March 31, 2008
A study of 40 patients on long-term standard HIV therapy found low levels of dormant virus, confirming that patients must take HIV drugs indefinitely and suggesting that any breaks run the risk of reviving the infection.
Dr. Sarah Palmer of the US National Cancer Institute and colleagues followed the patients for seven years. While doctors do not usually record HIV levels once they drop below 50 per ml of blood, the NCI team used highly sensitive equipment to measure infection below this threshold. They found HIV was still present at low levels in 77 percent of the patients.
Although potent antiretrovirals can suppress HIV infection to nearly undetectable levels, they cannot eliminate the virus, the researchers said. And while participants levels were low, they were high enough to prompt infection if treatment were interrupted.
HIV may be harbored by CD4+ cells, which play a role in immunity, the study suggests. These cells were likely infected before therapy was started, and the amount of virus they produce is small.
"It is extremely important that new drugs are developed to eradicate HIV infection as the side effects associated with long-term HIV treatment can be severe," said Palmer. In addition, she warned, failing to take HIV medicines as prescribed raises the risk of resistance, rendering future treatment less effective.
The study, "Low-Level Viremia Persists for at Least 7 Years in Patients on Suppressive Antiretroviral Therapy," was published in the Proceedings of the National Academy of Sciences (2008;105(10):3879-3884).