Structures of giant icosahedral eukaryotic dsDNA viruses

In the past twenty years, numerous giant, dsDNA, icosahedral viruses have been discovered and assigned to the nucleocytoplasmic large dsDNA virus (NCLDV) clade. The major capsid proteins of these viruses consist of two consecutive jelly-roll domains, assembled into trimers, with pseudo 6-fold symmetry. The capsomers are assembled into arrays that have either p6 (as in Paramecium bursaria Chlorella virus-1) or p3 symmetry (as in Mimivirus). Most of the NCLDV viruses have a membrane that separates the nucleocapsid from the external capsid.

• Giant icosahedral dsDNA viruses replicate in the host's cytoplasm. • Major capsid proteins have a double-jelly-roll fold. • Trimeric capsomers have pseudo-hexagonal symmetry. • Capsomers assemble into 2D arrays forming trisymmetrons and pentasymmetrons. • Some NCLDVs have special vertices for genome exit and making of virus factories. • Nucleocapsids inside the capsid are surrounded by a membrane.