HIV-1 Protease Research Articles

Premature Activation of the HIV-1 Protease Is Influenced by Polymorphisms in the Hinge Region.

HIV-1 protease inhibitors are an essential component of antiretroviral therapy. However, drug resistance is a pervasive issue motivating a persistent search for novel therapies. Recent reports found that when protease activates within the host cell's cytosol, it facilitates the pyroptotic killing of infected cells. This has led to speculation that promoting protease activation, rather than inhibiting it, could help to eradicate infected cells and potentially cure HIV-1 infection. Here, we used a nanoscale flow cytometry-based assay to characterize protease resistance mutations and polymorphisms. We quantified protease activity, viral concentration, and premature protease activation and confirmed previous findings that major resistance mutations generally destabilize the protease structure. Intriguingly, we found evidence that common polymorphisms in the hinge domain of protease can influence its susceptibility to premature activation. This suggests that viral heterogeneity could pose a considerable challenge for therapeutic strategies aimed at inducing premature protease activation in the future.

Performance of the Applied Biosystems HIV-1 Genotyping Kit with Integrase.

HIV genotyping is used to assess HIV susceptibility to antiretroviral drugs. The Applied Biosystems HIV-1 Genotyping Kit with Integrase (AB kit, Thermo Fisher Scientific) detects resistance-associated mutations (RAMs) in HIV protease (PR), reverse transcriptase (RT), and integrase (IN). We compared results from the AB kit with results obtained previously with the ViroSeq HIV-1 Genotyping System. DNA amplicons from the AB kit were also analyzed using next-generation sequencing (NGS). HIV RNA was extracted using the MagNA Pure 24 instrument (Roche Diagnostics; 96 plasma samples, HIV subtype B, viral load range: 530-737,741 copies/mL). FASTA files were generated from AB kit data using Exatype (Hyrax Biosciences). DNA amplicons from the AB kit were also analyzed by NGS using the Nextera XT kit (Illumina). Drug resistance was predicted using the Stanford HIV Drug Resistance Database. The mean genetic distance for sequences from ViroSeq and the AB kit was 0.02% for PR/RT and 0.04% for IN; 103 major RAMs were detected by both methods. Four additional major RAMs were detected by the AB kit only. These four major RAMs were also detected by NGS (detected in 18.1%-38.2% of NGS reads). NGS detected 27 major RAMs that were not detected with either of the Sanger sequencing-based kits. All major RAMs detected with ViroSeq were detected with the AB kit; additional RAMs were detected with the AB kit only. DNA amplicons from the AB kit can be used for NGS for more sensitive detection of RAMs.

Changing selection on amino acid substitutions in Gag protein between major HIV-1 subtypes.

Amino acid preferences at a protein site depend on the role of this site in protein function and structure as well as on external constraints. All these factors can change in the course of evolution, making amino acid propensities of a site time-dependent. When viral subtypes divergently evolve in different host subpopulations, such changes may depend on genetic, medical, and sociocultural differences between these subpopulations. Here, using our previously developed phylogenetic approach, we describe sixty-nine amino acid sites of the Gag protein of human immunodeficiency virus type 1 (HIV-1) where amino acids have different impact on viral fitness in six major subtypes of the type M. These changes in preferences trigger adaptive evolution; indeed, 32 (46 per cent) of these sites experienced strong positive selection at least in one of the subtypes. At some of the sites, changes in amino acid preferences may be associated with differences in immune escape between subtypes. The prevalence of an amino acid in a protein site within a subtype is only a poor predictor for whether this amino acid is preferred in this subtype according to the phylogenetic analysis. Therefore, attempts to identify the factors of viral evolution from comparative genomics data should integrate across multiple sources of information.

Molecular Docking Improved with Human Spatial Perception Using Virtual Reality.

