Structure of the hepatitis C virus E1/E2 envelope proteins in a homodimeric complex

Worldwide, 58 million individuals suffer from chronic hepatitis C virus (HCV) infection, a primary driver of liver cancer. The HCV envelope proteins, E1 and E2, form a heterodimer, which is the target for neutralizing antibodies. Despite high-resolution structural models of partial heterodimer elements, the structural landscape of higher-order E1/E2 oligomers remains unexplored. We determined a ~3.5 Å cryo-electron microscopy structure of membrane-extracted HCV E1/E2 in a homodimeric arrangement. This structure includes detailed information on the homodimer interface, the E2-binding pocket for hypervariable region 1, antigenic site 412 conformation, and the organization of the E1/E2 transmembrane regions, including one internal to E1. This higher-order E1/E2 assembly could play a pivotal role in the design of novel vaccine antigens better mimicking E1/E2 complexes on the HCV particle.