An IKBKE variant conferring functional cGAS/STING pathway deficiency and susceptibility to recurrent HSV-2 meningitis

The mechanisms underlying susceptibility to recurrent herpes simplex virus type 2 (HSV-2) meningitis remain incompletely understood. In a patient experiencing multiple episodes of HSV-2 meningitis, we identified a monoallelic variant in the IKBKE gene, which encodes the IKK epsilon kinase involved in induction of antiviral IFN genes. Patient cells displayed impaired induction of IFN-beta 1 (IFNB1) expression upon infection with HSV-2 or stimulation with double-stranded DNA (dsDNA) and failed to induce phosphorylation of STING, an activation marker of the DNA-sensing cyclic GMP-AMP synthase/stimulator of IFN genes (cGAS/STING) pathway. The patient allele encoded a truncated IKK epsilon protein with loss of kinase activity and also capable of exerting dominant-negative activity. In stem cell-derived microglia, HSV-2-induced expression of IFNB1 was dependent on cGAS, TANK binding kinase 1 (TBK1), and IKBKE, but not TLR3, and supernatants from HSV-2- treated microglia exerted IKBKE-dependent type I IFN-mediated antiviral activity upon neurons. Reintroducing wild-type IKBKE into patient cells rescued IFNB1 induction following treatment with HSV-2 or dsDNA and restored antiviral activity. Collectively, we identify IKK epsilon to be important for protection against HSV-2 meningitis and suggest a nonredundant role for the cGAS/STING pathway in human antiviral immunity.