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Journal of Virology Aug 2017Molluscum contagiosum virus (MCV) is a dermatotropic poxvirus that causes benign skin lesions. MCV lesions persist because of virally encoded immune evasion molecules...
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. 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.
Topics: Animals; Cell Line; Host-Pathogen Interactions; Humans; I-kappa B Kinase; Inhibitor of Apoptosis Proteins; Mice; Molluscum contagiosum virus; Protein Binding; Protein Processing, Post-Translational; Ubiquitination; Viral Proteins
PubMed: 28515292
DOI: 10.1128/JVI.00276-17 -
The Journal of General Virology Aug 2020Molluscum contagiosum virus (MCV) is a common cause of benign skin lesions in young children and currently the only endemic human poxvirus. Following the infection of...
Molluscum contagiosum virus (MCV) is a common cause of benign skin lesions in young children and currently the only endemic human poxvirus. Following the infection of primary keratinocytes in the epidermis, MCV induces the proliferation of infected cells and this results in the production of wart-like growths. Full productive infection is observed only after the infected cells differentiate. During this prolonged replication cycle the virus must avoid elimination by the host immune system. We therefore sought to investigate the function of the two major histocompatibility complex class-I-related genes encoded by the MCV genes mc033 and mc080. Following insertion into a replication-deficient adenovirus vector, codon-optimized versions of mc033 and mc080 were expressed as endoglycosidase-sensitive glycoproteins that localized primarily in the endoplasmic reticulum. MC080, but not MC033, downregulated cell-surface expression of endogenous classical human leucocyte antigen (HLA) class I and non-classical HLA-E by a transporter associated with antigen processing (TAP)-independent mechanism. MC080 exhibited a capacity to inhibit or activate NK cells in autologous assays in a donor-specific manner. MC080 consistently inhibited antigen-specific T cells being activated by peptide-pulsed targets. We therefore propose that MC080 acts to promote evasion of HLA-I-restricted cytotoxic T cells.
Topics: Antigen Presentation; CD8-Positive T-Lymphocytes; Cell Line; Down-Regulation; Endoplasmic Reticulum; Histocompatibility Antigens Class I; Host-Pathogen Interactions; Humans; Immune Evasion; Keratinocytes; Killer Cells, Natural; Molluscum contagiosum virus; T-Lymphocytes, Cytotoxic; Viral Proteins
PubMed: 32510303
DOI: 10.1099/jgv.0.001417 -
PloS One 2014Molluscum contagiosum virus (MCV) causes an innocuous yet persistent skin infection in immunocompetent individuals and is spread by contact with lesions. Studies point...
BACKGROUND
Molluscum contagiosum virus (MCV) causes an innocuous yet persistent skin infection in immunocompetent individuals and is spread by contact with lesions. Studies point to atopic dermatitis (AD) as a risk factor for MCV infection; however, there are no longitudinal studies that have evaluated this hypothesis.
METHODS
Outpatient visit data from fiscal years 2001-2009 for American Indian and Alaska Native (AI/AN) children were examined to describe the incidence of molluscum contagiosum (MC). We conducted a case-control study of patients <5 years old at an Indian Health Service (IHS) clinic to evaluate dermatological risk factors for infection.
RESULTS
The incidence rate for MC in children <5 years old was highest in the West and East regions. MC cases were more likely to have a prior or co-occurring diagnosis of eczema, eczema or dermatitis, impetigo, and scabies (p<0.05) compared to controls; 51.4% of MC cases had a prior or co-occurring diagnosis of eczema or dermatitis.
CONCLUSIONS
The present study is the first demonstration of an association between AD and MC using a case-control study design. It is unknown if the concurrent high incidence of eczema and MC is related, and this association deserves further investigation.
