The present invention relates to isolated proteins or polypeptides of grapevine leafroll virus (type 2). The encoding DNA molecules either alone in isolated form or in an expression system, a host cell, or a transgenic grape plant are also disclosed. Other aspects of the present invention relates to a method of imparting grapevine leafroll resistance to grape and tobacco plants by transforming them with the DNA molecules of the present invention, a method of imparting beet yellows virus resistance to a beet plant, a method of imparting tristeza virus resistance to a citrus plant, and a method of detecting the presence of a grapevine leafroll virus, such as GRLaV-2, in a sample.