Tomato spotted wilt virus particle morphogenesis in plant cells

A model for the maturation of tomato spotted wilt virus (TSWV) particles is proposed, mainly based on results with a protoplast infection system, in w hich the chronology of different maturation events could be determined. By using specific monoclonal and polyclonal antisera in immunofluorescence and electron microscopy, the site of TSWV particle morphogenesis was determine d to be the Golgi system. The viral glycoproteins G1 and G2 accumulate in t he Golgi prior to a process of wrapping, by which the viral nucleocapsids o btain a double membrane. In a later stage of the maturation, these doubly e nveloped particles fuse to each other and to the endoplasmic reticulum to f orm singly enveloped particles clustered in membranes. Similarities and dif ferences between the maturation of animal-infecting (bunya)viruses and plan t-infecting tospoviruses are discussed.