Hepatitis E virus antigens (HEV Ag)

Hepatitis E virus (HEV) antigens primarily consist of the proteins encoded by Open Reading Frames 2 (ORF2) and 3 (ORF3) of the viral genome. The ORF2 protein is the major capsid protein that assembles into the viral shell and mediates host cell attachment and entry by interacting with receptors like heparan sulfate proteoglycans (UniProt, 2024; Frontiers, 2021). It is the principal target for neutralizing antibodies and the basis for the only licensed vaccine, Hecolin (HEV 239), which uses a recombinant fragment to induce protective immunity (WHO, 2024; PMC, 2015). The ORF3 protein is a small phosphoprotein that acts as a viroporin, essential for the release of quasi-enveloped virions from infected hepatocytes into the blood (PMC, 2021; MDPI, 2024). These antigens play a dual role in pathogenesis: ORF2 can counteract host cell-intrinsic antiviral responses by interfering with TANK-binding kinase 1 signaling, while ORF3 modulates host signaling to facilitate viral egress (PMC, 2024; bioRxiv, 2025). Clinically, these antigens are used as diagnostic biomarkers, with the detection of soluble ORF2 (HEV Ag) in serum serving as a reliable indicator of active infection (PubMed, 2020).

Other names

HEV ORF2HEV ORF3HEV capsid proteinpORF2pORF3Hepatitis E virus structural proteins

Induction of neutralizing antibodies against the ORF2 capsid protein to prevent viral attachment and entry into host cells.