Adaptive steered molecular dynamics (ASMD) is a computational biophysics method in which an external force is applied to a selected set of atoms or a specific reaction coordinate to induce a particular molecular motion. Virtual reality (VR) based methods for protein-ligand docking are beneficial for visualizing on-the-fly interactive molecular dynamics and performing promising docking trajectories. In this paper, we propose a novel method to guide ASMD with optimal trajectories collected from human experiences using interactive molecular dynamics in virtual reality (iMD-VR). We also explain the benefits of using VR as a tool for expediting the process of ligand binding, outlining an experimental protocol that enables iMD-VR users to guide Amprenavir into and out of the binding pockets of HIV-1 protease and recreate their respective crystallographic binding poses within 5 minutes. Later, we discuss our analysis of the results from iMD-VR-assisted ASMD simulation and assess its performance compared to a standard ASMD simulation. From the accuracy point of view, our proposed method calculates higher Potential Mean Force (PMF) values consistently relative to a standard ASMD simulation with an almost twofold increase in all the experiments. Finally, we describe the novelty of the research and discuss results showcasing a faster and more effective convergence of the ligand to the protein's binding site as compared to a standard molecular dynamics simulation, proving the effectiveness of VR in the field of drug discovery. Future work includes the development of an artificial intelligence algorithm capable of predicting optimal binding trajectories for many protein-ligand pairs, as well as the required force needed to steer the ligand to follow the said trajectory.

Novel regulation of kidney function by gastrointestinal hormones

The control of whole-body energy metabolism involves intricate crosstalk between multiple organ systems including the gut and the brain that play well-recognized roles in this process. However, the important contributions and mechanisms by other organs are poorly understood. Errors in metabolic regulation can lead to human metabolic diseases including diabetes and obesity that affect 75% of the population and can lead to significant comorbidities. Improving our mechanistic understanding of multi-organ metabolic crosstalk in health and disease is essential for developing highly effcient and new therapeutic approaches. Macula densa (MD) cells in the kidney are chief regulators of renal blood flow and tissue remodeling. We hypothesized that the kidney is a major player in body metabolism via a new mechanism of gut-kidney crosstalk that involves the gut hormones gastrin and cholecystokinine (CCK) activating intrarenal, MD-specific mechanisms to increase blood flow and filtration, progenitor cells and tissue growth factors. High-resolution MD bulk and single-cell transcriptome analysis was performed from freshly isolated, enriched MD cells using MD-GFP mouse kidneys. Single cell MD Ca2+ signaling was analyzed in vivo using intravital multiphoton microscopy (MPM) of Sox2-GT mice that express the ratiometric Ca2+ reporter GCaMP6f/tdTomato in all renal cells. The altered expression of MD specific markers in response to gastrin/CCK8 stimuli was studied using western blot and the novel MDgeo immortalized cell line cultured in vitro. RNA sequencing and transcriptome analysis identified the gastrin/CCK receptor Cckbr as one of the highest expressed genes in MD versus control kidney cells. Intravital multiphoton imaging of Sox2-GCaMP6 reporter mouse kidneys revealed robust and entirely MD cell-specific calcium signaling in response to systemic gastrin/CCK injection. Using the novel MDgeo immortalized cell line cultured in vitro, CCK8 treatment led to 3-fold increases in MD cell synthesis of Prostaglandin E2 (PGE2)-generating COX2 and CCN1 that are established mediators of MD-induced glomerular hyperfiltration and tissue remodeling, respectively. Chronic treatment of Ren1d-Confetti mice with Darunavir, an HIV protease inhibitor significantly increased plasma CCK levels, Ren+ mesenchymal progenitor cell number and clonality, renal cell proliferation and tissue hypertrophy. This study uncovered new regulatory mechanisms of systemic metabolism especially the role of MD cells in the kidney. Repurposing the commonly used HIV drug Darunavir for kidney and metabolic diseases may provide therapeutic benefit for millions of patients worldwide. DK064234, DK123564, DK135290. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Therapeutic Potential of Quercetin Derivatives: In Silico Investigation of HIV-1 Protease Inhibition

Therapeutic Potential of Quercetin Derivatives: In Silico Investigation of HIV-1 Protease Inhibition

Integrating Explicit and Implicit Fullerene Models into UNRES Force Field for Protein Interaction Studies.

