Hepatitis E virus capsid protein

The **Hepatitis E virus capsid protein** is encoded by the ORF2 gene of the hepatitis E virus (family Hepeviridae). It forms the icosahedral capsid shell of the virion, mediates attachment and entry of the virus into susceptible host cells, and is essential for encapsidation of the viral RNA genome[5][7][9][10]. Structurally, the protein is comprised of three domains: S (continuous shell), P1 (threefold protrusions), and P2 (twofold spikes/homodimeric protruding domains), each containing potential polysaccharide-binding sites implicated in cell receptor recognition[2][4][6][9]. The dimerization of the P2 (E2s) domain is critical for interaction with host cells and is also where key neutralizing epitopes are located[3][6]. Two functionally distinct forms of the protein exist: the virion-incorporated capsid form (initiated from an internal ORF2 start site) and a secreted glycosylated form (initiated from the original start codon), the latter implicated in immune evasion by binding and sequestering neutralizing antibodies[7][10]. The capsid protein is highly immunogenic and is the basis for existing vaccine candidates. No small molecule drugs currently target this protein, but neutralizing antibody responses induced by vaccines can block its function and thus prevent infection. Detection of anti-HEV capsid antibodies in serum is the primary diagnostic biomarker for evaluating exposure or infection.

Other names

ORF2 proteinHEV capsid proteinHepatitis E virus ORF2

Vaccine-induced neutralizing antibody response against capsid protein blocks virus entry into host cells