HIV-1 Specific CD4 and CD8 T-cell Responses Associated With Low Viral Load in Treatment-Naïve HIV-1 Infected Individuals

In preparation for monitoring of vaccine-induced responses, we determined HIV-specific cell-mediated immune responses in 17 treatment naive HIV-1 infected individuals with > 400 CD4+ T cells/ml for at least 5 years including 9 patients with low viral load (VL, 5000 copies/ml). HIV-1 specific IFN-γ-production and cytolytic activity were higher in subjects with low VL. The differences between the two groups were statistically significant for CD4+ Tcell responses to Gag and Nef peptides, tested by a longterm (48 h) ICS assay and of border-line significance for the Gag-specific cytolytic responses measured by a flowcytometry assay and a chromium release assay. We also found a significant inverse correlation between VL and IFN-γ-production by CD8+ T-cells in response to Gag as measured by ICS. The ELISpot IFN-γ response was not significantly different in patients with high and low VL. During a median follow-up period of 2.4 years, 6 of 8 subjects with high VL and 1 of 9 with low VL showed decreasing CD4+ T-cell counts, and ARV treatment was more frequently initiated in the former patient group (5 of 8 versus 1 of 9). The CD4 and CD8 T cell immune responses found to be associated with low VL and stable CD4 counts may be of importance for protection. from 2005 International Meeting of The Institute of Human Virology Baltimore, USA, 29 August – 2 September 2005