Objective: We investigated the impact of neutralizing antibodies (NAbs) on CD4 T-cell count and viral load in a cohort of HAART recipients who underwent extended structured treatment interruption.
Design: Substudy of NAb in the AIDS Clinical Trials Group 5170 trial.
Methods: Early plasma samples from 50 volunteers who discontinued HAART were evaluated in a peripheral blood mononuclear cell-based neutralization assay against a panel of four subtype B primary isolates.
Results: We found that high-titer (90% inhibitory dose > 500) NAb against two or more isolates was associated with reduced viral load (P = 0.003 at 12-week posttreatment interruption). This effect faded with time, losing significance (P = 0.161) by study conclusion. Participants possessing the highest NAb levels against individual isolates appeared more likely to have lower viral loads with the association gaining significance against the R5-tropic primary isolate US1 (P = 0.005). There was no association between broader neutralization and CD4 T-cell slope over time.
Conclusion: The data suggest that high-titer NAb responses at the time of treatment interruption are associated with reduced viral load over time, but not CD4(+) T-cell decline.