The Structural Proteins of Tomato Spotted Wilt Virus

Abstract

SUMMARY Seven structural proteins referred to as proteins 1 to 7 in order of increasing mol. wt. were detected following electrophoresis of disrupted purified virus preparations. Proteins 1 to 4 occurred in largest amounts, whereas protein 5, 6 and 7 occurred in small amounts. The estimated mol. wt. of proteins 1 to 5 were 27000, 52000, 58000, 78000 and about 90000, respectively. Proteins 2, 3, 4 and 5 are glycoproteins that reacted well with Schiff’s reagent whereas protein 1 reacted only weakly. A Schiff-positive zone migrating in front of bromophenol blue and behaving like glycolipid was obtained by extracting purified virus with chloroform plus methanol. Iodination of intact and Nonidet P40-disrupted virus resulted in differential labelling of proteins 1 to 4. The results were interpreted as indicating that protein 1 is located inside the virus envelope and that proteins 2, 3, 4 and 5 are on the envelope surface. An infectious component containing only protein 1 and, presumably, RNA was obtained by disrupting the virus with Nonidet P40.