scholarly journals Addressing Antiretroviral Drug Resistance with Host-Targeting Drugs—First Steps towards Developing a Host-Targeting HIV-1 Assembly Inhibitor

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 451
Author(s):  
Jaisri R. Lingappa ◽  
Vishwanath R. Lingappa ◽  
Jonathan C. Reed
Keyword(s):  
Life Cycle ◽  
Small Molecule ◽  
Self Assembly ◽  
Antiretroviral Drugs ◽  
Host Protein ◽  
Capsid Assembly ◽  
Genetic Barriers ◽  
Novel Host ◽  
Post Entry ◽  
Hiv 1

The concerning increase in HIV-1 resistance argues for prioritizing the development of host-targeting antiviral drugs because such drugs can offer high genetic barriers to the selection of drug-resistant viral variants. Targeting host proteins could also yield drugs that act on viral life cycle events that have proven elusive to inhibition, such as intracellular events of HIV-1 immature capsid assembly. Here, we review small molecule inhibitors identified primarily through HIV-1 self-assembly screens and describe how all act either narrowly post-entry or broadly on early and late events of the HIV-1 life cycle. We propose that a different screening approach could identify compounds that specifically inhibit HIV-1 Gag assembly, as was observed when a potent rabies virus inhibitor was identified using a host-catalyzed rabies assembly screen. As an example of this possibility, we discuss an antiretroviral small molecule recently identified using a screen that recapitulates the host-catalyzed HIV-1 capsid assembly pathway. This chemotype potently blocks HIV-1 replication in T cells by specifically inhibiting immature HIV-1 capsid assembly but fails to select for resistant viral variants over 37 passages, suggesting a host protein target. Development of such small molecules could yield novel host-targeting antiretroviral drugs and provide insight into chronic diseases resulting from dysregulation of host machinery targeted by these drugs.

scholarly journals Identification of an antiretroviral small molecule that appears to be a host-targeting inhibitor of HIV-1 assembly.

2020 ◽  
Author(s):  
Jonathan C. Reed ◽  
Dennis Solas ◽  
Anatoliy Kitaygorodskyy ◽  
Beverly Freeman ◽  
Dylan T. B. Ressler ◽  
...  
Keyword(s):  
Life Cycle ◽  
Virus Production ◽  
Life Cycle Stage ◽  
Multidrug Resistant ◽  
Capsid Assembly ◽  
Resistance Mutations ◽  
Life Cycle Stages ◽  
Human T Cell ◽  
Gag Assembly ◽  
Hiv 1

Given the projected increase in multidrug resistant HIV-1, there is an urgent need for development of antiretrovirals that act on virus life-cycle stages not targeted by drugs currently in use. Host-targeting compounds are of particular interest because they can offer a high barrier to resistance. Here we report identification of two related small molecules that inhibit HIV-1 late events, an HIV-1 life cycle stage for which potent and specific inhibitors are lacking. This chemotype was discovered using cell-free protein synthesis and assembly systems that recapitulate intracellular host-catalyzed viral capsid assembly pathways. These compounds inhibit replication of HIV-1 in human T cell lines and PBMCs and are effective against a primary isolate. They reduce virus production, likely by inhibiting a post-translational step in HIV-1 Gag assembly. Notably, the compound colocalizes with HIV-1 Gag in situ; however, unexpectedly, selection experiments failed to identify compound-specific resistance mutations in gag or pol, even though known resistance mutations developed upon parallel nelfinavir selection. Thus, we hypothesized that instead of binding to Gag directly, these compounds localize to assembly intermediates, the intracellular multiprotein complexes containing Gag and host factors that form during immature HIV-1 capsid assembly. Indeed, imaging of infected cells shows compound colocalized with two host enzymes found in assembly intermediates, ABCE1 and DDX6, but not two host proteins found in other complexes. While the exact target and mechanism of action of this chemotype remain to be determined, these findings suggest that these compounds represent first-in-class, host-targeting inhibitors of intracellular events in HIV-1 assembly. IMPORTANCE The success of antiretroviral treatment for HIV-1 is at risk of being undermined by the growing problem of drug resistance. Thus, there is a need to identify antiretrovirals that act on viral life cycle stages not targeted by drugs in use, such as the events of HIV-1 Gag assembly. To address this gap, we developed a compound screen that recapitulates the intracellular events of HIV-1 assembly, including viral-host interactions that promote assembly. This effort led to identification of a new chemotype that inhibits HIV-1 replication at nanomolar concentrations, likely by acting on assembly. This compound colocalized with Gag and two host enzymes that facilitate capsid assembly. However, resistance selection did not result in compound-specific mutations in gag, suggesting that the chemotype does not directly target Gag. We hypothesize that this chemotype represents a first-in-class inhibitor of virus production that acts by targeting a viral-host complex important for HIV-1 Gag assembly.

scholarly journals Identification of an antiretroviral small molecule that appears to be a host-targeting inhibitor of HIV-1 assembly

2020 ◽  
Author(s):  
Jonathan C. Reed ◽  
Dennis Solas ◽  
Anatoliy Kitaygorodskyy ◽  
Beverly Freeman ◽  
Dylan T. B. Ressler ◽  
...  
Keyword(s):  
Life Cycle ◽  
Virus Production ◽  
Multidrug Resistant ◽  
Capsid Assembly ◽  
Resistance Mutations ◽  
Life Cycle Stages ◽  
Human T Cell ◽  
T Cell Lines ◽  
Gag Assembly ◽  
Hiv 1

ABSTRACTGiven the projected increase in multidrug resistant HIV-1, there is an urgent need for development of antiretrovirals that act on virus life-cycle stages that are not targeted by antiretrovirals currently in use. Host-targeting drugs are of particular interest because they can offer a high barrier to resistance. Here we report identification of two related small molecules that inhibit HIV-1 late events, a stage of the HIV-1 life cycle for which potent and specific inhibitors are lacking. This chemotype was discovered using cell-free protein synthesis and assembly systems that recapitulate intracellular host-catalyzed viral capsid assembly pathways. These compounds inhibit replication of HIV-1 in human T cell lines and PBMCs and are effective against a primary isolate. They reduce virus production, likely by inhibiting a post-translational step in HIV-1 Gag assembly. Notably, the compound colocalizes with HIV-1 Gag in situ; however, unexpectedly, selection experiments failed to identify compound-specific resistance mutations in gag or pol, even though known resistance mutations developed in a parallel nelfinavir selection. Thus, we hypothesized that instead of binding to Gag directly, these compounds might localize to assembly intermediates, the intracellular multiprotein complexes containing Gag and host factors that are formed during immature HIV-1 capsid assembly. Indeed, imaging of infected cells showed colocalization of the compound with two host enzymes found in assembly intermediates, ABCE1 and DDX6. While the exact target and mechanism of action of this chemotype remain to be determined, these findings suggest that these compounds represent first-in-class, host-targeting inhibitors of intracellular events in HIV-1 assembly.IMPORTANCEThe success of antiretroviral treatment for HIV-1 is at risk of being undermined by the growing problem of drug resistance. Thus, there is a need to identify antiretrovirals that act on viral life cycle stages not targeted by drugs in use, such as the events of HIV-1 Gag assembly. To address this gap, we developed a compound screen that recapitulates the intracellular events of HIV-1 assembly, including viral-host interactions that promote assembly. This effort led to identification of a new chemotype that inhibits HIV-1 replication at nanomolar concentrations by inhibiting virus production. This compound colocalized with Gag and two host enzymes that facilitate capsid assembly but resistance selection did not result in compound-specific mutations in gag, suggesting that the chemotype does not directly target Gag. We hypothesize that this chemotype may represent a first-in-class inhibitor of virus production that acts by targeting a viral-host complex important for HIV-1 Gag assembly.

scholarly journals Compensatory Substitutions in the HIV-1 Capsid Reduce the Fitness Cost Associated with Resistance to a Capsid-Targeting Small-Molecule Inhibitor

2014 ◽  
Vol 89 (1) ◽  
pp. 208-219 ◽  
Author(s):  
Jiong Shi ◽  
Jing Zhou ◽  
Upul D. Halambage ◽  
Vaibhav B. Shah ◽  
Mallori J. Burse ◽  
...  
Keyword(s):  
Amino Acid ◽  
Small Molecule ◽  
Therapeutic Target ◽  
Binding Pocket ◽  
Host Protein ◽  
Viral Capsid ◽  
Inhibitory Protein ◽  
Hiv 1 ◽  
Ca Protein

