Sarah Holte

Evidence for Human Immunodeficiency Virus Type 1 Replication In Vivo in CD14+ Monocytes and Its Potential Role as a Source of Virus in Patients on Highly Active Antiretroviral Therapy

ABSTRACT In vitro studies show that human immunodeficiency virus type 1 (HIV-1) does not replicate in freshly isolated monocytes unless monocytes differentiate to monocyte-derived macrophages. Similarly, HIV-1 may replicate in macrophages in vivo, whereas it is unclear whether blood monocytes are permissive to productive infection with HIV-1. We investigated HIV-1 replication in CD14+ monocytes and resting and activated CD4+ T cells by measuring the levels of cell-associated viral DNA and mRNA and the genetic evolution of HIV-1 in seven acutely infected patients whose plasma viremia had been <100 copies/ml for 803 to 1,544 days during highly active antiretroviral therapy (HAART). HIV-1 DNA was detected in CD14+ monocytes as well as in activated and resting CD4+ T cells throughout the course of study. While significant variation in the decay slopes of HIV-1 DNA was seen among individual patients, viral decay in CD14+ monocytes was on average slower than that in activated and resting CD4+ T cells. Measurements of HIV-1 sequence evolution and the concentrations of unspliced and multiply spliced mRNA provided evidence of ongoing HIV-1 replication, more pronounced in CD14+ monocytes than in resting CD4+ T cells. Phylogenetic analyses of HIV-1 sequences indicated that after prolonged HAART, viral populations related or identical to those found only in CD14+ monocytes were seen in plasma from three of the seven patients. In the other four patients, HIV-1 sequences in plasma and the three cell populations were identical. CD14+ monocytes appear to be one of the potential in vivo sources of HIV-1 in patients receiving HAART.

Evidence that low-level viremias during effective highly active antiretroviral therapy result from two processes : Expression of archival virus and replication of virus

ABSTRACT Episodes of low-level viremia (LLV), with plasma human immunodeficiency virus type 1 (HIV-1) RNA levels ranging from 50 to 400 copies (c)/ml, occur commonly during highly active antiretroviral therapy (HAART). LLV has been associated with virologic failure of HAART in some studies, while in others LLV did not appear to affect the clinical outcome. To understand the processes leading to LLV, genetic analyses were used to determine whether plasma virions emanated from archived or from newly evolved viral genomes. Episodes of LLV (plasma HIV-1 RNA, 50 to 379 [median, 77] c/ml) were detected in 21/37 (57%) HIV-1-infected children with median plasma HIV-1 RNA levels of <50 c/ml during 79 patient years of HAART. Viral sequences were derived by direct sequencing of PCR products from 21 plasma specimens diluted to end point. In phylogenetic analysis, LLV viral sequences grouped with virus from early in the course of infection in 8/11 subjects. Six specimens had multiple identical viral sequences, suggesting origin from clonally expanded infected cells. LLV plasma virus evolved over time, indicating viral replication, in 3/11 subjects. Two of these had frequent LLV, including the selection of drug-resistant mutants. In summary, plasma virus from episodes of LLV during effective HAART appeared to originate from two distinct processes, (i) clonal outgrowth from long-lived HIV-1-infected cells, presumably following activation and proliferation of these cells, and (ii) ongoing viral replication that included the selection of new drug-resistant mutants. These observations provide a plausible explanation for the divergent clinical outcomes previously associated with LLV.

Comprehensive Analysis of Human Immunodeficiency Virus Type 1 (HIV-1)-Specific Gamma Interferon-Secreting CD8+ T Cells in Primary HIV-1 Infection

