Publications by authors named "Melanie Dimapasoc"

8 Publications

  • Page 1 of 1

Tracking HIV Rebound following Latency Reversal Using Barcoded HIV.

Cell Rep Med 2020 Dec 22;1(9):100162. Epub 2020 Dec 22.

Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA.

HIV latency prevents cure of infection with antiretroviral therapy (ART) alone. One strategy for eliminating latently infected cells involves the induction of viral protein expression via latency-reversing agents (LRAs), allowing killing of host cells by viral cytopathic effects or immune effector mechanisms. Here, we combine a barcoded HIV approach and a humanized mouse model to study the effects of a designed, synthetic protein kinase C modulating LRA on HIV rebound. We show that administration of this compound during ART results in a delay in rebound once ART is stopped. Furthermore, the rebounding virus appears composed of a smaller number of unique barcoded viruses than occurs in control-treated animals, suggesting that some reservoir cells that would have contributed virus to the rebound process are eliminated by LRA administration. These data support the use of barcoded virus to study rebound and suggest that LRAs may be useful in HIV cure efforts.
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http://dx.doi.org/10.1016/j.xcrm.2020.100162DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7762775PMC
December 2020

Pharmacological Activation of Non-canonical NF-κB Signaling Activates Latent HIV-1 Reservoirs .

Cell Rep Med 2020 Jun 23;1(3):100037. Epub 2020 Jun 23.

Infectious and Inflammatory Disease Center, Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA.

"Shock and kill" strategies focus on purging the latent HIV-1 reservoir by treating infected individuals with therapeutics that activate the latent virus and subsequently eliminating infected cells. We have previously reported that induction of non-canonical nuclear factor κB (NF-κB) signaling through a class of small-molecule antagonists known as Smac mimetics can reverse HIV-1 latency. Here, we describe the development of Ciapavir (SBI-0953294), a molecule specifically optimized for HIV-1 latency reversal that was found to be more efficacious as a latency-reversing agent than other Smac mimetics under clinical development for cancer. Critically, this molecule induced activation of HIV-1 reservoirs in a bone marrow, liver, thymus (BLT) humanized mouse model without mediating systemic T cell activation. This study provides proof of concept for the efficacy and safety of Ciapavir and indicates that Smac mimetics can constitute a critical component of a safe and efficacious treatment strategy to eliminate the latent HIV-1 reservoir.
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http://dx.doi.org/10.1016/j.xcrm.2020.100037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7659604PMC
June 2020

Prodrugs of PKC modulators show enhanced HIV latency reversal and an expanded therapeutic window.

Proc Natl Acad Sci U S A 2020 05 5;117(20):10688-10698. Epub 2020 May 5.

Department of Chemistry, Stanford University, Stanford, CA 94305;

AIDS is a pandemic disease caused by HIV that affects 37 million people worldwide. Current antiretroviral therapy slows disease progression but does not eliminate latently infected cells, which resupply active virus, thus necessitating lifelong treatment with associated compliance, cost, and chemoexposure issues. Latency-reversing agents (LRAs) activate these cells, allowing for their potential clearance, thus presenting a strategy to eradicate the infection. Protein kinase C (PKC) modulators-including prostratin, ingenol esters, bryostatin, and their analogs-are potent LRAs in various stages of development for several clinical indications. While LRAs are promising, a major challenge associated with their clinical use is sustaining therapeutically meaningful levels of the active agent while minimizing side effects. Here we describe a strategy to address this problem based on LRA prodrugs, designed for controllable release of the active LRA after a single injection. As intended, these prodrugs exhibit comparable or superior in vitro activity relative to the parent compounds. Selected compounds induced higher in vivo expression of CD69, an activation biomarker, and, by releasing free agent over time, significantly improved tolerability when compared to the parent LRAs. More generally, selected prodrugs of PKC modulators avoid the bolus toxicities of the parent drug and exhibit greater efficacy and expanded tolerability, thereby addressing a longstanding objective for many clinical applications.
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http://dx.doi.org/10.1073/pnas.1919408117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7245087PMC
May 2020

Influence of sickle cell disease on susceptibility to HIV infection.

PLoS One 2020 8;15(4):e0218880. Epub 2020 Apr 8.

Vitalant Research Institute, San Francisco, CA, United States of America.

People with sickle cell disease (SCD) are reported to have low rates of HIV infection, slower progression to AIDS and lower HIV-associated mortality compared to the general population. Mechanisms of potential resistance to HIV in SCD are incompletely understood. We retrospectively reviewed the Transfusion Safety Study to compare HIV status between people with SCD and other congenital anemias who were routinely exposed to blood products during the high-risk period before HIV screening implementation. Non-SCD congenital anemia diagnosis was associated with a higher risk of HIV acquisition compared to SCD (OR 13.1 95%CI 1.6-108.9). In addition, we prospectively enrolled 30 SCD cases and 30 non-SCD controls to investigate potential mechanisms of resistance to HIV in SCD. CCR5 and CCR7 expression was lower and CD4 expression was higher on CD4+ T cells from SCD cases compared to controls. Surface expression of CD4+ T cell CXCR4, CD38 and HLA-DR did not differ between the groups. SCD CD4+ T cells were not less susceptible to HIV infection than controls. Levels of multiple cytokines were elevated in the SCD plasma, but SCD plasma compared to control plasma did not inhibit HIV infection of target cells. In conclusion, our epidemiological data support people with SCD being resistant to HIV infection. Potential mechanisms include lower CD4+ T cell expression of CCR5 and CCR7, balanced by increased CD4 expression and cytokine levels, which did not result in in vitro resistance to HIV infection. Further study is needed to define the risk and pathophysiology of HIV in persons with SCD.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0218880PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7141606PMC
July 2020

Assessing suitability of next-generation viral outgrowth assays as proxies for classic QVOA to measure HIV-1 latent reservoir size.

J Infect Dis 2020 Mar 9. Epub 2020 Mar 9.

Vitalant Research Institute, San Francisco, CA, USA.

Background: Evaluations of HIV curative interventions require reliable and efficient quantification of replication-competent latent reservoirs (LR). The "classic" quantitative viral outgrowth assay (QVOA) has been regarded as "gold standard," although prohibitively resource- and labor-intensive. We compared six "next-gen" VOA employing PCR or ultrasensitive p24 to assess their suitability as scalable proxies for QVOA.

Methods: Next-gen VOA were compared to classic QVOA using single leukapheresis-derived samples from five ART-suppressed HIV+ participants and one HIV- control; each lab tested blinded batches of three frozen and one fresh sample. Markov chain Monte Carlo methods estimated extra-Poisson variation at aliquot, batch, and lab levels. Models also estimated the effect of testing frozen versus fresh samples.

Results: Next-gen VOA had similar estimates of variation to QVOA. Assays with ultrasensitive readout reported higher IUPM than classic QVOA. Within-batch testing had 2.5-fold extra-Poisson variation (95%CI 2.1,3.5) for next-gen assays. Between-lab variation increased extra-Poisson variation to 3.4-fold (95% CI 2.6,5.4). Frozen storage did not substantially alter IUPM (-18%(-52%,+39%)).

Conclusions: The data offer cautious support for use of next-gen VOA as proxies for more laborious QVOA, while providing greater sensitivities and dynamic ranges. Measurement of LR in eradication strategies would benefit from high throughput and scalable assays.
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http://dx.doi.org/10.1093/infdis/jiaa089DOI Listing
March 2020

Assessing intra-lab precision and inter-lab repeatability of outgrowth assays of HIV-1 latent reservoir size.

PLoS Comput Biol 2019 04 12;15(4):e1006849. Epub 2019 Apr 12.

Blood Systems Research Institute, San Francisco, California, United States of America.

Quantitative viral outgrowth assays (QVOA) use limiting dilutions of CD4+ T cells to measure the size of the latent HIV-1 reservoir, a major obstacle to curing HIV-1. Efforts to reduce the reservoir require assays that can reliably quantify its size in blood and tissues. Although QVOA is regarded as a "gold standard" for reservoir measurement, little is known about its accuracy and precision or about how cell storage conditions or laboratory-specific practices affect results. Owing to this lack of knowledge, confidence intervals around reservoir size estimates-as well as judgments of the ability of therapeutic interventions to alter the size of the replication-competent but transcriptionally inactive latent reservoir-rely on theoretical statistical assumptions about dilution assays. To address this gap, we have carried out a Bayesian statistical analysis of QVOA reliability on 75 split samples of peripheral blood mononuclear cells (PBMC) from 5 antiretroviral therapy (ART)-suppressed participants, measured using four different QVOAs at separate labs, estimating assay precision and the effect of frozen cell storage on estimated reservoir size. We found that typical assay results are expected to differ from the true value by a factor of 1.6 to 1.9 up or down. Systematic assay differences comprised a 24-fold range between the assays with highest and lowest scales, likely reflecting differences in viral outgrowth readout and input cell stimulation protocols. We also found that controlled-rate freezing and storage of samples did not cause substantial differences in QVOA compared to use of fresh cells (95% probability of < 2-fold change), supporting continued use of frozen storage to allow transport and batched analysis of samples. Finally, we simulated an early-phase clinical trial to demonstrate that batched analysis of pre- and post-therapy samples may increase power to detect a three-fold reservoir reduction by 15 to 24 percentage points.
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http://dx.doi.org/10.1371/journal.pcbi.1006849DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6481870PMC
April 2019

Continued Transmission of HIV Among Young Adults Who Inject Drugs in San Francisco: Still Room for Improvement.

AIDS Behav 2018 04;22(4):1383-1394

Epidemiology, Biostatistics and Preventive Medicine, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM, USA.

We measured HIV incidence rate, trend and risk factors in 564 HIV-negative young people (< 30 years) who inject drugs (PWID) in San Francisco between 2000 and 2014. HIV incidence was 0.93/100 person-years (PY; 95% CI 0.50, 1.73). Incidence varied between 0.62/100 PY in 2000-2002 and 1.06/100 PY in 2012-2014 (P for trend = 1.0). HIV incidence varied significantly (P < 0.01) by race/ethnicity: among Hispanics it was 8.19/100 PY (95% CI 3.41, 19.68), African-Americans 4.59/100 PY (95% CI 1.15, 18.37), and Whites 0.26/100 PY (95% CI 0.06, 1.03). Male participants who reported sex with men (MSM) had higher HIV incidence (2.63/100 PY; 95% CI 1.31, 5.25) compared to males who did not report MSM (0.50/100 PY; 95% CI 0.12, 1.99) (P = 0.01). Despite an overall stable HIV incidence trend, incidence was elevated among African-American and Hispanic PWID, and men who have sex with men. Addressing prevention needs in these key populations is critical for the goal of eliminating HIV transmission.
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http://dx.doi.org/10.1007/s10461-017-1988-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6054135PMC
April 2018

Feasibility of routine ferritin testing for donor management: validation of delayed processing and demonstration of within donor reproducibility over time.

Transfusion 2016 Oct;56(10):2422-2425

Viral Reference Laboratory and Repository Core, Blood Systems Research Institute, San Francisco, California.

Background: Understanding the effect of delayed processing of whole blood on plasma ferritin will inform the feasibility of both routine ferritin testing in donors and clinical research study design.

Study Design And Methods: Whole blood tubes drawn from 16 donors were held at 4°C and centrifuged at 24-hour intervals to assess plasma ferritin concentration up to 5 days after draw. Intraindividual variation over time was measured in 21 healthy donors in blood samples collected weekly for 4 weeks and then at 12 weeks.

Results: No significant variation in plasma ferritin concentration was observed in blood stored at 4°C for up to 5 days after draw (p = 0.32). The estimated loss of 4.75% ferritin over 5 days was within the reported 5% variation of the assay. Moderate intraindividual variation occurs over time in both sexes, with variability increasing with the mean. No difference was detected between men and women in the regression of standard deviation on mean ferritin (p = 0.43).

Conclusions: Ferritin is stable in whole blood up to 5 days, demonstrating operational feasibility of its use in monitoring donor iron stores. Moderate fluctuations over time occur, but ferritin measurements are sufficiently reliable to determine donor iron status on the day of donation.
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http://dx.doi.org/10.1111/trf.13793DOI Listing
October 2016