Virus of Avian Myeloblastosis (BAI Strain A). XXIII. Morphology of Virus and Comparison With Strain R (Erythroblastosis)

Summary

The BAI strain A avian tumor virus was treated in various ways and then prepared for electron microscopic examination by thin sectioning, metal shadowing, and negative staining. As in earlier studies, the virus particles were essentially spheroidal but were readily distorted into sperm, crescent, and other forms under some conditions of drying. The particles had a relatively firm inner structure and an easily deformable outer coat. When the virus preparations were frozen and thawed or treated with ether, Freon, or saponin, the inner structure was revealed as a granular or filamentous nucleoid surrounded by a thin membrane separated from an outer membrane by a relatively electron-lucent space. The outer membrane was covered peripherally with a layer of knoblike projections. The results indicated that the two portions of the virus could be separated. Saponin treatment produced holes or pits in the outer membrane and caused general disruption of the virus particles. Particles in preparations of strain R avian tumor virus appeared to be of the same morphology as that of the BAI strain A agent.