Analysis of the effect of highly active antiretroviral therapy during acute HIV-1 infection on HIV-specific CD4 T cell functions

Background: It has been reported that antiretroviral therapy (HAART) during acute HIV-1 infection may rescue HIV-1-specific CD4 T cell responses. Objective: To determine the duration of this preserved response by investigating the long-term effects of HAART during acute infection on HIV-specific CD4 T cell function related to possible immune control during subsequent therapy interruption. Methods: A longitudinal analysis followed HIV-specific CD4 T cell reactivity in 17 individuals with well-documented acute HIV-1 infection where five out of 11 HAART-treated patients stopped therapy and six were untreated. Peripheral blood mononuclear cells were stimulated with overlapping peptide pools derived from Gag and Nef. Production of interferon-[gamma] (IFN-[gamma]) and interleukin-2 (IL-2) by CD4 T cells was analysed together with proliferative responses. Results: Absolute numbers, but not percentages, of Gag-specific IFN-[gamma]-, IL-2- or IFN-[gamma]/IL-2-producing CD4 T cells were increased in treated compared with untreated individuals up to 2 years after seroconversion. HAART during acute HIV-1 infection was associated with lower viral load but did not result in increased proliferation of HIV-specific CD4 T cells. One out of five individuals who discontinued therapy showed evidence for immune control. However, patients who failed to control viraemia also had measurable proliferative HIV-specific CD4 T cell responses and preserved numbers of cytokine-producing CD4 T cells. Conclusions: Early HAART during acute HIV-1 infection resulted in higher numbers of HIV-specific IFN-[gamma]- and IL-2-producing CD4 T cells, but this preservation in four out of five patients was not associated with control of viraemia upon treatment interruption