“…Although most CMV satRNAs attenuate the symptoms induced by CMV in all host species tested, some satellite isolates intensify symptoms in certain hosts, for example inducing chlorosis in tomato and tobacco (Palukaitis, 1988) or necrosis in tomato (Takanami, 1981 ;Sleat et al, 1994). Sequences in the sat-RNA that control the symptom intensification have been mapped to specific nucleotide residues, and it has been shown that a few nucleotide sequence changes can alter the host response (Palukaitis, 1988 ;Masuta & Takanami, 1989 ;Jaegle et al, 1990 ;Sleat & Palukaitis, 1990 ;Sleat et al, 1994 ;Zhang et al, 1994). Furthermore, identical sat-RNAs can have different effects on symptoms when associated with different helper virus strains (Roossinck et al, 1992).…”