Three-dimensional structure of the Epstein-Barr virus capsid.

Epstein-Barr virus (EBV), a gammaherpesvirus, infects >90 % of the world's population. Primary infection by EBV can lead to infectious mononucleosis, and EBV persistence is associated with several malignancies. Despite its importance for human health, little structural information is available on EBV. Here we report the purification of the EBV capsid by CsCl- or sucrose density-gradient centrifugation. Cryo-electron microscopy and image analysis resulted in two slightly different three-dimensional structures at about 20 Å resolution. These structures were compared with that of human herpesvirus 8, another gammaherpesvirus. CsCl-gradient purification leads to the removal of part of the triplex complex around the fivefold axes, whereas the complexes between hexons remained in place. This may be due to local differences in stability resulting from variation in quasi-equivalent interactions between pentons and hexons compared with those between hexons only.