Detection of HIV Type 1 Gag-Specific CD4 + T Cell Responses in Acutely Infected Infants

Abstract

Multiple HIV-1-specific cytokine and proliferative responses by CD4⁺ T cells have not been studied in acutely infected infants. Using an intracellular cytokine staining assay, 34 untreated clade C HIV-1-infected infants (2–102 days old) were assessed for IFN-γ, 28/34 for IL-2, and 26/34 for TNF-α responses to all HIV-1 proteins. Responses were detected in 29%, 36%, and 15% of infants, respectively. Twelve of the original 34 infants were then studied longitudinally for 14 months to determine the effect of viral load on IFN-γ Gag-specific responses: seven infants were treated for 1 year, stopped treatment, and resumed when CD4% was < 20 and five infants were treated only when the CD4% was <20. Following treatment cessation, there was an immediate increase in viral load followed by an increase in the magnitude of CD4⁺ Gag-specific responses. Despite this, the majority of infants (54%) had to restart treatment by 24 months of age, indicating that the immune responses were antigen driven but not associated with protection. Among untreated infants HIV-specific CD4⁺ responses were detected sporadically indicating a dysfunctional immune response in the face of constant exposure to high levels of viremia.