<p>Sensing of viral pathogens by RIG-I-like receptors (RLRs) requires their priming via dephosphorylation mediated by the protein phosphatase 1 regulatory subunit 12 C (R12C), which is activated upon virus-induced actin rearrangements. Here, we show that the HIV-1 accessory protein Nef prevents R12C-mediated RLR priming, thereby suppressing viral sensing. HIV-1 variants containing single point mutations in Nef (F/R191A) that ablate its ability to bind the actin-modulating kinase PAK2 trigger increased interferon (IFN) responses in primary CD4<sup>+</sup> T cells, macrophages, and dendritic cells. Neutralization of IFN suppresses innate immune activation and enhances the replication of Nef-mutated HIV-1. We further demonstrate that HIV-1 encoding Nef F/R191A is sensed by MDA5 after proviral integration in an R12C-dependent manner. Mechanistically, PAK2 binding by Nef promotes actin repair and stabilization, thereby preventing re-localization of R12C to MDA5 and RIG-I and their subsequent dephosphorylation. Our data identify Nef as an antagonist of actin-R12C-mediated RLR priming, enabling HIV-1 to escape immune control.</p>

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Nef stabilizes actin to prevent HIV-1 sensing by RIG-I-like receptors

  • Alexandre Laliberté,
  • Caterina Prelli Bozzo,
  • Dhiraj Acharya,
  • Aurora De Luna,
  • Maximilian Hirschenberger,
  • Junji Zhu,
  • Meta Volcic,
  • Bettina Stolp,
  • Cristina M. Rodriguez-Quinteros,
  • Oliver T. Fackler,
  • Michaela U. Gack,
  • Konstantin M. J. Sparrer,
  • Frank Kirchhoff

摘要

Sensing of viral pathogens by RIG-I-like receptors (RLRs) requires their priming via dephosphorylation mediated by the protein phosphatase 1 regulatory subunit 12 C (R12C), which is activated upon virus-induced actin rearrangements. Here, we show that the HIV-1 accessory protein Nef prevents R12C-mediated RLR priming, thereby suppressing viral sensing. HIV-1 variants containing single point mutations in Nef (F/R191A) that ablate its ability to bind the actin-modulating kinase PAK2 trigger increased interferon (IFN) responses in primary CD4+ T cells, macrophages, and dendritic cells. Neutralization of IFN suppresses innate immune activation and enhances the replication of Nef-mutated HIV-1. We further demonstrate that HIV-1 encoding Nef F/R191A is sensed by MDA5 after proviral integration in an R12C-dependent manner. Mechanistically, PAK2 binding by Nef promotes actin repair and stabilization, thereby preventing re-localization of R12C to MDA5 and RIG-I and their subsequent dephosphorylation. Our data identify Nef as an antagonist of actin-R12C-mediated RLR priming, enabling HIV-1 to escape immune control.