دانلود کتاب ویروس‌ها، مهاجمان صمیمی

This is a viral world: collectively, there are more viruses on Earth than any other life form. The original viruses were evolutionarily ancient and arose at the dawn of life forms on Earth. Now every single species of plants, animals, and bacteria has its cadre of viruses that can attack and infect it. These infections can range from benign, inapparent interactions to debilitating disease or death. During infection, viruses reproduce very quickly and can go through hundreds of generations in the course of a single infection, often acquiring mutations that can change their properties. Many of these viruses can also jump across species to gain new hosts, start new infections, and increase their diversity. Simultaneous co-infection of a host with different viruses can generate new hybrid viruses with unique and sometimes dangerous new characteristics. As a result of these properties, viruses are not static and instead are highly protean entities that are constantly changing and adapting. As viruses evolved, the incessant infections of their host species exerted evolutionary pressure on the hosts to develop anti-viral defenses. This endless conflict of attack and counterattack has driven the evolution of all life on Earth and continues to this day.