scholarly journals MC159 of Molluscum Contagiosum Virus Suppresses Autophagy by Recruiting Cellular SH3BP4 via an SH3 Domain-Mediated Interaction

2019 ◽  
Vol 93 (10) ◽  
Author(s):  
Constanze Schmotz ◽  
Hasan Uğurlu ◽  
Silja Vilen ◽  
Subhash Shrestha ◽  
Riku Fagerlund ◽  
...  
Keyword(s):  
Host Cell ◽  
Antiviral Immunity ◽  
Skin Lesions ◽  
Molluscum Contagiosum ◽  
Cell Protein ◽  
Binding Motif ◽  
Molluscum Contagiosum Virus ◽  
Cellular Functions ◽  
Inhibitory Protein ◽  
Novel Host

ABSTRACT MC159 is a viral FLIP (FLICE inhibitory protein) encoded by the molluscum contagiosum virus (MCV) enabling MCV to evade antiviral immunity and to establish persistent infections in humans. Here, we show that MC159 contains a functional SH3 binding motif, which mediates avid and selective binding to SH3BP4, a signaling protein known to regulate endocytic trafficking and suppress cellular autophagy. The capacity to bind SH3BP4 was dispensable for regulation of NF-κB-mediated transcription and suppression of proapoptotic caspase activation but contributed to inhibition of amino acid starvation-induced autophagy by MC159. These results provide new insights into the cellular functions of MC159 and reveal SH3BP4 as a novel host cell factor targeted by a viral immune evasion protein. IMPORTANCE After the eradication of smallpox, molluscum contagiosum virus (MCV) is the only poxvirus restricted to infecting humans. MCV infection is common and causes benign skin lesions that usually resolve spontaneously but may persist for years and grow large, especially in immunocompromised individuals. While not life threatening, MCV infections pose a significant global health burden. No vaccine or specific anti-MCV therapy is available. MCV encodes several proteins that enable it to evade antiviral immunity, a notable example of which is the MC159 protein. In this study, we describe a novel mechanism of action for MC159 involving hijacking of a host cell protein called SH3BP4 to suppress autophagy, a cellular recycling mechanism important for antiviral immunity. This study contributes to our understanding of the host cell interactions of MCV and the molecular function of MC159.

scholarly journals Molluscum Contagiosum Virus MC159 Abrogates cIAP1-NEMO Interactions and Inhibits NEMO Polyubiquitination

2017 ◽  
Vol 91 (15) ◽  
Author(s):  
Sunetra Biswas ◽  
Joanna L. Shisler
Keyword(s):  
Host Cell ◽  
Skin Neoplasms ◽  
Skin Lesions ◽  
Molluscum Contagiosum ◽  
Host Cells ◽  
Molluscum Contagiosum Virus ◽  
Antiviral Responses ◽  
Iκb Kinase ◽  
Apoptosis Protein ◽  
Ikk Complex

ABSTRACT Molluscum contagiosum virus (MCV) is a dermatotropic poxvirus that causes benign skin lesions. MCV lesions persist because of virally encoded immune evasion molecules that inhibit antiviral responses. The MCV MC159 protein suppresses NF-κB activation, a powerful antiviral response, via interactions with the NF-κB essential modulator (NEMO) subunit of the IκB kinase (IKK) complex. Binding of MC159 to NEMO does not disrupt the IKK complex, implying that MC159 prevents IKK activation via an as-yet-unidentified strategy. Here, we demonstrated that MC159 inhibited NEMO polyubiquitination, a posttranslational modification required for IKK and downstream NF-κB activation. Because MCV cannot be propagated in cell culture, MC159 was expressed independent of infection or during a surrogate vaccinia virus infection to identify how MC159 prevented polyubiquitination. Cellular inhibitor of apoptosis protein 1 (cIAP1) is a cellular E3 ligase that ubiquitinates NEMO. Mutational analyses revealed that MC159 and cIAP1 each bind to the same NEMO region, suggesting that MC159 may competitively inhibit cIAP1-NEMO interactions. Indeed, MC159 prevented cIAP1-NEMO interactions. MC159 also diminished cIAP1-mediated NEMO polyubiquitination and cIAP1-induced NF-κB activation. These data suggest that MC159 competitively binds to NEMO to prevent cIAP1-induced NEMO polyubiquitination. To our knowledge, this is the first report of a viral protein disrupting NEMO-cIAP1 interactions to strategically suppress IKK activation. All viruses must antagonize antiviral signaling events for survival. We hypothesize that MC159 inhibits NEMO polyubiquitination as a clever strategy to manipulate the host cell environment to the benefit of the virus. IMPORTANCE Molluscum contagiosum virus (MCV) is a human-specific poxvirus that causes persistent skin neoplasms. The persistence of MCV has been attributed to viral downregulation of host cell immune responses such as NF-κB activation. We show here that the MCV MC159 protein interacts with the NEMO subunit of the IKK complex to prevent NEMO interactions with the cIAP1 E3 ubiquitin ligase. This interaction correlates with a dampening of cIAP1 to polyubiquitinate NEMO and to activate NF-κB. This inhibition of cIAP1-NEMO interactions is a new viral strategy to minimize IKK activation and to control NEMO polyubiquitination. This research provides new insights into mechanisms that persistent viruses may use to cause long-term infection of host cells.

