Eukaryotic viruses are viruses that infect eukaryotic cells, which are cells that have a nucleus and other organelles. These viruses can infect a wide range of organisms, including animals, plants, and fungi. They rely on the host cell's machinery to replicate and produce new virus particles. These viruses can be classified into different families based on their structure and genetic material, such as DNA or RNA. Some well-known examples of eukaryotic viruses include influenza virus, HIV, and plant viruses like tobacco mosaic virus. Understanding these viruses is crucial for developing vaccines and treatments.