Hahn, Alexander S.

[["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","Viruses"],["dc.bibliographiccitation.volume","9"],["dc.contributor.author","Full, Florian"],["dc.contributor.author","Hahn, Alexander S."],["dc.contributor.author","Großkopf, Anna K."],["dc.contributor.author","Ensser, Armin"],["dc.date.accessioned","2019-07-09T11:44:45Z"],["dc.date.available","2019-07-09T11:44:45Z"],["dc.date.issued","2017-10-21"],["dc.description.abstract","Gammaherpesviruses like Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) subvert the ubiquitin proteasome system for their own benefit in order to facilitate viral gene expression and replication. In particular, viral tegument proteins that share sequence homology to the formylglycineamide ribonucleotide amidotransferase (FGARAT, or PFAS), an enzyme in the cellular purine biosynthesis, are important for disrupting the intrinsic antiviral response associated with Promyelocytic Leukemia (PML) protein-associated nuclear bodies (PML-NBs) by proteasome-dependent and independent mechanisms. In addition, all herpesviruses encode for a potent ubiquitin protease that can efficiently remove ubiquitin chains from proteins and thereby interfere with several different cellular pathways. In this review, we discuss mechanisms and functional consequences of virus-induced ubiquitination and deubiquitination for early events in gammaherpesviral infection."],["dc.identifier.doi","10.3390/v9100308"],["dc.identifier.pmid","29065450"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/14886"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/59084"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","1999-4915"],["dc.rights","CC BY-NC 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by-nc/4.0"],["dc.subject.ddc","610"],["dc.title","Gammaherpesviral Tegument Proteins, PML-Nuclear Bodies and the Ubiquitin-Proteasome System."],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2507"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Archives of Virology"],["dc.bibliographiccitation.lastpage","2512"],["dc.bibliographiccitation.volume","163"],["dc.contributor.author","Ensser, Armin"],["dc.contributor.author","Großkopf, Anna K."],["dc.contributor.author","Mätz-Rensing, Kerstin"],["dc.contributor.author","Roos, Christian"],["dc.contributor.author","Hahn, Alexander S."],["dc.date.accessioned","2018-11-28T13:57:57Z"],["dc.date.available","2018-11-28T13:57:57Z"],["dc.date.issued","2018"],["dc.description.abstract","SFVmmu-DPZ9524 represents the third completely sequenced rhesus macaque simian foamy virus (SFV) isolate, alongside SFVmmu_K3T with a similar SFV-1-type env, and R289HybAGM with a SFV-2-like env. Sequence analysis demonstrates that, in gag and pol, SFVmmu-DPZ9524 is more closely related to R289HybAGM than to SFVmmu_K3T, which, outside of env, is more similar to a Japanese macaque isolate than to the other two rhesus macaque isolates SFVmmu-DPZ9524 and R289HybAGM. Further, we identify bel as another recombinant locus in R289HybAGM, confirming that recombination contributes to sequence diversity in SFV."],["dc.identifier.doi","10.1007/s00705-018-3892-9"],["dc.identifier.pmid","29860676"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/56996"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.relation.eissn","1432-8798"],["dc.title","Isolation and sequence analysis of a novel rhesus macaque foamy virus isolate with a serotype-1-like env"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","8013"],["dc.bibliographiccitation.issue","17"],["dc.bibliographiccitation.journal","Journal of Virology"],["dc.bibliographiccitation.lastpage","8028"],["dc.bibliographiccitation.volume","90"],["dc.contributor.author","Hahn, Alexander S."],["dc.contributor.author","Großkopf, Anna K."],["dc.contributor.author","Jungnickl, Doris"],["dc.contributor.author","Scholz, Brigitte"],["dc.contributor.author","Ensser, Armin"],["dc.contributor.editor","Jung, J. U."],["dc.date.accessioned","2022-10-06T13:25:34Z"],["dc.date.available","2022-10-06T13:25:34Z"],["dc.date.issued","2016"],["dc.description.abstract","ABSTRACT\n \n Nuclear