Fullerenes, particularly C60, exhibit unique properties that make them promising candidates for various applications, including drug delivery and nanomedicine. However, their interactions with biomolecules, especially proteins, remain not fully understood. This study implements both explicit and implicit C60 models into the UNRES coarse-grained force field, enabling the investigation of fullerene-protein interactions without the need for restraints to stabilize protein structures. The UNRES force field offers computational efficiency, allowing for longer timescale simulations while maintaining accuracy. Five model proteins were studied: FK506 binding protein, HIV-1 protease, intestinal fatty acid binding protein, PCB-binding protein, and hen egg-white lysozyme. Molecular dynamics simulations were performed with and without C60 to assess protein stability and investigate the impact of fullerene interactions. Analysis of contact probabilities reveals distinct interaction patterns for each protein. FK506 binding protein (1FKF) shows specific binding sites, while intestinal fatty acid binding protein (1ICN) and uteroglobin (1UTR) exhibit more generalized interactions. The explicit C60 model shows good agreement with all-atom simulations in predicting protein flexibility, the position of C60 in the binding pocket, and the estimation of effective binding energies. The integration of explicit and implicit C60 models into the UNRES force field, coupled with recent advances in coarse-grained modeling and multiscale approaches, provides a powerful framework for investigating protein-nanoparticle interactions at biologically relevant scales without the need to use restraints stabilizing the protein, thus allowing for large conformational changes to occur. These computational tools, in synergy with experimental techniques, can aid in understanding the mechanisms and consequences of nanoparticle-biomolecule interactions, guiding the design of nanomaterials for biomedical applications.

Identifying and Assessing Putative Allosteric Sites and Modulators for CXCR4 Predicted through Network Modeling and Site Identification by Ligand Competitive Saturation.

The chemokine receptor CXCR4 is a critical target for the treatment of several cancer types and HIV-1 infections. While orthosteric and allosteric modulators have been developed targeting its extracellular or transmembrane regions, the intramembrane region of CXCR4 may also include allosteric binding sites suitable for the development of allosteric drugs. To investigate this, we apply the Gaussian Network Model (GNM) to the monomeric and dimeric forms of CXCR4 to identify residues essential for its local and global motions located in the hinge regions of the protein. Residue interaction network (RIN) analysis suggests hub residues that participate in allosteric communication throughout the receptor. Mutual residues from the network models reside in regions with a high capacity to alter receptor dynamics upon ligand binding. We then investigate the druggability of these potential allosteric regions using the site identification by ligand competitive saturation (SILCS) approach, revealing two putative allosteric sites on the monomer and three on the homodimer. Two screening campaigns with Glide and SILCS-Monte Carlo docking using FDA-approved drugs suggest 20 putative hit compounds including antifungal drugs, anticancer agents, HIV protease inhibitors, and antimalarial drugs. In vitro assays considering mAB 12G5 and CXCL12 demonstrate both positive and negative allosteric activities of these compounds, supporting our computational approach. However, in vivo functional assays based on the recruitment of β-arrestin to CXCR4 do not show significant agonism and antagonism at a single compound concentration. The present computational pipeline brings a new perspective to computer-aided drug design by combining conformational dynamics based on network analysis and cosolvent analysis based on the SILCS technology to identify putative allosteric binding sites using CXCR4 as a showcase.