Topics: Ambulatory Care; Case-Control Studies; Child, Preschool; Female; Humans; Incidence; Indians, North American; Infant; Male; Molluscum Contagiosum; Molluscum contagiosum virus; Odds Ratio; Risk Factors; United States
PubMed: 25072249
DOI: 10.1371/journal.pone.0103419 -
Viruses Nov 2023Molluscum contagiosum (MC) is characterized by skin lesions containing the highly contagious molluscum contagiosum poxvirus (MCV). MCV primarily infects children, with...
Molluscum contagiosum (MC) is characterized by skin lesions containing the highly contagious molluscum contagiosum poxvirus (MCV). MCV primarily infects children, with one US Food and Drug Administration (FDA)-approved drug-device treatment in use but no approved medications. Assessing antivirals is hindered by the inability of MCV to replicate in vitro. Here, we use vaccinia virus as a surrogate to provide evidence of the anti-poxvirus properties of berdazimer sodium, a new chemical entity, and the active substance in berdazimer gel, 10.3%, a nitric oxide-releasing topical in phase 3 development for the treatment of MC. We show that berdazimer sodium reduced poxvirus replication and, through a novel methodology, demonstrate that cells infected with drug-treated MCV virions have reduced early gene expression. Specifically, this is accomplished by studying the nuclear factor kappa-light-chain-enhancer of activated B cell (NF-kB)-blocking protein MC160 as an example of an early gene. The results provide a plausible unique antiviral mechanism of action supporting increased MCV resolution observed in patients treated with berdazimer gel, 10.3% and describe a novel methodology that overcomes limitations in investigating MCV response in vitro to a potential new MC topical medication.
Topics: United States; Child; Humans; Molluscum contagiosum virus; Molluscum Contagiosum; Siloxanes; Antiviral Agents
PubMed: 38140601
DOI: 10.3390/v15122360 -
The Journal of General Virology Feb 2018Molluscum contagiosum virus (MCV) causes persistent, benign skin neoplasm in children and adults. MCV is refractive to growth in standard tissue culture and there is no... (Comparative Study)
Comparative Study
Molluscum contagiosum virus (MCV) causes persistent, benign skin neoplasm in children and adults. MCV is refractive to growth in standard tissue culture and there is no relevant animal model of infection. Here we investigated whether another poxvirus (vaccinia virus; VACV) could be used to examine MCV immunoevasion protein properties in vivo. The MCV MC159L or MC160L genes, which encode NF-κB antagonists, were inserted into an attenuated VACV lacking an NF-κB antagonist (vΔA49), creating vMC159 and vMC160. vMC160 slightly increased vΔA49 virulence in the intranasal and intradermal routes of inoculation. vMC159 infection was less virulent than vΔA49 in both inoculation routes. vMC159-infected ear pinnae did not form lesions, but virus replication still occurred. Thus, the lack of lesions was not due to abortive virus replication. This system provides a new approach to examine MCV immunoevasion proteins within the context of a complete and complex immune system.
Topics: Administration, Intranasal; Animals; Child; Female; Humans; Injections, Intradermal; Mice, Inbred BALB C; Molluscum contagiosum virus; NF-kappa B; Vaccinia virus; Viral Proteins; Virulence
PubMed: 29393023
DOI: 10.1099/jgv.0.001006 -
Biology Feb 2024is a family of large, complex, enveloped, and double-stranded DNA viruses. The members of this family are ubiquitous and well known to cause contagious diseases in...
