HIV is able to survive drug attack by hiding out in the gut lining, US scientists have discovered.
HIV attacks immune system T-cells
Even when blood tests suggested antiretroviral treatment was working, the virus continued to replicate in the gut, suppressing immune function.
Writing in the Journal of Virology, the authors recommend earlier, aggressive drug treatment to combat this.
The University of California team also suggest monitoring patients with gut biopsies as well as blood tests.
Theirs is the first study to show that, while current HIV therapy is quite successful in reducing viral loads and increasing the number of immune T-cells to fight the infection in peripheral blood, it is not so effective in gut mucosa.
Dr Satya Dandekar and her team followed 10 patients being treated with highly active antiretroviral therapy, known as HAART.
They took blood and gut samples from the patients before and after three years of treatment. Three of the patients had been treated very early, within four to six weeks of first being infected with the virus, whereas the others had been infected for at least a year before receiving treatment.
The patients who had been treated earlier had fewer signs of gut inflammation before treatment and experienced greater recovery of the gut mucosal immune system function after treatment than the other patients.
Dr Dandekar explained: "We found a substantial delay in the time that it takes to restore the gut mucosal immune system in those with chronic infections.
"In these patients the gut is acting as a viral reservoir that keeps us from ridding patients of the virus."
She said the results suggested anti-inflammatory drugs might improve antiretroviral treatment outcomes and that genes involved with the repair and regeneration of the gut mucosal immune system would make excellent drug targets.
A spokeswoman from the HIV charity AVERT said: "This research offers an enlightening insight into one of the ways that HIV evades drugs in the body, and if further studies show that anti-inflammatory drugs improve the efficacy of antiretrovirals, they could prove a very useful addition to HIV therapy.
"However, the researchers' suggestion of starting HIV treatment earlier will need to be weighed up against the risk of earlier drug resistance forming, and the difficulties of drug toxicity and side effects before it is considered for adoption as standard medical practice."
Mary Lima, a treatment specialist at the Terrence Higgins Trust, agreed. She said: "At this stage we have to be cautious as starting treatment earlier, taking anti-inflammatory drugs and having gut biopsies would put an additional burden on people living with HIV.
"However, it's really important that research into this area continues so we can understand more about HIV and how it could be treated in future."