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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Research Article Genetics Infectious disease

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 3

The IRF7 variant (p.R100P) abolishes poly(I:C)-induced IRF3 transcriptional activity, type I IFN expression, and IRF7 DNA binding in THP1 and HEK293T cells.

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The IRF7 variant (p.R100P) abolishes poly(I:C)-induced IRF3 transcriptio...
(A) Model of IRF7 mapping of the p.R100P variant on the DNA-binding domain (DBD). IAD, IRF association domain; ID, inhibitory domain. (B and C) Ø and IRF7 reference WT and mut proteins [mut plasmids were transfected into THP1 cells 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 plasmids and treated with poly(I:C). *Control versus poly(I:C); **poly(I:C) Ø versus poly(I:C) plasmid; ***control Ø versus control plasmid; P < 0.05 (all). n = 5. (C) RNA expression of IRF7, IFNA, and IFNB was quantified in THP1 cell lysates obtained after the above treatments by qPCR. *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) Bright-field and fluorescence images of HEK293T cell lines stably expressing control Ø, IRF7 WT, and IRF7 mut, respectively. Original magnification, ×100. (E) HEK293T were transfected with pGL4-4X IRF7-minP-Luc, pRL-TK (thymidine kinase promoter–Renilla luciferase reporter plasmid), CFP-TLR3, Ø, and IRF7 WT or mut plasmids for 2 days. Cells were lysed and a luciferase assay was performed. Part of the cell lysate was used to quantify expression of IRF7 WT and mut protein by immunoblotting. †P < 0.0001. n = 4. (F) HEK293T cell lines stably expressing Ø, WT, or mut FLAG-tagged IRF7 protein were transfected with pGL4-4X IRF7-minP-Luc, pRL-TK, and CFP-TLR3 for 2 days. Cell lysates were used for luciferase assay and protein expression studies. ††P < 0.001. n = 4. A Mann-Whitney U test or ANOVA with post hoc Tukey’s test was used for analysis after testing for normality.