This article with diagrams explains what viruses are in structure and activity:-http://acsh.org/news/2016/02/02/viruses-natures-perfect-machine/-"I recently wrote that viruses do not come even close to meeting the standards that are generally accepted requirements in defining what “alive” means.-***-"Each virus contains the absolute minimum amount of “stuff” to do exactly what it is supposed to do: genetic material, enzymes, and proteins that keep it intact until it reaches the intended host cell. Then, the virus tricks the host cell into doing all the work for it. Before we go into how it works, here is a cartoon that represents a typical virus. Note that there isn't much there, especially when compared to any living organism. But it is remarkably efficient with what it has.-"What this “bag of chemicals,” which is about 100-times smaller than a bacterium, does is nothing short of amazing. It is way “smarter” than the cell that it infects. Using nothing more than a very specifically-shaped protein spike to locate and attach itself to the host cell, its own genetic material, and a few enzymes, each of which has a specific function, it turns the cell into a virus factory, letting the cell do all the work. The virus does nothing, except reproduce, courtesy of the cell, which provides the energy and the mechanism for viral replication. This is why viruses are called obligate parasites. They do not function in the absence of a host cell." (my bold)-Comment: Viruses are not fully 'alive' by definition. Without all existing animals and plants, they disappear.