Ebola Zaire Virus Blocks Type I Interferon Production by Exploiting the Host SUMO Modification Machinery

PLoS Pathogens

Mike Bray¹  Steven Jones²  Toru Kubota³  Tsung-Hsien Chang³  Keiko Ozato³  Mayumi Matsuoka³  Steven B. Bradfute⁴ 

[1] Integrated Research Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, Maryland, United States of America;Population and Public Health Branch, National Microbiology Laboratory, Canadian Science Centre for Human and Animal Health, Winnipeg, Manitoba, Canada;Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America;United States Army Medical Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America

关键词: SUMOylation;    Transcription factors;    Interferons;    Two-hybrid screening;    Immunoprecipitation;    293T cells;    Ligases;    Antibodies;   

DOI  :  10.1371/journal.ppat.1000493

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Ebola Zaire virus is highly pathogenic for humans, with case fatality rates approaching 90% in large outbreaks in Africa. The virus replicates in macrophages and dendritic cells (DCs), suppressing production of type I interferons (IFNs) while inducing the release of large quantities of proinflammatory cytokines. Although the viral VP35 protein has been shown to inhibit IFN responses, the mechanism by which it blocks IFN production has not been fully elucidated. We expressed VP35 from a mouse-adapted variant of Ebola Zaire virus in murine DCs by retroviral gene transfer, and tested for IFN transcription upon Newcastle Disease virus (NDV) infection and toll-like receptor signaling. We found that VP35 inhibited IFN transcription in DCs following these stimuli by disabling the activity of IRF7, a transcription factor required for IFN transcription. By yeast two-hybrid screens and coimmunoprecipitation assays, we found that VP35 interacted with IRF7, Ubc9 and PIAS1. The latter two are the host SUMO E2 enzyme and E3 ligase, respectively. VP35, while not itself a SUMO ligase, increased PIAS1-mediated SUMOylation of IRF7, and repressed Ifn transcription. In contrast, VP35 did not interfere with the activation of NF-κB, which is required for induction of many proinflammatory cytokines. Our findings indicate that Ebola Zaire virus exploits the cellular SUMOylation machinery for its advantage and help to explain how the virus overcomes host innate defenses, causing rapidly overwhelming infection to produce a syndrome resembling fulminant septic shock.

【 授权许可】

CC BY