Viruses are nucleic acid and protein agents that infect all living organisms, including plants and animals. Some plant viruses include tobacco mosaic virus (TMV) and potato mosaic virus Y (PVY), which cause damage to crops and lead to yield loss. They spread through vectors like insects and fungi. Animal viruses include influenza, HIV, and rabies viruses, which affect animals and humans. They are spread through contact, air, water, or vectors. Symptoms range from mild to severe, including respiratory issues and fever. The World Vaccines R&D Conference advances research to address plant and animal virus challenges, aiming to improve global health and agricultural productivity.