scholarly journals Poxvirus Protein MC132 from Molluscum Contagiosum Virus Inhibits NF-κB Activation by Targeting p65 for Degradation

2015 ◽  
Vol 89 (16) ◽  
pp. 8406-8415 ◽  
Author(s):  
Gareth Brady ◽  
Darya A. Haas ◽  
Paul J. Farrell ◽  
Andreas Pichlmair ◽  
Andrew G. Bowie
Keyword(s):  
Innate Immunity ◽  
Affinity Purification ◽  
Virus Detection ◽  
Antiviral Immunity ◽  
Skin Lesions ◽  
Molluscum Contagiosum ◽  
Human Infection ◽  
Molluscum Contagiosum Virus ◽  
Live Virus ◽  
C Complex

ABSTRACTMolluscum contagiosum virus (MCV) is unique in being the only known extant, human-adapted poxvirus, yet to date, it is very poorly characterized in terms of host-pathogen interactions. MCV causes persistent skin lesions filled with live virus, but these are generally immunologically silent, suggesting the presence of potent inhibitors of human antiviral immunity and inflammation. Fewer than five MCV immunomodulatory genes have been characterized in detail, but it is likely that many more remain to be discovered given the density of such sequences in all well-characterized poxviruses. Following virus infection, NF-κB activation occurs in response to both pattern recognition receptor (PRR) signaling and cellular activation by virus-elicited proinflammatory cytokines, such as tumor necrosis factor (TNF). As such, NF-κB activation is required for virus detection, antiviral signaling, inflammation, and clearance of viral infection. Hence, we screened a library of MCV genes for effects on TNF-stimulated NF-κB activation. This revealed MC132, a unique protein with no orthologs in other poxviral genomes, as a novel inhibitor of NF-κB. Interestingly, MC132 also inhibited PRR- and virus-activated NF-κB, since MC132 interacted with the NF-κB subunit p65 and caused p65 degradation. Unbiased affinity purification to identify host targets of MC132 revealed that MC132 acted by targeting NF-κB p65 for ubiquitin-dependent proteasomal degradation by recruiting p65 to a host Cullin-5/Elongin B/Elongin C complex. These data reveal a novel mechanism for poxviral inhibition of human innate immunity and further clarify how the human-adapted poxvirus MCV can so effectively evade antiviral immunity to persist in skin lesions.IMPORTANCEHow human cells detect and respond to viruses is incompletely understood, but great leaps in our understanding have been made by studying both the early innate immune response and the ways that viruses evade it. Poxviruses adapt to specific hosts over time by evolving elegantly precise inhibitors targeting the rate-limiting steps of immunity. These inhibitors reveal new features of the antiviral response while also offering potent new tools for approaching therapeutic intervention in autoimmunity. Molluscum contagiosum virus (MCV) is the only known extant poxvirus specifically adapted to human infection, yet it remains poorly characterized. In this study, we report the identification of the MCV protein MC132 as a potent inhibitor of NF-κB, an essential regulatory crux of innate immunity. Furthermore, identification of the mechanism of inhibition of NF-κB by MC132 reveals an elegant example of convergent evolution with human herpesviruses. This discovery greatly expands our understanding of how MCV so effectively evades human immunity.

scholarly journals Molluscum Contagiosum Virus Protein MC005 Inhibits NF-κB Activation by Targeting NEMO-Regulated IκB Kinase Activation

2017 ◽  
Vol 91 (15) ◽  
Author(s):  
Gareth Brady ◽  
Darya A. Haas ◽  
Paul J. Farrell ◽  
Andreas Pichlmair ◽  
Andrew G. Bowie
Keyword(s):  
Innate Immunity ◽  
Dynamic Models ◽  
Affinity Purification ◽  
Antiviral Immunity ◽  
Skin Lesions ◽  
Molluscum Contagiosum ◽  
Molluscum Contagiosum Virus ◽  
Live Virus ◽  
Iκb Kinase ◽  
Ikk Complex

