Abstract
Filamentous particles of beet yellows closterovirus (BYV) are built of two related capsid proteins, of which the minor species, p24, forms a 75 nm tail at one end of the virion. In the present work, we used polyclonal antibodies against p24 for isolating the 'tailed' virion segments from sonicated BYV particle preparations. The [gamma-32P]ATP- labelled RNA obtained from the antibody-selected particle segments consistently showed stronger hybridization with the 5'-terminal BYV cDNA clones than with the 3'-terminal cDNA clones. These data clearly indicate that it is the 5'-terminal portion of the closterovirus RNA genome that is encapsidated by p24.