A Virus is a submicroscopic infectious agent and they require a living host to complete its cycle so they are obligate parasites also. There are many symptoms that start appearing on the virus-infected plants such as some light or dark spots appear on the leaves in mosaic forms and leaves start to roll and curl. Due to chlorophyll degeneration, the plant parts start becoming yellow and veins also become translucent. The virus also affects the height of the plant so they remain dwarf and necrosis occurs (cells die) so all these symptoms appear when plants are infected with virus-like tobacco mosaic virus, potato mosaic virus, etc. They mostly affect plants of the Solanaceae family.