Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
Artículo en Inglés | MEDLINE | ID: mdl-33007476

RESUMEN

OBJECTIVES: Investigation whether in depth characterization of virus variant patterns can be used for epidemiological analysis of the first SARS-CoV-2 infection clusters in Hamburg, Germany. METHODS: Metagenomic RNA- and amplicon-sequencing and subsequent variant calling in 25 respiratory samples from SARS-CoV-2 infected patients involved in the earliest infection clusters in Hamburg. RESULTS: Amplikon sequencing and cluster analyses of these SARS-CoV-2 sequences allowed the identification of the first infection cluster and five non-related infection clusters occurring at the beginning of the viral entry of SARS-CoV-2 in the Hamburg metropolitan region. Viral genomics together with epidemiological analyses revealed that the index patient acquired the infection in Northern Italy and transmitted it to two out of 134 contacts. Single nucleotide polymorphisms clearly distinguished the virus variants of the index and other clusters and allowed to track in which sequences worldwide these mutations were first described. Minor variant analyses identified the transmission of intra-host variants in the index cluster and household clusters. CONCLUSIONS: SARS-CoV-2 variant tracing allows the identification of infection clusters and the follow up of infection chains occurring in the population. Furthermore, the follow up of minor viral variants in infection cluster can provide further resolution on transmission events indistinguishable on consensus sequence level.

2.
EMBO Mol Med ; 12(12): e13296, 2020 12 07.
Artículo en Inglés | MEDLINE | ID: mdl-33012091

RESUMEN

We describe a multifactorial investigation of a SARS-CoV-2 outbreak in a large meat processing complex in Germany. Infection event timing, spatial, climate and ventilation conditions in the processing plant, sharing of living quarters and transport, and viral genome sequences were analyzed. Our results suggest that a single index case transmitted SARS-CoV-2 to co-workers over distances of more than 8 m, within a confined work area in which air is constantly recirculated and cooled. Viral genome sequencing shows that all cases share a set of mutations representing a novel sub-branch in the SARS-CoV-2 C20 clade. We identified the same set of mutations in samples collected in the time period between this initial infection cluster and a subsequent outbreak within the same factory, with the largest number of confirmed SARS-CoV-2 cases in a German meat processing facility reported so far. Our results indicate climate conditions, fresh air exchange rates, and airflow as factors that can promote efficient spread of SARS-CoV-2 via long distances and provide insights into possible requirements for pandemic mitigation strategies in industrial workplace settings.

3.
PLoS Pathog ; 16(8): e1008562, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32833988

RESUMEN

Merkel Cell Polyomavirus (MCPyV) is the etiological agent of the majority of Merkel Cell Carcinomas (MCC). MCPyV positive MCCs harbor integrated, defective viral genomes that constitutively express viral oncogenes. Which molecular mechanisms promote viral integration, if distinct integration patterns exist, and if integration occurs preferentially at loci with specific chromatin states is unknown. We here combined short and long-read (nanopore) next-generation sequencing and present the first high-resolution analysis of integration site structure in MCC cell lines as well as primary tumor material. We find two main types of integration site structure: Linear patterns with chromosomal breakpoints that map closely together, and complex integration loci that exhibit local amplification of genomic sequences flanking the viral DNA. Sequence analysis suggests that linear patterns are produced during viral replication by integration of defective/linear genomes into host DNA double strand breaks via non-homologous end joining, NHEJ. In contrast, our data strongly suggest that complex integration patterns are mediated by microhomology-mediated break-induced replication, MMBIR. Furthermore, we show by ChIP-Seq and RNA-Seq analysis that MCPyV preferably integrates in open chromatin and provide evidence that viral oncogene expression is driven by the viral promoter region, rather than transcription from juxtaposed host promoters. Taken together, our data explain the characteristics of MCPyV integration and may also provide a model for integration of other oncogenic DNA viruses such as papillomaviruses.


