The clinical events surrounding acute HIV-1 infection have been well described, but little is known about whether the virologic course of acute HIV-1 infection influences the subsequent progression of disease.

To define the virologic natural history of acute and very early HIV infection.

Prospective, longitudinal cohort study.

University of Washington Research Clinic

74 adults enrolled soon after acquisition of HIV (mean, 69 days).

Plasma HIV-1 RNA levels; quantitative cell cultures; CD4 cell counts; and detailed clinical assessments done at study entry, biweekly for 1 month, monthly for 2 months, and quarterly thereafter.

In the first 30 days after acquisition of HIV, HIV-1 RNA levels varied greatly among participants (range, 27 200 to 1.6 × 10⁶ copies per mL of plasma). Levels of HIV-1 RNA decreased by a mean of 6.5% per week for the first 120 days and then increased by a mean of 0.15% per week. CD4 cell counts decreased by a mean of 5.2 cells/mm³ per week for the first 160 days and by a mean of 1.9 cells/mm³ per week thereafter (P < 0.01). Disease progressed faster in participants who sought medical care for their acute seroconversion syndrome (P = 0.01) and those who had high plasma HIV-1 RNA levels 120 to 365 days after acquisition (P < 0.01). Peak levels in the first 120 days were not predictive of disease progression.

The variability in viral RNA levels associated with acute HIV-1 infection is greater than previously appreciated. Within 120 days of acquisition, plasma HIV RNA levels rapidly decrease to an inflection point, after which they gradually increase. Virus-host interactions soon after acquisition seem to have a major influence on the long-term outcome of HIV-1 disease.