Abstract
An isometric virus, obtained from an isolate of Gaeumannomyces graminis, had the following properties: diameter 29 nm; sedimentation coefficient 127S; buoyant density in CsCl 1.40 g/ml; one double-stranded RNA component of 1.80 kilobase pairs; one capsid polypeptide species of mol. wt. 66000; A260/A280 1.7. The virus was unrelated serologically to three other viruses present in the same fungal isolate and to 12 previously described viruses belonging to G. graminis virus groups I, II and III. On the basis of its distinctive properties the virus is assigned to a new G. graminis virus group IV.