ABSTRACTThe HIV-1 capsid plays multiple roles in infection and is an emerging therapeutic target. The small-molecule HIV-1 inhibitor PF-3450074 (PF74) blocks HIV-1 at an early postentry stage by binding the viral capsid and interfering with its function. Selection for resistance resulted in accumulation of five amino acid changes in the viral CA protein, which collectively reduced binding of the compound to HIV-1 particles. In the present study, we dissected the individual and combinatorial contributions of each of the five substitutions Q67H, K70R, H87P, T107N, and L111I to PF74 resistance, PF74 binding, and HIV-1 infectivity. Q67H, K70R, and T107N each conferred low-level resistance to PF74 and collectively conferred strong resistance. The substitutions K70R and L111I impaired HIV-1 infectivity, which was partially restored by the other substitutions at positions 67 and 107. PF74 binding to HIV-1 particles was reduced by the Q67H, K70R, and T107N substitutions, consistent with the location of these positions in the inhibitor-binding pocket. Replication of the 5Mut virus was markedly impaired in cultured macrophages, reminiscent of the previously reported N74D CA mutant. 5Mut substitutions also reduced the binding of the host protein CPSF6 to assembled CA complexesin vitroand permitted infection of cells expressing the inhibitory protein CPSF6-358. Our results demonstrate that strong resistance to PF74 requires accumulation of multiple substitutions in CA to inhibit PF74 binding and compensate for fitness impairments associated with some of the sequence changes.IMPORTANCEThe HIV-1 capsid is an emerging drug target, and several small-molecule compounds have been reported to inhibit HIV-1 infection by targeting the capsid. Here we show that resistance to the capsid-targeting inhibitor PF74 requires multiple amino acid substitutions in the binding pocket of the CA protein. Three changes in CA were necessary to inhibit binding of PF74 while maintaining viral infectivity. Replication of the PF74-resistant HIV-1 mutant was impaired in macrophages, likely owing to altered interactions with host cell factors. Our results suggest that HIV-1 resistance to capsid-targeting inhibitors will be limited by functional constraints on the viral capsid protein. Therefore, this work enhances the attractiveness of the HIV-1 capsid as a therapeutic target.

scholarly journals 1E7-03, a Small Molecule Targeting Host Protein Phosphatase-1, Inhibits HIV-1 Transcription

2014 ◽  
pp. n/a-n/a ◽  
Author(s):  
Tatyana Ammosova ◽  
Maxim Platonov ◽  
Andrei Ivanov ◽  
Yasemin Saygideğer Kont ◽  
Namita Kumari ◽  
...  
Keyword(s):  
Small Molecule ◽  
Protein Phosphatase ◽  
Host Protein ◽  
Protein Phosphatase 1 ◽  
Hiv 1

scholarly journals Coarse-grained simulation reveals key features of HIV-1 capsid self-assembly

2016 ◽  
Author(s):  
John M A Grime ◽  
James F Dama ◽  
Barbie K Ganser-Pornillos ◽  
Cora L Woodward ◽  
Grant J Jensen ◽  
...  
Keyword(s):  
Self Assembly ◽  
Coarse Grained ◽  
Capsid Assembly ◽  
Molecular Crowding ◽  
Local Conditions ◽  
Conformational Variability ◽  
Multi Stage ◽  
Capsid Shell ◽  
Coarse Grained Simulations ◽  
Hiv 1

The maturation of HIV-1 viral particles is essential for viral infectivity. During maturation, many copies of the capsid protein (CA) self-assemble into a capsid shell to enclose the viral RNA. The mechanistic details of the initiation and early stages of capsid assembly remain to be delineated. We present coarse-grained simulations of capsid assembly under various conditions, considering not only capsid lattice self-assembly but also the potential disassembly of capsid upon delivery to the cytoplasm of a target cell. The effects of CA concentration, molecular crowding, and the conformational variability of CA are described, with results indicating that capsid nucleation and growth is a multi-stage process requiring well-defined metastable intermediates. Generation of the mature capsid lattice is sensitive to local conditions, with relatively subtle changes in CA concentration and molecular crowding influencing self-assembly and the ensemble of structural morphologies.

