Circadian clock proteins BMAL1 and CLOCK regulate HSV-1 entry into nerve cells through NECTIN-1

Herpes simplex virus type 1 (HSV-1) is a double-stranded DNA virus that establishes lifelong latency and can cause fatal herpes encephalitis. This study aimed to identify key clock genes regulating HSV-1 infection and to elucidate the underlying mechanisms.

Transcriptomic analyses of the brainstem and hippocampus in mice were conducted to identify clock genes potentially involved in HSV-1 regulation. A serum shock cell model was employed to assess the impact of temporal variations in NECTIN-1 expression on HSV-1 infection. Luciferase reporter assays and chromatin immunoprecipitation (ChIP) were used to investigate the transcriptional regulatory mechanisms.

NECTIN-1, a primary receptor mediating HSV-1 entry into neurons, exhibited rhythmic expression in both the brainstem and hippocampus of mice. In vitro assays further demonstrated that HSV-1 DNA copy numbers fluctuated in near synchrony with NECTIN-1 expression levels. Overexpression of the core clock factors BMAL1 and CLOCK significantly increased NECTIN-1 expression. Mechanistically, BMAL1 and CLOCK bind directly to E-box-like motifs in the NECTIN-1 promoter region, thereby enhancing its transcriptional activity. Furthermore, pharmacological inhibition of CLOCK using CLK8 markedly suppressed HSV-1 infection.

Together, our findings reveal a novel mechanism by which the circadian clock modulates HSV-1 entry through rhythmic regulation of the NECTIN-1 receptor. BMAL1 and CLOCK emerge as potential therapeutic targets for circadian-based antiviral strategies.