Interleukin-17A directly triggers Epstein-Barr virus lytic reactivation in latency I human B-cell models

ABSTRACT Epstein-Barr virus (EBV) is a ubiquitous human gammaherpesvirus implicated in inflammatory, malignant, and autoimmune diseases. Although EBV toggles between latent and lytic states, the host cues controlling this switch remain incompletely defined. Interleukin-17A (IL-17A), a signature Th17 cytokine, is enriched in EBV-associated inflammatory settings, and EBV products can augment IL-17A responses. Whether IL-17A directly regulates the EBV life cycle has remained unknown. Here, we show that IL-17A alone is sufficient to induce EBV lytic reactivation in latency I human B-cell models. IL-17A increased BZLF1/Zta, activated the BZLF1 promoter (Zp), induced early and late lytic genes and proteins, and promoted DNase-resistant EBV DNA release and infectious virion production. Mechanistically, IL-17A activated NF-κB and ERK/p38 MAPK signaling, including phosphorylation of p65, ERK1/2, and p38. IL-17RA blockade reduced IL-17A-induced signaling and lytic reactivation, and pharmacologic inhibition of NF-κB or p38 MAPK signaling attenuated EBV reactivation. Among IL-17 family members tested, only IL-17A induced reactivation. RNA-seq provided a transcriptome-wide view of the viral and cellular response to IL-17A, revealing broad EBV lytic transcription and inflammatory, NF-κB-associated, and B-cell activation programs. IL-17A responsiveness was latency- and cell-state restricted: latency I B-cell models responded, whereas latency II/III, lymphoblastoid, and EBV-positive epithelial models did not. Subinducing IL-17A (1 ng/mL) was insufficient alone but enhanced B-cell receptor-mediated reactivation, suggesting threshold-lowering activity in inflammatory B-cell niches. Together, these findings identify IL-17A as a receptor-linked inflammatory cue for EBV lytic entry and provide the first demonstration that IL-17A alone directly triggers EBV lytic reactivation in human cells. IMPORTANCE Epstein-Barr virus (EBV) persists for life by maintaining latency with lytic reactivation, yet the inflammatory cues that initiate this switch remain poorly defined. Here, we identify interleukin-17A (IL-17A), a Th17 cytokine, as a direct trigger of EBV lytic reactivation in latency I human B-cell models. IL-17A activates IL-17RA-linked NF-κB/MAPK signaling, induces BZLF1/Zta and downstream lytic genes, and promotes DNase-resistant EBV DNA release and infectious virion production. IL-17RA blockade and inhibition of NF-κB/p38 MAPK signaling reduce reactivation, supporting a receptor-linked mechanism rather than nonspecific stress. Subinducing IL-17A (1 ng/mL) was insufficient to reactivate EBV alone but enhanced B-cell receptor-mediated reactivation, suggesting threshold-lowering activity in inflammatory B-cell niches. The response is restricted by latency and cell state, indicating that IL-17A signaling must be coupled to a permissive EBV lytic switch. These findings connect Th17-skewed inflammation to EBV reactivation burden and suggest that IL-17A/IL-17R signaling may influence EBV pathogenesis in inflammatory and malignant settings.