Starting with the micrografting and progressing to RNAi technique our work was always focusing on crop improvement by making them free of virus particles. In the late seventies, the micrografting techniques was based on the use of less than one millimeter seized apical meristematic tip (of elite orange tree) as scion grafted on the two weeks old, in dark germinated wild grapet fruit seedling hypocotyls as root stock under the stereomicroscope and further in vitro cultivation on MS medium allowed the meristem to develop to a virusfree plantlet. In the eighties and nineties, our efforts were focused on antisense technology using transformation of antisense strand of CP gene alone or combined with Nib genes of the papaya ring spot virus (PRSV) into the local recipient papaya cultivar via Agrobacterium-mediated transformation resulted long-term resistance against local PRSV, but not against PSRV strains of foreign origins. The most advanced approach toward virus resistance was based on the RNAi technology in which multigene-fragment RNAi structures were constructed and introduced into the recipient tobacco model plant, or papaya and citrus cultivars resulting stable virus resistance.