The host gene CSTF2 regulates HBV replication via HBV PRE-induced nuclear export.

The persistent global burden of hepatitis B virus (HBV) infection has prompted ongoing investigations into host determinants of viral control. In this study, we investigate the regulatory influence of the host gene cleavage stimulation factor subunit 2 (CSTF2) on HBV replication dynamics. We demonstrate differential CSTF2 expression across the spectrum of HBV infection phases, with upregulated expression noted during the immune-reactive and inactive carrier states compared with the immune-tolerant phase. Notably, dose-responsive attenuation of HBV DNA, as well as surface and core protein levels, is observed subsequent to CSTF2 overexpression, whereas HBV RNA levels remain unaffected. Upon HBV transfection, a notable alteration in CSTF2 subcellular localization is discerned, suggesting active relocalization to the cytoplasm, potentially mediated through interaction with the HBV posttranscriptional regulatory element (PRE). This interaction appears to impede the nuclear export of HBV RNA. Additionally, distinct antiviral efficacies are attributed to the functional domains of the CSTF2 protein, indicating a multifaceted host defense mechanism. These insights increase the understanding of host-virus interplay and identify CSTF2 as a candidate for antiviral therapeutic strategies.