ABSTRACT Molluscum contagiosum virus (MCV), the only known extant human-adapted poxvirus, causes a long-duration infection characterized by skin lesions that typically display an absence of inflammation despite containing high titers of live virus. Despite this curious presentation, MCV is very poorly characterized in terms of host-pathogen interactions. The absence of inflammation around MCV lesions suggests the presence of potent inhibitors of human antiviral immunity and inflammation. However, only a small number of MCV immunomodulatory genes have been characterized in detail. It is likely that many more remain to be discovered, given the density of such sequences in other poxvirus genomes. NF-κB activation occurs in response to both virus-induced pattern recognition receptor (PRR) signaling and cellular activation by virus-induced proinflammatory cytokines like tumor necrosis factor and interleukin-1. Activated NF-κB drives cytokine and interferon gene expression, leading to inflammation and virus clearance. We report that MC005, which has no orthologs in other poxvirus genomes, is a novel inhibitor of PRR- and cytokine-stimulated NF-κB activation. MC005 inhibited NF-κB proximal to the IκB kinase (IKK) complex, and unbiased affinity purification revealed that MC005 interacts with the IKK subunit NEMO (NF-κB essential modulator). MC005 binding to NEMO prevents the conformational priming of the IKK complex that occurs when NEMO binds to ubiquitin chains during pathway activation. These data reveal a novel mechanism of poxvirus inhibition of human innate immunity, validate current dynamic models of NEMO-dependent IKK complex activation, and further clarify how the human-adapted poxvirus MCV can so effectively evade antiviral immunity and suppress inflammation to persist in human skin lesions. IMPORTANCE Poxviruses adapt to specific hosts over time, evolving and tailoring elegantly precise inhibitors of the rate-limiting steps within the signaling pathways that control innate immunity and inflammation. These inhibitors reveal new features of the antiviral response, clarify existing models of signaling regulation while offering potent new tools for approaching therapeutic intervention in autoimmunity and inflammatory disease. Molluscum contagiosum virus (MCV) is the only known extant poxvirus specifically adapted to human infection and appears adept at evading normal human antiviral responses, yet it remains poorly characterized. We report the identification of MCV protein MC005 as an inhibitor of the pathways leading to the activation of NF-κB, an essential regulator of innate immunity. Further, identification of the mechanism of inhibition of NF-κB by MC005 confirms current models of the complex way in which NF-κB is regulated and greatly expands our understanding of how MCV so effectively evades human immunity.

Widespread Skin Lesions in Tanzanian Horses Caused By Molluscum Contagiosum Virus-like Poxvirus

2018 ◽  
Vol 158 ◽  
pp. 143
Author(s):  
K. Brandes ◽  
K. von Schlippenbach ◽  
E. Stegmaier ◽  
M. Antwerpen ◽  
M. Walter ◽  
...  
Keyword(s):  
Skin Lesions ◽  
Molluscum Contagiosum ◽  
Molluscum Contagiosum Virus

scholarly journals Molluscum Contagiosum Virus Transcriptome in Abortively Infected Cultured Cells and a Human Skin Lesion

2016 ◽  
Vol 90 (9) ◽  
pp. 4469-4480 ◽  
Author(s):  
Jorge D. Mendez-Rios ◽  
Zhilong Yang ◽  
Karl J. Erlandson ◽  
Jeffrey I. Cohen ◽  
Craig A. Martens ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skin Lesion ◽  
Human Skin ◽  
Cultured Cells ◽  
Skin Lesions ◽  
Molluscum Contagiosum ◽  
Rna Seq ◽  
Molluscum Contagiosum Virus ◽  
Human Specific

ABSTRACTMolluscum contagiosum virus (MOCV), the only circulating human-specific poxvirus, has a worldwide distribution and causes benign skin lesions that may persist for months in young children and severe infections in immunosuppressed adults. Studies of MOCV are restricted by the lack of an efficient animal model or a cell culture replication system. We used next-generation sequencing to analyze and compare polyadenylated RNAs from abortive MOCV infections of several cell lines and a human skin lesion. Viral RNAs were detected for 14 days after MOCV infection of cultured cells; however, there was little change in the RNA species during this time and a similar pattern occurred in the presence of an inhibitor of protein synthesis, indicating a block preventing postreplicative gene expression. Moreover, a considerable number of MOCV RNAs mapped to homologs of orthopoxvirus early genes, but few did so to homologs of intermediate or late genes. The RNAs made duringin vitroinfections represent a subset of RNAs detected in human skin lesions which mapped to homologs of numerous postreplicative as well as early orthopoxvirus genes. Transfection experiments using fluorescent protein and luciferase reporters demonstrated that vaccinia virus recognized MOCV intermediate and late promoters, indicating similar gene regulation. The specific recognition of the intermediate promoter in MOCV-infected cells provided evidence for the synthesis of intermediate transcription factors, which are products of early genes, but not for late transcription factors. Transcriptome sequencing (RNA-seq) and reporter gene assays may be useful for testing engineered cell lines and conditions that ultimately could provide anin vitroreplication system.IMPORTANCEThe inability to propagate molluscum contagiosum virus, which causes benign skin lesions in young children and more extensive infections in immunosuppressed adults, has constrained our understanding of the biology of this human-specific virus. In the present study, we characterized the RNAs synthesized in abortively infected cultured cells and a human skin lesion by next-generation sequencing. These studies provided an initial transcription map of the MOCV genome, suggested temporal regulation of gene expression, and indicated that thein vitroreplication block occurs prior to intermediate and late gene expression. RNA-seq and reporter assays, as described here, may help to further evaluate MOCV gene expression and define conditions that could enable MOCV replicationin vitro.

