“Since the tissue and immune barriers of the orginal hosts were very similar o those of the new host, these virus would posses pre-envolved strategies that would work pretty much in the new host as they did in a very important characteristic in common. Once they entered an individual, or species, the never wnet away, not in terms of the entire affected population, or even the species. The biological term for such a relationship is "persistence" and viruses are said to be "persistant-viruses". The very nature of such a long-term, and inevitably intimate, relationship has a major implications for the virus-host evolutionary dynamics.”