Publications

There are marked differences in the spread and prevalence of HIV-1 subtypes worldwide, and differences in clinical progression have been reported. However, the biological reasons underlying these differences are unknown. Gag-protease is essential for HIV-1 replication, and Gag-protease-driven replication capacity has previously been correlated with disease progression. We show that Gag-protease replication capacity correlates significantly with that of whole isolates ( = 0.51; = 0.04), indicating that Gag-protease is a significant contributor to viral replication capacity. Furthermore, we investigated subtype-specific differences in Gag-protease-driven replication capacity using large well-characterized cohorts in Africa and the Americas. Patient-derived Gag-protease sequences were inserted into an HIV-1 NL4-3 backbone, and the replication capacities of the resulting recombinant viruses were measured in an HIV-1-inducible reporter T cell line by flow cytometry. Recombinant viruses expressing subtype C Gag-proteases exhibited substantially lower replication capacities than those expressing subtype B Gag-proteases ( < 0.0001); this observation remained consistent when representative Gag-protease sequences were engineered into an HIV-1 subtype C backbone. We identified Gag residues 483 and 484, located within the Alix-binding motif involved in virus budding, as major contributors to subtype-specific replicative differences. In East African cohorts, we observed a hierarchy of Gag-protease-driven replication capacities, i.e., subtypes A/C < D < intersubtype recombinants ( < 0.0029), which is consistent with reported intersubtype differences in disease progression. We thus hypothesize that the lower Gag-protease-driven replication capacity of subtypes A and C slows disease progression in individuals infected with these subtypes, which in turn leads to greater opportunity for transmission and thus increased prevalence of these subtypes. HIV-1 subtypes are unevenly distributed globally, and there are reported differences in their rates of disease progression and epidemic spread. The biological determinants underlying these differences have not been fully elucidated. Here, we show that HIV-1 Gag-protease-driven replication capacity correlates with the replication capacity of whole virus isolates. We further show that subtype B displays a significantly higher Gag-protease-mediated replication capacity than does subtype C, and we identify a major genetic determinant of these differences. Moreover, in two independent East African cohorts we demonstrate a reproducible hierarchy of Gag-protease-driven replicative capacity, whereby recombinants exhibit the greatest replication, followed by subtype D, followed by subtypes A and C. Our data identify Gag-protease as a major determinant of subtype differences in disease progression among HIV-1 subtypes; furthermore, we propose that the poorer viral replicative capacity of subtypes A and C may paradoxically contribute to their more efficient spread in sub-Saharan Africa.

Little is known about associations between viral suppression, adherence, and duration of prior viral suppression in sub-Saharan Africa. Study participants were from the UARTO study in Mbarara, Uganda. We fit regression models to characterize relationships between average adherence, treatment interruptions, and rebound viremia (>400 copies/mL) following a previously undetectable result. Our goal was to understand the impact of prior viral suppression on these relationships. 396 participants contributed 2864 quarterly visits. Restricted to periods with average adherence <50 %, each 10 % increase in adherence reduced the odds of rebound viremia by 74 % [adjusted odds ratio (AOR) = 0.26, P = 0.002] and 29 % (AOR = 0.71, P = 0.057) during the first 12 months of suppression and beyond 12 months respectively, interaction term P = 0.018. Among periods with adherence ≥50 %, the risk of rebound viremia decreased with increasing adherence during the first 12 months of viral suppression (AOR = 0.73 for each 10 % increase, P = 0.001), but not thereafter (AOR = 1.09, P = 0.67), interaction term P = 0.027. In contrast, 72-h interruptions, were associated with increased rebound viremia during the first 12 months (AOR = 1.30, P = 0.009) and after (AOR = 1.39, P = 0.005), interaction term P = 0.69. Completing 12 months of viral suppression decreases the impact of average adherence, but not prolonged treatment interruptions, on risk of rebound viremia.

Household air pollution (HAP) and chronic HIV infection are each associated with significant respiratory morbidity. Little is known about relationships between HAP and respiratory symptoms among people living with HIV. The objective of this study was to investigate the relationship between cooking fuel type and chronic respiratory symptoms in study participants from the Uganda AIDS Rural Treatment Outcomes Study. Study participants were enrolled at the time of antiretroviral therapy initiation and seen quarterly from 2005 to 2014 for health-focused questionnaires, CD4 count and HIV viral load. We used multivariable logistic regression and generalised estimating equations, with each study visit as a unit of observation, to investigate relationships between cooking fuel type and chronic respiratory symptoms. We observed an association between cooking with firewood ( charcoal) and chronic cough among HIV-infected females in rural Uganda (adjusted OR 1.41, 95% CI 1.00-1.99; p=0.047). We did not observe an association between cooking fuel type and respiratory symptoms among males (adjusted OR 0.88, 95% CI 0.47-1.63; p=0.658). Associations between cooking fuel and chronic cough in this HIV-infected cohort may be influenced by sex-based roles in meal preparation. This study raises important questions about relationships between household air pollution, HIV infection and respiratory morbidity.

PURPOSE

To evaluate the incidence of intermediate-stage age-related macular degeneration (AMD) in patients with acquired immunodeficiency syndrome (AIDS).

DESIGN

Cohort study.

METHODS

Patients enrolled in the Longitudinal Study of the Ocular Complications of AIDS (LSOCA) underwent 5- and 10-year follow-up retinal photographs. Intermediate-stage AMD (AREDS stage 3) was determined from these photographs by graders at a centralized Reading Center, using the Age-Related Eye Disease Study-2 grading system. The incidence of AMD in LSOCA was compared with that in the Multi-Ethnic Study of Atherosclerosis (MESA), a Human Immunodeficiency Virus (HIV)-uninfected cohort, which used a similar photographic methodology.

RESULTS

The incidence of AMD in LSOCA was 0.65/100 person-years (PY). In a multivariate analysis the only significant risk factor for AMD in LSOCA was smoking; the relative risk vs never-smokers was 3.4 for former smokers (95% confidence interval [CI] 1.3, 9.5; P = .02) and 3.3 for current smokers (95% CI 1.1, 9.7; P = .03). Compared with the MESA cohort, the race/ethnicity- and sex-adjusted risk of AMD in LSOCA was 1.75 (95% CI 1.16, 2.64; P = .008), despite the fact that the mean age of the MESA cohort was 17 years greater than the LSOCA cohort (61 ± 9 years vs 44 ± 8 years).

CONCLUSIONS

Patients with AIDS have a 1.75-fold increased race- and sex-adjusted incidence of intermediate-stage AMD compared with that found in an HIV-uninfected cohort. This increased incidence is consistent with the increased incidence of other age-related diseases in antiretroviral-treated, immune-restored, HIV-infected persons when compared with HIV-uninfected persons.