ABSTRACT Human immunodeficiency virus type 1 (HIV-1)-specific CD8+ T cells provide an important defense in controlling HIV-1 replication, particularly following acquisition of infection. To delineate the breadth and potency of these responses in patients upon initial presentation and before treatment, we determined the fine specificities and frequencies of gamma interferon (IFN-γ)-secreting CD8+ T cells recognizing all HIV-1 proteins in patients with primary infection. In these subjects, the earliest detected responses were directed predominantly against Nef, Tat, Vpr, and Env. Tat- and Vpr-specific CD8+ T cells accounted for the greatest frequencies of mean IFN-γ spot-forming cells (SFC). Nef-specific responses (10 of 21) were more commonly detected. A mean of 2.3 epitopes were recognized with various avidities per subject, and the number increased with the duration of infection (R = 0.47, P = 0.031). The mean frequency of CD8+ T cells (985 SFC/106 peripheral blood mononuclear cells) correlated with the number of epitopes recognized (R = 0.84, P < 0.0001) and the number of HLA-restricting alleles (R = 0.79, P < 0.0001). Neither the total SFC frequencies nor the number of epitopes recognized correlated with the concurrent plasma viral load. Seventeen novel epitopes were identified, four of which were restricted to HLA alleles (A23 and B72) that are common among African descendents. Thus, primary HIV-1 infection induces strong CD8+-T-cell immunity whose specificities broaden over time, but their frequencies and breadth do not correlate with HIV-1 containment when examined concurrently. Many novel epitopes, particularly directed to Nef, Tat, and Env, and frequently with unique HLA restrictions, merit further consideration in vaccine design.

A Multicenter Observational Study of the Potential Benefits of Initiating Combination Antiretroviral Therapy during Acute HIV Infection

OBJECTIVE Uncontrolled studies have suggested a benefit, after treatment discontinuation, of initiating highly active antiretroviral therapy (HAART) during primary human immunodeficiency virus (HIV) infection. We assessed whether initiation of HAART within 2 weeks of (acute treatment) or between 2 weeks and 6 months after (early treatment) HIV seroconversion was associated with improvements in the viral load and the CD4+ T cell count after discontinuation of treatment in an observational cohort. METHODS Subjects from the multicenter Acute Infection and Early Disease Research Program cohort were enrolled in the present study within 6 months of HIV seroconversion and self-selected whether to initiate HAART. Subjects who received acute (n=13) or early (n=45) treatment received HAART for at least 12 weeks and then subsequently stopped treatment, whereas untreated subjects (n=337) declined treatment. HIV RNA levels and CD4+ T cell counts at 24, 48, and 72 weeks after treatment cessation in the 2 treatment groups were compared with those noted in the untreated group during the same periods of observation after enrollment. RESULTS The acute treatment group had lower mean HIV RNA levels at 24 weeks without therapy (-0.48 log(10) copies/mL [95% confidence interval {CI}, -0.82 to -0.13 log(10) copies/mL]) and higher mean CD4+ T cell counts (112 cells/ mu L [95% CI, 20-205 cells/ microL]), compared with the untreated group at 24 weeks. The differences in the laboratory values for the acute treatment group versus the untreated group at 72 weeks without therapy were as follows: for the HIV RNA level, -0.35 log(10) copies/mL (95% CI, -0.91 to 0.21 log(10) copies/mL) and, for the CD4 T+ cell count, 112 cells/ microL (95% CI, -15 to 213 cells/ microL). The early treatment group had lower HIV RNA levels at 24 weeks than did the untreated group, but differences were no longer apparent by week 48; CD4+ T cell counts were higher in the early treatment group at week 24 (116 cells/ microL [95% CI, 75-157 cells/ microL]) and week 72 (70 cells/ microL [95% CI, 2-138 cells/ microL]). CONCLUSIONS Initiation of HAART within 2 weeks of antibody seroconversion was associated with viral load and CD4+ T cell count benefits for 24 weeks after termination of HAART, with there being trends toward a longer-term benefit. Later initiation of HAART was associated with a persistent but decreasing CD4+ T cell count benefit and a loss of the viral load benefit by week 72 after discontinuation of treatment.

Determinants of enrollment in a preventive HIV vaccine trial: hypothetical versus actual willingness and barriers to participation.

