icon-folder.gif   Conference Reports for NATAP  
 
  12th Conference on Retroviruses and Opportunistic Infections (CROI)
Feb 22-25, 2005
Boston, MA
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Impact of HAART on NeuroAIDS
 
 
  Ron Ellis
Univ of California, San Diego, USA
12th CROI Feb 2005
 
HIV-associated neurocognitive impairment (HNCI) is a significant burden to persons living with HIV infection, caregivers, and the healthcare system.
 
Although highly active antiretroviral therapy (HAART) has reduced the incidence of severe dementia and improves neurocognitive function in many, individual patient responses are quite variable, and the prevalence of HNCI remains high.
 
Thus the development of effective treatment strategies is of considerable public health importance. Current consensus antiretroviral therapy (ART) guidelines provide no specific recommendations on the management of HNCI. Evidence from in vitro and in vivo experiments and uncontrolled human studies has failed to resolve controversy on whether antiretroviral (ARV) central nervous system (CNS) penetration and cerebrospinal fluid (CSF) virologic suppression are clinically important, and no randomized, controlled trials have compared the neurocognitive benefits of regimens with differing CNS penetration. The chemical profile of many ARVs currently in development suggests that their CNS penetration will be negligible. Thus data on the importance of CNS penetration will become increasingly important as new agents are introduced into the clinical armamentarium. In natural history studies, we have observed that among individuals with HNCI initiating new ART, those on more CNS penetrating regimens had greater CSF viral load (VL) reduction, and those who achieved CSF virologic suppression had better neurocognitive outcomes.
 
Together, these observations argue for a multi-center, randomized clinical trial to evaluate a CNS-targeted antiretroviral treatment strategy. Such a trial would provide the level of evidence needed to formulate ART guidelines specific to HNCI.
 
Peripheral HIV-1 DNA Copy Number and HIV-1-associated Dementia
 
12th CROI abstract 408
Bruce Shiramizu*1, S Gartner2, A Williams1, C Shikuma1, S Ratto-Kim1, M Watters1, and V Valcour1
1Univ of Hawaii, Honolulu, USA and 2Johns Hopkins Univ, Baltimore, MD, USA
 
Background: HIV-1-associated dementia (HAD) continues to develop in individuals despite treatment with HAART. Monocytes/macrophages (M/MU) can harbor proviral DNA that is not eradicated by HAART. To determine whether HAD is associated with the level of HIV-1 infection within circulating leukocytes, we quantified HIV-1 DNA (HIV DNA) copy number in peripheral blood mononuclear cells (PBMC), and in PBMC subsets.
 
Methods: A cross-sectional analysis of the HIV DNA copy number was performed within the Hawaii Aging with HIV Cohort, comparing participants with HAD to those with normal cognition. Real-time PCR assays assessing HIV DNA copy number per million cells were performed on PBMC and subsets.
 
Results: Individuals with HAD (n = 27) had a median (interquartile range) of 9.11 (37.20) HIV DNA per 106 PBMC compared to 0.49 (0.89) HIV DNA per 106 PBMC in individuals with normal cognition (n = 22). Using a univariate analysis in the subset of individuals with undetectable viral load (HAD = 11; normal cognition = 13), the odds ratio of HAD attributable to HIV DNA copy number was 2.76 (1.28 to 5.94), p < 0.01). Preliminary analysis of a small subset of patients (n = 5) suggested that the primary source of HIV DNA may be the activated M/MU (CD14+/CD16+) subset.
 
Conclusions: These findings suggest a potentially important association between circulating provirus and HAD.
 
Long-term Effect of HAART on Intrathecal HIV-1 Replication despite Systemic Viro-Immunological Failure
 
12th CROI abstract 401
Authors and Affiliations: S Palmieri, L Galli, R Pedale, A Bestetti, S Sala, A Lazzarin, and Paola Cinque*
San Raffaele Sci Inst, Milan, Italy
 
Background: Following long-term HAART, many patients show virological failure in plasma. Because of poor penetration of some anti-HIV drugs in brain tissue, there is concern that virological failure might occur earlier and more importantly in cerebrospinal fluid (CSF) than in plasma. The objective of this study was to assess the proportion and magnitude of virologic failure in CSF in relation to plasma in long-term HAART-treated patients.
 
Methods: HIV-1 RNA load was prospectively measured in CSF and plasma from 267 patients with neurological symptoms in whom CSF was drawn for diagnostic purposes between January 1997 and December 2003 at the Infectious Diseases Clinic of San Raffaele Hospital, Milan. Only patients who received HAART continuously or were untreated for at least 6 months before sampling were included in the analysis. Univariate analysis was performed by e2 test to compare discrete variables and Wilcoxon 2-sample rank test to compare mean independent values. Multiple logistic regression was used to assess the independent contribution of potential risk factors on CSF virological failure.
 
Results: Data from 128 of the 267 subjects were included, of whom 61 were on HAART and 67 were untreated at the time of sampling. Based on cut-off level of 2.60 HIV-1 RNA log copies/mL in plasma, 24 treated patients were classified as HAART-success and 37 as HAART-failure. Median duration of HAART did not differ between HAART-success (median 642 days; IQR, 336 to 1247) and HAART-failure (median, 510 days; IQR, 324 to 1107). CSF HIV-1 RNA levels were > 2.60 log copies/mL in 56 of 67 HAART-untreated (84%), 1 of 23 HAART-success (4%), and 18 of 37 HAART-failure (49%) (HAART-untreated vs HAART-failure, p = 0.001). CSF HIV-1 RNA levels were lower in HAART-failure than HAART-untreated (median: 2.60 vs 4.00 log copies/mL, p < 0.0001). Also plasma HIV-1 RNA levels were lower and CD4 cell counts higher in HAART-failure than HAART-untreated (plasma HIV-1 RNA: median, 4.30 vs 5.36 log copies/mL, p < 0.0001) (CD4: median, 109 vs 50/L, p < 0.0001). However, in a multivariate model including only patients with plasma HIV-1 RNA > 2.60 log copies/mL, the risk of virologic failure in CSF was higher in HAART-untreated than HAART-failure (OR=1.86, 95% CI = 1.12 to 3.17, p = 0.018), but it was neither associated with higher HIV-1 RNA levels in plasma nor with lower CD4 cell counts.
 
Conclusions: HAART seems to maintain its efficacy on intrathecal virus replication in long-term treated patients irrespective of poor systemic viro-immunological responses.
 
Enfuvirtide Cerebrospinal Fluid Pharmacokinetics: a Potential Tool to Analyze CSF HIV Origin and the Therapeutic Role of Local Drug Penetration
 
12th CROI
Authors and Affiliations: Richard W Price*1, R Palmatier2, S Wring2, J Lu3,4, B Baker2, J Sailstad2, N Lollo1, S Spudich1, R Hoh5, T Liegler5, D Miralles2, D Kuritzkes3,4, and S Deeks5
 
1Univ of California, San Francisco, USA; 2Trimeris, Inc, Durham, NC, USA; 3Brigham & Women's Hosp, Harvard Med Sch, Boston, MA, USA; 4Harvard Med Sch, Boston, MA, USA; and 5Univ of California, San Francisco, USA
 
Background: The degree to which cerebrospinal fluid (CSF) HIV reflects recent blood-derived (transitory) virus vs local (autonomous) infection in different clinical settings remains undefined. Enfuvirtide (ENF, T-20) is a potent inhibitor of systemic HIV replication, but has uncertain activity in the CSF. Here, we define CSF ENF pharmacokinetics and show its potential utility to explore the origin of CSF HIV.
 
Methods: ENF CSF pharmacokinetics was assessed using 18 CSF and plasma sample pairs from 4 HIV-infected subjects. Drug levels were measured by LCMSMS using known standards, including spiked CSF samples from untreated, HIV subjects. HIV RNA levels were assessed by PCR. A segment of the gp41-coding region encompassing the HR-1 and HR-2 domains was amplified from selected CSF or plasma samples, and independent clones sequenced to assess resistance mutations.
 
Results: CSF and plasma samples obtained between 2 and 20 hours post-ENF injection showed plasma concentrations similar to previous reports (mean 3.687 1.828 eg/mL SD) with prolonged decay. By contrast, ENF in all CSF samples was below the assay detection limit of 0.025 eg/mL. In general, when plasma HIV RNA levels were undetectable so were those in CSF. However, 1 subject developed a transient increase in CSF HIV RNA to 171,000 copies/mL compared with plasma of 5440 copies/mL with marked CSF pleocytosis (260 cells/L). Notably, 7 of 7 CSF and 8 of 8 plasma clones from this subject had the same ENF-resistance-associated V38A mutation suggesting systemic viral selection. Another subject, resistant to ENF, stopped the drug (but remained on all other drugs) and showed a small transient increase in CSF virus parallel to an increase in plasma HIV, also likely indicating "overflow" of plasma virus to CSF. A third individual with atypical neuropathy showed disproportionate elevation of CSF HIV (8320 compared with plasma 26 copies/mL) and pleocytosis (resistance analysis pending).
 
Conclusions: ENF CSF penetration is negligible. However, since CSF infection often results from transitory mechanisms with transfer of virus and T cells from blood to CSF, ENF may help to control CSF HIV indirectly through effects on systemic infection. Because of its poor penetration and its unique site of action and associated mutational markers of resistance, ENF provides a tool to dissect the origin of CSF virus and explore the therapeutic settings where drug penetration is or is not important.
 
Signs of Neuronal Damage after Antiretroviral Treatment Interruption in HIV-1
 
12th CROI abstract LB16.
Authors and Affiliations: Magnus Gisslen*1, L Rosengren1, L Hagberg1, and R Price2
1Gteborg Univ, Sahlgrenska Univ Hospital, Gteborg, Sweden and 2San Francisco Gen Hosp, Univ of California, USA
 
Background: Neurofilament protein (NFL) is a major structural component of myelinated axons and when measured by ELISA in the cerebrospinal fluid (CSF) can serve as a sensitive marker of axonal damage in a number of conditions.
 
Methods: To assess whether antiviral treatment interruption might have an effect on the central nervous system (CNS), we measured neurofilament protein levels in 8 HIV-infected subjects stopping therapy. Decisions to stop treatment were made by the subjects and their primary caregivers independent of this study, and the subjects volunteered to undergo repeated lumbar punctures in a temporally well-defined study setting that affords an opportunity to observe the dynamics of HIV infection and resultant CSF perturbations. The subjects all had CSF HIV RNA concentrations < 50 copies/mL and were neurologically normal or identified as manifesting at the most AIDS dementia complex stage 0.5 (equivocal/subclinical) disease. Lumbar punctures were performed before treatment interruption and 1 to 6 (mean 2.9) times during the period off treatment.
 
Results: Treatment interruption resulted in an increase in CSF neurofilament protein in 3 of the subjects, rising from < 125 to a measured maximum of 880 (at day 148), 1010 (day 58) and 10,930 ng/L (day 101) respectively in those patients (normal < 250 ng/L). All 8 subjects exhibited an increase in CSF and plasma viral load after stopping therapy, accompanied by an intrathecal immunoactivation with CSF lymphocytic pleocytosis (7 of 8 patients) and increased CSF neopterin concentration (5of 6 patients). None of the subjects experienced new neurological symptoms or signs during the periods off treatment, and of 5 tested, none showed deterioration in their QNPZ-4 score, a quantitative index of neurological performance.
 
Conclusions: These findings suggest that in the setting of treatment interruption, the increase in viremia may result in nervous system injury, albeit asymptomatic, within the time frame of the study. Neurofilament protein is a sensitive marker of axonal injury which in the present setting seems to disclose subclinical injury. Further studies are warranted to examine this issue further.
 
A Rare and Extreme Etiology of HIV-1 in the Cerebrospinal Fluid and Blood in an HIV-infected Non-progressor
 
12th CROI abstract 374.
Authors and Affiliations: Bin Wang*1, M Mikhail1, W Dyer2, J Zaunders3, D Cooper3, A Kelleher3, B Brew4, and N Saksena1
 
1Westmead Millennium Inst, Westmead Hosp, Univ of, Sydney, Australia; 2Australian Red Cross, Sydney; 3St Vincent's Hosp, Darlinghurst, Australia; and 4St Vincent's Hosp, Sydney, Australia
 
Background: In > 30% of adults, HIV can enter the brain at an early stage and can also cause AIDS dementia complex (ADC). In chronically infected therapy nave non-progressors who remain below detection for viremia and maintain robust T-cell counts, the HIV infection of the central nervous system and the cerebrospinal fluid (CSF) remains enigmatic. In this study we describe a rare case of an HIV-infected, treatment-nave non-progressor, who has maintained high and stable CD4 and CD8 counts and was below detection for plasma viremia, but developed AIDS-related neurologic symptom.
 
