Perhaps virus are not likely to become the best vectors to use in somatic gene therapy. The changes we transhumanists wish to operate on our genome far extend the capacity of present virus to transport DNA. Avoiding aging will require changes in many genes, we're talking Mbases here. I somewhat think that a bacteria might be a better choice -- they're presently used to create transgenic plants. Or, and probably what will happen, a combination of several molecules from several sources: virus, bacteria and even human DNA (at least to make our vector stealth to the immune system); within the next few decades, when we fully understand the molecular mechanisms of life, we'll architect the perfect vector to change somatic human cells.