Anti-HSV Polyclonal antibody

Cyclic GMP-AMP synthase (cGAS) is an essential sensor of cytosolic DNA and critically mediates innate immune responses and autoimmunity. Modulating the activity and stability of cGAS provides potential strategies for treating viral or autoimmune diseases. Here, we report that ubiquitin-specific protease 29 (USP29) deubiquitinates and stabilizes cGAS and promotes cellular antiviral responses and autoimmunity. Knockdown or knockout of USP29 severely impairs Herpes simplex virus 1 (HSV-1)- or cytosolic DNA-induced expression of type I interferons (IFNs) and proinflammatory cytokines. Consistently, Usp29(m/m) mice produce decreased type I IFNs and proinflammatory cytokines after HSV-1 infection and are hypersensitive to HSV-1 infection compared to the wild-type littermates. In addition, genetic ablation of USP29 in Trex1(-/-) mice eliminated the detectable pathological and molecular autoimmune phenotypes. Mechanistically, USP29 constitutively interacts with cGAS, deconjugates K48-linked polyubiquitin chains from cGAS and stabilizes cGAS in uninfected cells or after HSV-1 infection. Reconstitution of cGAS into Usp29(-/-) cells fully rescues type I IFN induction and cellular antiviral responses after HSV-1 infection. Our findings thus reveal a critical role of USP29 in the innate antiviral responses against DNA viruses and autoimmune diseases and provide insight into the regulation of cGAS.

The DNA sensor cGAS catalyzes the production of the cyclic dinucleotide cGAMP, resulting in type I interferon responses. We addressed the functionality of cGAS-mediated DNA sensing in human and murine T cells. Activated primary CD4(+) T cells expressed cGAS and responded to plasmid DNA by upregulation of ISGs and release of bioactive interferon. In mouse T cells, cGAS KO ablated sensing of plasmid DNA, and TREX1 KO enabled cells to sense short immunostimulatory DNA. Expression of IFIT1 and MX2 was downregulated and upregulated in cGAS KO and TREX1 KO T cell lines, respectively, compared to parental cells. Despite their intact cGAS sensing pathway, human CD4(+) T cells failed to mount a reverse transcriptase (RT) inhibitor-sensitive immune response following HIV-1 infection. In contrast, infection of human T cells with HSV-1 that is functionally deficient for the cGAS antagonist pUL41 (HSV-1 Delta UL41N) resulted in a cGAS-dependent type I interferon response. In accordance with our results in primary CD4(+) T cells, plasmid challenge or HSV-1 Delta UL41N inoculation of T cell lines provoked an entirely cGAS-dependent type I interferon response, including IRF3 phosphorylation and expression of ISGs. In contrast, no RT-dependent interferon response was detected following transduction of T cell lines with VSV-G-pseudotyped lentiviral or gammaretroviral particles. Together, T cells are capable to raise a cGAS-dependent cell-intrinsic response to both plasmid DNA challenge or inoculation with HSV-1 Delta UL41N. However, HIV-1 infection does not appear to trigger cGAS-mediated sensing of viral DNA in T cells, possibly by revealing viral DNA of insufficient quantity, length, and/or accessibility to cGAS.