Tubular structures occurring in cells infected with herpesviruses

Certain viruses belonging to the Herpesviridae family generate tubular structures of three distinct size ranges late in the growth cycle. The smallest tubules are about 10 to 20 nm in diameter, and are restricted to the cell nucleus, tending to form palisades of lattice-like structures. The medium sized tubular structures are about the width of a core particle, measuring 55 to 65 nm in diameter, while the larger tubular structures are the same diameter as viral capsids, about 80 to 100 nm. Both are rigid capsomered structures, which are sometimes encountered outside the cell nucleus budding onto spherical particles. The available data on some properties of the various tubular structures, as well as speculations concerning their nature and significance are briefly reviewed. Their importance is emphasized for antigen and vaccine production, as well as in differentiating herpesviruses by electron microscopy.