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Background: Reversing immune exhaustion with an anti-PD-L1 antibody may improve human immunodeficiency virus type 1 (HIV-1)-specific immunity and increase clearance of HIV-1-expressing cells. Methods: We conducted a phase I, randomized, double-blind, placebo-controlled, dose-escalating study of BMS-936559, including HIV-1-infected adults aged >18 to <70 years on suppressive antiretroviral therapy with CD4+ counts >350 cells/µL and detectable plasma HIV-1 RNA by single-copy assay. Data on single infusions of BMS-936559 (0.3 mg/kg) versus placebo are described. The primary outcomes were safety defined as any grade 3 or greater or immune-related adverse event (AE) and the change in HIV-1 Gag-specific CD8+ T cell responses from baseline to day 28 after infusion. Results: Eight men enrolled: 6 received 0.3 mg/kg of BMS-936559, and 2 received placebo infusions. There were no BMS-936559-related grade 3 or greater AEs. In 1 participant, asymptomatic hypophysitis (a protocol-defined immune-related AE) was identified 266 days after BMS-936559 infusion; it resolved over time. The mean percentage of HIV-1 Gag-specific CD8+ T cells expressing interferon γ increased from baseline (0.09%) through day 28 (0.20%; P = .14), driven by substantial increases in 2 participants who received BMS-936559. Conclusions: In this first evaluation of an immunologic checkpoint inhibitor in healthy HIV-1-infected persons, single low-dose BMS-936559 infusions appeared to enhance HIV-1-specific immunity in a subset of participants. Clinical Trials Registration: NCT02028403.
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Antirretrovirais/uso terapêutico , Anticorpos Monoclonais/uso terapêutico , Antígeno B7-H1/antagonistas & inibidores , Infecções por HIV/tratamento farmacológico , Adulto , Linfócitos T CD8-Positivos , Infecções por HIV/imunologia , Infecções por HIV/virologia , HIV-1 , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Respiratory syncytial virus (RSV) can cause pulmonary complications in infants, elderly and immunocompromised patients. While two vaccines and two prophylactic monoclonal antibodies are now available, treatment options are still needed. JNJ-7184 is a non-nucleoside inhibitor of the RSV-Large (L) polymerase, displaying potent inhibition of both RSV-A and -B strains. Resistance selection and hydrogen-deuterium exchange experiments suggest JNJ-7184 binds RSV-L in the connector domain. JNJ-7184 prevents RSV replication and transcription by inhibiting initiation or early elongation. JNJ-7184 is effective in air-liquid interface cultures and therapeutically in neonatal lambs, acting to drastically reverse the appearance of lung pathology.
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Antivirais , Infecções por Vírus Respiratório Sincicial , Vírus Sincicial Respiratório Humano , Replicação Viral , Antivirais/farmacologia , Antivirais/química , Infecções por Vírus Respiratório Sincicial/tratamento farmacológico , Infecções por Vírus Respiratório Sincicial/virologia , Animais , Humanos , Replicação Viral/efeitos dos fármacos , Vírus Sincicial Respiratório Humano/efeitos dos fármacos , Ovinos , Farmacorresistência Viral , Proteínas Virais/antagonistas & inibidores , Proteínas Virais/metabolismo , Proteínas Virais/genética , Pulmão/virologiaRESUMO
Despite truly impressive achievements in the global battle against HIV there remains a need for new drugs directed against novel targets, and the viral capsid protein (CA) may represent one such target. Intense structural characterization of CA over the last two decades has provided unprecedented insight into the structure and assembly of this key viral protein. Furthermore, several inhibitor-binding sites that elicit antiviral activity have been reported on CA, two of which are located on its N-terminal domain (CANTD). In this work, the binding of a novel capsid-assembly inhibitor that targets a unique inhibitory site on CANTD is reported. Moreover, whereas cocrystallization of CANTD in complex with ligands has proven to be challenging in the past, the use of this inhibitor as a tool compound is shown to vastly facilitate ternary cocrystallizations with CANTD. This improvement in crystallization is likely to be achieved through the formation of a compound-mediated homodimer, the intrinsic symmetry of which greatly increases the prospect of generating a crystal lattice. While protein engineering has been used in the literature to support a link between the inherent symmetry of a macromolecule and its propensity to crystallize, to our knowledge this work represents the first use of a synthetic ligand for this purpose.