is a family of large, complex, enveloped, and double-stranded DNA viruses. The members of this family are ubiquitous and well known to cause contagious diseases in humans and other types of animals as well. Taxonomically, the family is classified into two subfamilies, namely (affecting vertebrates) and (affecting insects). The members of the subfamily are further divided into 18 genera based on the genome architecture and evolutionary relationship. Of these 18 genera, four genera, namely Molluscipoxvirus, Orthopoxvirus, Parapoxvirus, and Yatapoxvirus, are known for infecting humans. Some of the popular members of are variola virus, vaccine virus, Mpox (formerly known as monkeypox), cowpox, etc. There is still a pressing demand for the development of effective vaccines against poxviruses. Integrated immunoinformatics and artificial-intelligence (AI)-based methods have emerged as important approaches to design multi-epitope vaccines against contagious emerging infectious diseases. Despite significant progress in immunoinformatics and AI-based techniques, limited methods are available to predict the epitopes. In this study, we have proposed a unique method to predict the potential antigens and T-cell epitopes for multiple poxviruses. With PoxiPred, we developed an AI-based tool that was trained and tested with the antigens and epitopes of poxviruses. Our tool was able to locate 3191 antigen proteins from 25 distinct poxviruses. From these antigenic proteins, PoxiPred redundantly located up to five epitopes per protein, resulting in 16,817 potential T-cell epitopes which were mostly (i.e., 92%) predicted as being reactive to CD8+ T-cells. PoxiPred is able to, on a single run, identify antigens and T-cell epitopes for poxviruses with one single input, i.e., the proteome file of any poxvirus.
PubMed: 38392343
DOI: 10.3390/biology13020125 -
Journal of Virology Dec 2015Molluscum contagiosum virus (MCV) gene MC159 encodes a viral FLICE inhibitory protein (vFLIP) that inhibits caspase-8-mediated apoptosis. The MC159 protein was also...
UNLABELLED
Molluscum contagiosum virus (MCV) gene MC159 encodes a viral FLICE inhibitory protein (vFLIP) that inhibits caspase-8-mediated apoptosis. The MC159 protein was also reported to inhibit programmed necrosis (necroptosis) and modulate NF-κB activation by interacting with RIP1 and NEMO. The importance of MC159 during MCV infection has remained unknown, as there is no system for propagation and genetic manipulation of this virus. Here we investigated the functions of MC159 during viral infection using murine cytomegalovirus (MCMV) as a surrogate virus. MC159 was inserted into the MCMV genome, replacing M36 or M45, two MCMV genes with functions similar to those reported for MC159. M36 encodes a viral inhibitor of caspase-8-induced apoptosis (vICA) and M45 a viral inhibitor of RIP activation (vIRA), which inhibits RIP1/RIP3-mediated necroptosis. The M45 protein also blocks NF-κB activation by interacting with NEMO. When expressed by MCMV, MC159 blocked tumor necrosis factor alpha (TNF-α)-induced apoptosis of infected cells and partially restored MCMV replication in macrophages. However, MC159 did not fully replace M45, as it did not inhibit necroptosis in murine cells, but it reduced TNF-α-induced necroptosis in MCMV-infected human HT-29 cells. MC159 also differed from M45 in its effect on NF-κB. While MCMV-encoded M45 blocked NF-κB activation by TNF-α and interleukin-1β (IL-1β), MC159 inhibited TNF-α- but not IL-1β-induced NF-κB activation in infected mouse fibroblasts. These results indicate that the spectrum of MC159's functions differs depending on cell type and expression system and that a cell culture system for the propagation of MCV is needed to determine the biological relevance of presumed viral gene functions.
IMPORTANCE
MCV is a human-pathogenic poxvirus that cannot be propagated in cell culture or laboratory animals. Therefore, MCV gene products have been studied predominantly in cells expressing individual viral genes. In this study, we analyzed the function of the MCV gene MC159 by expressing it from a different virus and comparing its functions to those of two well-characterized MCMV genes. In this system, MC159 displayed some but not all of the previously described functions, suggesting that the functions of a viral gene depend on the conditions under which it is expressed. Until a cell culture system for the analysis of MCV becomes available, it might be necessary to analyze MCV genes in several different systems to extrapolate their biological importance.
Topics: Animals; Apoptosis Regulatory Proteins; Cell Line; Cell Survival; Humans; Immunologic Factors; Mice; Molluscum contagiosum virus; Muromegalovirus; Recombinant Proteins; Viral Proteins
PubMed: 26719271
DOI: 10.1128/JVI.02729-15 -
Journal of Virology Aug 2015Molluscum 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...
