Julia Blay-Cadanet

Metabolic reprogramming is a key component of antiviral immunity, yet how metabolite transport regulates innate immune signaling remains incompletely understood. Here, we show that infection with herpes simplex virus 1 (HSV-1) and stimulation with cytosolic DNA induce the cellular export of glutamate via the xCT (SLC7A11) transporter and that inhibition of xCT reduces cellular resistance to viral replication. Mechanistically, xCT inhibition impaired cGAS-STING signaling by reducing DNA-induced cGAMP production, thereby diminishing type I interferon (IFNα/β) responses and downstream induction of interferon-stimulated genes. Interestingly, modulating intracellular glutamate levels through inhibition of other glutamate pathways, e.g., glutaminolysis or glutamate import, also affected cellular IFN responses, suggesting that glutamate is a central control knob for DNA sensing. Finally, we demonstrate that HSV-1 suppresses xCT expression via a mechanism dependent on the immediate early viral protein ICP27, thereby promoting viral replication by limiting cGAS-dependent IFN induction. Together, these findings identify xCT-dependent glutamate transport as a critical metabolic regulator of cGAS-STING-mediated antiviral immunity.

The transcription factor erythroid 2 (NFE2)-related factor 2 (NRF2) is a key regulator of cellular homeostasis. Recent discoveries have identified agonists of NRF2 as inducers of broad cellular resistance to viral infection including SARS-CoV-2. Nevertheless, it is still unclear to what extent NRF2 itself is an inducer of anti-viral immunity and its downstream antiviral effectors have not been mapped. Here, we first demonstrate through specific genetic activation and silencing that NRF2 restricts SARS-CoV-2 replication. We then used a focused CRISPR-activation screen to map antiviral NRF2-inducible effector genes that restrict replication of SARS-CoV-2, Influenza A virus (IAV), Herpes Simplex virus 1 (HSV1) and Vaccinia virus (VACV). This approach allowed us to identify a range of antiviral effectors each of which restrict members of one or more virus families. Importantly, we identified the NRF2-inducible selective autophagy receptor p62/SQSTM1 as a broadly effective restriction factor across all the tested viruses. Importantly, p62 inhibited SARS-CoV-2 replication in cells treated with the lysosomal inhibitor bafilomycin A1, as well as in cells deficient in the autophagy protein ATG5. Similarly, p62 inhibited replication of HSV1 and IAV independently of ATG5 and ATG16L1, respectively. Thus, NRF2 restricts viral replication through a hitherto underappreciated network of antiviral restriction factors effective across multiple virus families. Importantly, we identify p62 as a broadly acting antiviral effector that restricts viral replication independently of canonical autophagy.