This investigation was carried out to achieve the following: 1. Conducting some molecular studies on PLRV such as : • Extraction of RNA • Reverse transcriptiom reaction • PCR • Purification of PCR product • Cloning of PCR product • Large scale plasmid preparation(Maxi-prep) • Subcloning • Large scale plasmid preparation(Maxi-prep) 2. Using of modern serological methods for rapid detection of PLRV such as: • ELISA • DBIA • TBIA 3. Recognize the intracellular changes induced by the PLRV using Electron Microscopy 4. Production of PLRV-free potato plants.