A New Strategy of Cross-Protection Based on Attenuated Vaccines: RNA Viruses Are Used as Vectors to Control DNA Viruses

Plant viruses can infect various types of plants, including food and oil crops, and ornamental flowers, threatening agricultural production and food supply. Cross-protection is an efficient strategy against severe viral strains. Due to distinct infection mechanisms, cross-protection cases involving RNA viruses and DNA viruses often rely on the utilization of corresponding attenuated strains for control purposes. In this study, we utilized cucumber mosaic virus (CMV), a member of the RNA virus group, as the foundational framework for developing attenuated vaccines. We developed four vaccines by inserting relevant sequences from tomato yellow leaf curl virus (TYLCV), a DNA virus. All vaccines demonstrated effective prevention against TYLCV infection, with relative control efficacies exceeding 80%. Subsequently, we evaluated the preventive effects of these vaccines on mixed infections of CMV and TYLCV. Our findings demonstrated that CMV (R2-2bPTI-TYC1C4), CMV (R2-2bPTII-TYC1C4), and CMV (R2-2bPTIII-TYRep) displayed significant efficacy in preventing mixed infections. Following pre-inoculation with these vaccines, the disease index of tomato plants decreased from 100 to 56. This work provides theoretical foundations and tangible resources for controlling TYLCV through cross-protection while suggesting a feasible strategy for utilizing weak RNA virus vaccines to control DNA viruses.