Asunto(s)
Carcinoma de Células de Merkel/patología , Reparación del ADN por Unión de Extremidades , Poliomavirus de Células de Merkel/genética , Infecciones por Polyomavirus/complicaciones , Infecciones Tumorales por Virus/complicaciones , Integración Viral , Replicación Viral , Antígenos Virales de Tumores , Neoplasias Óseas/genética , Neoplasias Óseas/secundario , Neoplasias Óseas/virología , Carcinoma de Células de Merkel/genética , Carcinoma de Células de Merkel/virología , Humanos , Infecciones por Polyomavirus/genética , Infecciones por Polyomavirus/virología , Recombinación Genética , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/virología , Infecciones Tumorales por Virus/genética , Infecciones Tumorales por Virus/virología , Proteínas Virales/genética
4.
mBio ; 11(2)2020 03 10.
Artículo en Inglés | MEDLINE | ID: mdl-32156811

RESUMEN

Merkel cell polyomavirus (MCPyV) is the only polyomavirus known to be associated with tumorigenesis in humans. Similarly to other polyomaviruses, MCPyV expresses a large tumor antigen (LT-Ag) that, together with a small tumor antigen (sT-Ag), contributes to cellular transformation and that is of critical importance for the initiation of the viral DNA replication. Understanding the cellular protein network regulated by MCPyV early proteins will significantly contribute to our understanding of the natural MCPyV life cycle as well as of the mechanisms by which the virus contributes to cellular transformation. We here describe KRAB-associated protein 1 (Kap1), a chromatin remodeling factor involved in cotranscriptional regulation, as a novel protein interaction partner of MCPyV T antigens sT and LT. Kap1 knockout results in a significant increase in the level of viral DNA replication that is highly suggestive of Kap1 being an important host restriction factor during MCPyV infection. Differently from other DNA viruses, MCPyV gene expression is unaffected in the absence of Kap1 and Kap1 does not associate with the viral genome. Instead, we show that in primary normal human dermal fibroblast (nHDF) cells, MCPyV DNA replication, but not T antigen expression alone, induces ataxia telangiectasia mutated (ATM) kinase-dependent Kap1 S824 phosphorylation, a mechanism that typically facilitates repair of double-strand breaks in heterochromatin by arresting the cells in G2 We show that MCPyV-induced inhibition of cell proliferation is mainly conferred by residues within the origin binding domain and thereby by viral DNA replication. Our data suggest that phosphorylation of Kap1 and subsequent Kap1-dependent G2 arrest/senescence represent host defense mechanisms against MCPyV replication in nHDF cells.IMPORTANCE We here describe Kap1 as a restriction factor in MCPyV infection. We report a novel, indirect mechanism by which Kap1 affects MCPyV replication. In contrast with from other DNA viruses, Kap1 does not associate with the viral genome in MCPyV infection and has no impact on viral gene expression. In MCPyV-infected nHDF cells, Kap1 phosphorylation (pKap1 S824) accumulates because of genomic stress mainly induced by viral DNA replication. In contrast, ectopic expression of LT or LT MCPyV mutants, previously shown to be important for induction of genotoxic stress, does not result in a similar extent of pKap1 accumulation. We show that cells actively replicating MCPyV accumulate pKap1 (in a manner dependent on the presence of ATM) and display a senescence phenotype reflected by G2 arrest. These results are supported by transcriptome analyses showing that LT antigen, in a manner dependent on the presence of Kap1, induces expression of secreted factors, which is known as the senescence-associated secretory phenotype (SASP).

