Virus in the Genome

http://www.nytimes.com/2010/01/12/science/12paleo.html?pagewanted=1&ref=science

This article is about how scientists have been discovering retroviruses in the human genome. These viruses are no longer active obviously but some of them do play important roles in the human genome. This is really quite interesting because this is described as "fossil hunting" in the genome. It shows a history of how our genome developed through evolution. This happens not because the virus inserts itself into the genome, but rather the genome absorbs it. Scientists are not exactly sure why this happens, but it has helped the human body defend against some other viruses. A major way this helped is when earlier in history when one virus was absorbed it was used to make placentas. In a test scientists pulled this virus out from the genome from mice and found that the placenta ended up deformed and unable to do its job. I found this really interesting and I think they could use this for another type of vaccination possibly. If scientists could find a way to insert certain viruses, unharmfully, into the genome to prevent diseases like HIV that would be a huge scientific breakthrough.