HSV-2 Infection Induces Lasting Transcriptional and Functional Changes in Vaginal Tissue NK Cells

Introduction/Rationale: Mucosal immunity in the vaginal tract (VT) remains poorly defined despite its essential role in defense against sexually transmitted infections. Natural killer (NK) cells are critical for antiviral control, and increasing evidence indicates that they can acquire adaptive-like features following infection. While memory-like NK cells have been established in response to CMV, it is unknown whether other viral infections elicit similar adaptive responses in NK cells, particularly within mucosal tissues.

Methods: To determine whether HSV-2 infection induces long-term changes in mucosal NK cells, we performed bulk RNA sequencing and high-parameter flow cytometry on vaginal NK cells isolated from naïve mice and from mice 10 days post intravaginal infection with HSV-2 (10dpi).

Results: Vaginal NK cells exhibited a distinct transcriptional profile following infection, with 10 dpi and naïve populations clustering separately by principal component analysis. Differential gene expression analysis revealed upregulation of Icos (adj. p = 0.22) and Ly6c2 (adj. p = 0.03) at 10 dpi compared to naïve NK cells. Notably, Ly6C has been associated with memory-like NK cells following viral challenge. Analysis by flow cytometry confirmed increased Ly6C expression (p = 0.017) and enhanced IFNγ production (p = 0.006) in NK cells from mice at 10 dpi, suggesting augmented effector capacity. Furthermore, transcripts characteristic of adaptive NK cell populations, including CD3 chain and histocompatibility gene family members, were elevated at 10 dpi.

Conclusion: Together, these findings demonstrate that local HSV-2 infection induces persistent transcriptional and functional changes in vaginal NK cells, supporting the development of a memory-like NK cell population within mucosal tissue.