A computational overview of integrase strand transfer inhibitors (INSTIs) against emerging and evolving drug-resistant HIV-1 integrase mutants.

AIDS (Acquired immunodeficiency syndrome) is one of the chronic and potentially life-threatening epidemics across the world. Hitherto, the non-existence of definitive drugs that could completely cure the Human immunodeficiency virus (HIV) implies an urgent necessity for the discovery of novel anti-HIV agents. Since integration is the most crucial stage in retroviral replication, hindering it can inhibit overall viral transmission. The 5 FDA-approved integrase inhibitors were computationally investigated, especially owing to the rising multiple mutations against their susceptibility. This comparative study will open new possibilities to guide the rational design of novel lead compounds for antiretroviral therapies (ARTs), more specifically the structure-based design of novel Integrase strand transfer inhibitors (INSTIs) that may possess a better resistance profile than present drugs. Further, we have discussed potent anti-HIV natural compounds and their interactions as an alternative approach, recommending the urgent need to tap into the rich vein of indigenous knowledge for reverse pharmacology. Moreover, herein, we discuss existing evidence that might change in the near future.

Erastin inhibits porcine epidemic diarrhea virus replication in Vero cells.

Background: Porcine epidemic diarrhea virus (PEDV), an intestinal pathogenic coronavirus, has caused significant economic losses to the swine industry worldwide. At present, there are several treatment methods, but there is still a lack of clinically effective targeted drugs, new antiviral mechanisms and drugs need to be explored. Methods: In this study, we established a model of erastin versus ferrostatin-1 treatment of Vero cells, and then detected virus proliferation and gene expression by RT-qPCR through PEDV infection experiments. Results: We demonstrated for the first time that erastin significantly inhibited the replication of PEDV upon entry into cells; Vero treated with erastin significantly regulated the expression of three genes, NRF2, ACSL4 and GPX4, notably erastin regulated the expression of these three genes negatively correlated with the expression induced by PEDV virus infection. Conclusions: Since NRF2, ACSL4 and GPX4 are classical Ferroptosis genes, this study speculates that erastin may inhibit the replication of PEDV in Vero cells in part through the regulation of ferroptosis pathway, and erastin may be a potential drug for the treatment of PEDV infection.

Discovery and Crystallographic Studies of Nonpeptidic Piperazine Derivatives as Covalent SARS-CoV-2 Main Protease Inhibitors.

The spread of SARS-CoV-2 keeps threatening human life and health, and small-molecule antivirals are in demand. The main protease (Mpro) is an effective and highly conserved target for anti-SARS-CoV-2 drug design. Herein, we report the discovery of potent covalent non-peptide-derived Mpro inhibitors. A series of covalent compounds with a piperazine scaffold containing different warheads were designed and synthesized. Among them, GD-9 was identified as the most potent compound with a significant enzymatic inhibition of Mpro (IC50 = 0.18 µM) and good antiviral potency against SARS-CoV-2 (EC50 = 2.64 µM), similar to that of remdesivir (EC50 = 2.27 µM). Additionally, GD-9 presented favorable target selectivity for SARS-CoV-2 Mpro versus human cysteine proteases. The X-ray co-crystal structure confirmed our original design concept showing that GD-9 covalently binds to the active site of Mpro. Our nonpeptidic covalent inhibitors provide a basis for the future development of more efficient COVID-19 therapeutics.

Dolutegravir Plus Lamivudine Dual-Drug Regimen in Treatment-Naive HIV-1-Infected Patients With High-Level Viral Load: Preliminary Data From the Real World.

