Protoplast were prepared from transgenic BY-2 cells expressing CPT42W, CPD77k, CPD77R, CPE50R or CPE50D, and then infected with TMV RNA. Protoplast samples were harvested at 11, 16, 24, and 36 hpi. The effect of the transgenic CP (mutant or wt) on the accumulation of the CP, the MR and the replicase of the infecting virus was assessed using antibodies directed against each of these viral proteins in ELISA experiments as described (Bendahmane et al., 1997).