Viruses

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Open AccessReview

The Chromatin Landscape of Kaposi’s Sarcoma-Associated Herpesvirus

by Zsolt Toth, Kevin Brulois and Jae U. Jung

Viruses 2013, 5(5), 1346-1373; https://doi.org/10.3390/v5051346 - 23 May 2013

Cited by 57 | Viewed by 10931

Kaposi’s sarcoma-associated herpesvirus is an oncogenic γ-herpesvirus that causes latent infection in humans. In cells, the viral genome adopts a highly organized chromatin structure, which is controlled by a wide variety of cellular and viral chromatin regulatory factors. In the past few years, [...] Read more.

Kaposi’s sarcoma-associated herpesvirus is an oncogenic γ-herpesvirus that causes latent infection in humans. In cells, the viral genome adopts a highly organized chromatin structure, which is controlled by a wide variety of cellular and viral chromatin regulatory factors. In the past few years, interrogation of the chromatinized KSHV genome by whole genome-analyzing tools revealed that the complex chromatin landscape spanning the viral genome in infected cells has important regulatory roles during the viral life cycle. This review summarizes the most recent findings regarding the role of histone modifications, histone modifying enzymes, DNA methylation, microRNAs, non-coding RNAs and the nuclear organization of the KSHV epigenome in the regulation of latent and lytic viral gene expression programs as well as their connection to KSHV-associated pathogenesis. Full article

(This article belongs to the Special Issue Chromatin Control of Viral Infection)

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1200 KiB

Open AccessArticle

Epigenetic Control of Cytomegalovirus Latency and Reactivation

by Xue-feng Liu, Xueqiong Wang, Shixian Yan, Zheng Zhang, Michael Abecassis and Mary Hummel

Viruses 2013, 5(5), 1325-1345; https://doi.org/10.3390/v5051325 - 23 May 2013

Cited by 38 | Viewed by 12248

Abstract

Cytomegalovirus (CMV) gene expression is repressed in latency due to heterochromatinization of viral genomes. In murine CMV (MCMV) latently infected mice, viral genomes are bound to histones with heterochromatic modifications, to enzymes that mediate these modifications, and to adaptor proteins that may recruit [...] Read more.

Cytomegalovirus (CMV) gene expression is repressed in latency due to heterochromatinization of viral genomes. In murine CMV (MCMV) latently infected mice, viral genomes are bound to histones with heterochromatic modifications, to enzymes that mediate these modifications, and to adaptor proteins that may recruit co-repressor complexes. Kinetic analyses of repressor binding show that these repressors are recruited at the earliest time of infection, suggesting that latency may be the default state. Kidney transplantation leads to epigenetic reprogramming of latent viral chromatin and reactivation of immediate early gene expression. Inflammatory signaling pathways, which activate transcription factors that regulate the major immediate early promoter (MIEP), likely mediate the switch in viral chromatin. Full article

(This article belongs to the Special Issue Chromatin Control of Viral Infection)

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1013 KiB

Open AccessReview

Hepatitis C Virus, Cholesterol and Lipoproteins — Impact for the Viral Life Cycle and Pathogenesis of Liver Disease

by Daniel J. Felmlee, Mohamed Lamine Hafirassou, Mathieu Lefevre, Thomas F. Baumert and Catherine Schuster

Viruses 2013, 5(5), 1292-1324; https://doi.org/10.3390/v5051292 - 23 May 2013

Cited by 116 | Viewed by 17940

Abstract

Hepatitis C virus (HCV) is a leading cause of chronic liver disease, including chronic hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. Hepatitis C infection associates with lipid and lipoprotein metabolism disorders such as hepatic steatosis, hypobetalipoproteinemia, and hypocholesterolemia. Furthermore, virus production is dependent on [...] Read more.

Hepatitis C virus (HCV) is a leading cause of chronic liver disease, including chronic hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. Hepatitis C infection associates with lipid and lipoprotein metabolism disorders such as hepatic steatosis, hypobetalipoproteinemia, and hypocholesterolemia. Furthermore, virus production is dependent on hepatic very-low-density lipoprotein (VLDL) assembly, and circulating virions are physically associated with lipoproteins in complexes termed lipoviral particles. Evidence has indicated several functional roles for the formation of these complexes, including co-opting of lipoprotein receptors for attachment and entry, concealing epitopes to facilitate immune escape, and hijacking host factors for HCV maturation and secretion. Here, we review the evidence surrounding pathogenesis of the hepatitis C infection regarding lipoprotein engagement, cholesterol and triglyceride regulation, and the molecular mechanisms underlying these effects. Full article

(This article belongs to the Section Animal Viruses)

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Open AccessReview

The Dynamics of HCF-1 Modulation of Herpes Simplex Virus Chromatin during Initiation of Infection

by Jodi L. Vogel and Thomas M. Kristie

Viruses 2013, 5(5), 1272-1291; https://doi.org/10.3390/v5051272 - 22 May 2013

Cited by 34 | Viewed by 10982

Abstract

Successful infection of herpes simplex virus is dependent upon chromatin modulation by the cellular coactivator host cell factor-1 (HCF-1). This review focuses on the multiple chromatin modulation components associated with HCF-1 and the chromatin-related dynamics mediated by this coactivator that lead to the [...] Read more.