Objective:To compare hypothetical and actual willingness to enroll in a preventive HIV vaccine trial and identify factors affecting enrollment. Methods:Participants previously enrolled in an HIV vaccine preparedness study (VPS) in 8 US cities were invited to be screened for a phase 2 HIV vaccine trial. Demographic and risk characteristics of those enrolling, ineligible, and refusing enrollment were compared using the χ2 or Fisher exact test. Multivariable logistic models were used to identify independent predictors of refusal. Results:Of 2531 high-risk HIV-uninfected former VPS participants contacted for the vaccine trial, 13% enrolled, 34% were ineligible, and 53% refused enrollment. Only 20% of those stating hypothetical willingness during the VPS actually enrolled in this vaccine trial. In multivariate analysis, refusal was higher among African Americans and lower in persons >40 years of age, those attending college, and those with ≥5 partners in the prior 6 months. All racial ethnic groups cited concerns about vaccine-induced seropositivity; African Americans also cited mistrust of government and safety concerns as barriers to enrollment. Conclusions:Steps can be taken to minimize potential social harms and to mobilize diverse communities to enroll in trials. Statements of hypothetical willingness to participate in future trials may overestimate true enrollment.

The effect of mental illness, substance use, and treatment for depression on the initiation of highly active antiretroviral therapy among HIV-infected individuals.

Information regarding the prevalence of mental illness and substance use among HIV-infected patients and the effect of these problems on HIV treatment is needed. We conducted an observational study of patients in the University of Washington (UW) HIV Cohort to determine prevalence rates for mental illness and substance use. Cox regression analyses were used to examine the relationship between mental illness and substance use, pharmacologic treatment for depression/anxiety, and initiation of highly active antiretroviral therapy (HAART) within 9 months of becoming eligible for HAART. Among 1774 patients in the UW HIV cohort during 2004, 63% had a mental illness (including mood, anxiety, psychotic, or personality disorders), 45% had a substance use disorder, and 38% had both. There were 278 patients who met criteria for HAART eligibility. After controlling for other factors, patients with depression and/or anxiety were significantly less likely to initiate HAART compared with patients without a mental illness (hazard ratio [HR] 0.4, p = 0.02). However, patients with depression/anxiety who received antidepressant/antianxiety medications were equally likely to initiate HAART as patients without a mental illness (HR 0.9, p = 0.5). We found that patients with mental illness or substance use disorders receive HAART at lower CD4+ cell counts and higher HIV-1 RNA levels than patients without these disorders. However, HAART initiation among patients who receive treatment for depression/anxiety is associated with no delay. Screening for these disorders in primary care settings and access to appropriate treatment are increasingly important components of providing care to HIV-infected patients.

Selection on the human immunodeficiency virus type 1 proteome following primary infection.

ABSTRACT Typically during human immunodeficiency virus type 1 (HIV-1) infection, a nearly homogeneous viral population first emerges and then diversifies over time due to selective forces that are poorly understood. To identify these forces, we conducted an intensive longitudinal study of viral genetic changes and T-cell immunity in one subject at ≤17 time points during his first 3 years of infection, and in his infecting partner near the time of transmission. Autologous peptides covering amino acid sites inferred to be under positive selection were powerful for identifying HIV-1-specific cytotoxic-T-lymphocyte (CTL) epitopes. Positive selection and mutations resulting in escape from CTLs occurred across the viral proteome. We detected 25 CTL epitopes, including 14 previously unreported. Seven new epitopes mapped to the viral Env protein, emphasizing Env as a major target of CTLs. One-third of the selected sites were associated with epitopic mutational escapes from CTLs. Most of these resulted from replacement with amino acids found at low database frequency. Another one-third represented acquisition of amino acids found at high database frequency, suggesting potential reversions of CTL epitopic sites recognized by the immune system of the transmitting partner and mutation toward improved viral fitness in the absence of immune targeting within the recipient. A majority of the remaining selected sites occurred in the envelope protein and may have been subjected to humoral immune selection. Hence, a majority of the amino acids undergoing selection in this subject appeared to result from fitness-balanced CTL selection, confirming CTLs as a dominant selective force in HIV-1 infection.

Initiation of antiretroviral therapy leads to a rapid decline in cervical and vaginal HIV-1 shedding.