domain 10 (ND10) components restrict herpesviral infection, and herpesviruses antagonize this restriction by a variety of strategies, including degradation or relocalization of ND10 proteins. The rhesus monkey rhadinovirus (RRV) shares many key biological features with the closely related Kaposi's sarcoma-associated herpesvirus (KSHV; human herpesvirus 8) and readily infects cells of both human and rhesus monkey origin. We used the clustered regularly interspaced short palindromic repeat-Cas9 (CRISPR-Cas9) technique to generate knockout (ko) cells for each of the four ND10 components, PML, SP100, DAXX, and ATRX. These ko cells were analyzed with regard to permissiveness for RRV infection. In addition, we analyzed the fate of the individual ND10 components in infected cells by immunofluorescence and Western blotting. Knockout of the ND10 component DAXX markedly increased RRV infection, while knockout of PML or SP100 had a less pronounced effect. In line with these observations, RRV infection resulted in rapid degradation of SP100, followed by degradation of PML and the loss of ND10 structures, whereas the protein levels of ATRX and DAXX remained constant. Notably, inhibition of the proteasome but not inhibition of\n de novo\n gene expression prevented the loss of SP100 and PML in cells that did not support lytic replication, compatible with proteasomal degradation of these ND10 components through the action of a viral tegument protein. Expression of the RRV FGARAT homolog ORF75 was sufficient to effect the loss of SP100 and PML in transfected or transduced cells, implicating ORF75 as the viral effector protein.\n \n \n IMPORTANCE\n Our findings highlight the antiviral role of ND10 and its individual components and further establish the viral FGARAT homologs of the gammaherpesviruses to be important viral effectors that counteract ND10-instituted intrinsic immunity. Surprisingly, even closely related viruses like KSHV and RRV evolved to use different strategies to evade ND10-mediated restriction. RRV first targets SP100 for degradation and then targets PML with a delayed kinetic, a strategy which clearly differs from that of other gammaherpesviruses. Despite efficient degradation of these two major ND10 components, RRV is still restricted by DAXX, another abundant ND10 component, as evidenced by a marked increase in RRV infection and replication upon knockout of DAXX. Taken together, our findings substantiate PML, SP100, and DAXX as key antiviral proteins, in that the first two are targeted for degradation by RRV and the last one still potently restricts replication of RRV."],["dc.identifier.doi","10.1128/JVI.01181-16"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/114871"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-602"],["dc.relation.eissn","1098-5514"],["dc.relation.issn","0022-538X"],["dc.relation.orgunit","Deutsches Primatenzentrum"],["dc.rights.uri","https://journals.asm.org/non-commercial-tdm-license"],["dc.title","Viral FGARAT Homolog ORF75 of Rhesus Monkey Rhadinovirus Effects Proteasomal Degradation of the ND10 Components SP100 and PML"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","e01093-19"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Journal of Virology"],["dc.bibliographiccitation.volume","94"],["dc.contributor.author","Hahn, Alexander S."],["dc.contributor.author","Bischof, Georg F."],["dc.contributor.author","Großkopf, Anna K."],["dc.contributor.author","Shin, Young C."],["dc.contributor.author","Domingues, Aline"],["dc.contributor.author","Gonzalez-Nieto, Lucas"],["dc.contributor.author","Rakasz, Eva G."],["dc.contributor.author","Watkins, David I."],["dc.contributor.author","Ensser, Armin"],["dc.contributor.author","Martins, Mauricio A."],["dc.contributor.editor","Longnecker, Richard M."],["dc.date.accessioned","2022-10-06T13:25:34Z"],["dc.date.available","2022-10-06T13:25:34Z"],["dc.date.issued","2020"],["dc.description.abstract","Kaposi’s sarcoma-associated herpesvirus (KSHV) is associated with a substantial disease burden in sub-Saharan Africa, often in the context of human immunodeficiency virus (HIV) infection. The related rhesus monkey rhadinovirus (RRV) has shown potential as a vector to immunize monkeys with antigens from simian immunodeficiency virus (SIV), the macaque model for HIV. KSHV and RRV engage cellular receptors from the Eph family via the viral gH/gL glycoprotein complex. We have now generated a recombinant RRV that expresses the SIV Gag antigen and does not express gL. This recombinant RRV was infectious by the intravenous route, established persistent infection in the B cell compartment, and elicited strong immune responses to the SIV Gag antigen. These results argue against a role for gL and Eph family receptors in B cell infection by RRV\n in vivo\n and have implications for the development of a live-attenuated KSHV vaccine or vaccine vector."],["dc.description.abstract","ABSTRACT\n \n A replication-competent, recombinant strain of rhesus monkey rhadinovirus (RRV) expressing the Gag protein of SIVmac239 was constructed in the context of a glycoprotein L (gL) deletion mutation. Deletion of gL detargets the virus from Eph family receptors. The ability of this gL-minus Gag recombinant RRV to infect, persist, and elicit immune responses was evaluated after intravenous inoculation of two\n Mamu-A*01\n +\n RRV-naive rhesus monkeys. Both monkeys responded with an anti-RRV antibody response, and quantitation of RRV DNA in peripheral blood mononuclear cells (PBMC) by real-time PCR revealed levels similar to those in monkeys infected with recombinant gL\n +\n RRV. Comparison of RRV DNA levels in sorted CD3\n +\n versus CD20\n +\n versus CD14\n +\n PBMC subpopulations indicated infection of the CD20\n +\n subpopulation by the gL-minus RRV. This contrasts with results obtained with transformed B cell lines\n in vitro\n , in which deletion of gL resulted in markedly reduced infectivity. Over a period of 20 weeks, Gag-specific CD8\n +\n T cell responses were documented by major histocompatibility complex class I (MHC-I) tetramer staining. Vaccine-induced CD8\n +\n T cell responses, which were predominantly directed against the Mamu-A*01-restricted Gag\n 181-189\n CM9 epitope, could be inhibited by blockade of MHC-I presentation. Our results indicate that gL and the interaction with Eph family receptors are dispensable for the colonization of the B cell compartment following high-dose infection by the intravenous route, which suggests the existence of alternative receptors. Further, gL-minus RRV elicits cellular immune responses that are predominantly canonical in nature.\n \n \n IMPORTANCE\n Kaposi’s sarcoma-associated herpesvirus (KSHV) is associated with a substantial disease burden in sub-Saharan Africa, often in the context of human immunodeficiency virus (HIV) infection. The related rhesus monkey rhadinovirus (RRV) has shown potential as a vector to immunize monkeys with antigens from simian immunodeficiency virus (SIV), the macaque model for HIV. KSHV and RRV engage cellular receptors from the Eph family via the viral gH/gL glycoprotein complex. We have now generated a recombinant RRV that expresses the SIV Gag antigen and does not express gL. This recombinant RRV was infectious by the intravenous route, established persistent infection in the B cell compartment, and elicited strong immune responses to the SIV Gag antigen. These results argue against a role for gL and Eph family receptors in B cell infection by RRV\n in vivo\n and have implications for the development of a live-attenuated KSHV vaccine or vaccine vector."],["dc.description.sponsorship","IZKF Erlangen"],["dc.description.sponsorship"," HHS | National Institutes of Health https://doi.org/10.13039/100000002"],["dc.description.sponsorship"," HHS | National Institutes of Health https://doi.org/10.13039/100000002"],["dc.description.sponsorship"," HHS | National Institutes of Health https://doi.org/10.13039/100000002"],["dc.description.sponsorship"," Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659"],["dc.description.sponsorship"," Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659"],["dc.description.sponsorship"," HHS | U.S. Public Health Service