Defects in LC3B2 and ATG4A underlie HSV2 meningitis and reveal a critical role for autophagy in antiviral defense in humans

Abstract

Recurrent herpesvirus infections can manifest in different forms of disease, including cold sores, genital herpes, and encephalitis. There is an incomplete understanding of the genetic and immunological factors conferring susceptibility to recurrent herpes simplex virus 2 (HSV2) infection in the central nervous system (CNS). Here, we describe two adult patients with recurrent HSV2 lymphocytic Mollaret’s meningitis that each carry a rare monoallelic variant in the autophagy proteins ATG4A or LC3B2. HSV2-activated autophagy was abrogated in patient primary fibroblasts, which also exhibited significantly increased viral replication and enhanced cell death. HSV2 antigen was captured in autophagosomes of infected cells, and genetic inhibition of autophagy by disruption of autophagy genes, including ATG4A and LC3B2, led to enhanced viral replication and cell death in primary fibroblasts and a neuroblastoma cell line. Activation of autophagy by HSV2 was sensitive to ultraviolet (UV) irradiation of the virus and inhibited in the presence of acyclovir, but HSV2-induced autophagy was independent of the DNA-activated STING pathway. Reconstitution of wild-type ATG4A and LC3B2 expression using lentiviral gene delivery or electroporation of in vitro transcribed mRNA into patient cells restored virus-induced autophagy and the ability to control HSV2 replication. This study describes a previously unknown link between defective autophagy and an inborn error of immunity that can lead to increased susceptibility to HSV2 infection, suggesting an important role for autophagy in antiviral immunity in the CNS.

Implications of Innate Immunity in Post-Acute Sequelae of Non-Persistent Viral Infections

“…Notably, it was shown that activity of the innate immune system protects against neurological complications [176]. It was recently reported that herpes-simplex-virus-2 (HSV-2) patients with defects in the autophagy genes ATG4A and LC3B2 develop recurrent meningitis (Mollaret's meningitis), a recurrent or chronic form of inflammation of the protective membranes covering the CNS [177,178]. Mechanistically, autophagy mediates the clearance of HSV-2 antigen in non-defective cells.…”

“…Mechanistically, autophagy mediates the clearance of HSV-2 antigen in non-defective cells. Genetic disruption of ATG4A and LC3B2 expression led to enhanced viral replication and subsequent cell death in patient cells and cell lines [177].…”

Recent Issues in Varicella-Zoster Virus Latency

“…Mollaret's meningitis, the molecular and immunological pathogenesis of which is largely unexplored, is such a condition, and consists of recurrent lymphocytic meningitis caused by HSV-2 reactivation, in rare cases by VZV or HSV-1 [121][122][123]. Whole exome sequencing of patients with Mollaret's meningitis recently led to the identification of rare mono-allelic missense variants in the autophagy genes ATG4A and LC3B2 in two adult patients and was the first study to associate defective autophagy with viral infection in humans [124,125]. HSV-2 infection of fibroblasts from these patients demonstrated impaired virus-induced autophagy as well as increased viral replication and enhanced cell death, and this cellular phenotype was reconstituted/rescued to normal by expression of WT ATG4 and LC3B2 in the two patients, respectively [125].…”

“…Whole exome sequencing of patients with Mollaret's meningitis recently led to the identification of rare mono-allelic missense variants in the autophagy genes ATG4A and LC3B2 in two adult patients and was the first study to associate defective autophagy with viral infection in humans [124,125]. HSV-2 infection of fibroblasts from these patients demonstrated impaired virus-induced autophagy as well as increased viral replication and enhanced cell death, and this cellular phenotype was reconstituted/rescued to normal by expression of WT ATG4 and LC3B2 in the two patients, respectively [125]. These findings revealed a role for autophagy in antiviral defense and suggest that defective autophagy represents a rare inborn error of immunity associated with susceptibility to HSV2 CNS infection in humans.…”

The Role of Autophagy in Varicella Zoster Virus Infection

“…Recently, studies on patients with HSV-2-induced recurrent lymphocytic Mollaret meningitis have begun to shed more light on a potentially important role of autophagy in viral infections and disease pathogenesis in humans. Whole-exome sequencing has revealed mutations in the autophagy genes LC3B2 and ATG4A in such patients, which were associated with impaired HSV-2-induced autophagy, increased viral replication and enhanced cell death in patient fibroblasts and in neuronal cells harboring the autophagy variants [71]. Based on these findings, it was suggested that autophagy may play an important role in antiviral defense in the CNS and that autophagy defects may represent an inborn error of immunity predisposing patients to viral meningitis and encephalitis [71].…”