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Antivirais/química , Proteínas do Capsídeo/química , Capsídeo/química , HIV-1/química , Antivirais/metabolismo , Sítios de Ligação , Capsídeo/metabolismo , Proteínas do Capsídeo/antagonistas & inibidores , Proteínas do Capsídeo/metabolismo , Cristalização , HIV-1/metabolismo , Modelos Moleculares , Difração de Raios XRESUMO
The identification of novel antiretroviral agents is required to provide alternative treatment options for HIV-1-infected patients. The screening of a phenotypic cell-based viral replication assay led to the identification of a novel class of 4,5-dihydro-1H-pyrrolo[3,4-c]pyrazol-6-one (pyrrolopyrazolone) HIV-1 inhibitors, exemplified by two compounds: BI-1 and BI-2. These compounds inhibited early postentry stages of viral replication at a step(s) following reverse transcription but prior to 2 long terminal repeat (2-LTR) circle formation, suggesting that they may block nuclear targeting of the preintegration complex. Selection of viruses resistant to BI-2 revealed that substitutions at residues A105 and T107 within the capsid (CA) amino-terminal domain (CANTD) conferred high-level resistance to both compounds, implicating CA as the antiviral target. Direct binding of BI-1 and/or BI-2 to CANTD was demonstrated using isothermal titration calorimetry and nuclear magnetic resonance (NMR) chemical shift titration analyses. A high-resolution crystal structure of the BI-1:CANTD complex revealed that the inhibitor bound within a recently identified inhibitor binding pocket (CANTD site 2) between CA helices 4, 5, and 7, on the surface of the CANTD, that also corresponds to the binding site for the host factor CPSF-6. The functional consequences of BI-1 and BI-2 binding differ from previously characterized inhibitors that bind the same site since the BI compounds did not inhibit reverse transcription but stabilized preassembled CA complexes. Hence, this new class of antiviral compounds binds CA and may inhibit viral replication by stabilizing the viral capsid.
Assuntos
Fármacos Anti-HIV/farmacologia , Proteínas do Capsídeo/metabolismo , HIV-1/efeitos dos fármacos , Fármacos Anti-HIV/química , Linhagem Celular , Cristalografia por Raios X , HIV-1/fisiologia , Humanos , Espectroscopia de Ressonância Magnética , Reação em Cadeia da Polimerase , Replicação Viral/efeitos dos fármacosRESUMO
The emergence of resistance to existing classes of antiretroviral drugs necessitates finding new HIV-1 targets for drug discovery. The viral capsid (CA) protein represents one such potential new target. CA is sufficient to form mature HIV-1 capsids in vitro, and extensive structure-function and mutational analyses of CA have shown that the proper assembly, morphology, and stability of the mature capsid core are essential for the infectivity of HIV-1 virions. Here we describe the development of an in vitro capsid assembly assay based on the association of CA-NC subunits on immobilized oligonucleotides. This assay was used to screen a compound library, yielding several different families of compounds that inhibited capsid assembly. Optimization of two chemical series, termed the benzodiazepines (BD) and the benzimidazoles (BM), resulted in compounds with potent antiviral activity against wild-type and drug-resistant HIV-1. Nuclear magnetic resonance (NMR) spectroscopic and X-ray crystallographic analyses showed that both series of inhibitors bound to the N-terminal domain of CA. These inhibitors induce the formation of a pocket that overlaps with the binding site for the previously reported CAP inhibitors but is expanded significantly by these new, more potent CA inhibitors. Virus release and electron microscopic (EM) studies showed that the BD compounds prevented virion release, whereas the BM compounds inhibited the formation of the mature capsid. Passage of virus in the presence of the inhibitors selected for resistance mutations that mapped to highly conserved residues surrounding the inhibitor binding pocket, but also to the C-terminal domain of CA. The resistance mutations selected by the two series differed, consistent with differences in their interactions within the pocket, and most also impaired virus replicative capacity. Resistance mutations had two modes of action, either directly impacting inhibitor binding affinity or apparently increasing the overall stability of the viral capsid without affecting inhibitor binding. These studies demonstrate that CA is a viable antiviral target and demonstrate that inhibitors that bind within the same site on CA can have distinct binding modes and mechanisms of action.
