Cell Reports (Sep 2019)

A VP35 Mutant Ebola Virus Lacks Virulence but Can Elicit Protective Immunity to Wild-Type Virus Challenge

  • Courtney Woolsey,
  • Andrea R. Menicucci,
  • Robert W. Cross,
  • Priya Luthra,
  • Krystle N. Agans,
  • Viktoriya Borisevich,
  • Joan B. Geisbert,
  • Chad E. Mire,
  • Karla A. Fenton,
  • Allen Jankeel,
  • Sneha Anand,
  • Hideki Ebihara,
  • Thomas W. Geisbert,
  • Ilhem Messaoudi,
  • Christopher F. Basler

Journal volume & issue
Vol. 28, no. 12
pp. 3032 – 3046.e6

Abstract

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Summary: Zaire ebolavirus (EBOV) VP35 protein is a suppressor of type I interferon (IFN) production, an inhibitor of dendritic cell maturation, and a putative virulence determinant. Here, a recombinant EBOV encoding a mutant VP35 virus (VP35m) is demonstrated to activate RIG-I-like receptor signaling and innate antiviral pathways. When inoculated into cynomolgus macaques, VP35m exhibits dramatic attenuation as compared to wild-type EBOV (wtEBOV), with 20 or 300 times the standard 100% lethal challenge dose not causing EBOV disease (EVD). Further, VP35m infection, despite limited replication in vivo, activates antigen presentation and innate immunity pathways and elicits increased frequencies of proliferating memory T cells and B cells and production of anti-EBOV antibodies. Upon wtEBOV challenge, VP35m-immunized animals survive, exhibiting host responses consistent with an orderly immune response and the absence of excessive inflammation. These data demonstrate that VP35 is a critical EBOV immune evasion factor and provide insights into immune mechanisms of EBOV control. : Woolsey et al. demonstrate that immune evasion functions of the Ebola virus VP35 protein are critical for virulence in non-human primates. A VP35 mutant Ebola virus does not cause lethal disease and instead elicits adaptive immune responses that can protect animals from wild-type Ebola virus challenge. Keywords: Ebola, filovirus, primate, VP35, RIG-I, RLR signaling, interferon, innate immunity, pathogenesis