5.
J Virol ; 94(5)2020 02 14.
Artículo en Inglés | MEDLINE | ID: mdl-31801860

RESUMEN

Merkel cell polyomavirus (MCPyV) is the major cause for Merkel cell carcinoma (MCC), a rare but highly aggressive skin cancer predominantly found in elderly and immunosuppressed patients. The early viral gene products large T-antigen (LT) and small T-antigen (sT) are important for efficient viral DNA replication, and both contribute to transformation processes. These functions are executed mainly through interactions with host factors. Here, we identify the cellular ubiquitin-specific processing protease 7 (Usp7) as a new interaction partner of the MCPyV LT. Using glutathione S-transferase pulldown experiments, we show that MCPyV LT directly binds to Usp7 and that N- as well as C-terminal regions of LT bind to the TRAF (tumor necrosis factor receptor-associated) domain of Usp7. We demonstrate that endogenous Usp7 coprecipitates with MCPyV T-antigens and relocalizes to viral DNA replication centers in cells actively replicating MCPyV genomes. We show that Usp7 does not alter ubiquitination levels of the T-antigens; however, Usp7 binding increases the binding affinity of LT to the origin of replication, thereby negatively regulating viral DNA replication. Together, these data identify Usp7 as a restriction factor of MCPyV replication. In contrast to other DNA viruses, Usp7 does not affect MCPyV gene expression via its ubiquitination activity but influences MCPyV DNA replication solely via a novel mechanism that modulates binding of LT to viral DNA.IMPORTANCE MCPyV is the only human polyomavirus that is associated with cancer; the majority of Merkel cell cancers have a viral etiology. While much emphasis was placed on investigations to understand the transformation process by MCPyV oncoproteins and cellular factors, we have only limited knowledge of cellular factors participating in the MCPyV life cycle. Here, we describe Usp7, a cellular deubiquitination enzyme, as a new factor involved in MCPyV replication. Usp7 is known in the context of large DNA tumor viruses, Epstein-Barr virus (EBV) and Kaposi's sarcoma herpesvirus, to restrict viral replication. Similar to EBV, where Usp7 binding to EBNA1 increases EBNA1 binding affinity to viral DNA, we find MCPyV LT binding to the origin of replication to be increased in the presence of Usp7, resulting in restriction of viral DNA replication. However, Usp7-induced restriction of MCPyV replication is independent of its enzymatic activity, thereby constituting a novel mechanism of Usp7-induced restriction of viral replication.


Asunto(s)
Antígenos Virales de Tumores/metabolismo , ADN Viral/metabolismo , Poliomavirus de Células de Merkel/genética , Poliomavirus de Células de Merkel/metabolismo , Peptidasa Específica de Ubiquitina 7/metabolismo , Replicación Viral/fisiología , Carcinoma de Células de Merkel/virología , Línea Celular , Proliferación Celular , Células HEK293 , Humanos , Poliomavirus de Células de Merkel/crecimiento & desarrollo , Infecciones por Polyomavirus/virología , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Infecciones Tumorales por Virus/virología
6.
Int J Cancer ; 141(1): 160-171, 2017 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-28380668

RESUMEN

Merkel cell carcinoma (MCC) is an aggressive skin cancer entity that frequently leads to rapid death due to its high propensity to metastasize. The etiology of most MCC cases is linked to Merkel cell polyomavirus (MCPyV), a virus which is monoclonally integrated in up to 95% of tumors. While there are presently no animal models to study the role of authentic MCPyV infection on transformation, tumorigenesis or metastasis formation, xenograft mouse models employing engrafted MCC-derived cell lines (MCCL) represent a promising approach to study certain aspects of MCC pathogenesis. Here, the two MCPyV-positive MCC cell lines WaGa and MKL-1 were subcutaneously engrafted in scid mice. Engraftment of both MCC cell lines resulted in the appearance of circulating tumor cells and metastasis formation, with WaGa-engrafted mice showing a significantly shorter survival time as well as increased numbers of spontaneous lung metastases compared to MKL-1 mice. Interestingly, explanted tumors compared to parental cell lines exhibit an upregulation of MCPyV sT-Antigen expression in all tumors, with WaGa tumors showing significantly higher sT-Antigen expression than MKL-1 tumors. RNA-Seq analysis of explanted tumors and parental cell lines furthermore revealed that in the more aggressive WaGa tumors, genes involved in inflammatory response, growth factor activity and Wnt signalling pathway are significantly upregulated, suggesting that sT-Antigen is the driver of the observed differences in metastasis formation.