The RRE-REV module has no effect on the packaging efficiency of cas9 and Gag proteins into nanomedic virus-like particles

Delivery of ribonucleoprotein complexes of Cas9 nuclease and guide RNA into target cells with virus-like particles (VLP) is one of the novel methods of genome editing, suitable for gene therapy of human diseases in the future. Efficiency of genome editing with VLPs depends on the packaging of Cas9 into VLPs, that is mediated by viral Gag protein. To increase the packaging of Cas9 into NanoMEDIC system VLPs plasmid constructs for expression of Cas9 and Gag were modified by the addition of HIV RRE (Rev response element), that is expected to increase the nuclear export of RRE-containing transcripts to cytosol via accessory protein Rev, as described for Vpr-Cas9-based VLP system. Here we found that Cas9 and Gag protein levels in the cell lysates are increased upon cotransfection of either Rev-expressing plasmid or empty control plasmid. Moreover, this effect does not depend on the presence of RRE in the transcript. On the top of that, we showed that AP21967-induced dimerization of FRB and FKBP12, but not the modification of plasmids with RRE and/or cotransfection of Rev-expressing plasmid, plays the major role in packaging of Cas9 into NanoMEDIC system VLPs. These data suggest that it is impractical to use the RRE-Rev module to enhance the packing of Cas9 nuclease into VLPs.

A validated in-house assay for HIV drug resistance mutation surveillance from dried blood spot specimens

Despite increasing scale-up of antiretroviral therapy (ART) coverage, challenges related to adherence and HIV drug resistance (HIVDR) remain. The high cost of HIVDR surveillance is a persistent challenge with implementation in resource-constrained settings. Dried blood spot (DBS) specimens have been demonstrated to be a feasible alternative to plasma or serum for HIVDR genotyping and are more suitable for lower resource settings. There is a need for affordable HIVDR genotyping assays which can amplify HIV-1 sequences from DBS specimens, particularly those with low viral loads, at a low cost. Here, we present an in-house assay capable of reliably amplifying HIV-1 protease and partial reverse transcriptase genes from DBS specimens, which covers the complete World Health Organization 2009 list of drug resistance mutations under surveillance. DBS specimens were prepared using whole blood spiked with HIV-1 at concentrations of 10,000, 5000, 1000, and 500 copies/mL (n=30 for each concentration). Specimens were tested in triplicate. A two-step approach was used consisting of cDNA synthesis followed by nested PCR. The limit of detection of the assay was calculated to be approximately 5000 (95% CI: 3200–10,700) copies/mL for the protease gene and 3600 (95% CI: 2200–10,000) copies/mL for reverse transcriptase. The assay was observed to be most sensitive with higher viral load specimens (97.8% [95% CI: 92.2–99.7]) for both protease and reverse transcriptase at 10,000 copies/mL with performance decreasing with the use of specimens with lower viral loads (46.7% [36.1–57.5] and 60.0% [49.1–70.2] at 500 copies/mL for protease and reverse transcriptase, respectively). Ultimately, this assay presents a promising opportunity for use in resource-constrained settings. Future work should involve validation under field conditions including sub-optimal storage conditions and preparation of DBS with fingerprick blood in order to accurately reflect real-world collection scenarios.

Paxlovid (Nirmatrelvir/ritonavir): An Innovative Method Method for Treating Covid-19?

Nirmatrelvir Ritonavir 3-c like protease COVID-19 SARS-COV-2Despite the need for innovative, efficient treatment for the Covid Pandemic, there is currently no curative regimen available, leaving patients to rely on supportive and general treatments. The 3C like-protease (3CLpro) and the main protease (Mpro), two SARS-COV-2 proteins, have been identified as potential targets for antiviral medications. The Mpro might be viable therapeutic target since it plays a significant role in both the pathogenesis of the virus and processing. Nirmatrelvir, an antiviral medication, prevents SARS-CoV-2 from reproducing by blocking Mpro. Another HIV protease inhibitor, ritonavir, was coupled with nirmatrelvir to develop. Ritonavir inhibits the cytochrome P450 3A metabolizing enzyme, extending the half-life of nirmatrelvir and serving as pharmacological enhancer. Despite major modification of the SARS-COV-2 viral genome, nirmatrelvir still has strong antiviral effectiveness against contemporary coronavirus strains. However, there are still a number of open issues. The effectiveness of nirmatrelvir and ritonavir in treating SARS-COV-2 infection, as well as their safety and potential adverse effects are discussed in this review of literature.

