AEGiS-14IAC: Semen viral dynamics in acute HIV infection: implications for sexual transmission.

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

Semen viral dynamics in acute HIV infection: implications for sexual transmission.

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no.. ThOrC1487)

Pilcher CD, Tien H, Vernazza PL, Stewart P, Chakraborty H, Eron JJ, Cohen MS
UNC-Chapel Hill, Chapel Hill, NC, United States

BACKGROUND: Non-human primate studies suggest a parallel relationship between semen and blood viral load over time during acute HIV infection. We hypothesized a similar pattern would hold in humans.

METHODS: We measured concurrent blood and semen HIV RNA concentrations from 32 individuals with acute HIV (+RNA, -HIV Ab <30d) with known dates of symptoms onset, and from 40 HIV+ pts with CD4>200. 33 other acute patients contributed 153 blood-only data points. Acute HIV RNA concentrations were plotted for each compartment vs. time from infection. Estimates for semen HIV dynamic parameters were first developed from observations in blood using piecewise regression on longitudinal data. The dynamic model was then adjusted for the observed semen set point distribution. Precision and bias of the final model were assessed by agreement with observed acute HIV RNA data in semen and blood. Estimated changes in per act male-female transmission probabilities were calculated from semen HIV burden using a previously published probabilistic model.

RESULTS: Semen HIV burden was greater <50d post infection than later in acute infection or in chronic infection (p<.05). The final model provided excellent agreement with observed semen and blood data over the course of acute infection. This model predicted peak viral burden in semen at 23 d post infection, or 9 d post symptoms onset (peak RNA 1.58 log cp/ml > set point). Per act transmission probabilities for patients with a range of set point semen RNA concentrations are predicted to be 20-fold higher at peak than at set point.

CONCLUSIONS: Changes in semen viral load appear to closely follow those measured in blood during acute HIV infection. Susceptible partners of individuals with acute HIV infection may be at 20 fold greater risk per exposure compared to partners of individuals at virologic set point due to higher HIV shedding in semen.

Keywords: AEGIS, HIV Infections, Semen, HIV, Viral Load, Anti-HIV Agents, HIV Protease Inhibitors, HIV Seropositivity, Models, Statistical, Female, Human, Male, transmission, virology, blood

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ThOrC1487