Background:Antiretroviral therapy (ART) may decrease HIV-1 infectivity in women by reducing genital HIV-1 shedding. Objectives:To evaluate the time course and magnitude of decay in cervical and vaginal HIV-1 shedding as women initiate ART. Methods:This prospective, observational study of 20 antiretroviral-naive women initiating ART with stavudine, lamivudine, and nevirapine measured HIV-1 RNA in plasma, cervical secretions, and vaginal secretions. Qualitative polymerase chain reaction estimated HIV-1 DNA in cervical and vaginal samples. Perelsons two-phase viral decay model and non-linear random effects were used to compare RNA decay rates. Decreases in proviral DNA were evaluated using logistic regression and generalized estimating equations. Results:Significant decreases in the quantity of HIV-1 RNA were observed by day 2 in plasma (P < 0.001), day 2 in cervical secretions (P = 0.001), and day 4 in vaginal secretions (P < 0.001). Modeled initial and subsequent RNA decay rates in plasma, cervical secretions, and vaginal secretions were 0.6, 0.8, and 1.2 log10 virions/day, and 0.04, 0.05, and 0.06 log10 virions/day, respectively. The initial decay rate for vaginal HIV-1 RNA was more rapid than for plasma RNA (P = 0.02). Detection of HIV-1 DNA decreased significantly in vaginal secretions during the first week (P < 0.001). At day 28, 10 women had detectable HIV-1 RNA or proviral DNA in genital secretions. Conclusions:Genital HIV-1 shedding decreased rapidly after ART initiation, consistent with a rapid decrease in infectivity. However, incomplete viral suppression in half of these women may indicate an ongoing risk of transmission.

Role for HLA class II molecules in HIV-1 suppression and cellular immunity following antiretroviral treatment

HIV-1-infected patients treated early with combination antiretrovirals respond favorably, but not all maintain viral suppression and improved HIV-specific Th function. To understand if genetic factors contribute to this variation, we prospectively evaluated over 18 months 21 early-treated patients stratified by alleles of class II haplotypes. All seven subjects with the DRB1*13-DQB1*06 haplotype, but only 21% of other subjects, maintained virus suppression at every posttreatment measurement. Following HIV-1 p24 antigen stimulation, PBMCs from patients with this haplotype demonstrated higher mean lymphoproliferation and IFN-gamma secretion than did cells from patients with other haplotypes. Two DRB1*13-restricted Gag epitope regions were identified, a promiscuous one that bound its putative restriction element with nanomolar affinity, and another that mapped to a highly conserved region. These findings suggest that class II molecules, particularly the DRB1*13 haplotype, have an important impact on virologic and immunologic responses. The advantage of the haplotype may relate to selection of key HIV-1 Th1 epitopes in highly conserved regions with avid binding to class II molecules. Eliciting responses to the promiscuous epitope region may be beneficial in vaccine strategies.

Sentinel Surveillance of Sexually Transmitted Infections/HIV and Risk Behaviors in Vulnerable Populations in 5 Central American Countries

In El Salvador, Guatemala, Honduras, Nicaragua, and Panama, we recruited 2466 female sex workers (FSWs) by probabilistic or comprehensive sampling and 1418 men who have sex with men (MSM) by convenience sampling to measure sociobehavioral risk and sexually transmitted infections. For MSM, HIV seroprevalence ranged from 7.6% in Nicaragua to 15.3% in El Salvador, and estimated HIV seroincidence per 100 person-years ranged from 2.7 in Panama to 14.4 in Nicaragua; 61% reported using condoms consistently with casual male partners, 29% reported exposure to behavioral interventions, and 22% reported recent sex with male and female partners. For FSWs, HIV seroprevalence ranged from 0.2% in Nicaragua and Panama to 9.6% in Honduras, where estimated HIV seroincidence was also highest (3.2 per 100 person-years); 77% and 72% of FSWs reported using condoms consistently with new and regular clients. Herpes simplex virus (HSV)-2 seroprevalence averaged 85.3% in FSWs and 48.2% in MSM, and syphilis seropositivity averaged 9.6% in FSWs and 8.3% in MSM. Chlamydia trachomatis and Neisseria gonorrhoeae prevalences in FSWs averaged 20.1% and 8.1%, and Trichomonas vaginalis and bacterial vaginosis prevalences averaged 11.0% and 54.8%. An ongoing HIV epidemic involves Central American MSM with potential bridging to women. In FSWs, HSV-2 infection was associated with HIV infection (odds ratio = 11.0, 95% confidence interval: 2.9 to 7.9). For these vulnerable populations, prevention must incorporate acceptable and effective sexual health services, including improved condom access and promotion.