Evolution of HIV-1-Specific CD4+ and CD8+ T Cell Responses during STI

<div><p>(A–D) Magnitude and breadth of increase of HIV-specific CD8+ T cells during supervised treatment interruptions.</p> <p>(A and B) Magnitude (A) and breadth (B) of HIV-specific CD8+ responses at the first day of treatment interruption (black bars) and at the last day off therapy (white bars). Data represent the mean and standard deviation.</p> <p>(C and D) Correlation between the increase of the magnitude (C) or breadth (D) of CD8+ T cell responses and the time off therapy during the first treatment interruption.</p> <p>(E and F) Evolution of CD4+ T helper cell responses during supervised treatment interruptions.</p> <p>(E) Magnitude of CD4 T helper cell responses at baseline and at the first day of treatment interruption (closed circles) and last day off therapy (open circles). Horizontal bars correspond to median values. An stimulation index greater than five was considered significant.</p> <p>(F) Correlation between the magnitude of p24-specific lymphocyte proliferative responses at the beginning of the first treatment interruption and the time patients were able to remain off therapy during the subsequent STI.</p></div

HIV-1 Viral Loads and CD4+ T Cell Counts in the 14 Study Participants

<p>Time zero corresponds to first institution of highly active antiretroviral therapy (HAART). Closed squares, HIV-1 plasma viral loads; open circles, CD4+ T cell counts; shaded areas, treatment with HAART according to protocol; diagonally shaded areas, patient restarted therapy without meeting criteria of virological failure; vertical dotted lines, virological failure without reinstitution of HAART. Patients are ordered by increasing number of supervised treatment interruptions.</p

Evolution of Viral Load and CD4+ T Cell Counts during STI

<div><p>(A) Survival curves of time to virologic failure during the first three supervised treatment interruptions. Virologic failure was defined as having a viral load of greater than 5,000 copies RNA/ml plasma for 3 wk or greater than 50,000 copies once. Patients still achieving viral control at the last visit and individuals restarting therapy without meeting criteria or lost in follow-up are censored at the last evaluable time point. The horizontal axis represents the time off therapy since the beginning of the treatment interruption, the vertical axis corresponds to the number of patients maintaining control of viremia. The curves for first, second, and third STIs do not differ significantly from each other (log-rank test, <i>p ></i> 0.05).</p> <p>(B) Evolution of CD4+ T cell counts during the longest treatment interruption. Slopes of CD4+ T cell counts during the first year of the longest treatment interruption are shown for patients who experienced a cessation of therapy of at least 12 mo (all except AC13, AC25, and AC45), compared to the natural decline of CD4+ T cell counts in untreated patients of the MACS cohort with early chronic HIV-1 infection (CD4+ counts of >350 cells/mm³). CD4+ T cell losses were calculated on a regression line based on least squares fit. The two groups differed significantly from each other (Mann-Whitney <i>U</i> test, <i>p =</i> 0.02).</p> <p>(C) CD4+ T cell count at intercept and CD4+ T cell slopes during the longest treatment interruption. The CD4+ T cell slopes of the same 11 patients shown in (B) and of untreated patients of the MACS cohort are represented according to the CD4+ T cell count at the intercept of the regression line based on least squares fit with the vertical axis (day 0 of treatment interruption).</p></div

Figure 1

<div><p>Immunodominance Patterns for HIV-1-Specific CD8⁺ T Cell Responses Restricted by Individual HLA Class I Alleles</p> <p>Peptides corresponding to described optimal HIV-1-specific CD8⁺ T cell epitopes were tested in all study participants expressing the respective HLA class I allele. The average magnitude of CD8⁺ T cell responses specific for each tested peptide, given as SFCs per million input PBMCs (SFC/Mill PBMC), are shown as bars in the left part of each graph. The percentage of participants expressing the respective allele that had a detectable peptide-specific CD8⁺ T cell response are shown as bars on the right part of each graph. Epitopes are aligned for each HLA class I allele according to their frequency of recognition from top to bottom. The peptide number corresponds to the peptide sequence listed for each HLA allele and number in <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.0030403#pmed-0030403-t002" target="_blank">Table 2</a>. Data are shown only for HLA class I alleles that were expressed in at least three individuals, and for which at least three HIV-1-specific optimal CD8⁺ T cell epitopes had been defined.</p></div

Immunodomination of HLA-B57- and HLA-B27-Restricted HIV-1-Specific CD8⁺ T Cell Responses

<p>The percent contribution (left graphs) and the absolute magnitude (right graphs, given as SFCs per million input PBMCs [SFC/Mill PBMC]) of HLA-A1-, -A2-, -A3-, and -A24-restricted HIV-1-specific CD8⁺ T cell responses in individuals expressing these HLA class I alleles alone, or in conjunction with HLA-B57 or HLA-B27, are shown. Each dot represents data for one individual. The contribution, as well as the absolute magnitude, of HIV-1-specific CD8⁺ T cell responses directed against HLA-A1-, -A2-, and -A24-restricted CD8⁺ T cell epitopes was significantly lower in participants that also coexpressed HLA-B57 or HLA-B27. The same trend was observed for HLA-A3, but did not reach statistical significance. HLA-A1-, -A2-, -A3-, and -A24-restricted HIV-1-specific CD8⁺ T cell response did not differ between individuals expressing other frequent HLA class B alleles, such as HLA-B7, -B8, -B35, or -B44 (unpublished data).</p

CD8⁺ T Cell responses Directed against the Most Frequently Recognized CD8⁺ T Cell Epitopes Were Also of the Highest Magnitude

<div><p>(A) For each HLA class I allele studied, the four most frequently targeted HIV-1-specific CD8⁺ T cell epitopes were listed according to their hierarchy (for HLA class I alleles with only three described epitopes, the fourth value was excluded from the analysis). The average magnitudes of CD8⁺ T cell responses directed against the 1st, 2nd, 3rd, and 4th most frequently targeted epitope for each allele were calculated (given as SFCs per million input PBMCs [SFC/Mill PBMC]) and are shown as box plots. The average magnitude of the most frequently targeted HIV-1-specific CD8⁺ T cell epitopes restricted by each allele were significantly higher than the average magnitude of the 3rd and 4th most frequently targeted epitopes, and the respective <i>p</i>-values are provided above the box plot.</p> <p>(B) The sequence conservation within targeted CD8⁺ T cell epitopes does not contribute significantly to the observed immunodominance patterns of HIV-1-specific CD8⁺ T cell response in primary infection. For each HLA class I alleles studied, the four most frequently targeted HIV-1-specific CD8⁺ T cell epitopes were listed according to their hierarchy (for HLA class I alleles with only three described epitopes; the fourth value was excluded from the analysis). The average sequence conservations, in comparison to HIV-1 clade B sequences published in the Los Alamos Database, of the 1st, 2nd, 3rd, and 4th most frequently targeted epitope for each allele were calculated (given as percent sequence conservation) and are shown as box plots. The average percentage of sequence conservation of the four most frequently targeted HIV-1-specific CD8⁺ T cell epitopes restricted by each allele did not differ significantly.</p></div

Different HLA Class I Alleles Differ in Their Contribution to the Total HIV-1-Specific CD8⁺ T Cell Response

<p>The percentage contribution of HIV-1-specific CD8⁺ T cell responses restricted by each individual HLA class I allele to the total HIV-1-specific CD8⁺ T cell response in individuals expressing the respective allele is shown. HLA class I alleles are listed according to their contribution from left to right. HLA-B57 and HLA-B27 contributed 66% and 65.4%, respectively, to the total HIV-1-specific CD8⁺ T cell response in individuals expressing these alleles.</p