Use of a Shear Reduction Surface for Prehospital Transport: A Randomized Crossover Study.

Objective: To compare the effectiveness of an antishear mattress overlay (ASMO) with a standard ambulance stretcher surface in reducing pressure and shear and increasing patient comfort.

Methods: In this randomized, crossover design, adults in three body mass index categories served as their own controls. Pressure/shear sensors were applied to the sacrum, ischial tuberosity, and heel.

Recommendations for analytical antiretroviral treatment interruptions in HIV research trials-report of a consensus meeting.

Analytical antiretroviral treatment interruption (ATI) is an important feature of HIV research, seeking to achieve sustained viral suppression in the absence of antiretroviral therapy (ART) when the goal is to measure effects of novel therapeutic interventions on time to viral load rebound or altered viral setpoint. Trials with ATIs also intend to determine host, virological, and immunological markers that are predictive of sustained viral control off ART. Although ATI is increasingly incorporated into proof-of-concept trials, no consensus has been reached on strategies to maximise its utility and minimise its risks.

Highlights from the Fourth Biennial Strategies for an HIV Cure Meeting, 10-12 October 2018, Bethesda, MD, USA.

The National Institute of Allergy and Infectious Diseases (NIAID) organised the Strategies for an HIV Cure 2018 meeting focused on research to develop innovative strategies for eradicating or achieving long-term remission of HIV infection. The purpose was to bring together researchers studying HIV persistence and cure strategies, including the six National Institutes of Health (NIH)-funded Martin Delaney Collaboratories for HIV Cure Research (MDCs), as well as industry and community partners, to share scientific results and stimulate active discussion among all stakeholders about the merits of various approaches under investigation. These discussions were intended to stimulate new collaborations and ideas for future research.

Highlights from the 8 International Workshop on HIV Persistence during Therapy, 12-15 December 2017, Miami, FL, USA.

Over 4 days, more than 500 scientists involved in HIV persistence research shared their new unpublished data and designed future perspectives towards ART-free HIV remission. This followed the format of past conferences but further focused on encouraging participation of young investigators, especially through submission of oral and poster presentations. The topic of the workshop was HIV persistence.

Highlights from the Third Biennial Strategies for an HIV Cure Meeting: 14-16 November 2016, Bethesda, MD, USA.

Since the first Strategies for an HIV Cure Meeting organised by the National Institute of Allergy and Infectious Diseases (NIAID) in 2012, one of the primary purposes of the meeting has been to facilitate communication and foster collaboration across the NIAID-funded Martin Delaney Collaboratories for HIV cure research (MDC), the broader HIV cure-related research field, and industry and community stakeholders. This year's meeting agenda reflected NIAID's increasing investment over the last 5 years in research to identify strategies for eradicating or achieving long-term remission of HIV infection. Overviews and research highlights were presented from each of the Martin Delaney Collaboratories, as well as projects funded through the Beyond HAART programme, the Consortia for Innovative AIDS Research in Nonhuman Primates (CIAR) programme, the ACTG and IMPAACT clinical trial networks, and the NIAID Vaccine Research Center in hopes of stimulating cross-talk and synergy among these and other programmes focused on HIV cure research.

Highlights from the Seventh International Workshop on HIV Persistence during Therapy, 8-11 December 2015, Miami, Florida, USA.

Over 4 days, more than 270 scientists involved in HIV persistence research convened to share their data and discuss future avenues to control HIV without continuous antiretroviral therapy. This 7(th) International Workshop on HIV Persistence followed the format of the preceding conferences but more time was given for discussing abstracts submitted by the participants and selected by the Steering and Scientific Committees. The topic of the workshop is HIV persistence: consequently, issues of HIV reservoirs and HIV cure are also addressed.

The prototype HIV-1 maturation inhibitor, bevirimat, binds to the CA-SP1 cleavage site in immature Gag particles.

Background: Bevirimat, the prototype Human Immunodeficiency Virus type 1 (HIV-1) maturation inhibitor, is highly potent in cell culture and efficacious in HIV-1 infected patients. In contrast to inhibitors that target the active site of the viral protease, bevirimat specifically inhibits a single cleavage event, the final processing step for the Gag precursor where p25 (CA-SP1) is cleaved to p24 (CA) and SP1.

Results: In this study, photoaffinity analogs of bevirimat and mass spectrometry were employed to map the binding site of bevirimat to Gag within immature virus-like particles.

A single polymorphism in HIV-1 subtype C SP1 is sufficient to confer natural resistance to the maturation inhibitor bevirimat.

3-O-(3',3'-Dimethylsuccinyl) betulinic acid (DSB), also known as PA-457, bevirimat (BVM), or MPC-4326, is a novel HIV-1 maturation inhibitor. Unlike protease inhibitors, BVM blocks the cleavage of the Gag capsid precursor (CA-SP1) to mature capsid (CA) protein, resulting in the release of immature, noninfectious viral particles. Despite the novel mechanism of action and initial progress made in small-scale clinical trials, further development of bevirimat has encountered unexpected challenges, because patients whose viruses contain genetic polymorphisms in the Gag SP1 (positions 6 to 8) protein do not generally respond well to BVM treatment.

