General estimating equation models predicting UAI in partnerships.

<p>The HIV-positive status of partner was a strong predictor of sexual practices in partnerships and for individual episodes of intercourse; partners of unknown status were not treated very differently from HIV-negative partners. The analysis also revealed strategic positioning by showing that positive participants were several times more likely to practice insertive rather than receptive UAI in serodiscordant partnerships. ^A HIV-negative partners are the reference group in all cases. ^B Designates the sexual position of the HIV-positive participant.</p

A network “sexiogram” differentiates sexual linkages that may or may not have caused new infections.

<p>The individuals represented by the labels A–B and C–D were couples enrolled in the study. The other nodes are sexual partners described by the enrollees. The partnerships were not necessarily concurrent and included all those reported during the 3 months before A's enrollment and those of D, who enrolled 6 months later. Thus, the partnerships spanned a 9-month interval altogether. In some analyses, all partnerships of these HIV-positive individuals known to practice UAI would be counted as potential transmission linkages. This diagram illustrates the preponderance of low-risk partnerships (solid lines) compared with potential transmission linkages (broken lines).</p

Characteristics of HIV-positive men who have sex with men (MSM) in San Francisco in the Options cohort at the time of first ACASI, 2009–2010.

<p>Characteristics of HIV-positive men who have sex with men (MSM) in San Francisco in the Options cohort at the time of first ACASI, 2009–2010.</p

Estimated mean number of sexual partners per prior 3-month period and 95% confidence intervals [CI] for each sexual behavior variable of interest among MSM in Options/San Francisco, 2009–2010.

∧<p>Number of participants who contribute to each time point varies because this was not a strictly longitudinal cohort study. All participants started contributing data in 2009, and were at various times since diagnosis when they completed their ACASIs.</p>∧∧<p>PDP = potentially discordant partners (HIV-negative or unknown-status partners).</p>*<p>UAI = unprotected anal intercourse.</p>**<p>uIAI = unprotected insertive anal intercourse.</p>***<p>For participants with plasma viral load <500 copies/ml, number of PDP with whom uIAI occurred was set to 0.</p

Mean number of partners of various types per 3 months since HIV diagnosis among HIV-positive MSM in San Francisco, 2009–2010.

<p>An immediate drop in the total number of male partners in the first year of infection was followed by increases in number of partners over the following 3–4 years. The trend was similar for potentially serodiscordand partners (PDPs) although they comprised only 1/3 to 1/2 of total partnerships. However, unprotected anal intercourse (UAI) with PDPs occurred in far fewer partnerships throughout the follow-up period. Partnerships in which the HIV-positive participant was the insertive partner during unprotected anal intercourse (uIAI) accounted for fewer than 10% of all partnerships and in very few of those partnerships did the participant have sufficient plasma viral load (VL >500 copies/ml) to present a significant transmission risk.</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

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