Alexandra Schuetz

Impact of Multi-Targeted Antiretroviral Treatment on Gut T Cell Depletion and HIV Reservoir Seeding during Acute HIV Infection

Background Limited knowledge exists on early HIV events that may inform preventive and therapeutic strategies. This study aims to characterize the earliest immunologic and virologic HIV events following infection and investigates the usage of a novel therapeutic strategy. Methods and Findings We prospectively screened 24,430 subjects in Bangkok and identified 40 AHI individuals. Thirty Thais were enrolled (8 Fiebig I, 5 Fiebig II, 15 Fiebig III, 2 Fiebig IV) of whom 15 completed 24 weeks of megaHAART (tenofovir/emtricitabine/efavirenz/raltegravir/maraviroc). Sigmoid biopsies were completed in 24/30 at baseline and 13/15 at week 24. At baseline, the median age was 29 years and 83% were MSM. Most were symptomatic (87%), and were infected with R5-tropic (77%) CRF01_AE (70%). Median CD4 was 406 cells/mm3. HIV RNA was 5.5 log10 copies/ml. Median total blood HIV DNA was higher in Fiebig III (550 copy/106 PBMC) vs. Fiebig I (8 copy/106 PBMC) (p = 0.01) while the median %CD4+CCR5+ gut T cells was lower in Fiebig III (19%) vs. Fiebig I (59%) (p = 0.0008). After 24 weeks of megaHAART, HIV RNA levels of <50 copies were achieved in 14/15 in blood and 13/13 in gut. Total blood HIV DNA at week 0 predicted reservoir size at week 24 (p<0.001). Total HIV DNA declined significantly and was undetectable in 3 of 15 in blood and 3 of 7 in gut. Frequency of CD4+CCR5+ gut T cells increased from 41% at baseline to 64% at week 24 (p>0.050); subjects with less than 40% at baseline had a significant increase in CD4+CCR5+ T cells from baseline to week 24 (14% vs. 71%, p = 0.02). Conclusions Gut T cell depletion and HIV reservoir seeding increases with progression of AHI. MegaHAART was associated with immune restoration and reduced reservoir size. Our findings could inform research on strategies to achieve HIV drug-free remission.

Preferential infection and depletion of Mycobacterium tuberculosis–specific CD4 T cells after HIV-1 infection

HIV-1 preferentially infects M. tuberculosis-specific CD4+ T cells due to their increased production of IL-2.

The Thai Phase III Trial (RV144) Vaccine Regimen Induces T Cell Responses That Preferentially Target Epitopes within the V2 Region of HIV-1 Envelope

The Thai HIV phase III prime/boost vaccine trial (RV144) using ALVAC-HIV (vCP1521) and AIDSVAX B/E was, to our knowledge, the first to demonstrate acquisition efficacy. Vaccine-induced, cell-mediated immune responses were assessed. T cell epitope mapping studies using IFN-γ ELISPOT was performed on PBMCs from HIV-1–uninfected vaccine (n = 61) and placebo (n = 10) recipients using HIV-1 Env peptides. Positive responses were measured in 25 (41%) vaccinees and were predominantly CD4+ T cell-mediated. Responses were targeted within the HIV Env region, with 15 of 25 (60%) of vaccinees recognizing peptides derived from the V2 region of HIV-1 Env, which includes the α4β7 integrin binding site. Intracellular cytokine staining confirmed that Env responses predominated (19 of 30; 63% of vaccine recipients) and were mediated by polyfunctional effector memory CD4+ T cells, with the majority of responders producing both IL-2 and IFN-γ (12 of 19; 63%). HIV Env Ab titers were higher in subjects with IL-2 compared with those without IL-2–secreting HIV Env-specific effector memory T cells. Proliferation assays revealed that HIV Ag-specific T cells were CD4+, with the majority (80%) expressing CD107a. HIV-specific T cell lines obtained from vaccine recipients confirmed V2 specificity, polyfunctionality, and functional cytolytic capacity. Although the RV144 T cell responses were modest in frequency compared with humoral immune responses, the CD4+ T cell response was directed to HIV-1 Env and more particularly the V2 region.

Early depletion of Mycobacterium tuberculosis-specific T helper 1 cell responses after HIV-1 infection

BACKGROUND The acid-fast bacillus Mycobacterium tuberculosis is often the first manifestation of acquired immunodeficiency syndrome in patients infected with human immunodeficiency virus (HIV). This study was conducted to better understand the mechanism underlying M. tuberculosis-specific pathogenicity early after onset of HIV infection. METHODS M. tuberculosis-specific T helper 1 (Th1) cells were studied in HIV negative (n=114) and chronically HIV infected (n=68) Tanzanian subjects by using early secreted antigenic target 6 (ESAT6) protein or tuberculin (purified protein derivative) with interferon-gamma ELISPOT and intracellular cytokine staining. In a longitudinal study, the effect of acute HIV infection on M. tuberculosis-specific Th1 cells was determined by polychromatic flow cytometric analysis in 5 subjects with latent M. tuberculosis infection who became infected with HIV. RESULTS In tuberculosis (TB)-asymptomatic subjects (i.e., subjects with unknown TB status who did not show clinical signs suggestive of TB), chronic HIV infection was associated with a decreased percentage of subjects with detectable M. tuberculosis-specific Th1 cells (P< .001) a decrease which was not observed among subjects with active TB. Acute HIV infection induced a rapid depletion of M. tuberculosis-specific Th1 cells in 4 subjects remained TB asymptomatic, whereas the population of these cells remained stable in subjects who remained HIV negative (P< .01). CONCLUSIONS Taken together, these data suggest a mechanism of rapid M. tuberculosis-specific Th1 cell depletion that may contribute to the early onset of TB in individuals with latent M. tuberculosis infection who become HIV infected.