Asunto(s)
Carcinoma de Células de Merkel/virología , Neoplasias Pulmonares/virología , Poliomavirus de Células de Merkel/patogenicidad , Infecciones por Polyomavirus/virología , Infecciones Tumorales por Virus/virología , Animales , Carcinoma de Células de Merkel/patología , Línea Celular Tumoral , Linaje de la Célula , Humanos , Neoplasias Pulmonares/patología , Neoplasias Pulmonares/secundario , Ratones , Metástasis de la Neoplasia , Infecciones por Polyomavirus/patología , Infecciones Tumorales por Virus/patología , Ensayos Antitumor por Modelo de Xenoinjerto
7.
J Gen Virol ; 97(11): 2926-2938, 2016 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-27580912

RESUMEN

Merkel cell polyomavirus (MCPyV) is associated with Merkel cell carcinoma (MCC), a rare but aggressive skin cancer. The virus is highly prevalent: 60-80 % of adults are seropositive; however, cells permissive for MCPyV infection are unknown. Consequently, very little information about the MCPyV life cycle is available. Until recently, MCPyV replication could only be studied using a semi-permissive in vitro replication system (Neumann et al., 2011; Feng et al., 2011, Schowalter et al., 2011). MCPyV replication most likely depends on subnuclear structures such as promyelocytic leukemia protein nuclear bodies (PML-NBs), which are known to play regulatory roles in the infection of many DNA viruses. Here, we investigated PML-NB components as candidate host factors to control MCPyV DNA replication. We showed that PML-NBs change in number and size in cells actively replicating MCPyV proviral DNA. We observed a significant increase in PML-NBs in cells positive for MCPyV viral DNA replication. Interestingly, a significant amount of cells actively replicating MCPyV did not show any Sp100 expression. While PML and Daxx had no effect on MCPyV DNA replication, MCPyV replication was increased in cells depleted for Sp100, strongly suggesting that Sp100 is a negative regulator of MCPyV DNA replication.


Asunto(s)
Carcinoma de Células de Merkel/metabolismo , Cuerpos de Inclusión Viral/metabolismo , Poliomavirus de Células de Merkel/fisiología , Infecciones por Polyomavirus/metabolismo , Proteína de la Leucemia Promielocítica/metabolismo , Infecciones Tumorales por Virus/metabolismo , Replicación Viral , Antígenos Nucleares/genética , Antígenos Nucleares/metabolismo , Autoantígenos/genética , Autoantígenos/metabolismo , Carcinoma de Células de Merkel/genética , Carcinoma de Células de Merkel/virología , Replicación del ADN , ADN Viral/genética , ADN Viral/metabolismo , Humanos , Cuerpos de Inclusión Viral/genética , Cuerpos de Inclusión Viral/virología , Poliomavirus de Células de Merkel/genética , Infecciones por Polyomavirus/genética , Infecciones por Polyomavirus/virología , Proteína de la Leucemia Promielocítica/genética , Infecciones Tumorales por Virus/genética , Infecciones Tumorales por Virus/virología
8.
Curr Protoc Microbiol ; 38: 14F.2.1-19, 2015 Aug 03.
Artículo en Inglés | MEDLINE | ID: mdl-26237107

RESUMEN

Merkel cell polyomavirus (MCPyV) genomes are clonally integrated in tumor cells of ∼95% of all Merkel cell carcinoma (MCC) cases. The virus is highly prevalent; however, where the virus persists and which cell types are permissive for MCPyV replication is still unknown. As a consequence, very little information is available about the life cycle and no fully permissive in vitro replication system has been established. Recently, semi-permissive replication systems based on wild-type MCPyV genomes recovered from the skin of healthy donors or synthetic MCPyV genomes constructed from consensus sequences have been established. The transfection of this intramolecular re-circularized MCPyV DNA into some human cell lines recapitulates efficient DNA replication of the viral genome, viral gene expression as well as moderate levels of virus particle formation. However, serial transmission of infectious virus is still restricted in these cells.