https://doi.org/10.13039/100007197"],["dc.identifier.doi","10.1128/JVI.01093-19"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/114870"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-602"],["dc.relation.eissn","1098-5514"],["dc.relation.issn","0022-538X"],["dc.relation.orgunit","Deutsches Primatenzentrum"],["dc.rights.uri","https://journals.asm.org/non-commercial-tdm-license"],["dc.title","A Recombinant Rhesus Monkey Rhadinovirus Deleted of Glycoprotein L Establishes Persistent Infection of Rhesus Macaques and Elicits Conventional T Cell Responses"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","e1008979"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","PLOS Pathogens"],["dc.bibliographiccitation.volume","17"],["dc.contributor.author","Großkopf, Anna K."],["dc.contributor.author","Schlagowski, Sarah"],["dc.contributor.author","Fricke, Thomas"],["dc.contributor.author","Ensser, Armin"],["dc.contributor.author","Desrosiers, Ronald C."],["dc.contributor.author","Hahn, Alexander S."],["dc.contributor.editor","Zheng, Zhi-Ming"],["dc.date.accessioned","2022-10-06T13:26:22Z"],["dc.date.available","2022-10-06T13:26:22Z"],["dc.date.issued","2021"],["dc.description.abstract","The rhesus monkey rhadinovirus (RRV), a γ2-herpesvirus of rhesus macaques, shares many biological features with the human pathogenic Kaposi’s sarcoma-associated herpesvirus (KSHV). Both viruses, as well as the more distantly related Epstein-Barr virus, engage cellular receptors from the Eph family of receptor tyrosine kinases (Ephs). However, the importance of the Eph interaction for RRV entry varies between cell types suggesting the existence of Eph-independent entry pathways. We therefore aimed to identify additional cellular receptors for RRV by affinity enrichment and mass spectrometry. We identified an additional receptor family, the Plexin domain containing proteins 1 and 2 (Plxdc1/2) that bind the RRV gH/gL glycoprotein complex. Preincubation of RRV with soluble Plxdc2 decoy receptor reduced infection by ~60%, while overexpression of Plxdc1 and 2 dramatically enhanced RRV susceptibility and cell-cell fusion of otherwise marginally permissive Raji cells. While the Plxdc2 interaction is conserved between two RRV strains, 26–95 and 17577, Plxdc1 specifically interacts with RRV 26–95 gH. The Plxdc interaction is mediated by a short motif at the N-terminus of RRV gH that is partially conserved between isolate 26–95 and isolate 17577, but absent in KSHV gH. Mutation of this motif abrogated the interaction with Plxdc1/2 and reduced RRV infection in a cell type-specific manner. Taken together, our findings characterize Plxdc1/2 as novel interaction partners and entry receptors for RRV and support the concept of the N-terminal domain of the gammaherpesviral gH/gL complex as a multifunctional receptor-binding domain. Further, Plxdc1/2 usage defines an important biological difference between KSHV and RRV."],["dc.description.sponsorship"," Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659"],["dc.description.sponsorship"," Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659"],["dc.description.sponsorship"," Wilhelm Sander-Stiftung http://dx.doi.org/10.13039/100008672"],["dc.description.sponsorship","Interdisciplinary Center for Clinical Research Erlangen"],["dc.description.sponsorship"," Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659"],["dc.description.sponsorship"," National Institutes of Health http://dx.doi.org/10.13039/100000002"],["dc.description.sponsorship"," Foundation for the National Institutes of Health http://dx.doi.org/10.13039/100000009"],["dc.identifier.doi","10.1371/journal.ppat.1008979"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/115069"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-602"],["dc.relation.eissn","1553-7374"],["dc.relation.orgunit","Deutsches Primatenzentrum"],["dc.rights.uri","http://creativecommons.org/licenses/by/4.0/"],["dc.title","Plxdc family members are novel receptors for the rhesus monkey rhadinovirus (RRV)"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","e1006912"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","PLoS