Potato (Solanum tuberosum L.) is considered as one of the most economically important solanaceous crops that are cultivated in different regions in Egypt. In contrast, potato is a host to many bacterial, fungal and viral diseases. More than three dozen plant viruses, a viroid and phytoplasmas can infect potato crop and hardly reduce the yields.The present study aims to detect and characterize potato leaf roll virus (PLRV) and potato virus Y (PVY). To achieve this purpose, isolates of the viruses were randomly collected from infected leaves of potato from different regions of 7 different Egyptian Localities (EL-Beheira, EL-Gharbia, Alexandria, EL-Dakahlya, Elkalyobia, EL-Menofia and Matrouh), and some biological, serological and molecular techniques were carried out. In addition, some viral genes were identified and PLRV coat protein (CP) gene was expressed. The expressed proteins were purified to use it as an antigen and induce its polyclonal antiserum in rabbit blood cells for the detection of PLRV in infected plants. Moreover, the defense system response was detected and quantify for infected potato plant with PLRV or/and PVY.