BACKGROUND: Some inpatients with HIV-RNA ≥500,000 copies/mL in China need to use 2-drug regimen for some reasons, although limited data are available for dolutegravir plus lamivudine (3TC) in those patients with ultra-high viral loads. METHODS: We conducted a single-center retrospective-prospective study in China and enrolled 42 ART-naive HIV-infected inpatients who use a once-daily 2-drug regimen because of various reasons (drug interaction, renal impairment, age, and other related comorbidities).They were divided into 2 groups, low viral load group (baseline viral load <500,000 copies/mL, n = 20) and high viral load group (baseline viral load ≥500,000 copies/mL, n = 22). All patients were followed up for 48 weeks. RESULTS: The median of baseline viral load was 5.74 log10 copies/mL and CD4+ T-cell count was 59 cells/µL. At week 48, there was no significant difference (P = 0.598) in proportions of participants with HIV-1 RNA <50 copies/mL [90%, 95% confidence interval (CI) (75.6% to 104.4%) in low viral load groups vs 95.5%, 95% CI (86.0% to 104.9%) in high viral load groups]. No differences were found in mean increase of CD4+ T-cell count from baseline between 2 groups (218 ± 122 vs 265 ± 127 cells/µL, P = 0.245). There is no grade 3 or higher treatment-related adverse events and none discontinued treatment because of adverse events. CONCLUSIONS: The results of our study in real world support dolutegravir + 3TC dual regimen as a promising therapy option for treatment-naive HIV-infected patient with baseline viral load ≥500,000 copies/mL.

Discovery and Crystallographic Studies of Trisubstituted Piperazine Derivatives as Non-Covalent SARS-CoV-2 Main Protease Inhibitors with High Target Specificity and Low Toxicity.

The continuous spread of SARS-CoV-2 calls for more direct-acting antiviral agents to combat the highly infectious variants. The main protease (Mpro) is an promising target for anti-SARS-CoV-2 drug design. Here, we report the discovery of potent non-covalent non-peptide Mpro inhibitors featuring a 1,2,4-trisubstituted piperazine scaffold. We systematically modified the non-covalent hit MCULE-5948770040 by structure-based rational design combined with multi-site binding and privileged structure assembly strategies. The optimized compound GC-14 inhibits Mpro with high potency (IC50 = 0.40 µM) and displays excellent antiviral activity (EC50 = 1.1 µM), being more potent than Remdesivir. Notably, GC-14 exhibits low cytotoxicity (CC50 > 100 µM) and excellent target selectivity for SARS-CoV-2 Mpro (IC50 > 50 µM for cathepsins B, F, K, L, and caspase 3). X-ray co-crystal structures prove that the inhibitors occupy multiple subpockets by critical non-covalent interactions. These studies may provide a basis for developing a more efficient and safer therapy for COVID-19.

Determinants of Survival of HIV Patients Receiving Dolutegravir: A Prospective Cohort Study in Conflict-Affected Bunia, Democratic Republic of Congo.

This study aims to determine the factors influencing HIV-related mortality in settings experiencing continuous armed conflict atrocities. In such settings, people living with HIV (PLHIV), and the partners of those affected may encounter specific difficulties regarding adherence to antiretroviral therapy (ART), and retention in HIV prevention, treatment, and care programs. Between July 2019 and July 2021, we conducted an observational prospective cohort study of 468 PLHIV patients treated with Dolutegravir at all the ART facilities in Bunia. The probability of death being the primary outcome, as a function of time of inclusion in the cohort, was determined using Kaplan-Meier plots. We used the log-rank test to compare survival curves and Cox proportional hazard modeling to determine mortality predictors from the baseline to 31 July 2021 (endpoint). The total number of person-months (p-m) was 3435, with a death rate of 6.70 per 1000 p-m. Compared with the 35-year-old reference group, older patients had a higher mortality risk. ART-naïve participants at the time of enrollment had a higher mortality risk than those already using ART. Patients with a high baseline viral load (≥1000 copies/mL) had a higher mortality risk compared with the reference group (adjusted hazard ratio = 6.04; 95% CI: 1.78-20.43). One-fourth of deaths in the cohort were direct victims of armed conflict, with an estimated excess death of 35.6%. Improving baseline viral load monitoring, starting ART early in individuals with high baseline viral loads, the proper tailoring of ART regimens and optimizing long-term ART, and care to manage non-AIDS-related chronic complications are recommended actions to reduce mortality. Not least, fostering women's inclusion, justice, peace, and security in conflict zones is critical in preventing premature deaths in the general population as well as among PLHIV.

Increased viral load in a hospitalized patient on treatment with crushed bictegravir/emtricitabine/tenofovir alafenamide: A case report and review of the literature.

