Pseudorabies Virus Infection Triggers NF-κB Activation via the DNA Damage Response but Actively Inhibits NF-κB-Dependent Gene Expression

Abstract

The nuclear factor kappa B (NF-κB) pathway is known to integrate signaling associated with very diverse intra- and extracellular stressors including virus infections, and triggers a powerful (pro-inflammatory) response through the expression of NF-κB-regulated genes. Typically, the NF-κB pathway collects and transduces threatening signals at the cell surface or in the cytoplasm leading to nuclear import of activated NF-κB transcription factors. In the current work, we demonstrate that the swine alphaherpesvirus pseudorabies virus (PRV) induces a peculiar mode of NF-κB activation known as “inside-out” NF-κB activation. We show that PRV triggers the DNA damage response (DDR) and that this DDR response drives NF-κB activation since inhibition of the nuclear ataxia telangiectasia-mutated (ATM) kinase, a chief controller of DDR, abolished PRV-induced NF-κB activation. Initiation of the DDR-NF-κB signaling axis requires viral protein synthesis but occurs before active viral genome replication. In addition, the initiation of the DDR-NF-κB signaling axis is followed by a virus-induced complete shutoff of NF-κB-dependent gene expression that depends on viral DNA replication. In summary, the results presented in this study reveal that PRV infection triggers a non-canonical DDR-NF-κB activation signaling axis and that the virus actively inhibits the (potentially antiviral) consequences of this pathway, by inhibiting NF-κB-dependent gene expression. IMPORTANCE: The NF-κB signaling pathway plays a critical role in coordination of innate immune responses that are of vital importance in the control of infections. The current report generates new insights in the interaction of the alphaherpesvirus pseudorabies virus (PRV) with the NF-κB pathway, as they reveal that (i) PRV infection leads to NF-κB activation via a peculiar “inside-out’ nucleus-to-cytoplasm signal that is triggered via the DNA damage response (DDR), (ii) the DDR-NF-κB signaling axis requires expression of viral proteins but is initiated before active PRV replication, and (iii) late viral factor(s) allow PRV to actively and efficiently inhibit NF-κB-dependent (pro-inflammatory) gene expression. These data suggest that activation of the DDR-NF-κB during PRV infection is host-driven and that its potential antiviral consequences are actively inhibited by the virus.

Pseudorabies virus exploits N6-methyladenosine modification to promote viral replication

“…Hypomethylated genes were also enriched in NF-κB signaling pathway. PRV triggered the activation of NF-κB signaling pathway through DNA damage response, and viral late factors could effectively inhibit NF-κB-dependent genes expression (Romero and Favoreel, 2021), which might also be regulated by m 6 A modification. PRV infection might regulate the expression of these cytokines by changing m 6 A modification, and the specific mechanism needed further study.…”

Peptidomic Analysis on Mouse Lung Tissue Reveals AGDP as a Potential Bioactive Peptide against Pseudorabies Virus Infection

“…PRV infection [ 18 ] and the RAGE-HMGB1 axis [ 33 ] could all induce the inflammatory response by activating the signaling pathway of NF-κB. To further investigate the anti-inflammatory function of AGDP during PRV infection, the effects of AGDP on the activities of IκBα and P65 proteins were further explored, which are thought of as the important checkpoints in the NF-κB signaling pathway.…”

“…NF-κB signaling can be activated by various stimulus factors and has thus typically resulted in a robust surge of several proinflammatory factors, along with negative feedback factors to inhibit excessive inflammation [ 15 , 16 ]. Additionally, two recent studies have addressed the fact that PRV infection could trigger a non-canonical NF-κB pathway independent of IKKβ kinase activity, which would not result in the expression of tumor necrosis factor alpha (TNF-α) or interleukin-6 (IL-6), and not induce the negative-feedback-loop genes, such as IκBα [ 17 , 18 ]. These studies indicated that PRV could efficiently inhibit the potentially antiviral response of hosts by triggering the activation of a non-canonical DDR-NF-κB signaling axis, but these results could not exclude the other potential signaling pathways.…”

A Tug of War: Pseudorabies Virus and Host Antiviral Innate Immunity

“…The DDR-NF-κB signaling axis requires the expression of viral proteins but is initiated before active PRV replication. However, late PRV proteins inhibit NF-κB-dependent gene expression [ 85 ].…”