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Primary HIV Infection — Predicting the Set Point

Having a greater number of symptoms during primary infection was associated with a higher initial viral load, which, in turn, was associated with a higher viral set point.

Unfortunately, diagnosis of acute HIV infection is an uncommon event, and the advantages of such early diagnosis are not always apparent to the patient or even to the provider. Understanding the association between symptoms, initial HIV viremia, and ultimate viral set point may help determine treatment decisions for such patients.

Investigators in San Francisco conducted a prospective cohort study involving 57 patients with primary HIV infection and 127 patients with recent HIV seroconversion. Upon enrollment, all study participants were asked about a recent history of any of 21 symptoms that are characteristic of primary infection.

Patients who had their HIV infection diagnosed before seroconversion (i.e., during acute or primary infection) reported significantly more symptoms than did those who received their diagnosis after seroconversion (mean, 9 vs. 6); they also had significantly higher viral loads at study entry (mean, 5.1 vs. 4.4 log copies/mL). In both groups, having a greater number of symptoms during acute infection was associated with a higher initial viral load. Among the 48 patients (6 with acute infection, 42 with seroconversion) who did not start antiretroviral therapy (ART) before a set point was established, a higher initial viral load was, in turn, associated with a higher set point.

The predictive value of the initial viral load on the subsequent set point was considered by the authors to suggest that early interactions between the virus and the host’s innate immune system were important in determining the set point. By extension, the adaptive immune response (which develops later) was thought to be less critical, although the number of patients with acute infection who did not initiate ART was quite low, making any such conclusions tenuous.

Comment: These findings support the results of previous studies that showed more-rapid rates of progression to AIDS among patients who present with more-symptomatic acute HIV infection. The higher viral set point seen in the more-symptomatic patients in this study may reflect a less-effective immune response to the initial infection or, alternatively, a more pathogenic virus. Given the association between number of symptoms, initial viral load, and ultimate viral set point, one might be tempted to speculate that patients with more symptoms would benefit from early initiation of treatment during primary HIV infection. However, data demonstrating value from such an approach are not compelling. Nonetheless, the possibility that ART that was administered during symptomatic primary infection might favorably affect the viral set point provides an additional reason to advocate treatment during acute HIV infection.

— Charles B. Hicks, MD

Published in AIDS Clinical Care June 18, 2007

Citation(s):

Kelley CF et al. The relation between symptoms, viral load, and viral load set point in primary HIV infection. J Acquir Immune Defic Syndr 2007 May 17; [e-pub ahead of print].

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