PURPOSE: To describe a case of increased viral load in a patient with HIV-1 infection receiving treatment with crushed bictegravir/emtricitabine/tenofovir alafenamide (B/FTC/TAF). SUMMARY: A 43-year-old man, newly diagnosed with HIV, was hospitalized due to failure to thrive, neurological changes, and hypotension. Before treatment, the HIV viral load (VL) was 769,704 copies/mL and the CD4+ T-cell count was 36 cells/µL. On hospital day (HD) 8, B/FTC/TAF by mouth daily was initiated. During the hospitalization, the patient's course was complicated by opportunistic infections, bilateral pneumothorax, seizure activity, and acute respiratory distress, requiring multiple intubations and extended time in the intensive care unit. A repeat VL measurement on HD 28 was 5,887 copies/mL after the patient had received 14 of 20 scheduled B/FTC/TAF doses. Because of a failed swallow study and continued nutritional deficits, a percutaneous endoscopic gastrostomy (PEG) tube was placed on HD 38 and continuous tube feeds via the PEG tube were initiated. Subsequently, the B/FTC/TAF order was modified to be crushed, mixed in 30 mL water, and administered daily via the PEG tube. A repeat VL measurement on HD 65 showed an increase to 8,047 copies/mL, despite receipt of 37 consecutive doses of B/FTC/TAF. B/FTC/TAF was discontinued and dolutegravir 50 mg twice daily, darunavir 800 mg plus ritonavir 100 mg (DRV/r), and tenofovir disoproxil fumarate/FTC 300 mg/200 mg were started due to virological increase, need for a viable option compatible with PEG tube delivery, and potential for integrase inhibitor resistance. At the time of regimen change (HD 67), a resistance panel showed minor mutations, E157Q and V118I. The regimen was streamlined with discontinuation of DRV/r on HD 92. The patient was discharged on HD 161. The PEG tube was removed 2 months after discharge, oral B/FTC/TAF was reinitiated, and the patient was virologically suppressed at 1 year after discharge. CONCLUSION: Controlled studies are needed to verify acceptable pharmacokinetic and pharmacodynamic metrics for crushed B/FTC/TAF given via tube, with and without tube feeds, before use in this manner.

Eicosanoid signalling blockade protects middle-aged mice from severe COVID-19.

Coronavirus disease 2019 (COVID-19) is especially severe in aged populations1. Vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are highly effective, but vaccine efficacy is partly compromised by the emergence of SARS-CoV-2 variants with enhanced transmissibility2. The emergence of these variants emphasizes the need for further development of anti-SARS-CoV-2 therapies, especially for aged populations. Here we describe the isolation of highly virulent mouse-adapted viruses and use them to test a new therapeutic drug in infected aged animals. Many of the alterations observed in SARS-CoV-2 during mouse adaptation (positions 417, 484, 493, 498 and 501 of the spike protein) also arise in humans in variants of concern2. Their appearance during mouse adaptation indicates that immune pressure is not required for selection. For murine SARS, for which severity is also age dependent, elevated levels of an eicosanoid (prostaglandin D2 (PGD2)) and a phospholipase (phospholipase A2 group 2D (PLA2G2D)) contributed to poor outcomes in aged mice3,4. mRNA expression of PLA2G2D and prostaglandin D2 receptor (PTGDR), and production of PGD2 also increase with ageing and after SARS-CoV-2 infection in dendritic cells derived from human peripheral blood mononuclear cells. Using our mouse-adapted SARS-CoV-2, we show that middle-aged mice lacking expression of PTGDR or PLA2G2D are protected from severe disease. Furthermore, treatment with a PTGDR antagonist, asapiprant, protected aged mice from lethal infection. PTGDR antagonism is one of the first interventions in SARS-CoV-2-infected animals that specifically protects aged animals, suggesting that the PLA2G2D-PGD2/PTGDR pathway is a useful target for therapeutic interventions.

Adherence to Antiretroviral Therapy and Associated Factors Among People Living With HIV Following the Introduction of Dolutegravir Based Regimens in Dar es Salaam, Tanzania.