Associating protein sequence positions with the modulation of quantitative phenotypes

Although protein sequences encode the information for folding and function, understanding their link is not an easy task. Unluckily, the prediction of how specific amino acids contribute to these features is still considerably impaired. Here, we developed a simple algorithm that finds positions in a protein sequence with potential to modulate the studied quantitative phenotypes. From a few hundred protein sequences, we perform multiple sequence alignments, obtain the per-position pairwise differences for both the sequence and the observed phenotypes, and calculate the correlation between these last two quantities. We tested our methodology with four cases: archaeal Adenylate Kinases and the organisms optimal growth temperatures, microbial rhodopsins and their maximal absorption wavelengths, mammalian myoglobins and their muscular concentration, and inhibition of HIV protease clinical isolates by two different molecules. We found from 3 to 10 positions tightly associated with those phenotypes, depending on the studied case. We showed that these correlations appear using individual positions but an improvement is achieved when the most correlated positions are jointly analyzed. Noteworthy, we performed phenotype predictions using a simple linear model that links per-position divergences and differences in the observed phenotypes. Predictions are comparable to the state-of-art methodologies which, in most of the cases, are far more complex. All of the calculations are obtained at a very low information cost since the only input needed is a multiple sequence alignment of protein sequences with their associated quantitative phenotypes. The diversity of the explored systems makes our work a valuable tool to find sequence determinants of biological activity modulation and to predict various functional features for uncharacterized members of a protein family.

An enzymatic route to the synthesis of tricyclic fused hexahydrofuranofuran P2-Ligand for a series of highly potent HIV-1 protease inhibitors

We describe a stereoselective synthesis of an optically active (1R, 3aS, 5R, 6S, 7aR)-octahydro-1,6-epoxy-isobenzo-furan-5-ol derivative. This stereochemically defined heterocycle serves as a high-affinity ligand for a variety of HIV-1 protease inhibitors. The key synthetic steps involve a highly enantioselective enzymatic desymmetrization of meso-1,2(dihydroxymethyl)cyclohex-4-ene and conversion of the resulting optically active alcohol to a methoxy hexahydroisobenzofuran derivative. A substrate controlled stereoselective dihydroxylation afforded syn-1,2-diols. Oxidation of diol provided the substituted 1,2-diketone and L-Selectride reduction provided the corresponding inverted syn-1,2-diols. Acid catalyzed cyclization furnished the ligand alcohol in optically active form.

HIV protease resistance mutations in patients receiving second-line antiretroviral therapy in Libreville, Gabon

IntroductionIn 2022, the WHO reported that 29.8 million people around the world were living with HIV (PLHIV) and receiving antiretroviral treatment (ART), including 25‌ 375 people in Gabon (54% of all those living with HIV in the country). The literature reports a frequency of therapeutic failure with first-line antiretrovirals (ARVs) of between 20% and 82%. Unfortunately, data relating to the failure of second-line ARVs are scarce in Gabon. This study aims to determine the profiles of HIV drug resistance mutations related to protease inhibitors in Gabon.MethodologyPlasma from 84 PLHIV receiving ARVs was collected from 2019 to 2021, followed by RNA extraction, amplification, and sequencing of the protease gene. ARV resistance profiles were generated using the Stanford interpretation algorithm version 8.9-1 (https://hivdb.stanford.edu) and statistical analyses were performed using EpiInfo software version 7.2.1.0 (CDC, USA).ResultsOf 84 HIV plasma samples collected from 45 men and 39 women, 342 mutations were detected. Of these, 43.3% (148/342) were associated with nucleoside reverse transcriptase inhibitors (NRTIs), 30.4% (104/342) with non-nucleoside reverse transcriptase inhibitors (NNRTIs), and 26.3% (90/342) with protease inhibitors (PIs). Most NRTI mutations were associated with thymidine analogues (TAMs) (50.7%; 75/148), including T215F/V (14.9%; 22/148), D67DN/E/G/N/T (10.1%; 15/148), M41L (9.5%; 14/148), and K70E/KN/S/R (9.5%; 14/148). Resistance mutations related to non-TAM NRTIs (33.1%; 49/148) were M184V (29.1%; 43/148), and L74I/V (8.1%; 12/148). NNRTI mutations were predominantly K103N/S (32.7%; 34/104), V108I (10.6%; 11/104), A98G (10.6%; 11/104), and P225H (9.6%; 10/104). Minor mutations associated with PIs (60.0%; 54/90) were predominantly K20I (15.6%; 14/90) and L10F/I/V (14.5%; 13/90). The major mutations associated with PIs (40.0%; 36/90) were M41L (12.2%; 11/90), I84V (6.7%; 06/90), and V82A (6.7%; 06/90). The four most prescribed therapeutic regimens were TDF + 3TC + LPV/r (20.3%; 17/84), ABC + DDI + LPV/r (17.9%; 15/84), TDF + FTC + LPV/r (11.9%; 10/84), and ABC + 3TC + LPV/r (11.9%; 10/84).ConclusionThis study revealed that HIV drug resistance mutations are common in Gabon. The major mutations associated with PIs were M41L, I84V, and V82A. There is a need for access to new NRTIs, NNRTIs, and PIs for a better therapeutic management of PLHIV in Gabon.