Polymorphisms in Gag spacer peptide 1 confer varying levels of resistance to the HIV- 1 maturation inhibitor bevirimat.

Background: The maturation inhibitor bevirimat (BVM) potently inhibits human immunodeficiency virus type 1 (HIV-1) replication by blocking capsid-spacer peptide 1 (CA-SP1) cleavage. Recent clinical trials demonstrated that a significant proportion of HIV-1-infected patients do not respond to BVM. A patient's failure to respond correlated with baseline polymorphisms at SP1 residues 6-8.

Elevated temperature triggers human respiratory syncytial virus F protein six-helix bundle formation.

Human respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract infection in infants, immunocompromised patients, and the elderly. The RSV fusion (F) protein mediates fusion of the viral envelope with the target cell membrane during virus entry and is a primary target for antiviral drug and vaccine development. The F protein contains two heptad repeat regions, HR1 and HR2.

Complementation of diverse HIV-1 Env defects through cooperative subunit interactions: a general property of the functional trimer.

Background: The HIV-1 Env glycoprotein mediates virus entry by catalyzing direct fusion between the virion membrane and the target cell plasma membrane. Env is composed of two subunits: gp120, which binds to CD4 and the coreceptor, and gp41, which is triggered upon coreceptor binding to promote the membrane fusion reaction. Env on the surface of infected cells is a trimer consisting of three gp120/gp41 homo-dimeric protomers.

Virus maturation as a new HIV-1 therapeutic target.

Development of novel therapeutic targets against HIV-1 is a high research priority owing to the serious clinical consequences associated with acquisition of resistance to current antiretroviral drugs. The HIV-1 structural protein Gag represents a potential new therapeutic target as it plays a central role in virus particle production yet is not targeted by any of the antiretroviral drugs approved at present. The Gag polyprotein precursor multimerizes to form immature particles that bud from the infected cell.

Anti-AIDS agents. 78. Design, synthesis, metabolic stability assessment, and antiviral evaluation of novel betulinic acid derivatives as potent anti-human immunodeficiency virus (HIV) agents.

In a continuing study of potent anti-HIV agents, seventeen 28,30-disubstituted betulinic acid (BA, 1) derivatives and seven novel 3,28-disubstituted BA analogues were designed, synthesized, and evaluated for in vitro antiviral activity. Among them, compound 21 showed an improved solubility and equal anti-HIV potency (EC(50) = 0.09 microM) when compared to HIV entry inhibitors 3b (IC9564, (3R,4S)-N'-[N-[3beta-hydroxy-lup-20(29)-en-28-oyl]-8-aminooctanoyl]-4-amino-3-hydroxy-6-methylheptanoic acid) and 4 (A43-D, [[N-[3beta-O-(3',3'-dimethylsuccinyl)-lup-20(29)-en-28-oyl]-7-aminoheptyl]carbamoyl]methane).

Impact of human immunodeficiency virus type 1 resistance to protease inhibitors on evolution of resistance to the maturation inhibitor bevirimat (PA-457).

The maturation inhibitor bevirimat [3-O-(3',3'dimethysuccinyl)betulinic acid; BVM; also known as PA-457 or DSB] potently inhibits human immunodeficiency virus type 1 (HIV-1) replication by blocking protease (PR)-mediated cleavage at the junction between capsid (CA) and spacer peptide 1 (SP1) in Gag. We previously isolated a panel of single-amino-acid substitutions that confer resistance to BVM in vitro (C. S.

Susceptibility of human immunodeficiency virus type 1 to the maturation inhibitor bevirimat is modulated by baseline polymorphisms in Gag spacer peptide 1.

In this study, we evaluated baseline susceptibility to bevirimat (BVM), the first in a new class of antiretroviral agents, maturation inhibitors. We evaluated susceptibility to BVM by complete gag genotypic and phenotypic testing of 20 patient-derived human immunodeficiency virus type 1 isolates and 20 site-directed mutants. We found that reduced BVM susceptibility was associated with naturally occurring polymorphisms at positions 6, 7, and 8 in Gag spacer peptide 1.

Bevirimat: a novel maturation inhibitor for the treatment of HIV-1 infection.

Existing antiretroviral treatments for HIV type-1 (HIV-1) disease are limited by problems of resistance and drug-drug interactions. Bevirimat is a novel HIV-1 maturation inhibitor with a mechanism of action that is distinct from other antiretroviral agents. Specific inhibition of the final rate-limiting step in Gag processing by bevirimat prevents release of mature capsid protein from its precursor (CA-SP1), resulting in the production of immature, non-infectious virus particles.

Maturation inhibitors: a new therapeutic class targets the virus structure.

The current standard of care for HIV/AIDS in the developed world is HAART therapy, usually a combination of two reverse transcriptase inhibitors and a protease inhibitor. Despite the success of this regimen, there is a continuing need for new drug options to overcome problems with tolerability and the emergence of viral resistance. In this review we discuss the discovery of a potential new class of antiretroviral therapeutics, known as maturation inhibitors, and the development of the first-in-class compound, bevirimat.