Background: Adherence to antiretroviral therapy (ART) is the key determinant of virological suppression in people living with HIV (PLHIV). This study reports factors associated with non-adherence among PLHIV one year after introducing dolutegravir (DTG) based regimens in Tanzania. Methods: A hospital-based cross-sectional study was conducted in two health facilities in Dar es Salaam, Tanzania, in 2020. Results: A total of 406 PLHIV were recruited, where the majority (73.4%) were females, with 94.6% of patients being on DTG based regimens. Factors such as refill interval and sharing of antiretrovirals had significant effects on adherence. Multivariate analysis found that patients attending care and treatment center (CTC) at Temeke Regional Referral Hospital (RRH) were 4.3 times more likely to have non-adherence compared to those attending Amana RRH (aOR [adjusted odds ratio] 4.3, 95% CI [confidence interval]: 2.38 - 7.91, p-value < 0.0001). Conclusions: Sustainable adherence counseling is warranted to overcome non-adherence to ART.

South African healthcare workers' knowledge of dolutegravir's drug-drug interactions in the first year of its rollout: a cross-sectional online survey.

INTRODUCTION: In December 2019, dolutegravir-based treatment was recommended as first-line antiretroviral therapy (ART) in South Africa. Dolutegravir has clinically significant interactions with several commonly used drugs, such as rifampicin, metformin and cation-containing medicines. National guidelines detail these interactions and how to manage them. While previous international studies have shown low healthcare worker knowledge of drug-drug interactions, there is a paucity of information on antiretroviral interaction knowledge in the South African setting, where much ART is nurse-led. The study aimed to determine this knowledge and to describe which variables were associated with gaps in knowledge. METHODS: An anonymous online survey of healthcare workers in the field of HIV was conducted in August/September 2020. The survey was designed, tested and piloted, and included sections on demographics, guideline access and training, interaction knowledge, counselling and the effect of COVID-19. Dissemination was via e-mail and social media (convenience sampling). Descriptive and inferential analysis was done using proportions and the 95% confidence interval to determine relationships between independent and dependent variables. Research ethics approval was obtained from the University of Cape Town's Human Research Ethics Committee (HREC Ref: 357/2020). RESULTS AND DISCUSSION: In total, 1950 survey responses were included in the analysis - 47.1% nurses, 35.8% doctors and 8.9% pharmacists. When asked whether they were aware that dolutegravir has interactions, 70% said yes, 13.9% said no and 16.1% did not answer. Knowledge of specific interactions and the dosing changes needed was low with a wide range between different drugs: 79.7% knew to double the dolutegravir dose with rifampicin, but with calcium, 5.1% picked both correct dosing options and 33.7% picked one of the two correct options. Access to guidelines and training were positively associated with drug interaction knowledge. CONCLUSIONS: There are gaps in the awareness and knowledge of dolutegravir interactions and how to adjust dosing among South African healthcare workers.

Neoechinulin A as a Promising SARS-CoV-2 Mpro Inhibitor: In Vitro and In Silico Study Showing the Ability of Simulations in Discerning Active from Inactive Enzyme Inhibitors.

The COVID-19 pandemic and its continuing emerging variants emphasize the need to discover appropriate treatment, where vaccines alone have failed to show complete protection against the new variants of the virus. Therefore, treatment of the infected cases is critical. This paper discusses the bio-guided isolation of three indole diketopiperazine alkaloids, neoechinulin A (1), echinulin (2), and eurocristatine (3), from the Red Sea-derived Aspergillus fumigatus MR2012. Neoechinulin A (1) exhibited a potent inhibitory effect against SARS-CoV-2 Mpro with IC50 value of 0.47 µM, which is comparable to the reference standard GC376. Despite the structural similarity between the three compounds, only 1 showed a promising effect. The mechanism of inhibition is discussed in light of a series of extensive molecular docking, classical and steered molecular dynamics simulation experiments. This paper sheds light on indole diketopiperazine alkaloids as a potential structural motif against SARS-CoV-2 Mpro. Additionally, it highlights the potential of different molecular docking and molecular dynamics simulation approaches in the discrimination between active and inactive structurally related Mpro inhibitors.

