The organization of frog virus 3 as revealed by freeze-etching.

A variety of freeze-fracture techniques has been employed in this study with the aim of dissecting the frog virus 3 virion and obtaining further information about its architecture. The icosahedral capsid has a skew symmetry with a triangulation number of 133 or 147. The capsomers are closely packed with a center-to-center spacing of 72 A. The inner membrane contains transmembrane proteins which appear as intra-membranous particles on both fracture faces. Rod-like structures (about 100 A in diameter) are present in the virus interior suggesting that the DNA-protein complex is highly organized.