Studies mainly performed in children revealed that the TLR3 pathway is essential and non-redundant for induction of IFN-α, β, λ and γ in the central nervous system (CNS) [5] and that the pathogenesis of HSE and its recurrence may result from single-gene inborn errors of TLR3/IFN pathway-mediated immunity [6–14]. This evidence concerns the gene IFNA1 and herpes simplex encephalitis.