Inhibitors of Anti-apoptotic Bcl-2 Family Proteins Exhibit Potent and Broad-Spectrum Anti-mammarenavirus Activity via Cell Cycle Arrest at G0/G1 Phase.

Targeting host factors is a promising strategy to develop broad-spectrum antiviral drugs. Drugs targeting anti-apoptotic Bcl-2 family proteins that were originally developed as tumor suppressors have been reported to inhibit multiplication of different types of viruses. However, the mechanisms whereby Bcl-2 inhibitors exert their antiviral activity remain poorly understood. In this study, we have investigated the mechanisms by which obatoclax (OLX) and ABT-737 Bcl-2 inhibitors exhibited a potent antiviral activity against the mammarenavirus lymphocytic choriomeningitis virus (LCMV). OLX and ABT-737 potent anti-LCMV activity was not associated with their proapoptotic properties but rather with their ability to induce cell arrest at the G0/G1 phase. OLX- and ABT-737-mediated inhibition of Bcl-2 correlated with reduced expression levels of thymidine kinase 1 (TK1), cyclin A2 (CCNA2), and cyclin B1 (CCNB1) cell cycle regulators. In addition, small interfering RNA (siRNA)-mediated knockdown of TK1, CCNA2, and CCNB1 resulted in reduced levels of LCMV multiplication. The antiviral activity exerted by Bcl-2 inhibitors correlated with reduced levels of viral RNA synthesis at early times of infection. Importantly, ABT-737 exhibited moderate efficacy in a mouse model of LCMV infection, and Bcl-2 inhibitors displayed broad-spectrum antiviral activities against different mammarenaviruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our results suggest that Bcl-2 inhibitors, actively being explored as anticancer therapeutics, might be repositioned as broad-spectrum antivirals. IMPORTANCE Antiapoptotic Bcl-2 inhibitors have been shown to exert potent antiviral activities against various types of viruses via mechanisms that are currently poorly understood. This study has revealed that Bcl-2 inhibitors' mediation of cell cycle arrest at the G0/G1 phase, rather than their proapoptotic activity, plays a critical role in blocking mammarenavirus multiplication in cultured cells. In addition, we show that Bcl-2 inhibitor ABT-737 exhibited moderate antimammarenavirus activity in vivo and that Bcl-2 inhibitors displayed broad-spectrum antiviral activities against different mammarenaviruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our results suggest that Bcl-2 inhibitors, actively being explored as anticancer therapeutics, might be repositioned as broad-spectrum antivirals.

Dexamethasone sensitizes to ferroptosis by glucocorticoid receptor-induced dipeptidase-1 expression and glutathione depletion.

Dexamethasone is widely used as an immunosuppressive therapy and recently as COVID-19 treatment. Here, we demonstrate that dexamethasone sensitizes to ferroptosis, a form of iron-catalyzed necrosis, previously suggested to contribute to diseases such as acute kidney injury, myocardial infarction, and stroke, all of which are triggered by glutathione (GSH) depletion. GSH levels were significantly decreased by dexamethasone. Mechanistically, we identified that dexamethasone up-regulated the GSH metabolism regulating protein dipeptidase-1 (DPEP1) in a glucocorticoid receptor (GR)-dependent manner. DPEP1 knockdown reversed the phenotype of dexamethasone-induced ferroptosis sensitization. Ferroptosis inhibitors, the DPEP1 inhibitor cilastatin, or genetic DPEP1 inactivation reversed the dexamethasone-induced increase in tubular necrosis in freshly isolated renal tubules. Our data indicate that dexamethasone sensitizes to ferroptosis by a GR-mediated increase in DPEP1 expression and GSH depletion. Together, we identified a previously unknown mechanism of glucocorticoid-mediated sensitization to ferroptosis bearing clinical and therapeutic implications.

Synthesis and Antiviral Activities of Neoechinulin B and Its Derivatives.

We have previously reported that neoechinulin B (1a), a prenylated indole diketopiperazine alkaloid, shows antiviral activities against hepatitis C virus (HCV) via the inactivation of the liver X receptors (LXRs) and the resultant disruption of double-membrane vesicles. In this study, a two-step synthesis of the diketopiperazine scaffold of 1a was achieved by the base-induced coupling of 1,4-diacetyl-3-{[(tert-butyldimethylsilyl)oxy]methyl}piperazine-2,5-dione with aldehydes, followed by the treatment of the resultant coupling products with tetra-n-butylammonium fluoride. Compound 1a and its 16 derivatives 1b-q were prepared using this method. Furthermore, variecolorin H, a related alkaloid, was obtained by the acid treatment of 1a in MeOH. The antiviral evaluation of 1a and its derivatives revealed that 1a, 1c, 1d, 1h, 1j, 1l, and 1o exhibited both anti-HCV and anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) activities. The results of this study indicate that the exomethylene moiety on the diketopiperazine ring is important for the antiviral activities. The antiviral compounds can inhibit the production of HCV and SARS-CoV-2 by inactivating LXRs.

Comparing the effectiveness of Atazanavir/Ritonavir/Dolutegravir/Hydroxychloroquine and Lopinavir/Ritonavir/Hydroxychloroquine treatment regimens in COVID-19 patients.

The purpose of this study was to compare the effectiveness of Atazanavir/Ritonavir/Dolutegravir/Hydroxychloroquine and Lopinavir/Ritonavir/Hydroxychloroquine treatment regimens in COVID-19 patients based on clinical and laboratory parameters. We prospectively evaluated the clinical and laboratory outcomes of 62 moderate to severe COVID-19 patients during a 10-day treatment plan. Patients were randomly assigned to either KH (receiving Lopinavir/Ritonavir [Kaletra] plus Hydroxychloroquine) or ADH (receiving Atazanavir/Ritonavir, Dolutegravir, and Hydroxychloroquine) groups. During this period, clinical and laboratory parameters and outcomes such as intensive care unit (ICU) admission or mortality rate were recorded. Compared to the KH group, after the treatment period, patients in the ADH group had higher activated partial thromboplastin time (aPTT) (12, [95% confidence interval [CI]: 6.97, 17.06), p = <0.01), international normalized ratio (INR) (0.17, [95% CI: 0.07, 0.27), p = <0.01) and lower C-reactive protein (CRP) (-14.29, (95% CI: -26.87, -1.71), p = 0.03) and potassium (-0.53, (95% CI: -1.03, -0.03), p = 0.04) values. Moreover, a higher number of patients in the KH group needed invasive ventilation (6 (20%) vs. 1 (3.1%), p = 0.05) and antibiotic administration (27 (90%) vs. 21(65.6), p = 0.02) during hospitalization while patients in the ADH group needed more corticosteroid administration (9 (28.1%) vs. 2 (6.7%), p = 0.03). There was no difference in mortality rate, ICU admission rate, and hospitalization period between the study groups. Our results suggest that the Atazanavir/Dolutegravir treatment regimen may result in a less severe disease course compared to the Lopinavir/Ritonavir treatment regimen and can be considered as an alternative treatment option beside standard care. However, to confirm our results, larger-scale studies are recommended.

High-Throughput Virtual Screening and Validation of a SARS-CoV-2 Main Protease Noncovalent Inhibitor.

Despite the recent availability of vaccines against the acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the search for inhibitory therapeutic agents has assumed importance especially in the context of emerging new viral variants. In this paper, we describe the discovery of a novel noncovalent small-molecule inhibitor, MCULE-5948770040, that binds to and inhibits the SARS-Cov-2 main protease (Mpro) by employing a scalable high-throughput virtual screening (HTVS) framework and a targeted compound library of over 6.5 million molecules that could be readily ordered and purchased. Our HTVS framework leverages the U.S. supercomputing infrastructure achieving nearly 91% resource utilization and nearly 126 million docking calculations per hour. Downstream biochemical assays validate this Mpro inhibitor with an inhibition constant (Ki) of 2.9 µM (95% CI 2.2, 4.0). Furthermore, using room-temperature X-ray crystallography, we show that MCULE-5948770040 binds to a cleft in the primary binding site of Mpro forming stable hydrogen bond and hydrophobic interactions. We then used multiple µs-time scale molecular dynamics (MD) simulations and machine learning (ML) techniques to elucidate how the bound ligand alters the conformational states accessed by Mpro, involving motions both proximal and distal to the binding site. Together, our results demonstrate how MCULE-5948770040 inhibits Mpro and offers a springboard for further therapeutic design.

