Expression of Zinc-Finger Antiviral Protein in hCMEC/D3 Human Cerebral Microvascular Endothelial Cells: Effect of a Toll-Like Receptor 3 Agonist

Antiviral Activity of Zinc Finger Antiviral Protein (ZAP) in Different Virus Families

The CCCH-type zinc finger antiviral protein (ZAP) in humans, specifically isoforms ZAP-L and ZAP-S, is a crucial component of the cell's intrinsic immune response. ZAP acts as a post-transcriptional RNA restriction factor, exhibiting its activity during infections caused by retroviruses and alphaviruses. Its function involves binding to CpG (cytosine-phosphate-guanine) dinucleotide sequences present in viral RNA, thereby directing it towards degradation. Since vertebrate cells have a suppressed frequency of CpG dinucleotides, ZAP is capable of distinguishing foreign genetic elements. The expression of ZAP leads to the reduction of viral replication and impedes the assembly of new virus particles. However, the specific mechanisms underlying these effects have yet to be fully understood. Several questions regarding ZAP's mechanism of action remain unanswered, including the impact of CpG dinucleotide quantity on ZAP's activity, whether this sequence is solely required for the binding between ZAP and viral RNA, and whether the recruitment of cofactors is dependent on cell type, among others. This review aims to integrate the findings from studies that elucidate ZAP's antiviral role in various viral infections, discuss gaps that need to be filled through further studies, and shed light on new potential targets for therapeutic intervention.