Successful infection of herpes simplex virus is dependent upon chromatin modulation by the cellular coactivator host cell factor-1 (HCF-1). This review focuses on the multiple chromatin modulation components associated with HCF-1 and the chromatin-related dynamics mediated by this coactivator that lead to the initiation of herpes simplex virus (HSV) immediate early gene expression. Full article

(This article belongs to the Special Issue Chromatin Control of Viral Infection)

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826 KiB

Open AccessArticle

Role and Functional Domain of Hepatitis B Virus X Protein in Regulating HBV Transcription and Replication in Vitro and in Vivo

by Dao-Yin Gong, En-Qiang Chen, Fei-Jun Huang, Xiao-Hua Leng, Xing Cheng and Hong Tang

Viruses 2013, 5(5), 1261-1271; https://doi.org/10.3390/v5051261 - 22 May 2013

Cited by 31 | Viewed by 7883

Abstract

The role of hepatitis B virus (HBV) X protein (HBx) in the regulation of HBV replication remains controversial. In the present study, the role of HBx in regulating HBV replication was initially investigated in both HepG2 and Huh7 in vitro cell lines with [...] Read more.

The role of hepatitis B virus (HBV) X protein (HBx) in the regulation of HBV replication remains controversial. In the present study, the role of HBx in regulating HBV replication was initially investigated in both HepG2 and Huh7 in vitro cell lines with a transient transfection system. Next, the regions of HBx responsible for transcriptional transactivation and promotion of HBV replication were mapped in an HBV replication mouse model by in vivo transfection of a series of HBx expression plasmids. In an in vitro setting, HBx deﬁciency had little effect on HBV replication in Huh7 cells, but impaired HBV replication in HepG2 cells. In an in vivo setting, HBx had a strong enhancing effect on HBV transcription and replication. For the C-terminal two-thirds of the protein (amino acids [aa] 51 to 154) was required for this function of HBx, and the regions spanning aa 52 to 72 and 88 to 154 were found to be important for the stimulatory function of HBx on HBV replication. In conclusion, the role of HBx in HBV replication regulation is affected by host cell type, and HBx has an important role in stimulating HBV transcription and replication in hepatocytes in vivo. Further, the transcriptional transactivation function of HBx may be crucial for its stimulatory effect on HBV transcription and replication. Full article

(This article belongs to the Section Animal Viruses)

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423 KiB

Open AccessReview

Suppression of Coronavirus Replication by Cyclophilin Inhibitors

by Yoshikazu Tanaka, Yuka Sato and Takashi Sasaki

Viruses 2013, 5(5), 1250-1260; https://doi.org/10.3390/v5051250 - 22 May 2013

Cited by 132 | Viewed by 14544

Abstract

Coronaviruses infect a variety of mammalian and avian species and cause serious diseases in humans, cats, mice, and birds in the form of severe acute respiratory syndrome (SARS), feline infectious peritonitis (FIP), mouse hepatitis, and avian infectious bronchitis, respectively. No effective vaccine or [...] Read more.

Coronaviruses infect a variety of mammalian and avian species and cause serious diseases in humans, cats, mice, and birds in the form of severe acute respiratory syndrome (SARS), feline infectious peritonitis (FIP), mouse hepatitis, and avian infectious bronchitis, respectively. No effective vaccine or treatment has been developed for SARS-coronavirus or FIP virus, both of which cause lethal diseases. It has been reported that a cyclophilin inhibitor, cyclosporin A (CsA), could inhibit the replication of coronaviruses. CsA is a well-known immunosuppressive drug that binds to cellular cyclophilins to inhibit calcineurin, a calcium-calmodulin-activated serine/threonine-specific phosphatase. The inhibition of calcineurin blocks the translocation of nuclear factor of activated T cells from the cytosol into the nucleus, thus preventing the transcription of genes encoding cytokines such as interleukin-2. Cyclophilins are peptidyl-prolyl isomerases with physiological functions that have been described for many years to include chaperone and foldase activities. Also, many viruses require cyclophilins for replication; these include human immunodeficiency virus, vesicular stomatitis virus, and hepatitis C virus. However, the molecular mechanisms leading to the suppression of viral replication differ for different viruses. This review describes the suppressive effects of CsA on coronavirus replication. Full article

(This article belongs to the Special Issue Cyclophilins and Viruses)

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446 KiB

Open AccessReview

Biochemical and Functional Interactions of Human Papillomavirus Proteins with Polycomb Group Proteins

by Margaret E. McLaughlin-Drubin and Karl Munger

Viruses 2013, 5(5), 1231-1249; https://doi.org/10.3390/v5051231 - 14 May 2013

Cited by 28 | Viewed by 10175

Abstract

The role of enzymes involved in polycomb repression of gene transcription has been studied extensively in human cancer. Polycomb repressive complexes mediate oncogene-induced senescence, a principal innate cell-intrinsic tumor suppressor pathway that thwarts expansion of cells that have suffered oncogenic hits. Infections with [...] Read more.

