Undetectable HIV Viral Load without Therapy in Patients with HIV Seroconversion: An Uncommon Phenomenon?

The objective of this French study was to identify the frequency and characteristics of patients with HIV infection who had spontaneously achieved viremia below the detection limit of either 400 or 500 copies/mL (depending on the test used) and to describe the duration of undetectable viremia without antiretroviral therapy (ART).

In the French Agence Nationale de Recherches sur le SIDA SEROCO cohort, 426 patients with HIV seroconversion (i.e., seroconverters) enrolled between 1988 and 1995 had serial measurement of HIV RNA levels during follow-up (with a cutoff date of 31 December 2002).

Factors that distinguished those patients who had spontaneously achieved undetectable viremia (2 consecutive viral loads <400 or <500 copies/mL while not receiving ART) were identified by logistic regression. A Cox model was used to estimate the predictive value of factors related to the duration of undetectable viremia.

Results

· Undetectable viremia had been spontaneously achieved in 36 of 426 seroconverters.

· Women and subjects with baseline HIV RNA level 3.76 log10 copies/mL, baseline HIV DNA level 2.61 log10 copies/mL, and high baseline CD4+ cell count were more likely to have achieved undetectable viremia.

· The sustainability of this phenomenon (median duration, 11.9 months; range, 4.662.8 months) was associated with low baseline HIV DNA and RNA levels.

Conclusions

Based on these findings, the authors conclude, “Achieving undetectable viremia without ART was not rare, because 6.7% of seroconverters still had a viral load of <400 or <500 copies/mL 5 years after seroconversion.”

“These data should be considered when assessing virologic outcome for patients who interrupt highly active ART initiated during primary infection.”

Discussion

In this study of 426 seroconverters from the SEROCO cohort, which was started in 1988, the researchers found that 36 seroconverters had spontaneously achieved undetectable viremia (2 consecutive viral load measurements <400 or <500 copies/mL).

This phenomenon was not rare: at 5 years after seroconversion, 6.7% of the seroconverters who were followed as part of the cohort still had undetectable viremia.

Predictive factors for undetectable viremia included low baseline HIV RNA and DNA levels and high baseline CD4+ cell count. Women were also more likely to have achieved undetectable viremia, which agrees with previous findings describing lower viral loads in women than in men.

The sustainability of undetectable viremia was highly variable: 13 seroconverters still had undetectable viremia 5 years after infection, and 3 seroconverters had undetectable viremia as long as 10 years after infection. The duration of the period of undetectable viremia was associated with low baseline HIV RNA and DNA levels but not with baseline CD4+ cell count.

The decay in CD4+ cell count during and even after the period of undetectable viremia was remarkably slow, compared with the mean decreases in CD4+ cell count described in studies of the natural course of infection. Patients in whom viral load replication is spontaneously controlled over a long period are likely to present with viral and/or immunologic specificities that require further investigation.

Department of Epidemiology and Department of Medicine, Hôpital de Bicêtre, and Department of Virology, Necker Hospital, Paris, France.

Reference

Y Madec and others (for the SEROCO Study Group). Undetectable Viremia without Antiretroviral Therapy in Patients with HIV Seroconversion: An Uncommon Phenomenon? Clinical Infectious Diseases  40(9): 1350-1354. May 1, 2005.

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