scholarly journals EARLY HOST CELL-MOLLUSCUM CONTAGIOSUM VIRUS INTERACTIONS

1977 ◽  
Vol 69 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Joh. Vreeswijk ◽  
W. Leene ◽  
G.L. Kalsbeek
Keyword(s):  
Host Cell ◽  
Molluscum Contagiosum ◽  
Molluscum Contagiosum Virus ◽  
Virus Interactions

Interferon Effect on Cellular Functions: Enhancement of Virus Induced Inhibition of Host Cell Protein Synthesis in Interferon-Treated Cells

1974 ◽  
Vol 29 (9-10) ◽  
pp. 623-629 ◽  
Author(s):  
M Suh ◽  
G Bodo ◽  
W Wolf ◽  
G Viehhauser ◽  
C Jungwirth
Keyword(s):  
Protein Synthesis ◽  
Chick Embryo ◽  
Host Cell ◽  
Total Protein ◽  
Cell Protein ◽  
Cellular Functions ◽  
Amino Acid Incorporation ◽  
Host Cell Proteins ◽  
Mouse Cells ◽  
Embryo Fibroblasts

Abstract Total protein synthesis in mouse cells but not in confluent chick embryo fibroblasts (CEF) is inhibited shortly after infection with vaccinia virus. This inhibition by the infecting virus is enhanced drastically if the mouse cells have been pretreated with homologous interferon pre­parations. The enhanced reduction of protein synthesis also occurs if the cells are treated with actinomycin D and is therefore to a large extent caused by an enhanced inhibition of amino acid incorporation into host cell proteins. Enhanced inhibition of total protein synthesis during the early stages of infection may be a prerequisite for the complete degeneration of the cells (lysis) which occurs later. Various alterations of mouse cells and chick embryo fibroblasts due to exposure to homologous interferon preparations are discussed with respect to the antiviral state induced in these cells

scholarly journals A Novel Target and Approach for Identifying Antivirals against Molluscum Contagiosum Virus

2014 ◽  
Vol 58 (12) ◽  
pp. 7383-7389 ◽  
Author(s):  
Hancheng Guan ◽  
Manunya Nuth ◽  
Natalia Zhukovskaya ◽  
Yih Ling Saw ◽  
Edward Bell ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Sexual Transmission ◽  
Skin Lesions ◽  
Molluscum Contagiosum ◽  
Health Concern ◽  
Target System ◽  
Molluscum Contagiosum Virus ◽  
Dermatological Disease ◽  
Novel Target

ABSTRACTThe dermatological disease molluscum contagiosum (MC) presents as lesions restricted solely to the skin. The poxvirus molluscum contagiosum virus (MCV) is responsible for this skin disease that is easily transmitted through casual contact among all populations, with greater frequency in children and immunosuppressed individuals. In addition, sexual transmission of MCV in adolescents and adults is a health concern. Although the skin lesions ultimately resolve in immunocompetent individuals, they can persist for extended periods, be painful, and result in scarring. Treatment is problematic, and there is no drug that specifically targets MCV. The inability of MCV to propagate in cell culture has impeded drug development. To overcome these barriers, we integrated three new developments. First, we identified a new MCV drug target (mD4) that is essential for processive DNA synthesisin vitro. Second, we discovered a small chemical compound that binds to mD4 and prevents DNA synthesisin vitro. Third, and most significant, we engineered a hybrid vaccinia virus (mD4-VV) in which the natural vaccinia D4 (vD4) gene is replaced by the mD4 target gene. This hybrid virus is dependent on mD4 for viral growth in culture and is inhibited by the small compound. This target system provides, for the first time, a platform and approach for the discovery and evaluation of new therapeutics that can be used to treat MC.

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