ISG15 governs mitochondrial function in macrophages following vaccinia virus infection

PLoS Pathog. 2017 Oct 27;13(10):e1006651. doi: 10.1371/journal.ppat.1006651. eCollection 2017 Oct.


The interferon (IFN)-stimulated gene 15 (ISG15) encodes one of the most abundant proteins induced by interferon, and its expression is associated with antiviral immunity. To identify protein components implicated in IFN and ISG15 signaling, we compared the proteomes of ISG15-/- and ISG15+/+ bone marrow derived macrophages (BMDM) after vaccinia virus (VACV) infection. The results of this analysis revealed that mitochondrial dysfunction and oxidative phosphorylation (OXPHOS) were pathways altered in ISG15-/- BMDM treated with IFN. Mitochondrial respiration, Adenosine triphosphate (ATP) and reactive oxygen species (ROS) production was higher in ISG15+/+ BMDM than in ISG15-/- BMDM following IFN treatment, indicating the involvement of ISG15-dependent mechanisms. An additional consequence of ISG15 depletion was a significant change in macrophage polarization. Although infected ISG15-/- macrophages showed a robust proinflammatory cytokine expression pattern typical of an M1 phenotype, a clear blockade of nitric oxide (NO) production and arginase-1 activation was detected. Accordingly, following IFN treatment, NO release was higher in ISG15+/+ macrophages than in ISG15-/- macrophages concomitant with a decrease in viral titer. Thus, ISG15-/- macrophages were permissive for VACV replication following IFN treatment. In conclusion, our results demonstrate that ISG15 governs the dynamic functionality of mitochondria, specifically, OXPHOS and mitophagy, broadening its physiological role as an antiviral agent.

MeSH terms

  • Animals
  • Arginase / genetics
  • Arginase / metabolism
  • Cytokines / genetics
  • Cytokines / metabolism*
  • Enzyme Activation / genetics
  • Macrophages / metabolism*
  • Macrophages / pathology
  • Mice
  • Mice, Knockout
  • Mitochondria / genetics
  • Mitochondria / metabolism*
  • Mitochondria / pathology
  • Mitophagy*
  • Nitric Oxide / metabolism
  • Oxidative Phosphorylation
  • Ubiquitins / genetics
  • Ubiquitins / metabolism
  • Vaccinia / genetics
  • Vaccinia / metabolism*
  • Vaccinia virus / metabolism*


  • Cytokines
  • G1p2 protein, mouse
  • Ubiquitins
  • Nitric Oxide
  • Arg1 protein, mouse
  • Arginase

Grant support

This research is supported by a grant from Spanish Ministry of Economy and Competitiveness (MINECO) to SG (SAF2014-54623-R), and to JV from MINECO (BIO2015-67580-P) and from the Carlos III Institute of Health-Fondo de Investigación Sanitaria (PRB2, IPT13/0001—ISCIII-SGEFI/FEDER, ProteoRed). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.