ABSTRACT
The Tombusvirus group consists of tomato bushy stunt virus (TBSV), the type member, and several related viruses. All members have isometric particles about 34 nm in diameter with rounded outlines, sedimenting at about 135S. Several viruses with small isometric particles are in some respects similar to Tombusviruses, but are at present not included in this or any other group. The structure of the TBSV particle has been extensively studied by both electron microscopy and X-ray diffraction. Although Turnip crinkle virus is not at present a definite member of the Tombusvirus group, the structure of its particles has been studied extensively and shown to be very similar to that of TBSV. Cells infected by Tombusviruses contain densely staining particles about 26 nm in diameter. The particles accumulate in large numbers in the cytoplasm and vacuoles where they sometimes form crystalline arrays.