Phase I and II study of the safety, virologic effect, and pharmacokinetics/pharmacodynamics of single-dose 3-o-(3',3'-dimethylsuccinyl)betulinic acid (bevirimat) against human immunodeficiency virus infection.

Bevirimat [3-O-(3',3'-dimethylsuccinyl)betulinic acid] is the first in a new class of anti-human immunodeficiency virus (HIV) drugs that inhibit viral maturation by specifically blocking cleavage of the Gag capsid (CA) precursor, CA-SP1, to mature CA protein, resulting in defective core condensation and release of immature noninfectious virions. Four cohorts of six HIV-infected adults, with CD4 counts of >200 and plasma viral loads of 5,000 to 250,000 transcripts/ml and not currently receiving antiretroviral therapy, were randomized to receive a single oral dose of placebo, 75, 150, or 250 mg of bevirimat. Thirty blood samples for drug concentrations and 20 HIV RNA measures were collected from each subject over a 20-day period.

In vitro resistance to the human immunodeficiency virus type 1 maturation inhibitor PA-457 (Bevirimat).

3-O-(3',3'-dimethylsuccinyl)betulinic acid (PA-457 or bevirimat) potently inhibits human immunodeficiency virus type 1 (HIV-1) maturation by blocking a late step in the Gag processing pathway, specifically the cleavage of SP1 from the C terminus of capsid (CA). To gain insights into the mechanism(s) by which HIV-1 could evolve resistance to PA-457 and to evaluate the likelihood of such resistance arising in PA-457-treated patients, we sought to identify and characterize a broad spectrum of HIV-1 variants capable of conferring resistance to this compound. Numerous independent rounds of selection repeatedly identified six single-amino-acid substitutions that independently confer PA-457 resistance: three at or near the C terminus of CA (CA-H226Y, -L231F, and -L231M) and three at the first and third residues of SP1 (SP1-A1V, -A3T, and -A3V).

Determinants of activity of the HIV-1 maturation inhibitor PA-457.

3-O-(3',3'-dimethylsuccinyl) betulinic acid, also termed PA-457 or DSB, is a novel HIV-1 inhibitor that blocks virus maturation by disrupting cleavage of the capsid precursor, CA-SP1. To better define the molecular target for PA-457, we prepared a panel of mutant viruses with point deletions spanning the CA-SP1 cleavage domain and characterized each of these viruses for PA-457 sensitivity. Our results indicate that amino acid residues in the N-terminal half of SP1 serve as determinants of PA-457 activity, while residues in the C-terminal half of SP1 were not involved in compound activity.

3-O-(3',3'-dimethysuccinyl) betulinic acid inhibits maturation of the human immunodeficiency virus type 1 Gag precursor assembled in vitro.

3-O-(3',3'-Dimethysuccinyl) betulinic acid (PA-457) has been shown to potently inhibit human immunodeficiency virus (HIV) replication in culture. In contrast to inhibitors that act upon the viral proteinase, PA-457 appears to block only the final maturational cleavage of p25CA-p2 to p24CA. However, attempts to replicate this effect in vitro using recombinant Gag have failed, leading to the hypothesis that activity is dependent upon the assembly state of Gag.

PA-457: a potent HIV inhibitor that disrupts core condensation by targeting a late step in Gag processing.

New HIV therapies are urgently needed to address the growing problem of drug resistance. In this article, we characterize the anti-HIV drug candidate 3-O-(3',3'-dimethylsuccinyl) betulinic acid (PA-457). We show that PA-457 potently inhibits replication of both WT and drug-resistant HIV-1 isolates and demonstrate that the compound acts by disrupting a late step in Gag processing involving conversion of the capsid precursor (p25) to mature capsid protein (p24).

Direct evidence that C-peptide inhibitors of human immunodeficiency virus type 1 entry bind to the gp41 N-helical domain in receptor-activated viral envelope.

While it has been established that peptides modeling the C-helical region of human immunodeficiency virus type 1 gp41 are potent in vivo inhibitors of virus replication, their mechanism of action has yet to be determined. It has been proposed, but never directly demonstrated, that these peptides block virus entry by interacting with gp41 to disrupt the formation or function of a six-helix bundle structure. Using a six-helix bundle-specific monoclonal antibody with isolate-restricted Env reactivity, we provide the first direct evidence that, in receptor-activated viral Env, C-peptide entry inhibitors bind to the gp41 N-helical coiled-coil to form a peptide/protein hybrid structure and, in doing so, disrupt native six-helix bundle formation.

Cooperative subunit interactions within the oligomeric envelope glycoprotein of HIV-1: functional complementation of specific defects in gp120 and gp41.

The envelope glycoprotein (Env) of HIV-1 is displayed on the surface of the virion or infected cell as an oligomer of multiple gp120/gp41 complexes. We sought to unravel the relationships between this oligomeric structure and the requirements for sequential interactions with CD4 and coreceptor (CCR5 or CXCR4). We used a quantitative cell fusion assay to examine the effects of coexpressing pairs of Envs, each nonfunctional because of a specific defect in one of the essential properties.