I just wanted to come back on my last posting to be fait to Dr. Robert Gallo, a great scientist nevertheless. I found THIS ARTICLE that makes a good primer to Gallo's career.
"For the record, here is what Gallo did achieve: He first described retroviruses, which is the class of viruses to which HIV belongs, and he linked a retrovirus to a rare leukemia--this alone is deserving of the Nobel. (In an interview that I read, he considers this his most significant scientific achievement). Then, his lab discovered a "T cell growth factor" that turned out to be pivotal in sustaining the growth of T cells in culture, cells that are the target of HIV."