It may also offer hope for a vaccine, he said. "It shows there is some immune response," he said, "that can be stimulated not just to control infection but to prevent infection if that part of the immune system can be primed and activated."
Indeed, the researchers argued that study of these patients and others like them could "open up new therapeutic perspectives" for people with HIV.
Among other things, they found that the immune systems of post-treatment controllers don't resemble those of "elite controllers" – the 1 percent of the HIV-positive population that appears to have a natural ability to control the virus.
The elite controllers tend to have protective HLA class I alleles, but the 14 patients tended to have HLA variants associated with a higher risk of HIV progression, they reported.
As well, elite controllers have large numbers of highly efficient HIV-specific CD8-positive T cells; the post-treatment controllers have "very weak" and in some cases barely detectable HIV-specific CD8 responses.
On the other hand, there's at least one important similarity: Both groups have small HIV "reservoirs" -- groups of infected cells that give rise to new virus, leading to viral rebound when therapy is stopped.
The finding suggests that "limiting the pool of infected cells is crucial for the successful control of viral replication in the absence of therapy," Sáez-Cirión and colleagues argued.
And, they concluded, early therapy, continued over a prolonged period, "likely played an important role in reducing the reservoirs."
That said, it remains "unclear" what factors distinguish the patients who achieved control from those who did not.