses type 1 (oHSVs) such as G47Delta and G207 are genetically engineered for selective replication competence in cancer cells. Several factors can influence the overall effectiveness of oHSV tropism, including HSV-1 receptor expression, extracellular matrix milieu and cellular permissiveness. We have taken advantage of human prostate organ cultures derived from radical prostatectomies to investigate oHSV tropism. In this study, we show that both G47Delta and G207 specifically replicate in epithelial cells of the prostatic glands but not in the surrounding stroma. In contrast, both the epithelial and stromal cell compartments were readily infected by wild-type HSV-1. Analysis of oHSV replication in prostate surgical specimens 3 days post infection showed that G47Delta generated approximately 30-fold more viral progeny than did G207. This correlated with the enhanced expression of G47Delta-derived glycoprotein gB protein levels as compared with G207. In benign prostate tissues, G207 and G47Delta titers were notably reduced, whereas strain F titers were maintained at similar levels compared with prostate cancer specimens. Overall, our results show that these oncolytic herpes vectors show both target specificity and replication competence in human prostate cancer specimens and point to the utility of using human prostate organ cultures in assessing oHSV tropism and cellular specificity.

Oncolytic Viruses for Cancer Therapy: Overcoming the Obstacles

Targeted therapy of cancer using oncolytic viruses has generated much interest over the past few years in the light of the limited efficacy and side effects of standard cancer therapeutics for advanced disease. In 2006, the world witnessed the first government-approved oncolytic virus for the treatment of head and neck cancer. It has been known for many years that viruses have the ability to replicate in and lyse cancer cells. Although encouraging results have been demonstrated in vitro and in animal models, most oncolytic viruses have failed to impress in the clinical setting. The explanation is multifactorial, determined by the complex interactions between the tumor and its microenvironment, the virus, and the host immune response. This review focuses on discussion of the obstacles that oncolytic virotherapy faces and recent advances made to overcome them, with particular reference to adenoviruses.

Precision-cut slice cultures of tumors from MMTV-neu mice for the study of the ex vivo response to cytokines and cytotoxic drugs

Ex vivo analysis of signaling pathways operating in tumor tissue is complicated by the three-dimensional structure, in particular by stroma-epithelial interactions. Studies performed with pure populations of tumor cells usually do not take into account this issue. One possibility to preserve the tissue architecture is the use of tumor slices. However, diffusion of oxygen and nutrients may become limiting factors, resulting in decreased cell viability and change of tissue morphology, especially after long-term incubation of slices. By using precision cut slices of defined thickness, we were able to establish culture conditions for tumor material obtained from MMTV-neu transgenic mice, which allow the study of the action of cytokines and cytotoxic drugs for up to 24 h. A slice thickness of 160 mum was found to be optimal for viability and handling of material. These slices were highly responsive to the action of the cytokine IFN-gamma, as evident form the increase of pY701 STAT1, detected by both immunohistochemistry and western blotting, and by the increase of mRNA levels of the IFN-gamma response genes IRF-1, SOCS-1, and STAT1, analyzed by reverse transcriptase-polymerase chain reaction. Furthermore, induction of apoptosis and increase of DNA damage could be monitored after treatment with IFN-gamma or doxorubicin. The slices were also a convenient source for the establishment of explant cultures of tumor epithelial cells. It is concluded that cultivation of precision-cut tumor slices provides a convenient way for the ex vivo molecular analysis of MMTV-neu tumor tissue under conditions which closely simulate the situation in vivo and can provide an alternative to in vivo experiments.

Herpes simplex virus delivery to orthotopic rectal carcinoma results in an efficient and selective antitumor effect

Cancer of the rectum poses a complex therapeutic challenge because of its proximity to adjacent organs and anal sphincters. The addition of radiotherapy before surgical resection has been shown to confer good survival rates while preserving sphincter function. Nevertheless, radiation is associated with significant side effects. On the basis of our previous work showing that herpes simplex virus type-1 (HSV-1) preferentially infects human colon cancer, we set out to examine the oncolytic effect of HSV-1 on orthotopic rectal tumors in mice. Two vectors were compared for oncolytic activity, HSV-1(Gbeta) with wild-type replication and an attenuated HSV-1 vector (HSV-G47Delta). Intratumoral injection of HSV-1(Gbeta) and HSV-G47Delta resulted in a significant reduction or disappearance of the tumors and increased survival of mice. Although the use of HSV-1(Gbeta) was associated with systemic toxicity, HSV-G47Delta appears to possess a selective oncolytic activity. Moreover, infection with HSV-G47Delta resulted in the activation of the double-stranded RNA-dependent protein kinase (PKR) pathway. A significant improvement in viral replication and the antitumor effect was observed when the PKR inhibitor 2-aminopurine was coadministered with HSV-G47Delta to the tumor. In conclusion, the efficacy of local delivery of HSV-G47Delta combined with a specific chemical inhibitor of antiviral activity points to a novel therapeutic modality for rectal cancer and other solid tumors.