The apparent cure was possible because the man's HIV was CCR5-tropic -- it preferentially used the CCR5 receptor to enter target cells -- and the donor had a mutation that left his immune cells without that receptor.
The patient's virus may still be present, Maldarelli said, but it is apparently not replicating.
Researchers are now trying to see if the apparent cure can be duplicated therapeutically, perhaps through gene transfer technology.
That's one of the "breakthroughs and changes in the science" that have renewed interest in searching for a cure, according to Carl Dieffenbach, who directs the AIDS division at the National Institute of Allergy and Infectious Diseases.
Among others, Dieffenbach said, are the invention of highly sensitive tests that can detect single copies of HIV RNA, making it possible for the first time to address the question of how the virus persists, and the development of safe vectors for gene transfer.
He and others would also like to see the development of small molecules that would target HIV-infected cells, he said.
Because of those breakthrough, the idea of curing HIV infection is "less of a taboo" than it once was, Dieffenbach said.
But Dieffenbach conceded that even at his institute, which has perhaps the most money of any HIV research program in the world, the search for a cure is not getting a huge share of available resources. He and the leaders of two major European research organizations said their total budget for such research is no more than about $100 million.
More than half of that is from the NIAID, Dieffenbach said.
But that's a tiny fraction of the $1.54 billion the institute spent on HIV and AIDS research in 2009, according to activist Kate Krauss, of the San Francisco-based AIDS Policy Project. She said cure research amounts to about 3 percent of the budget for HIV and AIDS.
Cure research "is astonishingly underfunded," she said.