APHID TRANSMISSION OF BEET WESTERN YELLOWS LUTEOVIRUS REQUIRES THE MINOR CAPSID READ-THROUGH PROTEIN P74

Beet western yellows luteovirus is obligately transmitted by the aphid Myzus persicae in a circulative, non-propagative fashion, Virus movement across the epithelial cells of the digestive tube into the hemocoel and from the hemocoel into the accessory salivary glands is believed to occur by receptor-mediated endocytosis and exocytosis. Virions contain two types of protein; the major 22 kDa capsid protein and the minor read-through protein, P74, which is composed of the major capsid protein fused by translational read-through to a long C-terminal extension called the read-through domain, Beet western yellows virus carrying various mutations in the read-through domain was tested for its ability to be transmitted to test plants by aphids fed on agro-infected plants and semi-purified or purified virus preparations, The results establish that the read-through domain carries determinants that are essential for aphid transmission, The findings also reveal that the read-through domain is important for accumulation of the virus in agro-infected plants.