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Fármacos Anti-HIV/farmacologia , Capsídeo/efeitos dos fármacos , Produtos do Gene gag/antagonistas & inibidores , Infecções por HIV/virologia , HIV-1/efeitos dos fármacos , Benzimidazóis/farmacologia , Benzodiazepinas/farmacologia , Capsídeo/metabolismo , Linhagem Celular , Produtos do Gene gag/química , Produtos do Gene gag/genética , Produtos do Gene gag/metabolismo , Infecções por HIV/tratamento farmacológico , HIV-1/química , HIV-1/genética , HIV-1/fisiologia , Humanos , Estrutura Terciária de Proteína , Montagem de Vírus/efeitos dos fármacosRESUMO
A uHTS campaign led to the discovery of a 5-(5-furan-2-ylpyrazol-1-yl)-1H-benzimidazole series that inhibits assembly of HIV-1 capsid. Synthetic manipulations at N1, C2 and C16 positions improved the antiviral potency by a . The X-ray structure of 33 complexed with the capsid N-terminal domain allowed identification of major interactions between the inhibitor and the protein.
Assuntos
Antivirais/farmacologia , Benzimidazóis/farmacologia , Proteínas do Capsídeo/antagonistas & inibidores , HIV-1/efeitos dos fármacos , Antivirais/síntese química , Antivirais/química , Benzimidazóis/síntese química , Benzimidazóis/química , Relação Dose-Resposta a Droga , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
The worldwide outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. Alongside vaccines, antiviral therapeutics are an important part of the healthcare response to countering the ongoing threat presented by COVID-19. Here, we report the discovery and characterization of PF-07321332, an orally bioavailable SARS-CoV-2 main protease inhibitor with in vitro pan-human coronavirus antiviral activity and excellent off-target selectivity and in vivo safety profiles. PF-07321332 has demonstrated oral activity in a mouse-adapted SARS-CoV-2 model and has achieved oral plasma concentrations exceeding the in vitro antiviral cell potency in a phase 1 clinical trial in healthy human participants.
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Tratamento Farmacológico da COVID-19 , Lactamas/farmacologia , Lactamas/uso terapêutico , Leucina/farmacologia , Leucina/uso terapêutico , Nitrilas/farmacologia , Nitrilas/uso terapêutico , Prolina/farmacologia , Prolina/uso terapêutico , SARS-CoV-2/efeitos dos fármacos , Inibidores de Protease Viral/farmacologia , Inibidores de Protease Viral/uso terapêutico , Administração Oral , Animais , COVID-19/virologia , Ensaios Clínicos Fase I como Assunto , Coronavirus/efeitos dos fármacos , Modelos Animais de Doenças , Quimioterapia Combinada , Humanos , Lactamas/administração & dosagem , Lactamas/farmacocinética , Leucina/administração & dosagem , Leucina/farmacocinética , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Nitrilas/administração & dosagem , Nitrilas/farmacocinética , Prolina/administração & dosagem , Prolina/farmacocinética , Ensaios Clínicos Controlados Aleatórios como Assunto , Ritonavir/administração & dosagem , Ritonavir/uso terapêutico , SARS-CoV-2/fisiologia , Inibidores de Protease Viral/administração & dosagem , Inibidores de Protease Viral/farmacocinética , Replicação Viral/efeitos dos fármacosRESUMO
COVID-19 caused by the SARS-CoV-2 virus has become a global pandemic. 3CL protease is a virally encoded protein that is essential across a broad spectrum of coronaviruses with no close human analogs. PF-00835231, a 3CL protease inhibitor, has exhibited potent in vitro antiviral activity against SARS-CoV-2 as a single agent. Here we report, the design and characterization of a phosphate prodrug PF-07304814 to enable the delivery and projected sustained systemic exposure in human of PF-00835231 to inhibit coronavirus family 3CL protease activity with selectivity over human host protease targets. Furthermore, we show that PF-00835231 has additive/synergistic activity in combination with remdesivir. We present the ADME, safety, in vitro, and in vivo antiviral activity data that supports the clinical evaluation of PF-07304814 as a potential COVID-19 treatment.
