Virus : <span>Any of various submicroscopic agents that infect living organisms, often causing disease, and that consist of a single or double strand of RNA or DNA surrounded by a protein coat. Unable to replicate without a host cell, </span>viruses<span> are typically not considered living organisms
Virion : T</span><span>he infectious particle that is designed for transmission of the nucleic acid genome among hosts or host cells. A </span>virion<span> is not the same as a virus. I </span>define<span> virus as a distinct </span>biological<span> entity with five different characteristics
</span>Viroid: An infectious agent that consists solely of a single strand of RNA and causes disease in certain plants. Viroids<span> lack the protein coat (known as a capsid) of viruses and are the smallest known infectious agents.</span>
