IRF7 and UNC93B1 variants in an infant with recurrent herpes simplex virus infection
Megan H. Tucker, … , Nikita Raje, Venkatesh Sampath
Megan H. Tucker, … , Nikita Raje, Venkatesh Sampath
Published April 25, 2023
Citation Information: J Clin Invest. 2023;133(11):e154016. https://doi.org/10.1172/JCI154016.
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IRF7 and UNC93B1 variants in an infant with recurrent herpes simplex virus infection

Abstract

Neonatal herpes simplex virus (HSV) infection is a devastating disease with substantial morbidity and mortality. The genetic basis of susceptibility to HSV in neonates remains undefined. We evaluated a male infant with neonatal skin/eye/mouth (SEM) HSV-1 disease, who had complete recovery after acyclovir but developed HSV-1 encephalitis at 1 year of age. An immune workup showed an anergic PBMC cytokine response to TLR3 stimulation but no other TLRs. Exome sequencing identified rare missense variants in IFN-regulatory factor 7 (IRF7) and UNC-93 homolog B1 (UNC93B1). PBMC single-cell RNA-Seq done during childhood revealed decreased expression of several innate immune genes and a repressed TLR3 pathway signature at baseline in several immune cell populations, including CD14 monocytes. Functional studies in fibroblasts and human leukemia monocytic THP1 cells showed that both variants individually suppressed TLR3-driven IRF3 transcriptional activity and the type I IFN response in vitro. Furthermore, fibroblasts expressing the IRF7 and UNC93B1 variants had higher intracellular viral titers with blunting of the type I IFN response upon HSV-1 challenge. This study reports an infant with recurrent HSV-1 disease complicated by encephalitis associated with deleterious variants in the IRF7 and UNC93B1 genes. Our results suggest that TLR3 pathway mutations may predispose neonates to recurrent, severe HSV.

Authors

Megan H. Tucker, Wei Yu, Heather Menden, Sheng Xia, Carl F. Schreck, Margaret Gibson, Daniel Louiselle, Tomi Pastinen, Nikita Raje, Venkatesh Sampath

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Figure 4

Functional analysis of the UNC93B1 variant (p.P404S) in THP1 cells showing that the UNC93B1 variant abolishes poly(I:C)-induced IRF3 transcriptional activity, type I IFN expression, and binding to the TLR3 protein.

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Functional analysis of the UNC93B1 variant (p.P404S) in THP1 cells showi...
(A) Model of UNC93B1 showing localization of the p.P404S variant to transmembrane domain 9 (TM9), implicated in physical binding to TLR3. (B–E) THP1 cells were transfected with empty plasmid (Ø), UNC93B1 WT, and mut plasmids prior to treatment with 1 μg/mL poly(I:C) for 24 hours. (B) IRF3 transcriptional activity was measured by quantifying luciferase in culture supernatants obtained from THP1 cells transfected with the indicated plasmids following 24 hours of poly(I:C) treatment. †††P < 0.05. n = 5. (C) mRNA expression of UNC93B1 (UNC), IFNA, and IFNB was quantified by qPCR in THP1 cell lysates obtained after the above treatments. *Control versus poly(I:C); **poly(I:C) Ø versus poly(I:C) plasmid; ***control Ø versus control plasmid; P < 0.05 (all). n = 3. (D and E) TLR3 was immunoprecipitated from THP1 clarified lysates (D) to demonstrate that binding of UNC93B1 to TLR3 was repressed with the UNC93B1 variant (top panel). Bottom panel shows expression of transfected WT and mut UNC93B1 alleles in THP1 cells. (E) Densitometric quantification of the Western blots shown in D. ††P < 0.001. n = 5. ANOVA with Tukey’s test was used for statistical analysis.