Pathogens"],["dc.bibliographiccitation.volume","14"],["dc.contributor.author","Großkopf, Anna K."],["dc.contributor.author","Ensser, Armin"],["dc.contributor.author","Neipel, Frank"],["dc.contributor.author","Jungnickl, Doris"],["dc.contributor.author","Schlagowski, Sarah"],["dc.contributor.author","Desrosiers, Ronald C."],["dc.contributor.author","Hahn, Alexander S."],["dc.contributor.editor","Hutt-Fletcher, Lindsey"],["dc.date.accessioned","2022-10-06T13:26:22Z"],["dc.date.available","2022-10-06T13:26:22Z"],["dc.date.issued","2018"],["dc.description.sponsorship"," Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659"],["dc.description.sponsorship","Interdisciplinary Center for Clinical Research Erlangen (IZKF)"],["dc.description.sponsorship"," Wilhelm Sander-Stiftung http://dx.doi.org/10.13039/100008672"],["dc.description.sponsorship"," Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659"],["dc.description.sponsorship","Interdisciplinary Center for Clinical Research Erlangen (IZKF)"],["dc.description.sponsorship"," Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659"],["dc.description.sponsorship"," Deutsches Primatenzentrum http://dx.doi.org/10.13039/501100004938"],["dc.description.sponsorship"," National Institutes of Health http://dx.doi.org/10.13039/100000002"],["dc.identifier.doi","10.1371/journal.ppat.1006912"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/115068"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-602"],["dc.relation.eissn","1553-7374"],["dc.relation.orgunit","Deutsches Primatenzentrum"],["dc.rights.uri","http://creativecommons.org/licenses/by/4.0/"],["dc.title","A conserved Eph family receptor-binding motif on the gH/gL complex of Kaposi’s sarcoma-associated herpesvirus and rhesus monkey rhadinovirus"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","541"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Viruses"],["dc.bibliographiccitation.volume","14"],["dc.contributor.author","Fricke, Thomas"],["dc.contributor.author","Großkopf, Anna K."],["dc.contributor.author","Ensser, Armin"],["dc.contributor.author","Backovic, Marija"],["dc.contributor.author","Hahn, Alexander S."],["dc.date.accessioned","2022-04-01T10:02:08Z"],["dc.date.available","2022-04-01T10:02:08Z"],["dc.date.issued","2022"],["dc.description.abstract","Kaposi’s sarcoma herpesvirus (KSHV) is associated with a significant disease burden, in particular in Sub-Sahara Africa. A KSHV vaccine would be highly desirable, but the mechanisms underlying neutralizing antibody responses against KSHV remain largely unexplored. The complex made of glycoproteins H and L (gH/gL) activates gB for the fusion of viral and cellular membranes in all herpesviruses. KSHV gH/gL also interacts with cellular Eph family receptors. To identify optimal antigens for vaccination and to elucidate neutralization mechanisms, we primed mice with recombinantly expressed, soluble gH/gL (gHecto/gL) that was either wildtype (WT), lacking defined glycosylation sites or bearing modified glycosylation, followed by boosts with WT gHecto/gL. We also immunized with a gL-gHecto fusion protein or a gHecto-ferritin/gL nanoparticle. Immune sera neutralized KSHV and inhibited EphA2 receptor binding. None of the regimens was superior to immunization with WT gHecto/gL with regard to neutralizing activity and EphA2 blocking activity, the gL-gHecto fusion protein was equally effective, and the ferritin construct was inferior. gH/gL-targeting sera inhibited gB-mediated membrane fusion and inhibited infection also independently from receptor binding and gL, as demonstrated by neutralization of a novel KSHV mutant that does not or only marginally incorporate gL into the gH/gL complex and infects through an Eph-independent route."],["dc.identifier.doi","10.3390/v14030541"],["dc.identifier.pii","v14030541"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/105828"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-530"],["dc.relation.eissn","1999-4915"],["dc.title","Antibodies Targeting KSHV gH/gL Reveal Distinct Neutralization Mechanisms"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]