Methods: Full-length HIV-1 genomes were amplified over time (1992 to 2004), using long-distance PCR from peripheral blood cells and only in 2004 from the CSF. The genomes were sequenced by amplification of individual genomic regions. The individual genomic segments were cloned in PGEM-T vector and sequenced. Maximum likelihood and neighbor-joining algorithms were used for phylogenetic estimations. We used 1000 bootstrap estimates to predict the statistical support for phylogenetic relationships in blood and CSF. G-to-A hypermutation was analyzed using HYPER-MUT from the Los Alamos Database.
 
Results: There was complete absence of viral evolution in vivo throughout the course of HIV infection in all blood-derived HIV-1 genomes between 1992 and 2004. This was attributed to the presence of stop codons in the p17, p24, and protease regions resulting from extensive G-to-A hypermutation in blood-derived virus. In late 2003, the patient started to show neurological symptoms and the lumbar puncture revealed 14,000 copies of HIV/mL in the CSF. Comparison of full-length genomes from blood and CSF in 2004 revealed only 1.4% divergence. All of the stop codons and G-to-A hypermutation were absent in the CSF-derived virus. This is the first evidence of complete absence of viral evolution in blood and low-level evolution in the CSF (< 1.4% divergence). The molecular analysis clearly showed that despite the attenuation of strain in blood compartment, the wild type strain could independently survive in the CSF for almost 17 years with extremely low-level replication and caused neurologic symptoms.
 
Conclusions: The CSF may behave as a distinct viral compartment, which may not depend on disease stage. Importantly, the high CD4+ and CD8+ T-cell counts and below-detection plasma viremia may not protect against neurologic symptoms in some cases. HIV-infected non-progressors should opt for lumbar puncture examination.
 
Compartmentalized HIV-1 Variants Present in Cerebrospinal Fluid of Asymptomatic Subjects Are Produced by Short-lived Cells
 
12th CROI abstract 12
Authors and Affiliations: Patrick R Harrington*1, D Haas2, and R Swanstrom3 1Lineberger Cancer Ctr, Univ of North Carolina at Chapel Hill, USA; 2Vanderbilt Meharry Ctr for AIDS Res, Vanderbilt Univ Med Sch, Nashville, TN, USA; and 3Lineberger Cancer Ctr, Univ of North Carolina at Chapel Hill, USA
 
Background: Little is known about the mechanisms by which HIV-1 persists in the central nervous system over the course of infection. We examined HIV-1 population dynamics in asymptomatic subjects to characterize infected cell sources of HIV-1 in the central nervous system. A major challenge in studying HIV-1 dynamics in the central nervous system is the inability to directly monitor viruses in the brain of infected patients. Studies of HIV-1 in cerebrospinal fluid (CSF) provide a useful surrogate for the sampling of virus in the CNS, but are complicated by the fact that infected cells in local central nervous system tissues and in the periphery contribute to the population pool of HIV-1 in CSF.
 
Methods: We examined viral population dynamics in CSF and peripheral blood plasma during the initial days of antiretroviral therapy in 4 asymptomatic individuals. Heteroduplex tracking assays targeting the V1/V2 and V4/V5 hypervariable regions of env were used to first distinguish between CSF HIV-1 variants that were either shared with peripheral blood plasma or compartmentalized to CSF, and therefore presumably derived from local central nervous system tissues. Individual CSF HIV-1 variants were then tracked longitudinally by heteroduplex tracking assay and phosphor-imaging to monitor their relative decline during therapy.
 
Results: Compartmentalized HIV-1 variants in CSF were readily detected by heteroduplex tracking assay. HIV-1 variants compartmentalized in CSF declined rapidly during the initial days of therapy, often more rapidly than CSF variants shared with the peripheral blood. The maximum half-life of compartmentalized HIV-1 variants in CSF were 1 to 3 days, emulating the kinetics of HIV-1 produced by short-lived CD4+ T cells in the periphery.
 
Conclusions: These results suggest that a short-lived infected cell population exists within the central nervous system and contributes to the vast majority of compartmentalized HIV-1 in CSF of asymptomatic patients. We propose a model whereby short-lived, uninfected CD4+ T cells trafficking into the central nervous system amplify the HIV-1 population produced by longer-lived cells in the central nervous system. These findings illustrate the dynamic nature of HIV-1 replication in the central nervous system and raise the possibility that trafficking CD4+ T cells play a role in HIV-1 persistence and pathogenesis in the central nervous system.