The role of enzymes involved in polycomb repression of gene transcription has been studied extensively in human cancer. Polycomb repressive complexes mediate oncogene-induced senescence, a principal innate cell-intrinsic tumor suppressor pathway that thwarts expansion of cells that have suffered oncogenic hits. Infections with human cancer viruses including human papillomaviruses (HPVs) and Epstein-Barr virus can trigger oncogene-induced senescence, and the viruses have evolved strategies to abrogate this response in order to establish an infection and reprogram their host cells to establish a long-term persistent infection. As a consequence of inhibiting polycomb repression and evading oncogene induced-senescence, HPV infected cells have an altered epigenetic program as evidenced by aberrant homeobox gene expression. Similar alterations are frequently observed in non-virus associated human cancers and may be harnessed for diagnosis and therapy. Full article

(This article belongs to the Special Issue Chromatin Control of Viral Infection)

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Open AccessArticle

Antiviral Activity of Bacillus sp. Isolated from the Marine Sponge Petromica citrina against Bovine Viral Diarrhea Virus, a Surrogate Model of the Hepatitis C Virus

by Juliana Cristina Santiago Bastos, Luciana Konecny Kohn, Fabiana Fantinatti-Garboggini, Marina Aiello Padilla, Eduardo Furtado Flores, Bárbara Pereira Da Silva, Cláudia Beatriz Afonso De Menezes and Clarice Weis Arns

Viruses 2013, 5(5), 1219-1230; https://doi.org/10.3390/v5051219 - 29 Apr 2013

Cited by 21 | Viewed by 7085

Abstract

The Hepatitis C virus causes chronic infections in humans, which can develop to liver cirrhosis and hepatocellular carcinoma. The Bovine viral diarrhea virus is used as a surrogate model for antiviral assays for the HCV. From marine invertebrates and microorganisms isolated from them, [...] Read more.

The Hepatitis C virus causes chronic infections in humans, which can develop to liver cirrhosis and hepatocellular carcinoma. The Bovine viral diarrhea virus is used as a surrogate model for antiviral assays for the HCV. From marine invertebrates and microorganisms isolated from them, extracts were prepared for assessment of their possible antiviral activity. Of the 128 tested, 2 were considered active and 1 was considered promising. The best result was obtained from the extracts produced from the Bacillus sp. isolated from the sponge Petromica citrina. The extracts 555 (500 µg/mL, SI>18) and 584 (150 µg/mL, SI 27) showed a percentage of protection of 98% against BVDV, and the extract 616, 90% of protection. All of them showed activity during the viral adsorption. Thus, various substances are active on these studied organisms and may lead to the development of drugs which ensure an alternative therapy for the treatment of hepatitis C. Full article

(This article belongs to the Section Viral Immunology, Vaccines, and Antivirals)

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Open AccessReview

The Role of the CoREST/REST Repressor Complex in Herpes Simplex Virus 1 Productive Infection and in Latency

by Guoying Zhou, Te Du and Bernard Roizman

Viruses 2013, 5(5), 1208-1218; https://doi.org/10.3390/v5051208 - 29 Apr 2013

Cited by 23 | Viewed by 8656

Abstract

REST is a key component of the HDAC1 or 2, CoREST, LSD1, REST (HCLR) repressor complex. The primary function of the HCLR complex is to silence neuronal genes in non-neuronal cells. HCLR plays a role in regulating the expression of viral genes in [...] Read more.

REST is a key component of the HDAC1 or 2, CoREST, LSD1, REST (HCLR) repressor complex. The primary function of the HCLR complex is to silence neuronal genes in non-neuronal cells. HCLR plays a role in regulating the expression of viral genes in productive infections as a donor of LDS1 for expression of α genes and as a repressor of genes expressed later in infection. In sensory neurons the HCLR complex is involved in the silencing of viral genome in the course of establishment of latency. The thesis of this article is that (a) sensory neurons evolved a mechanism to respond to the presence and suppress the transmission of infectious agents from the periphery to the CNS and (b) HSV evolved subservience to the HCLR with at least two objectives: to maintain a level of replication consistent with maximal person-to-person spread and to enable it to take advantage of neuronal innate immune responses to survive and be available for reactivation shielded from adaptive immune responses of the host. Full article

(This article belongs to the Special Issue Chromatin Control of Viral Infection)

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Viruses, Volume 5, Issue 5 (May 2013) – 9 articles , Pages 1208-1373

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