Assuntos
Tratamento Farmacológico da COVID-19 , Proteases 3C de Coronavírus/antagonistas & inibidores , Inibidores de Protease de Coronavírus/administração & dosagem , Indóis/administração & dosagem , Leucina/administração & dosagem , Pirrolidinonas/administração & dosagem , Monofosfato de Adenosina/administração & dosagem , Monofosfato de Adenosina/efeitos adversos , Monofosfato de Adenosina/análogos & derivados , Monofosfato de Adenosina/farmacocinética , Alanina/administração & dosagem , Alanina/efeitos adversos , Alanina/análogos & derivados , Alanina/farmacocinética , Animais , COVID-19/virologia , Chlorocebus aethiops , Coronavirus Humano 229E/efeitos dos fármacos , Coronavirus Humano 229E/enzimologia , Inibidores de Protease de Coronavírus/efeitos adversos , Inibidores de Protease de Coronavírus/farmacocinética , Modelos Animais de Doenças , Desenho de Fármacos , Sinergismo Farmacológico , Quimioterapia Combinada , Células HeLa , Humanos , Indóis/efeitos adversos , Indóis/farmacocinética , Infusões Intravenosas , Leucina/efeitos adversos , Leucina/farmacocinética , Camundongos , Pirrolidinonas/efeitos adversos , Pirrolidinonas/farmacocinética , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/efeitos dos fármacos , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/enzimologia , SARS-CoV-2/efeitos dos fármacos , SARS-CoV-2/enzimologia , Células VeroRESUMO
COVID-19 caused by the SARS-CoV-2 virus has become a global pandemic. 3CL protease is a virally encoded protein that is essential across a broad spectrum of coronaviruses with no close human analogs. The designed phosphate prodrug PF-07304814 is metabolized to PF-00835321 which is a potent inhibitor in vitro of the coronavirus family 3CL pro, with selectivity over human host protease targets. Furthermore, PF-00835231 exhibits potent in vitro antiviral activity against SARS-CoV-2 as a single agent and it is additive/synergistic in combination with remdesivir. We present the ADME, safety, in vitro , and in vivo antiviral activity data that supports the clinical evaluation of this compound as a potential COVID-19 treatment.
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Abstractï¼ Virus-like vesicles (VLV) are hybrid vectors based on an evolved Semliki Forest virus (SFV) RNA replicon and the envelope glycoprotein (G) from vesicular stomatitis virus (VSV) [...].
RESUMO
Blockade of the programmed cell death protein/ligand 1 (PD-1/PD-L1) pathway with monoclonal antibodies (mAb) is now commonly used for cancer immunotherapy and has therapeutic potential in chronic viral infections including HIV-1. PD-1/PD-L1 blockade could augment HIV-1-specific immune responses and reverse HIV-1 latency, but the latter effect has not been clearly shown. We tested the ability of the human anti-PD-L1 mAb BMS-936559 and the human anti-PD-1 mAb nivolumab to increase HIV-1 virion production ex vivo from different peripheral blood mononuclear cell populations obtained from donors on suppressive antiretroviral therapy (ART). Fresh peripheral blood mononuclear cells (PBMC), CD8-depleted PBMC, total CD4+ T cells, and resting CD4+ T cells were purified from whole blood of HIV-1-infected donors and cultured in varying concentrations of BMS-936559 (20, 5, or 1.25µg/mL) or nivolumab (5 or 1.25µg/mL), with or without anti-CD3/CD28 stimulatory antibodies. Culture supernatants were assayed for virion HIV-1 RNA by qRT-PCR. Ex vivo exposure to BMS-936559 or nivolumab, with or without anti-CD3/CD28 stimulation, did not consistently increase HIV-1 virion production from blood mononuclear cell populations. Modest (2-fold) increases in virus production were observed in a subset of donors and in some cell types but were not reproducible in longitudinal samples. Cell surface expression of PD-1 and PD-L1 were not associated with changes in virus production. Ex vivo blockade of the PD-1 axis alone has limited effects on HIV-1 latency.
