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Bussey, K.* ; Reimer, E.* ; Todt, H.* ; Denker, B.* ; Gallo, A.* ; Konrad, A.* ; Ottinger, M.* ; Adler, H. ; Stürzl, M.* ; Brune, W.* ; Brinkmann, M.M.*

The gammaherpesviruses Kaposi's sarcoma-associated herpesvirus and murine gammaherpesvirus 68 modulate the toll-like receptor-induced proinflammatory cytokine response.

J. Virol. 88, 9245-9259 (2014)
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The human pathogen Kaposi's sarcoma-associated herpesvirus (KSHV), the etiological agent of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease, establishes lifelong latency upon infection. Murine gammaherpesvirus 68 (MHV68) is a well-established model for KSHV. Toll-like receptors (TLRs) play a crucial role for the innate immune response to pathogens. Although KSHV and MHV68 are detected by TLRs, studies suggest they modulate TLR4 and TLR9 signaling, respectively. In this study we show that in bone marrow-derived macrophages (BMDMs), MHV68 did not induce a detectable proinflammatory cytokine response. Furthermore, MHV68 abrogated the response to TLR2, 4, 7, and 9 agonists in BMDMs. Similarly to observations with MHV68, infection with KSHV efficiently inhibited TLR2 signaling in THP-1 monocytes. Using a KSHV ORF library, we found that K4.2, ORF21, ORF31, and RTA/ORF50 inhibited TLR2-dependent nuclear factor kappa B (NF-κB) activation in HEK293 TLR2-YFP and Flag-TLR2 transfected HEK 293T cells. Of the identified ORFs, the replication and transcription activator protein, RTA/ORF50, strongly downregulated TLR2 and TLR4 signaling by reducing TLR2 and TLR4 protein expression. Confocal microscopy revealed that TLR2 and TLR4 were no longer localized to the plasma membrane in cells expressing RTA/ORF50. In this study, we have shown that the gammaherpesviruses MHV68 and KSHV efficiently downmodulate TLR signaling in macrophages and have identified a novel function of RTA/ORF50 in modulation of the innate immune response. Importance Statement The Toll-like receptors (TLR) are an important class of pattern recognition receptors of the innate immune system. They induce a potent proinflammatory cytokine response upon detection of a variety of pathogens. In this study, we found that the gammaherpesviruses murine gammaherpesvirus 68 (MHV68) and Kaposi's sarcoma-associated herpesvirus (KSHV) efficiently inhibit the TLR-mediated innate immune response. We further identified the KSHV-encoded replication and transcription activator protein (RTA) as a novel modulator of TLR signaling. Our data suggest that the gammaherpesviruses MHV68 and KSHV prevent activation of the innate immune response by targeting TLR signaling.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords Nf-kappa-b; Pattern-recognition Receptors; Bacterial Artificial Chromosome; Respiratory Syncytial Virus; Innate Immunity; Mouse Cytomegalovirus; Dendritic Cells; Activation; Macrophages; Tlr9
ISSN (print) / ISBN 0022-538X
e-ISSN 1098-5514
Journal Journal of Virology
Quellenangaben Volume: 88, Issue: 16, Pages: 9245-9259 Article Number: , Supplement: ,
Publisher American Society for Microbiology (ASM)
Publishing Place Washington
Non-patent literature Publications
Reviewing status Peer reviewed
Institute(s) Research Unit Gene Vector (AGV)