scholarly journals From Entry to Egress: Strategic Exploitation of the Cellular Processes by HIV-1

2020 ◽  
Vol 11 ◽  
Author(s):  
Pavitra Ramdas ◽  
Amit Kumar Sahu ◽  
Tarun Mishra ◽  
Vipin Bhardwaj ◽  
Ajit Chande
Keyword(s):  
Life Cycle ◽  
Nuclear Import ◽  
Arms Race ◽  
Surface Proteins ◽  
Restriction Factors ◽  
Host Restriction ◽  
Cellular Processes ◽  
Host Restriction Factors ◽  
Post Entry ◽  
Hiv 1

HIV-1 employs a rich arsenal of viral factors throughout its life cycle and co-opts intracellular trafficking pathways. This exquisitely coordinated process requires precise manipulation of the host microenvironment, most often within defined subcellular compartments. The virus capitalizes on the host by modulating cell-surface proteins and cleverly exploiting nuclear import pathways for post entry events, among other key processes. Successful virus–cell interactions are indeed crucial in determining the extent of infection. By evolving defenses against host restriction factors, while simultaneously exploiting host dependency factors, the life cycle of HIV-1 presents a fascinating montage of an ongoing host–virus arms race. Herein, we provide an overview of how HIV-1 exploits native functions of the host cell and discuss recent findings that fundamentally change our understanding of the post-entry replication events.

scholarly journals Inhibition of HIV-1 Maturation via Small-Molecule Targeting of the Amino-Terminal Domain in the Viral Capsid Protein

2017 ◽  
Vol 91 (9) ◽  
Author(s):  
Weifeng Wang ◽  
Jing Zhou ◽  
Upul D. Halambage ◽  
Kellie A. Jurado ◽  
Augusta V. Jamin ◽  
...  
Keyword(s):  
Amino Acid ◽  
Binding Site ◽  
Capsid Protein ◽  
Small Molecule ◽  
Single Amino Acid ◽  
Viral Capsid ◽  
Capsid Assembly ◽  
Amino Terminal ◽  
Terminal Domain ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) capsid protein is an attractive therapeutic target, owing to its multifunctionality in virus replication and the high fitness cost of amino acid substitutions in capsids to HIV-1 infectivity. To date, small-molecule inhibitors have been identified that inhibit HIV-1 capsid assembly and/or impair its function in target cells. Here, we describe the mechanism of action of the previously reported capsid-targeting HIV-1 inhibitor, Boehringer-Ingelheim compound 1 (C1). We show that C1 acts during HIV-1 maturation to prevent assembly of a mature viral capsid. However, unlike the maturation inhibitor bevirimat, C1 did not significantly affect the kinetics or fidelity of Gag processing. HIV-1 particles produced in the presence of C1 contained unstable capsids that lacked associated electron density and exhibited impairments in early postentry stages of infection, most notably reverse transcription. C1 inhibited assembly of recombinant HIV-1 CA in vitro and induced aberrant cross-links in mutant HIV-1 particles capable of spontaneous intersubunit disulfide bonds at the interhexamer interface in the capsid lattice. Resistance to C1 was conferred by a single amino acid substitution within the compound-binding site in the N-terminal domain of the CA protein. Our results demonstrate that the binding site for C1 represents a new pharmacological vulnerability in the capsid assembly stage of the HIV-1 life cycle. IMPORTANCE The HIV-1 capsid protein is an attractive but unexploited target for clinical drug development. Prior studies have identified HIV-1 capsid-targeting compounds that display different mechanisms of action, which in part reflects the requirement for capsid function at both the efferent and afferent phases of viral replication. Here, we show that one such compound, compound 1, interferes with assembly of the conical viral capsid during virion maturation and results in perturbations at a specific protein-protein interface in the capsid lattice. We also identify and characterize a mutation in the capsid protein that confers resistance to the inhibitor. This study reveals a novel mechanism by which a capsid-targeting small molecule can inhibit HIV-1 replication.

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