Assuntos
Antirretrovirais/farmacologia , Anticorpos Monoclonais/farmacologia , Linfócitos T CD4-Positivos/metabolismo , Infecções por HIV/tratamento farmacológico , HIV-1/fisiologia , Nivolumabe/farmacologia , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Vírion/metabolismo , Latência Viral/efeitos dos fármacos , Replicação Viral/efeitos dos fármacos , Anticorpos Monoclonais Humanizados , Linfócitos T CD4-Positivos/patologia , Linfócitos T CD4-Positivos/virologia , Infecções por HIV/metabolismo , Infecções por HIV/patologia , Humanos , Receptor de Morte Celular Programada 1/metabolismoRESUMO
Infections with hepatitis B virus (HBV) can initiate chronic hepatitis and liver injury, causing more than 600,000 deaths each year worldwide. Current treatments for chronic hepatitis B are inadequate and leave an unmet need for immunotherapeutic approaches. We designed virus-like vesicles (VLV) as self-amplifying RNA replicons expressing three HBV antigens (polymerase, core, and middle surface) from a single vector (HBV-VLV) to break immune exhaustion despite persistent HBV replication. The HBV-VLV induces HBV-specific T cells in naive mice and renders them resistant to acute challenge with HBV. Using a chronic model of HBV infection, we demonstrate efficacy of HBV-VLV priming in combination with DNA booster immunization, as 40% of treated mice showed a decline of serum HBV surface antigen below the detection limit and marked reduction in liver HBV RNA accompanied by induction of HBsAg-specific CD8 T cells. These results warrant further evaluation of HBV-VLV for immunotherapy of chronic hepatitis B.
RESUMO
Immune clearance of Hepatitis B virus (HBV) is characterized by broad and robust antiviral T cell responses, while virus-specific T cells in chronic hepatitis B (CHB) are rare and exhibit immune exhaustion that includes programmed-death-1 (PD-1) expression on virus-specific T cells. Thus, an immunotherapy able to expand and activate virus-specific T cells may have therapeutic benefit for CHB patients. Like HBV-infected patients, woodchucks infected with woodchuck hepatitis virus (WHV) can have increased hepatic expression of PD-1-ligand-1 (PD-L1), increased PD-1 on CD8+ T cells, and a limited number of virus-specific T cells with substantial individual variation in these parameters. We used woodchucks infected with WHV to assess the safety and efficacy of anti-PD-L1 monoclonal antibody therapy (αPD-L1) in a variety of WHV infection states. Experimentally-infected animals lacked PD-1 or PD-L1 upregulation compared to uninfected controls, and accordingly, αPD-L1 treatment in lab-infected animals had limited antiviral effects. In contrast, animals with naturally acquired WHV infections displayed elevated PD-1 and PD-L1. In these same animals, combination therapy with αPD-L1 and entecavir (ETV) improved control of viremia and antigenemia compared to ETV treatment alone, but with efficacy restricted to a minority of animals. Pre-treatment WHV surface antigen (sAg) level was identified as a statistically significant predictor of treatment response, while PD-1 expression on peripheral CD8+ T cells, T cell production of interferon gamma (IFN-γ) upon in vitro antigen stimulation (WHV ELISPOT), and circulating levels of liver enzymes were not. To further assess the safety of this strategy, αPD-L1 was tested in acute WHV infection to model the risk of liver damage when the extent of hepatic infection and antiviral immune responses were expected to be the greatest. No significant increase in serum markers of hepatic injury was observed over those in infected, untreated control animals. These data support a positive benefit/risk assessment for blockade of the PD-1:PD-L1 pathway in CHB patients and may help to identify patient groups most likely to benefit from treatment. Furthermore, the efficacy of αPD-L1 in only a minority of animals, as observed here, suggests that additional agents may be needed to achieve a more robust and consistent response leading to full sAg loss and durable responses through anti-sAg antibody seroconversion.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Antígeno B7-H1/imunologia , Modelos Animais de Doenças , Hepatite B/terapia , Animais , Anticorpos Monoclonais/efeitos adversos , MarmotaRESUMO
RNA-dependent RNA polymerase from respiratory syncytial virus (RSV) is a multi-subunit ribonucleoprotein (RNP) complex that, in addition to synthesizing the full 15 222 nt viral genomic RNA, is able to synthesize all 10 viral mRNAs. We have prepared crude RNP from RSV-infected HEp-2 cells, based on a method previously used for Newcastle disease virus, and established a novel polyadenylation-dependent capture [poly(A) capture] assay to screen for potential inhibitors of RSV transcriptase activity. In this homogeneous assay, radiolabeled full-length polyadenylated mRNAs produced by the viral RNP are detected through capture on immobilized biotinylated oligo(dT) in a 96-well streptavidin-coated FlashPlate. Possible inhibitors identified with this assay could interfere at any step required for the production of complete RSV mRNAs, including transcription, polyadenylation and, potentially, co-transcriptional guanylylation. A specific inhibitor of RSV transcriptase with antiviral activity was identified through screening of this assay.
