A cure for HIV remains elusive, but scientists say the hunt is more hopeful than ever, based on the prospects of new research described at the International AIDS Society conference this week.
Scientists reported on progress on gene therapy and using antibodies to neutralise HIV, research into why some HIV-infected people are able to stay in remission off drugs after treatment, and a hypothesis that vaccines, yet to be invented, could be used to "shock and kill" the virus in HIV-infected people.
"Insights into the virus, its progression and the body's response to HIV are helping to narrow and concentrate the focus of the HIV cure research agenda," said Francoise Barre-Sinoussi of France's Pasteur Institute, a Nobel Laureate and former IAS president.
Christopher Peterson of the Fred Hutchinson Cancer Research Center in Seattle, Washington, released findings from a study on modified stem cells in monkeys.
The researchers successfully "edited" cells to block HIV from entering immune system cells through pathways known as "Trojan horse" receptors, said the study.
"With enough protected cells, the virus shouldn't be able to spread and we'd be looking at a functional cure," Peterson told reporters at AIDS 2015 in this Western Canadian city, attended by about 6000 scientists, including from Australia, and other HIV experts.
Another study, led by John Mascola of the US National Institutes of Health, administered HIV-1 monoclonal antibodies to eight HIV-infected people.
Within three months of a receiving one antibody infusion, the plasma viral load in six of the people "decreased by approximately 10- to 50-fold," said Mascola's report.
It said the two people unaffected by the infusion carried an HIV strain resistant to the antibody used.
Antibodies may have several uses in treating HIV, Mascola told a press conference, including the possibility of helping to "kill the viral reservoir" hiding in the cells of infected people.
None of the new findings have yet led to practical treatments, and all "raise more questions than answer questions", noted Steven Deeks of the University of California, San Francisco.
But Deeks said they will lead to "bigger studies, which will often fail, but lead to more studies. That is how science plays out."
Asier Saez-Cirion of the Institut Pasteur in Paris led research on a French girl infected with HIV at birth, whose family stopped her treatment after several years, and who then was able to remain healthy for 12 years.
But just how she has been able to stay in remissions for so long remains poorly understood.
"We need a lot of basic research," said Saez-Cirion.
The scientists called for continued funding for cure research, most of it basic research that may not show immediate results.
"Less than one percent of [global] AIDS funding is for cure" research, noted Australian scientist Sharon Lewin.
Lewin earlier told AFP that success in treating infected people could lead to officials and the public thinking "AIDS and HIV are not a big deal, that we've solved it, when the reality is there are still two million new infections and 1.5 million deaths a year from HIV, and 35 million people living with HIV".
Lewin told reporters the next steps in "cure" research include clinical trials on helping infected people stay in remission after stopping treatment with antiretroviral medications, treatments to "shock and cure" the virus, and bolstering the immune systems of patients.