Total T cell activation was not influenced by exposure.

<p>The expression level of activation markers CD38 and HLA-DR were compared between VP group (squares, n = 6) and NVP group (circles, n = 10). The expression of CD38 on total CD4⁺ (A) and total CD8⁺ (B) T cells showed no significant difference. No significant difference was seen in CD4⁺ T cell co-expression of CD38 and HLA-DR (C). However, CD8⁺ T cells from the VP group co-expressed significantly higher of CD38 and HLA-DR compared to the NVP group (denoted by *) (D).</p

Direction of exposure and T cell IFN-γ response correlations.

<p>IFN-γ T cell responses from the viremic partner (VP) group were plotted against the corresponding average number of unprotected receptive (A) or insertive (B) anal exposures to a partner's HIV-1. Significant correlations (denoted by *) were determined by two-tailed nonparametric spearmans correlation, spearman r (r), and linear regression analysis was plotted as straight lines.</p

Clinical parameters of each study group.

<p>Clinical parameters of each study group.</p

Sexual exposure and direction of exposure to a partner between the two groups.

<p>Sexual exposure and direction of exposure to a partner between the two groups.</p

The influence of clinical parameters on T cell responses.

*<p>indicates significant correlations.</p>†<p>denotes significant correlations that did not hold when tested by least squares linear regression.</p><p>ns = no significant correlation could be found.</p

Clinical data of 8 individuals from VPG at time point 0 and 1 year later at time point 1.

*<p>indicates that the individuals partner started to receive anti-retroviral therapy after time point 0, and had a viral load below 50 copies per ml.</p

Exposure did not increase poly-functionality.

<p>The ability of CD8⁺ (A) and CD4⁺ (B) T cells to express IFN-γ and IL-2 was assessed in both the VP group (shaded boxes, n = 5) and NVP group (open boxes, n = 8). Poly-functionality was determined by the expression of both cytokines. Only the percentage of IL-2 expressing CD8⁺ T cells was significantly higher in the VP group (p = 0.0059), denoted by *.</p

IFN-γ responses are derived from both CD4⁺

<p>and CD8⁺ T cells. CD4⁺ (open boxes) and CD8⁺ (shaded boxes) T cell IFN-γ responses towards HIV-1 derived peptide pools Gag, Protease, RT, Integrase and Nef, plus the cumulative anti-HIV-1 response and a SEB positive control. No significant difference was observed between the two T cell subsets (n = 5).</p

Responses to HIV-1 peptides and the CEF pool.

<p>A) Percentage of individuals making responses from either group: solid bars indicate the viremic partner group and open bars represent the non-viremic partner group. There was a significant difference in the number of individuals responding to Protease and Integrase peptide pools (p = 0.04 and p = 0.002 respectively), as determined by Fishers exact test. No difference was seen for any other stimuli. B) Magnitude of IFN-γ T cell responses to the HIV-1 or CEF peptide pools, and the total cumulative anti-HIV-1 response. Responses from individuals within the viremic partner group (closed symbols) and individuals within the non-viremic partner group (open symbols) showed significant differences for Protease, RT, Integrase and the total cumulative anti-HIV-1 response, *p<0.001 and **p = 0.0274 respectively. The median of each group is plotted as a horizontal line.</p