Recombinant hepatitis e capsid protein self-assembles into a dual-domain T=1 particle presenting native virus epitopes

The three-dimensional structure of a self-assembled, recombinant hepatitis E virus particle has been solved to 22-Angstrom resolution by cryo-electron microscopy and three-dimensional image reconstruction. The single subunit of 50 kDa is derived from a truncated Version of the open reading frame-2 gene of the Virus expressed in a baculovirus system. This is the first structure of a T = 1 particle with protruding dimers at the icosahedral two-fold axes solved by cryo-electron microscopy. The protein shell of these hollow particles extends from a radius of 50 Angstrom outward to a radius of 135 Angstrom. In the reconstruction, the capsid is dominated by dimers that define the 30 morphological units. The outer domain of the homodimer forms a protrusion, which corresponds to the spike-like density seen in the cryo-electron micrograph. This particle retains native virus epitopes, suggesting its potential value as a vaccine. (C) 1999 Academic Press.