Abstract B016: Repurposing nelfinavir for re-sensitizing platinum-resistant high grade serous ovarian cancer cells

Abstract B016: Repurposing nelfinavir for re-sensitizing platinum-resistant high grade serous ovarian cancer cells

Food Insecurity Is High in a Multi-Site Cohort of Transgender Women Vulnerable to or Living with HIV in the Eastern and Southern United States: Baseline Findings from the LITE Cohort.

The prevalence and correlates of food insecurity-the unavailability of food and limited access to it-have not been adequately considered among transgender women (TW), particularly alongside other health-related conditions burdening this population, such as HIV infection. This study examined the prevalence and correlates of food insecurity among TW. Between 2018 and 2020, 1590 TW in the Eastern and Southern U.S. completed a multi-site baseline assessment (socio-behavioral survey and HIV testing). Descriptive statistics were calculated and multivariable Poisson models with robust error variance were used to estimate prevalence ratios and 95% confidence intervals for correlates of food insecurity (dichotomized as sometimes-to-always vs. seldom-to-never running out of food). Eighteen percent of TW were living with HIV and nearly half of participants (44%) reported food insecurity. Correlates of food insecurity included being Black, multiracial, or another race/ethnicity; having < college education, low income, unstable housing, and high anticipated discrimination; and a history of sex work and sexual violence (all p < 0.05). Food insecurity was highly prevalent among TW. Current programs to provide food support do not adequately meet the needs of TW. HIV pr evention and care programs may benefit from addressing food insecurity.

Preventing lipophilic aggregation in cosolvent molecular dynamics simulations with hydrophobic probes using Plumed Automatic Restraining Tool (PART)

Cosolvent molecular dynamics (MD) simulations are molecular dynamics simulations used to identify preferable locations of small organic fragments on a protein target. Most cosolvent molecular dynamics workflows make use of only water-soluble fragments, as hydrophobic fragments would cause lipophilic aggregation. To date the two approaches that allow usage of hydrophobic cosolvent molecules are to use a low (0.2 M) concentration of hydrophobic probes, with the disadvantage of a lower sampling speed, or to use force field modifications, with the disadvantage of a difficult and inflexible setup procedure. Here we present a third alternative, that does not suffer from low sampling speed nor from cumbersome preparation procedures. We have built an easy-to-use open source command line tool PART (Plumed Automatic Restraining Tool) to generate a PLUMED file handling all intermolecular restraints to prevent lipophilic aggregation. We have compared restrained and unrestrained cosolvent MD simulations, showing that restraints are necessary to prevent lipophilic aggregation at hydrophobic probe concentrations of 0.5 M. Furthermore, we benchmarked PART generated restraints on a test set of four proteins (Factor-Xa, HIV protease, P38 MAP kinase and RNase A), showing that cosolvent MD with PART generated restraints qualitatively reproduces binding features of cocrystallised ligands.

