A genome-wide CRISPR screen identifies ZCCHC14 as a host factor required for hepatitis B surface antigen production

A hallmark of chronic hepatitis B virus (CHB) infection is the presence of high circulating levels of non-infectious small lipid HBV surface antigen (HBsAg) vesicles. Although rare, sustained HBsAg loss is the idealized endpoint of any CHB therapy. A novel small molecule RG7834 has been previously reported to inhibit HBsAg expression by targeting terminal nucleotidyltransferase protein 4A and 4B (TENT4A and TENT4B). In this study, we describe a genome-wide CRISPR screen to identify other potential novel host factors required for HBsAg expression and to gain further insights into the mechanism of RG7834. We report more than 60 genes involved in regulating HBsAg and identified novel factors involved in RG7834 activity, including a zinc finger CCHC-type containing 14 (ZCCHC14) protein. We show that ZCCHC14, together with TENT4A/B, stabilizes HBsAg expression through HBV RNA tailing, providing a potential new therapeutic target to achieve functional cure in CHB patients.