Molluscum 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-B 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-B 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-B activation. This revealed MC132, a unique protein with no orthologs in other poxviral genomes, as a novel inhibitor of NF-B. Interestingly, MC132 also inhibited PRR- and virus-activated NF-B, since MC132 interacted with the NF-B subunit p65 and caused p65 degradation. Unbiased affinity purification to identify host targets of MC132 revealed that MC132 acted by targeting NF-B 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.
Topics: Chromatography, Liquid; Enzyme-Linked Immunosorbent Assay; Humans; Immune Tolerance; Immunity, Innate; Immunoblotting; Immunoprecipitation; Microscopy, Confocal; Molluscum contagiosum virus; NF-kappa B; Oligonucleotides; Proteolysis; RNA Interference; Real-Time Polymerase Chain Reaction; Receptors, Pattern Recognition; Tandem Mass Spectrometry; Viral Proteins; eIF-2 Kinase
PubMed: 26041281
DOI: 10.1128/JVI.00799-15 -
PloS One 2014Squirrelpox virus (SQPV) shows little evidence for morbidity or mortality in North American grey squirrels (Sciurus carolinensis), in which the virus is endemic....
Squirrelpox virus (SQPV) shows little evidence for morbidity or mortality in North American grey squirrels (Sciurus carolinensis), in which the virus is endemic. However, more recently the virus has emerged to cause epidemics with high mortality in Eurasian red squirrels (S. vulgaris) in Great Britain, which are now threatened. Here we report the genome sequence of SQPV. Comparison with other Poxviridae revealed a core set of poxvirus genes, the phylogeny of which showed SQPV to be in a new Chordopoxvirus subfamily between the Molluscipoxviruses and Parapoxviruses. A number of SQPV genes were related to virulence, including three major histocomaptibility class I homologs, and one CD47 homolog. In addition, a novel potential virulence factor showing homology to mammalian oligoadenylate synthetase (OAS) was identified. This family of proteins normally causes activation of an endoribonuclease (RNaseL) within infected cells. The putative function of this novel SQPV protein was predicted in silico.
Topics: Animal Diseases; Animals; Chordopoxvirinae; Poxviridae Infections; Sciuridae; Sequence Homology, Amino Acid; United Kingdom; Viral Proteins; Virulence Factors
PubMed: 24983354
DOI: 10.1371/journal.pone.0096439 -
Virology May 2017Apoptosis is a powerful host cell defense to prevent viruses from completing replication. Poxviruses have evolved complex means to dampen cellular apoptotic responses....
Apoptosis is a powerful host cell defense to prevent viruses from completing replication. Poxviruses have evolved complex means to dampen cellular apoptotic responses. The poxvirus, Molluscum Contagiosum Virus (MCV), encodes numerous host interacting molecules predicted to antagonize immune responses. However, the function of the majority of these MCV products has not been characterized. Here, we show that the MCV MC163 protein localized to the mitochondria via an N-terminal mitochondrial localization sequence and transmembrane domain. Transient expression of the MC163 protein prevented mitochondrial membrane permeabilization (MMP), an event central to cellular apoptotic responses, induced by either Tumor Necrosis Factor alpha (TNF-α) or carbonyl cyanide 3-chlorophenylhydrazone (CCCP). MC163 expression prevented the release of a mitochondrial intermembrane space reporter protein when cells were challenged with TNF-α. Inhibition of MMP was also observed in cell lines stably expressing MC163. MC163 expression may contribute to the persistence of MCV lesions by dampening cellular apoptotic responses.
Topics: Apoptosis; Caspase 3; Cell Line, Tumor; Cell Membrane Permeability; HeLa Cells; Humans; Hydrazones; Mitochondria; Mitochondrial Membranes; Molluscum Contagiosum; Molluscum contagiosum virus; Poly (ADP-Ribose) Polymerase-1; Staurosporine; Tumor Necrosis Factor-alpha; Viral Proteins
PubMed: 28235685
DOI: 10.1016/j.virol.2017.02.017