HIV replication continues in intestinal mucosa even if a patient is taking successful antiretroviral therapy, according to a study published in the October edition of AIDS.
Potent antiretroviral therapy reduces viral load an increases CD4 cell count in peripheral blood. But only 2 - 5% of lymphocyte cells are in peripheral blood, the rest being in lymphoid tissue. Gut-associated lymphoid tissue is the largest lymphoid organ and write the investigators, “is extremely permissive of HIV-1 infection and supportive of HIV-1 replication, providing a persistent viral reservoir.”
Studies have previously shown that HIV replication persists in lymphoid tissue for at least two years, despite the complete suppression of viral load in the blood with antiretroviral therapy. Although the presence of HIV in intestinal mucosa has been demonstrated, there are few data illustrative of the effects of potent anti-HIV therapy on such tissue.
Investigators therefore looked at the presence of HIV in duodenal mucosa biopsies obtained from 44 HIV-positive individuals, 25 of whom had been taking potent antiretroviral therapy for more than four years. Mean age was 38 years, 30 were men, and mean plasma CD4 cell count was 265 cells/mm3.
Viral load was undetectable (below 50 copies/ml) in the plasma of 19 individuals from whom the samples were obtained.
The investigators conducted tests to see if HIV’s genetic material could be extracted from the intestinal biopsies. The tests on 20 (46%) samples were positive.
Ten of these samples were obtained from patients with an undetectable viral load, the other ten coming from patients with a blood plasma viral load above 100,000 copies/ml.
Furthermore, HIV was detected in the intestinal biopsies of nine of the 19 patients taking potent antiretroviral therapy.
“Our results show that HIV RNA can be detected in patients with successful highly active antiretroviral therapy, confirming that residual HIV reservoirs remain in spite of successful treatment”, comment the investigators. They add, “the detection of HIV in the duodenum was not influenced by treatment.”
The investigators conclude, “in our study, the plasma viral load did not predict the presence of HIV-1 RNA in the duodenum. These data suggest that the intestinal mucosa can be a reservoir that is not influenced by levels of plasma viral load or antiretroviral therapy. Ongoing HIV replication in the intestine may be a source that repopulates the body with virus after therapy is withdrawn.”
Belmonte L et al. The intestinal mucosa as a reservoir of HIV-1 infection after successful HAART. AIDS: 2106 – 2108, 2007.