A Phase 1/2 Study of a Multiclade HIV-1 DNA Plasmid Prime and Recombinant Adenovirus Serotype 5 Boost Vaccine in HIV-Uninfected East Africans (RV 172)

BACKGROUND Human immunodeficiency virus (HIV) vaccine development remains a global priority. We describe the safety and immunogenicity of a multiclade DNA vaccine prime with a replication-defective recombinant adenovirus serotype 5 (rAd5) boost. METHODS The vaccine is a 6-plasmid mixture encoding HIV envelope (env) subtypes A, B, and C and subtype B gag, pol, and nef, and an rAd5 expressing identical genes, with the exception of nef. Three hundred and twenty-four participants were randomized to receive placebo (n=138), a single dose of rAd5 at 10(10) (n = 24) or 10(11) particle units (n = 24), or DNA at 0, 1, and 2 months, followed by rAd5 at either 10(10) (n= 114) or 10(11) particle units (n = 24) boosting at 6 months. Participants were followed up for 24 weeks after the final vaccination. RESULTS The vaccine was safe and well tolerated. HIV-specific T cell responses were detected in 63% of vaccinees. Titers of preexisting Ad5 neutralizing antibody did not affect the frequency and magnitude of T cell responses in prime-boost recipients but did affect the response rates in participants that received rAd5 alone (P = .037). CONCLUSION The DNA/rAd5 vaccination regimen was safe and induced HIV type 1 multi-clade T cell responses, which were not significantly affected by titers of preexisting rAd5 neutralizing antibody. Trial Registration. ClinicalTrials.gov identifier: NCT00123968 .

A novel acute HIV infection staging system based on 4th generation immunoassay.

BackgroundFourth generation (4thG) immunoassay (IA) is becoming the standard HIV screening method but was not available when the Fiebig acute HIV infection (AHI) staging system was proposed. Here we evaluated AHI staging based on a 4thG IA (4thG staging).FindingsScreening for AHI was performed in real-time by pooled nucleic acid testing (NAT, n=48,828 samples) and sequential enzyme immunoassay (EIA, n=3,939 samples) identifying 63 subjects with non-reactive 2nd generation EIA (Fiebig stages I (n=25), II (n=7), III (n=29), IV (n=2)). The majority of samples tested (n=53) were subtype CRF_01AE (77%). NAT+ subjects were re-staged into three 4thG stages: stage 1 (n=20; 4th gen EIA-, 3rd gen EIA-), stage 2 (n=12; 4th gen EIA+, 3rd gen EIA-), stage 3 (n=31; 4th gen EIA+, 3rd gen EIA+, Western blot-/indeterminate). 4thG staging distinguishes groups of AHI subjects by time since presumed HIV exposure, pattern of CD8+ T, B and natural killer cell absolute numbers, and HIV RNA and DNA levels. This staging system further stratified Fiebig I subjects: 18 subjects in 4thG stage 1 had lower HIV RNA and DNA levels than 7 subjects in 4thG stage 2.ConclusionsUsing 4th generation IA as part of AHI staging distinguishes groups of patients by time since exposure to HIV, lymphocyte numbers and HIV viral burden. It identifies two groups of Fiebig stage I subjects who display different levels of HIV RNA and DNA, which may have implication for HIV cure. 4th generation IA should be incorporated into AHI staging systems.

HIV DNA Reservoir Increases Risk for Cognitive Disorders in cART-Naïve Patients

Objectives Cognitive impairment remains frequent in HIV, despite combination antiretroviral therapy (cART). Leading theories implicate peripheral monocyte HIV DNA reservoirs as a mechanism for spread of the virus to the brain. These reservoirs remain present despite cART. The objective of this study was to determine if the level of HIV DNA in CD14+ enriched monocytes predicted cognitive impairment and brain injury. Methods We enrolled 61 cART-naïve HIV-infected Thais in a prospective study and measured HIV DNA in CD14+ enriched monocyte samples in a blinded fashion. We determined HAND diagnoses by consensus panel and all participants underwent magnetic resonance spectroscopy (MRS) to measure markers of brain injury. Immune activation was measured via cytokines in cerebrospinal fluid (CSF). Results The mean (SD) age was 35 (6.9) years, CD4 T-lymphocyte count was 236 (139) and log10 plasma HIV RNA was 4.8 (0.73). Twenty-eight of 61 met HAND criteria. The log10 CD14+ HIV DNA was associated with HAND in unadjusted and adjusted models (p = 0.001). There was a 14.5 increased odds ratio for HAND per 1 log-value of HIV DNA (10-fold increase in copy number). Plasma CD14+ HIV DNA was associated with plasma and CSF neopterin (p = 0.023) and with MRS markers of neuronal injury (lower N-acetyl aspartate) and glial dysfunction (higher myoinositol) in multiple brain regions. Interpretation Reservoir burden of HIV DNA in monocyte-enriched (CD14+) peripheral blood cells increases risk for HAND in treatment-naïve HIV+ subjects and is directly associated with CSF immune activation and both brain injury and glial dysfunction by MRS.

