Objective To develop and validate an easy-to-use prediction model for HIV acquisition among men who have sex with men (MSM). Methods We developed prediction models using medical records data from an STD clinic (2001–2008) and validated these models using data from the control arm of Project Explore, an HIV prevention trial (1999–2003). Results Of 1903 MSM who tested for HIV more than once in the development sample, 101 acquired HIV over 6.7 years of follow-up. Annual HIV incidence was 2.57% (95% confidence interval [CI]: 2.09%, 3.12%). During 4 years of follow-up of 2081 Project Explore control arm participants, 144 acquired HIV for an incidence of 2.32% (95%CI: 1.96%, 2.73%). A prediction model that included variables indicating use of methamphetamine or inhaled nitrites in the prior 6 months, unprotected anal intercourse with a partner of positive or unknown HIV status in the prior year, ≥10 male sex partners in the prior year, and current diagnosis or history of bacterial sexually transmitted infection was well calibrated overall (expected-observed ratio = 1.01; 95%CI: 0.97, 1.05) and had modest discriminatory accuracy at 1 year (area under the receiver-operator characteristic curve [AUC]=0.67; 95%CI: 0.60, 0.75) and at 4 years (AUC=0.66; 95%CI: 0.61, 0.71). Over four years, cumulative incidence ranged from 3.9% to 14.3% for groups of men defined by the prediction model. Conclusions A new risk score was predictive of HIV acquisition and could assist providers in counseling MSM and in targeting intensified prevention to MSM at greatest risk for HIV infection. Its accuracy requires further evaluation.

In HIV‐1 encephalitis, HIV‐1 replicates predominantly in macrophages and microglia. Astrocytes also carry HIV‐1, but the infection of oligodendrocytes and neurons is debated. In this study we examined the presence of HIV‐1 DNA in different brain cell types in 6 paraffin embedded, archival post‐mortem pediatric and adult brain tissues with HIV‐1 encephalitis by Laser Capture Microdissection (LCM). Sections from frontal cortex and basal ganglia were stained by immunohistochemistry for CD68 (microglia), GFAP (astrocytes), MAP2 (neurons), and p24 (HIV‐1 positive cells) and different cell types were microdissected by LCM. Individual cells or pools of same type of cells were lysed, the cell lysates were subjected to PCR using HIV‐1 gag SK38/SK39 primers, and presence of HIV‐1 DNAwas confirmed by Southern blotting. HIV‐1 gag DNAwas consistently detected by this procedure in the frontal cortex and basal ganglia in 1 to 20 p24 HIV‐1 capsid positive cells, and in pools of 50 to 100 microglia/macrophage cells, 100 to 200 astrocytes, and 100 to 200 neurons in HIV‐1 positive cases but not in HIV‐1 negative controls. These findings suggest that in addition to microglia, the infection of astro‐cytes and neurons by HIV‐1 may contribute to the development of HIV‐1 disease in the brain.

Objective We sought to estimate how serosorting may affect HIV prevalence and individual risk among MSM in Seattle, Washington, and how the results vary under different assumptions of HIV testing frequency, heterogeneity in sexual behavior, and condom use. Methods We developed a deterministic mathematical model of HIV transmission dynamics. Data from the 2003 random digit dial study of MSM conducted in Seattle, Washington (n = 400) are used to parameterize the model. Results Predicted population-level HIV prevalence as well as an individual’s risk of HIV acquisition decreases when the odds of serosorting are increased in the mathematical model. In our model based on observed levels of serosorting, we predict an HIV prevalence of 16%. In contrast, if serosorting were eliminated in the population, we predict that HIV prevalence would increase to 24.5%. However, our findings depend on rates of condom use, mean anal sex contact rates, and HIV testing in the population. Conclusions Under realistic scenarios of sexual behavior and testing frequency for MSM in the US, serosorting can be an effective harm reduction strategy.

BackgroundMethamphetamine use is associated with HIV acquisition and transmission among men who have sex with men (MSM). Contingency management (CM), providing positive reinforcement for drug abstinence and withholding reinforcement when abstinence is not demonstrated, may facilitate reduced methamphetamine use and sexual risk. We compared CM as a stand-alone intervention to a minimal intervention control to assess the feasibility of conducting a larger, more definitive trial of CM; to define the frequency of behavioral outcomes to power such a trial; and, to compute preliminary estimates of CM's effectiveness.MethodsWe randomly assigned 127 MSM from Seattle, WA who use methamphetamine to receive a 12-week CM intervention (n = 70) or referral to community resources (n = 57).ResultsRetention at 24 weeks was 84%. Comparing consecutive study visits, non-concordant UAI declined significantly in both study arms. During the intervention, CM and control participants were comparably likely to provide urine samples containing methamphetamine (adjusted relative risk [aRR] = 1.09; 95%CI: 0.71, 1.56) and to report non-concordant UAI (aRR = 0.80; 95%CI: 0.47, 1.35). However, during post-intervention follow-up, CM participants were somewhat more likely to provide urine samples containing methamphetamine than control participants (aRR = 1.21; 95%CI: 0.95, 1.54, P = 0.11). Compared to control participants, CM participants were significantly more likely to report weekly or more frequent methamphetamine use and use of more than eight quarters of methamphetamine during the intervention and post-intervention periods.ConclusionsWhile it is possible to enroll and retain MSM who use methamphetamine in a trial of CM conducted outside drug treatment, our data suggest that CM is not likely to have a large, sustained effect on methamphetamine use.Trial RegistrationClinicalTrials.gov Identifier NCT01174654