Asunto(s)
Replicación del ADN , Poliomavirus de Células de Merkel/fisiología , Replicación Viral , Línea Celular , Humanos , Poliomavirus de Células de Merkel/genética , Biología Molecular/métodos , Virología/métodos
9.
J Virol ; 88(6): 3144-60, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24371076

RESUMEN

UNLABELLED: Interference with tumor suppressor pathways by polyomavirus-encoded tumor antigens (T-Ags) can result in transformation. Consequently, it is thought that T-Ags encoded by Merkel cell polyomavirus (MCPyV), a virus integrated in ∼90% of all Merkel cell carcinoma (MCC) cases, are major contributors to tumorigenesis. The MCPyV large T-Ag (LT-Ag) has preserved the key functional domains present in all family members but has also acquired unique regions that flank the LxCxE motif. As these regions may mediate unique functions, or may modulate those shared with T-Ags of other polyomaviruses, functional studies of MCPyV T-Ags are required. Here, we have performed a comparative study of full-length or MCC-derived truncated LT-Ags with regard to their biochemical characteristics, their ability to bind to retinoblastoma (Rb) and p53 proteins, and their transforming potential. We provide evidence that full-length MCPyV LT-Ag may not directly bind to p53 but nevertheless can significantly reduce p53-dependent transcription in reporter assays. Although early region expression constructs harboring either full-length or MCC-derived truncated LT-Ag genes can transform primary baby rat kidney cells, truncated LT-Ags do not bind to p53 or reduce p53-dependent transcription. Interestingly, shortened LT-Ags exhibit a very high binding affinity for Rb, as shown by coimmunoprecipitation and in vitro binding studies. Additionally, we show that truncated MCPyV LT-Ag proteins are expressed at higher levels than those for the wild-type protein and are able to partially relocalize Rb to the cytoplasm, indicating that truncated LT proteins may have gained additional features that distinguish them from the full-length protein. IMPORTANCE: MCPyV is one of the 12 known polyomaviruses that naturally infect humans. Among these, it is of particular interest since it is the only human polyomavirus known to be involved in tumorigenesis. MCPyV is thought to be causally linked to MCC, a rare skin tumor. In these tumors, viral DNA is monoclonally integrated into the genome of the tumor cells in up to 90% of all MCC cases, and the integrated MCV genomes, furthermore, harbor signature mutations in the so-called early region that selectively abrogate viral replication while preserving cell cycle deregulating functions of the virus. This study describes comparative studies of early region T-Ag protein characteristics, their ability to bind to Rb and p53, and their transforming potential.


Asunto(s)
Antígenos Virales de Tumores/metabolismo , Carcinoma de Células de Merkel/metabolismo , Poliomavirus de Células de Merkel/metabolismo , Infecciones por Polyomavirus/metabolismo , Proteína de Retinoblastoma/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Infecciones Tumorales por Virus/metabolismo , Secuencias de Aminoácidos , Animales , Antígenos Virales de Tumores/química , Antígenos Virales de Tumores/genética , Carcinoma de Células de Merkel/genética , Carcinoma de Células de Merkel/patología , Carcinoma de Células de Merkel/virología , Línea Celular Tumoral , Transformación Celular Viral , Regulación hacia Abajo , Humanos , Cinética , Poliomavirus de Células de Merkel/química , Poliomavirus de Células de Merkel/genética , Infecciones por Polyomavirus/genética , Infecciones por Polyomavirus/patología , Infecciones por Polyomavirus/virología , Unión Proteica , Transporte de Proteínas , Ratas , Ratas Sprague-Dawley , Proteína de Retinoblastoma/química , Proteína de Retinoblastoma/genética , Proteína p53 Supresora de Tumor/química , Proteína p53 Supresora de Tumor/genética , Infecciones Tumorales por Virus/genética , Infecciones Tumorales por Virus/patología , Infecciones Tumorales por Virus/virología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA