Orally efficacious lead of the AVG inhibitor series targeting a dynamic interface in the respiratory syncytial virus polymerase.
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ABSTRACT:
SUBMITTER: Sourimant J
PROVIDER: S-EPMC9232112 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Morbidity and mortality resulting from influenza-like disease are a threat, especially for older adults. To improve case management, next-generation broad-spectrum antiviral therapeutics that are efficacious against major drivers of influenza-like disease, including influenza viruses and respiratory syncytial virus (RSV), are urgently needed. Using a dual-pathogen high-throughput screening protocol for influenza A virus (IAV) and RSV inhibitors, we have identified N4-hydroxycytidine (NHC) as a potent inhibitor of RSV, influenza B viruses, and IAVs of human, avian, and swine origins. Biochemical in vitro polymerase assays and viral RNA sequencing revealed that the ribonucleotide analog is incorporated into nascent viral RNAs in place of cytidine, increasing the frequency of viral mutagenesis. Viral passaging in cell culture in the presence of an inhibitor did not induce robust resistance. Pharmacokinetic profiling demonstrated dose-dependent oral bioavailability of 36 to 56%, sustained levels of the active 5'-triphosphate anabolite in primary human airway cells and mouse lung tissue, and good tolerability after extended dosing at 800 mg/kg of body weight/day. The compound was orally efficacious against RSV and both seasonal and highly pathogenic avian IAVs in mouse models, reducing lung virus loads and alleviating disease biomarkers. Oral dosing reduced IAV burdens in a guinea pig transmission model and suppressed virus spread to uninfected contact animals through direct transmission. Based on its broad-spectrum efficacy and pharmacokinetic properties, NHC is a promising candidate for future clinical development as a treatment option for influenza-like diseases.
| S-EPMC6105843 | biostudies-other
Project description:ObjectivesRespiratory Syncytial Virus (RSV) is a leading cause of death and hospitalization among infants and young children. People with an immunocompromised status are also at risk for severe RSV infection. There is no specific treatment for RSV infection available. Ribavirin, an antiviral drug approved for severe lung infection by RSV, has shown limited clinical efficacies with severe side effects. Additionally, given the genetic variability of RSV genomes and seasonal change of different strains, a broad-spectrum antiviral drug is highly desirable. The RNA-dependent RNA polymerase (RdRp) domain is relatively conserved and indispensable for the replication of the virus genome and therefore serves as a potential therapeutic target. Previous attempts to identify an RdRp inhibitor have not been successful due to lack of potency or high enough blood exposure. DZ7487 is a novel orally available small molecule inhibitor specifically designed to target the RSV RdRp. Here we present our data showing that DZ7487 can potently inhibited all clinical viral isolates tested, with large safety margin predicted for human.MethodsHEp-2 cells were infected by RSV A and B. Antiviral activities were assessed by in vitro cytopathic effect assay (CPE) and Reverse transcription-quantitative polymerase chain reaction (RT-qPCR). DZ7487 antiviral effects in lower airway cells were evaluated in A549 and human small airway epithelial cells (SAEC) cells. DZ7487 induced RSV A2 escape mutations were selected through continuous culture with increasing DZ7487 concentrations in the culture medium. Resistant mutations were identified by next generation sequencing and confirmed by recombinant RSV CPE assays. RSV infection models in both BALB/c mice and cotton rats were used to evaluate DZ7487 in vivo antiviral effects.ResultsDZ7487 potently inhibited viral replication of all clinical isolates of both RSVA and B subtypes. In lower airway cells, DZ7487 showed superior efficacy than the nucleoside analog ALS-8112. Acquired resistant mutation was predominantly restricted at the RdRp domain resulting asparagine to threonine mutation (N363T) of the L protein. This finding is consistent with DZ7487's presumed binding mode. DZ7487 was well tolerated in animal models. Unlike fusion inhibitors, which can only prevent viral infection, DZ7487 potently inhibited RSV replication before and after RSV infection in vitro and in vivo.ConclusionsDZ7487 demonstrated potent anti-RSV replication effect both in vitro and in vivo assays. It has the desired drug-like physical properties to be an effective orally available anti-RSV replication drug with broad spectrum.
| S-EPMC10086872 | biostudies-literature
Project description:Paramyxoviruses such as human parainfluenza virus type-3 (HPIV3) and measles virus (MeV) are a substantial health threat. In a high-throughput screen for inhibitors of HPIV3 (a major cause of acute respiratory infection), we identified GHP-88309-a non-nucleoside inhibitor of viral polymerase activity that possesses unusual broad-spectrum activity against diverse paramyxoviruses including respiroviruses (that is, HPIV1 and HPIV3) and morbilliviruses (that is, MeV). Resistance profiles of distinct target viruses overlapped spatially, revealing a conserved binding site in the central cavity of the viral polymerase (L) protein that was validated by photoaffinity labelling-based target mapping. Mechanistic characterization through viral RNA profiling and in vitro MeV polymerase assays identified a block in the initiation phase of the viral polymerase. GHP-88309 showed nanomolar potency against HPIV3 isolates in well-differentiated human airway organoid cultures, was well tolerated (selectivity index > 7,111) and orally bioavailable, and provided complete protection against lethal infection in a Sendai virus mouse surrogate model of human HPIV3 disease when administered therapeutically 48 h after infection. Recoverees had acquired robust immunoprotection against reinfection, and viral resistance coincided with severe attenuation. This study provides proof of the feasibility of a well-behaved broad-spectrum allosteric antiviral and describes a chemotype with high therapeutic potential that addresses major obstacles of anti-paramyxovirus drug development.
| S-EPMC7529989 | biostudies-literature
Project description:BMS-433771 was found to be a potent inhibitor of respiratory syncytial virus (RSV) replication in vitro. It exhibited excellent potency against multiple laboratory and clinical isolates of both group A and B viruses, with an average 50% effective concentration of 20 nM. Mechanism-of-action studies demonstrated that BMS-433771 inhibits the fusion of lipid membranes during both the early virus entry stage and late-stage syncytium formation. After isolation of resistant viruses, resistance was mapped to a series of single amino acid mutations in the F1 subunit of the fusion protein. Upon oral administration, BMS-433771 was able to reduce viral titers in the lungs of mice infected with RSV. This new class of orally active RSV fusion inhibitors offers potential for clinical development.
| S-EPMC321540 | biostudies-literature
Project description:?-Secretase inhibitors are potentially disease-modifying treatments for Alzheimer's disease. Previous efforts in our laboratory have resulted in hydroxyethylamine-derived inhibitors such as 1 with low nanomolar potency against ?-site amyloid precursor protein cleaving enzyme (BACE). When dosed intravenously, compound 1 was also shown to significantly reduce A?40 levels in plasma, brain, and cerebral spinal fluid. Herein, we report further optimizations that led to the discovery of inhibitor 16 as a novel, potent, and orally efficacious BACE inhibitor.
| S-EPMC4025811 | biostudies-other
Project description:Background and purposeEffective anti-respiratory syncytial virus (RSV) agents are still not available for clinical use. Current major targets are virus surface proteins, such as a fusion protein involved in viral entry, but agents effective after RSV infection is established are required. Here we have investigated the effects of late therapeutic intervention with a novel inhaled RSV polymerase inhibitor, PC786, on RSV infection in human airway epithelium.Experimental approachAir liquid interface-cultured bronchial or small airway epithelium was infected with RSVA2. PC786 was applied apically or basolaterally once daily following peak virus load on Day 3 post inoculation. Apical wash was collected daily for determination of viral burden by PCR and plaque assay (primary endpoints) and biomarker analyses. The effects were compared with those of ALS-8112, an anti-RSV nucleoside analogue, and GS-5806, a fusion-protein inhibitor, which were treated basolaterally.Key resultsLate intervention with GS-5806 did not show significant anti-viral effects, but PC786 produced potent, concentration-dependent inhibition of viral replication with viral load falling below detectable limits 3 days after treatment commenced in airway epithelium. These effects were superior to those of ALS-8112. PC786 showed inhibitory activities against RSV-induced increases of CCL5, IL-6, double-strand DNA and mucin. The effects of PC786 were also confirmed in small airway epithelium.Conclusion and implicationsLate therapeutic intervention with the RSV polymerase inhibitor, PC786, reduced the viral burden quickly in human airway epithelium. Thus, PC786 demonstrates the potential to be an effective therapeutic agent to treat active RSV infection.
| S-EPMC5980447 | biostudies-literature
Project description:The ribonucleocapsid complex of respiratory syncytial virus (RSV) is responsible for both viral mRNA transcription and viral replication during infection, though little is known about how this dual function is achieved. Here, we report the use of a recombinant RSV virus with a FLAG-tagged large polymerase protein, L, to characterize and localize RSV ribonucleocapsid structures during the early and late stages of viral infection. Through proximity ligation assays and super-resolution microscopy, viral RNA and proteins in the ribonucleocapsid complex were revealed to dynamically rearrange over time, particularly between 6 and 8 hours post infection, suggesting a connection between the ribonucleocapsid structure and its function. The timing of ribonucleocapsid rearrangement corresponded with an increase in RSV genome RNA accumulation, indicating that this rearrangement is likely involved with the onset of RNA replication and secondary transcription. Additionally, early overexpression of RSV M2-2 from in vitro transcribed mRNA was shown to inhibit virus infection by rearranging the ribonucleocapsid complex. Collectively, these results detail a critical understanding into the localization and activity of RSV L and the ribonucleocapsid complex during RSV infection.
| S-EPMC7575074 | biostudies-literature
Project description:Although respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection in infants and young children, attempts to develop an effective therapy have so far proved unsuccessful. Here we report the preclinical profiles of PC786, a potent nonnucleoside RSV L protein polymerase inhibitor, designed for inhalation treatment of RSV infection. PC786 demonstrated a potent and selective antiviral activity against laboratory-adapted or clinical isolates of RSV-A (50% inhibitory concentration [IC50], <0.09 to 0.71 nM) and RSV-B (IC50, 1.3 to 50.6 nM), which were determined by inhibition of cytopathic effects in HEp-2 cells without causing detectable cytotoxicity. The underlying inhibition of virus replication was confirmed by PCR analysis. The effects of PC786 were largely unaffected by the multiplicity of infection (MOI) and were retained in the face of established RSV replication in a time-of-addition study. Persistent anti-RSV effects of PC786 were also demonstrated in human bronchial epithelial cells. In vivo intranasal once daily dosing with PC786 was able to reduce the virus load to undetectable levels in lung homogenates from RSV-infected mice and cotton rats. Treatment with escalating concentrations identified a dominant mutation in the L protein (Y1631H) in vitro In addition, PC786 potently inhibited RSV RNA-dependent RNA polymerase (RdRp) activity in a cell-free enzyme assay and minigenome assay in HEp-2 cells (IC50, 2.1 and 0.5 nM, respectively). Thus, PC786 was shown to be a potent anti-RSV agent via inhibition of RdRp activity, making topical treatment with this compound a novel potential therapy for the treatment of human RSV infections.
| S-EPMC5571287 | biostudies-literature
Project description:Respiratory syncytial virus (RSV) represents a significant health threat to infants and to elderly or immunocompromised individuals. There are currently no vaccines available to prevent RSV infections, and disease management is largely limited to supportive care, making the identification and development of effective antiviral therapeutics against RSV a priority. To identify effective chemical scaffolds for managing RSV disease, we conducted a high-throughput anti-RSV screen of a 57,000-compound library. We identified a hit compound that specifically blocked activity of the RSV RNA-dependent RNA polymerase (RdRp) complex, initially with moderate low-micromolar potency. Mechanistic characterization in an in vitro RSV RdRp assay indicated that representatives of this compound class block elongation of RSV RNA products after initial extension by up to three nucleotides. Synthetic hit-to-lead exploration yielded an informative 3D quantitative structure-activity relationship (3D-QSAR) model and resulted in analogs with more than 20-fold improved potency and selectivity indices (SIs) of >1,000. However, first-generation leads exhibited limited water solubility and poor metabolic stability. A second optimization strategy informed by the 3D-QSAR model combined with in silico pharmacokinetics (PK) predictions yielded an advanced lead, AVG-233, that demonstrated nanomolar activity against both laboratory-adapted RSV strains and clinical RSV isolates. This anti-RSV activity extended to infection of established cell lines and primary human airway cells. PK profiling in mice revealed 34% oral bioavailability of AVG-233 and sustained high drug levels in the circulation after a single oral dose of 20 mg/kg. This promising first-in-class lead warrants further development as an anti-RSV drug.
| S-EPMC6204889 | biostudies-literature
Project description:Numerous interventions are in clinical development for respiratory syncytial virus (RSV) infection, including small molecules that target viral transcription and replication. These processes are catalyzed by a complex comprising the RNA-dependent RNA polymerase (L) and the tetrameric phosphoprotein (P). RSV P recruits multiple proteins to the polymerase complex and, with the exception of its oligomerization domain, is thought to be intrinsically disordered. Despite their critical roles in RSV transcription and replication, structures of L and P have remained elusive. Here, we describe the 3.2-Å cryo-EM structure of RSV L bound to tetrameric P. The structure reveals a striking tentacular arrangement of P, with each of the four monomers adopting a distinct conformation. The structure also rationalizes inhibitor escape mutants and mutations observed in live-attenuated vaccine candidates. These results provide a framework for determining the molecular underpinnings of RSV replication and transcription and should facilitate the design of effective RSV inhibitors.
| S-EPMC7111336 | biostudies-literature