Monitoring CD27 expression to evaluate mycobacterium tuberculosis activity in HIV-1 infected individuals in vivo

The level of bacterial activity is only poorly defined during asymptomatic Mycobacterium tuberculosis (MTB) infection. The objective was to study the capacity of a new biomarker, the expression of the T cell maturation marker CD27 on MTB-specific CD4 T cells, to identify active tuberculosis (TB) disease in subjects from a MTB and HIV endemic region. The frequency and CD27 expression of circulating MTB-specific CD4 T cells was determined in 96 study participants after stimulation with purified protein derivative (PPD) using intracellular cytokine staining for IFNgamma (IFNγ). Subjects were then stratified by their TB and HIV status. Within PPD responders, a CD27− phenotype was associated with active TB in HIV− (p = 0.0003) and HIV+ (p = 0.057) subjects, respectively. In addition, loss of CD27 expression preceded development of active TB in one HIV seroconverter. Interestingly, in contrast to HIV− subjects, MTB-specific CD4 T cell populations from HIV+ TB-asymptomatic subjects were often dominated by CD27− cells. These data indicate that down-regulation of CD27 on MTB-specific CD4 T cell could be used as a biomarker of active TB, potentially preceding clinical TB disease. Furthermore, these data are consistent with the hypothesis that late, chronic HIV infection is frequently associated with increased mycobacterial activity in vivo. The analysis of T cell maturation and activation markers might thus be a useful tool to monitor TB disease progression.

Minor viral and host genetic polymorphisms can dramatically impact the biologic outcome of an epitope-specific CD8 T-cell response

Human immunodeficiency virus-1 subtypes A and C differ in the highly conserved Gag-TL9 epitope at a single amino acid position. Similarly, the TL9 presenting human leukocyte antigen (HLA) class I molecules B42 and B81 differ only at 6 amino acid positions. Here, we addressed the influence of such minor viral and host genetic variation on the TL9-specific CD8 T-cell response. The clonotypic characteristics of CD8 T-cell populations elicited by subtype A or subtype C were distinct, and these responses differed substantially with respect to the recognition and selection of TL9 variants. Irrespective of the presenting HLA class I molecule, CD8 T-cell responses elicited by subtype C exhibited largely comparable TL9 variant cross-recognition properties, expressed T-cell receptors that used almost exclusively the TRBV 12-3 gene, and selected for predictable patterns of viral variation within TL9. In contrast, subtype A elicited TL9-specific CD8 T-cell populations with completely different, more diverse TCRBV genes and did not select for viral variants. Moreover, TL9 variant cross-recognition properties were extensive in B81(+) subjects but limited in B42(+) subjects. Thus, minor viral and host genetic polymorphisms can dramatically alter the immunologic and virologic outcome of an epitope-specific CD8 T-cell response.

Randomized, Double-Blind Evaluation of Late Boost Strategies for HIV-Uninfected Vaccine Recipients in the RV144 HIV Vaccine Efficacy Trial

Background The RV144 ALVAC-HIV prime, AIDSVAX B/E boost afforded 60% efficacy against human immunodeficiency virus (HIV) acquisition at 1 year, waning to 31.2% after 3.5 years. We hypothesized that additional vaccinations might augment immune correlates of protection. Methods In a randomized placebo-controlled double-blind study of 162 HIV-negative RV144 vaccine recipients, we evaluated 2 additional boosts, given 6-8 years since RV144 vaccination, for safety and immunogenicity, at weeks 0 and 24. Study groups 1-3 received ALVAC-HIV+AIDSVAX B/E, AIDSVAX B/E, and ALVAC-HIV, respectively, or placebo. Results Vaccines were well tolerated. For groups 1 and 2, plasma immunoglobulin (Ig) G, IgA, and neutralizing antibody responses at week 2 were all significantly higher than 2 weeks after the last RV144 vaccination. IgG titers against glycoprotein (gp) 70V1V2 92TH023 increased 14-fold compared with 2 weeks after the last RV144 vaccination (14069 vs 999; P < .001). Groups 1 and 2 did not differ significantly from each other, whereas group 3 was similar to placebo recipients. Responses in groups 1 and 2 declined by week 24 but were boosted by the second vaccination, albeit at lower magnitude than for week 2. Conclusions In RV144 vaccinees, AIDSVAX B/E with or without ALVAC-HIV 6-8 years after initial vaccination generated higher humoral responses than after RV144, but these responses were short-lived, and their magnitude did not increase with subsequent boost. Clinical Trials Registration NCT01435135.