Structural, Electronic, and Electrostatic Determinants for Inhibitor Binding to Subsites S1 and S2 in SARS-CoV-2 Main Protease.

Creating small-molecule antivirals specific for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins is crucial to battle coronavirus disease 2019 (COVID-19). SARS-CoV-2 main protease (Mpro) is an established drug target for the design of protease inhibitors. We performed a structure-activity relationship (SAR) study of noncovalent compounds that bind in the enzyme's substrate-binding subsites S1 and S2, revealing structural, electronic, and electrostatic determinants of these sites. The study was guided by the X-ray/neutron structure of Mpro complexed with Mcule-5948770040 (compound 1), in which protonation states were directly visualized. Virtual reality-assisted structure analysis and small-molecule building were employed to generate analogues of 1. In vitro enzyme inhibition assays and room-temperature X-ray structures demonstrated the effect of chemical modifications on Mpro inhibition, showing that (1) maintaining correct geometry of an inhibitor's P1 group is essential to preserve the hydrogen bond with the protonated His163; (2) a positively charged linker is preferred; and (3) subsite S2 prefers nonbulky modestly electronegative groups.

A reflective process led by a family physician to develop a renal-protection surveillance tool for HIV patients newly started on dolutegravir.

A group of Vanguard Community Health Centre doctors embarked on a Health System's Improvement (HSI) project with the aim of reducing harm to renal function in patients who were either commenced on or switched to a dolutegravir (DTG)-based antiretroviral therapy (ART) regimen since 2019, when the usual monitoring and evaluation of ART-regimen switches were disrupted by the coronavirus disease 2019 (COVID-19) pandemic. This intended harm-reduction exercise, involving a reflective process that was facilitated by the family physician, led to the development of a Vanguard Renal Protection Surveillance tool, which is now used at Vanguard to detect and prevent renal decline.

New Drugs 2021, Part 2.

ABSTRACT: The second of a two-part series, this article describes eight recently approved drugs, including the first drug approved for the treatment of SARS-CoV-2, a first-in-class HIV attachment inhibitor, and a new intravenous injection indicated for the treatment of acute pain in adults for whom other treatments are ineffective.

A Clinical-Stage Cysteine Protease Inhibitor blocks SARS-CoV-2 Infection of Human and Monkey Cells.

Host-cell cysteine proteases play an essential role in the processing of the viral spike protein of SARS coronaviruses. K777, an irreversible, covalent inactivator of cysteine proteases that has recently completed phase 1 clinical trials, reduced SARS-CoV-2 viral infectivity in several host cells: Vero E6 (EC50< 74 nM), HeLa/ACE2 (4 nM), Caco-2 (EC90 = 4.3 µM), and A549/ACE2 (<80 nM). Infectivity of Calu-3 cells depended on the cell line assayed. If Calu-3/2B4 was used, EC50 was 7 nM, but in the ATCC Calu-3 cell line without ACE2 enrichment, EC50 was >10 µM. There was no toxicity to any of the host cell lines at 10-100 µM K777 concentration. Kinetic analysis confirmed that K777 was a potent inhibitor of human cathepsin L, whereas no inhibition of the SARS-CoV-2 cysteine proteases (papain-like and 3CL-like protease) was observed. Treatment of Vero E6 cells with a propargyl derivative of K777 as an activity-based probe identified human cathepsin B and cathepsin L as the intracellular targets of this molecule in both infected and uninfected Vero E6 cells. However, cleavage of the SARS-CoV-2 spike protein was only carried out by cathepsin L. This cleavage was blocked by K777 and occurred in the S1 domain of the SARS-CoV-2 spike protein, a different site from that previously observed for the SARS-CoV-1 spike protein. These data support the hypothesis that the antiviral activity of K777 is mediated through inhibition of the activity of host cathepsin L and subsequent loss of cathepsin L-mediated viral spike protein processing.