“…Tenuiviruses exhibit properties that are quite different from those of other plant RNA viruses (Gingery, 1987). Some of these properties are: (i) virus particles appear as fine filaments 3 to 8 nm wide and of variable length that may adopt a circular configuration (Gingery et al, 1981 ;Toriyama, 1982;Morales & Niessen, 1983;Hibino et al, 1985); (ii) they are persistently transmitted by a delphacid planthopper in which they are also transovarially passed (Zeigler & Morales, 1990); (iii) a single species of nucleocapsid (NC) protein of 31K to 34K is part of the infectious nucleoprotein (Gingery et al, 1981 ;Toriyama, 1982;Morales & Niessen, 1983;Hibino et al, 1985); (iv) they induce the accumulation in infected plants of large amounts of a 16K to 21K non-structural (NS) protein, also designated non-capsid protein (Gin-1" Permanent address: Universidad de Costa Rica, Ciudad Universitaria Rodrigo Facio, San Jos6, Costa Rica.…”