Roles of RNA scaffolding in nanoscale Gag multimerization and selective protein sorting at HIV membranes.

HIV-1 Gag proteins can multimerize upon the viral genomic RNA or multiple random cellular messenger RNAs to form a virus particle or a virus-like particle, respectively. To date, whether the two types of particles form via the same Gag multimerization process has remained unclarified. Using photoactivated localization microscopy to illuminate Gag organizations and dynamics at the nanoscale, here, we showed that genomic RNA mediates Gag multimerization in a more cluster-centric, cooperative, and spatiotemporally coordinated fashion, with the ability to drive dense Gag clustering dependent on its ability to act as a long-stranded scaffold not easily attainable by cellular messenger RNAs. These differences in Gag multimerization were further shown to affect downstream selective protein sorting into HIV membranes, indicating that the choice of RNA for packaging can modulate viral membrane compositions. These findings should advance the understanding of HIV assembly and further benefit the development of virus-like particle-based therapeutics.

Targeting Viral and Cellular Cysteine Proteases for Treatment of New Variants of SARS-CoV-2.

The continuous emergence of SARS-CoV-2 variants caused the persistence of the COVID-19 epidemic and challenged the effectiveness of the existing vaccines. The viral proteases are the most attractive targets for developing antiviral drugs. In this scenario, our study explores the use of HIV-1 protease inhibitors against SARS-CoV-2. An in silico screening of a library of HIV-1 proteases identified four anti-HIV compounds able to interact with the 3CLpro of SARS-CoV-2. Thus, in vitro studies were designed to evaluate their potential antiviral effectiveness against SARS-CoV-2. We employed pseudovirus technology to simulate, in a highly safe manner, the adsorption of the alpha (α-SARS-CoV-2) and omicron (ο-SARS-CoV-2) variants of SARS-CoV-2 and study the inhibitory mechanism of the selected compounds for cell-virus interaction. The results reported a mild activity against the viral proteases 3CLpro and PLpro, but efficient inhibitory effects on the internalization of both variants mediated by cathepsin B/L. Our findings provide insights into the feasibility of using drugs exhibiting antiviral effects for other viruses against the viral and host SARS-CoV-2 proteases required for entry.

Preclinical characterization of a non-peptidomimetic HIV protease inhibitor with improved metabolic stability.

Protease inhibitors (PIs) remain an important component of antiretroviral therapy for the treatment of HIV-1 infection due to their high genetic barrier to resistance development. Nevertheless, the two most commonly prescribed HIV PIs, atazanavir and darunavir, still require co-administration with a pharmacokinetic boosting agent to maintain sufficient drug plasma levels which can lead to undesirable drug-drug interactions. Herein, we describe GS-9770, a novel investigational non-peptidomimetic HIV PI with unboosted once-daily oral dosing potential due to improvements in its metabolic stability and its pharmacokinetic properties in preclinical animal species. This compound demonstrates potent inhibitory activity and high on-target selectivity for recombinant HIV-1 protease versus other aspartic proteases tested. In cell culture, GS-9770 inhibits Gag polyprotein cleavage and shows nanomolar anti-HIV-1 potency in primary human cells permissive to HIV-1 infection and against a broad range of HIV subtypes. GS-9770 demonstrates an improved resistance profile against a panel of patient-derived HIV-1 isolates with resistance to atazanavir and darunavir. In resistance selection experiments, GS-9770 prevented the emergence of breakthrough HIV-1 variants at all fixed drug concentrations tested and required multiple protease substitutions to enable outgrowth of virus exposed to escalating concentrations of GS-9770. This compound also remained fully active against viruses resistant to drugs from other antiviral classes and showed no in vitro antagonism when combined pairwise with drugs from other antiretroviral classes. Collectively, these preclinical data identify GS-9770 as a potent, non-peptidomimetic once-daily oral HIV PI with potential to overcome the persistent requirement for pharmacological boosting with this class of antiretroviral agents.