Assuntos
DNA Polimerase Dirigida por RNA/metabolismo , Vírus Sinciciais Respiratórios/enzimologia , Inibidores da Transcriptase Reversa/análise , Linhagem Celular , Técnicas Genéticas , Humanos , Poliadenilação , RNA Mensageiro/metabolismo , DNA Polimerase Dirigida por RNA/isolamento & purificação , Inibidores da Transcriptase Reversa/química , Inibidores da Transcriptase Reversa/farmacologia , Transcrição GênicaRESUMO
Optimization of pyridine-based noncatalytic site integrase inhibitors (NCINIs) based on compound 2 has led to the discovery of molecules capable of inhibiting virus harboring N124 variants of HIV integrase (IN) while maintaining minimal contribution of enterohepatic recirculation to clearance in rat. Structure-activity relationships at the C6 position established chemical space where the extent of enterohepatic recirculation in the rat is minimized. Desymmetrization of the C4 substituent allowed for potency optimization against virus having the N124 variant of integrase. Combination of these lessons led to the discovery of compound 20, having balanced serum-shifted antiviral potency and minimized excretion in to the biliary tract in rat, potentially representing a clinically viable starting point for a new treatment option for individuals infected with HIV.
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A scaffold replacement approach was used to identifying the pyridine series of noncatalytic site integrase inhibitors. These molecules bind with higher affinity to a tetrameric form compared to a dimeric form of integrase. Optimization of the C6 and C4 positions revealed that viruses harboring T124 or A124 amino acid substitutions are highly susceptible to these inhibitors, but viruses having the N124 amino acid substitution are about 100-fold less susceptible. Compound 20 had EC50 values <10 nM against viruses having T124 or A124 substitutions in IN and >800 nM in viruses having N124 substitions. Compound 20 had an excellent in vitro ADME profile and demonstrated reduced contribution of biliary excretion to in vivo clearance compared to BI 224436, the lead compound from the quinoline series of NCINIs.
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An assay recapitulating the 3' processing activity of HIV-1 integrase (IN) was used to screen the Boehringer Ingelheim compound collection. Hit-to-lead and lead optimization beginning with compound 1 established the importance of the C3 and C4 substituent to antiviral potency against viruses with different aa124/aa125 variants of IN. The importance of the C7 position on the serum shifted potency was established. Introduction of a quinoline substituent at the C4 position provided a balance of potency and metabolic stability. Combination of these findings ultimately led to the discovery of compound 26 (BI 224436), the first NCINI to advance into a phase Ia clinical trial.
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The nucleocapsid (NC) protein is an essential factor with multiple functions within the human immunodeficiency virus type 1 (HIV-1) replication cycle. In this study, we describe the discovery of a novel series of inhibitors that targets HIV-1 NC protein by blocking its interaction with nucleic acids. This series was identified using a previously described capsid (CA) assembly assay, employing a recombinant HIV-1 CA-NC protein and immobilized TG-rich deoxyoligonucleotides. Using visible absorption spectroscopy, we were able to demonstrate that this new inhibitor series binds specifically and reversibly to the NC with a peculiar 2:1 stoichiometry. A fluorescence-polarization-based binding assay was also developed in order to monitor the inhibitory activities of this series of inhibitors. To better characterize the structural aspect of inhibitor binding onto NC, we performed NMR studies using unlabeled and (13)C,(15)N-double-labeled NC(1-55) protein constructs. This allowed the determination of the solution structure of a ternary complex characterized by two inhibitor molecules binding to the two zinc knuckles of the NC protein. To the best of our knowledge, this represents the first report of a high-resolution structure of a small-molecule inhibitor bound to NC, demonstrating sub-micromolar potency and moderate antiviral potency with one analogue of the series. This structure was compared with available NC/oligonucleotide complex structures and further underlined the high flexibility of the NC protein, allowing it to adopt many conformations in order to bind its different oligonucleotide/nucleomimetic targets. In addition, analysis of the interaction details between the inhibitor molecules and NC demonstrated how this novel inhibitor series is mimicking the guanosine nucleobases found in many reported complex structures.
Assuntos
Fármacos Anti-HIV/isolamento & purificação , Fármacos Anti-HIV/metabolismo , HIV-1/efeitos dos fármacos , Produtos do Gene gag do Vírus da Imunodeficiência Humana/química , Produtos do Gene gag do Vírus da Imunodeficiência Humana/metabolismo , Fármacos Anti-HIV/química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura Molecular , Ligação Proteica , Conformação Proteica , Produtos do Gene gag do Vírus da Imunodeficiência Humana/antagonistas & inibidoresRESUMO
The HIV-1 capsid (CA) protein, a domain of Gag, which participates in formation of both the mature and immature capsid, represents a potential target for anti-viral drug development. Characterization of hits obtained via high-throughput screening of an in vitro capsid assembly assay led to multiple compounds having this potential. We previously presented the characterization of two inhibitor series that bind the N-terminal domain of the capsid (CA(NTD)), at a site located at the bottom of its helical bundle, often referred to as the CAP-1 binding site. In this work we characterize a novel series of benzimidazole hits. Initial optimization of this series led to compounds with improved in vitro assembly and anti-viral activity. Using NMR spectroscopy we found that this series binds to a unique site on CA(NTD), located at the apex of the helical bundle, well removed from previously characterized binding sites for CA inhibitors. 2D (1)H-(15)N HSQC and (19)F NMR showed that binding of the benzimidazoles to this distinct site does not affect the binding of either cyclophilin A (CypA) to the CypA-binding loop or a benzodiazepine-based CA assembly inhibitor to the CAP-1 site. Unfortunately, while compounds of this series achieved promising in vitro assembly and anti-viral effects, they also were found to be quite sensitive to a number of naturally occurring CA(NTD) polymorphisms observed among clinical isolates. Despite the negative impact of this finding for drug development, the discovery of multiple inhibitor binding sites on CA(NTD) shows that capsid assembly is much more complex than previously realized.
Assuntos
Fármacos Anti-HIV/química , Fármacos Anti-HIV/farmacologia , Proteínas do Capsídeo/antagonistas & inibidores , Proteínas do Capsídeo/química , Proteínas do Capsídeo/metabolismo , HIV-1 , Fármacos Anti-HIV/metabolismo , Benzimidazóis/química , Sítios de Ligação , Ligação Competitiva , Cristalografia por Raios X , Ciclofilina A/metabolismo , Ciclofilina A/farmacologia , HIV-1/genética , HIV-1/isolamento & purificação , Espectroscopia de Ressonância Magnética , Polimorfismo Genético , Conformação Proteica , Relação Estrutura-AtividadeRESUMO
The emergence of resistance to existing classes of antiretroviral drugs underlines the need to find novel human immunodeficiency virus (HIV)-1 targets for drug discovery. The viral capsid protein (CA) represents one such potential target. Recently, a series of benzodiazepine inhibitors was identified via high-throughput screening using an in vitro capsid assembly assay (CAA). Here, we demonstrate how a combination of NMR and X-ray co-crystallography allowed for the rapid characterization of the early hits from this inhibitor series. Ligand-based (19)F NMR was used to confirm inhibitor binding specificity and reversibility as well as to identify the N-terminal domain of the capsid (CA(NTD)) as its molecular target. Protein-based NMR ((1)H and (15)N chemical shift perturbation analysis) identified key residues within the CA(NTD) involved in inhibitor binding, while X-ray co-crystallography confirmed the inhibitor binding site and its binding mode. Based on these results, two conformationally restricted cyclic inhibitors were designed to further validate the possible binding modes. These studies were crucial to early hit confirmation and subsequent lead optimization.