A comparative analysis of remdesivir and other repurposed antivirals against SARS-CoV-2

Recent Advances in the Synthesis of Acyclic Nucleosides and Their Therapeutic Applications

DNA is commonly known as the "molecule of life" because it holds the genetic instructions for all living organisms on Earth. The utilization of modified nucleosides holds the potential to transform the management of a wide range of human illnesses. Modified nucleosides and their role directly led to the 2023 Nobel prize. Acyclic nucleosides, due to their distinctive physiochemical and biological characteristics, rank among the most adaptable modified nucleosides in the field of medicinal chemistry. Acyclic nucleosides are more resistant to chemical and biological deterioration, and their adaptable acyclic structure makes it possible for them to interact with various enzymes. A phosphonate group, which is linked via an aliphatic functionality to a purine or a pyrimidine base, distinguishes acyclic nucleoside phosphonates (ANPs) from other nucleotide analogs. Acyclic nucleosides and their derivatives have demonstrated various biological activities such as anti-viral, anti-bacterial, anti-cancer, anti-microbial, etc. Ganciclovir, Famciclovir, and Penciclovir are the acyclic nucleoside-based drugs approved by FDA for the treatment of various diseases. Thus, acyclic nucleosides are extremely useful for generating a variety of unique bioactive chemicals. Their biological activities as well as selectivity is significantly influenced by the stereochemistry of the acyclic nucleosides because chiral acyclic nucleosides have drawn a lot of interest due to their intriguing biological functions and potential as medicines. For example, tenofovir's (R) enantiomer is roughly 50 times more potent against HIV than its (S) counterpart. We can confidently state, "The most promising developments are yet to come in the realm of acyclic nucleosides!" Herein, we have covered the most current developments in the field of chemical synthesis and therapeutic applications of acyclic nucleosides based upon our continued interest and activity in this field since mid-1990's.

In-vitro antiviral activity and in-silico targeted study of quinoline-3-carboxylate derivatives against SARS-Cov-2 isolate

In recent years, the viral outbreak named COVID-19 showed that infectious diseases have a huge impact on both global health and the financial and economic sectors. The lack of efficacious antiviral drugs worsened the health problem. Based on our previous experience, we investigated in vitro and in silico a series of quinoline-3-carboxylate derivatives against a SARS-CoV-2 isolate. In the present study, the in-vitro antiviral activity of a series of quinoline-3-carboxylate compounds and the in silico target-based molecular dynamics (MD) and metabolic studies are reported. The compounds' activity against SARS-CoV-2 was evaluated using plaque assay and RT-qPCR. Moreover, from the docking scores, it appears that the most active compounds (1j and 1o) exhibit stronger binding affinity to the primary viral protease (NSP5) and the exoribonuclease domain of non structural protein 14 (NSP14). Additionally, the in-silico metabolic analysis of 1j and 1o defines CYP2C9 and CYP3A4 as the major P450 enzymes involved in their metabolism.

Further preclinical characterization of molnupiravir against SARS-CoV-2: Antiviral activity determinants and viral genome alteration patterns

The SARS-CoV-2 pandemic has highlighted the need for broad-spectrum antiviral drugs to respond promptly to viral emergence. We conducted a preclinical study of molnupiravir (MOV) against SARS-CoV-2 to fully characterise its antiviral properties and mode of action. The antiviral activity of different concentrations of MOV was evaluated ex vivo on human airway epithelium (HAE) and in vivo in a hamster model at three escalating doses (150, 300 and 400 mg/kg/day) according to three different regimens (preventive, pre-emptive and curative). We assessed viral loads and infectious titres at the apical pole of HAE and in hamster lungs, and MOV trough concentration in plasma and lungs. To explore the mode of action of the MOV, the entire genomes of the collected viruses were deep-sequenced. MOV effectively reduced viral titres in HAE and in the lungs of treated animals. Early treatment after infection was a key factor in efficacy, probably associated with high lung concentrations of MOV, suggesting good accumulation in the lung. MOV induced genomic alteration in viral genomes with an increase in the number of minority variants, and predominant G to A transitions. The observed reduction in viral replication and its mechanism of action leading to lethal mutagenesis, supported by clinical trials showing antiviral action in humans, provide a convincing basis for further research as an additional means in the fight against COVID-19 and other RNA viruses.

Developing nucleoside tailoring strategies against SARS-CoV-2 via ribonuclease targeting chimera

In response to the urgent need for potent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) therapeutics, this study introduces an innovative nucleoside tailoring strategy leveraging ribonuclease targeting chimeras. By seamlessly integrating ribonuclease L recruiters into nucleosides, we address RNA recognition challenges and effectively inhibit severe acute respiratory syndrome coronavirus 2 replication in human cells. Notably, nucleosides tailored at the ribose 2'-position outperform those modified at the nucleobase. Our in vivo validation using hamster models further bolsters the promise of this nucleoside tailoring approach, positioning it as a valuable asset in the development of innovative antiviral drugs.

Syringa reticulata potently inhibits the activity of SARS-CoV-2 3CL protease

The ongoing coronavirus infectious disease (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) still urgently requires effective treatments. The 3C-like (3CL) protease of SARS-CoV-2 is a highly conserved cysteine protease that plays an important role in the viral life cycle and host inflammation, providing an ideal target for developing broad-spectrum antiviral drugs. Herein, we describe the discovery of a large number of herbs mainly produced in Heilongjiang Province, China, that exhibited different inhibitory activities against SARS-CoV-2 3CL protease. We confirmed that Syringa reticulata, which is used for clinical treatment of chronic bronchitis and asthma, is a specific and potent inhibitor of 3CL protease. A 70 % ethanol extract of S. reticulata dose-dependently inhibited the cleavage activity of 3CL protease in a fluorescence resonance energy transfer assay with an IC50 value of 0.0018 mg/mL, but had minimal effect in pseudovirus-based cell entry and luciferase-based RNA-dependent RNA polymerase assays. These results suggest that S. reticulata will be a potential leading candidate for COVID-19 treatment.

Clinical development of antivirals against SARS-CoV-2 and its variants

The unceasing global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) calls for the development of novel therapeutics. Although many newly developed antivirals and repurposed antivirals have been applied to the treatment of coronavirus disease 2019 (COVID-19), antivirals showing satisfactory clinical efficacy are few in number. In addition, the loss of sensitivity to variants of concern (VOCs) and lack of oral bioavailability have also limited the clinical application of some antivirals. These facts remind us to develop more potent and broad-spectrum antivirals with better pharmacokinetic/pharmacodynamic properties to fight against infections from SARS-CoV-2, its variants, and other human coronaviruses (HCoVs). In this review, we summarize the latest advancements in the clinical development of antivirals against infections by SARS-CoV-2 and its variants.

Modulation of various host cellular machinery during COVID-19 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) emerged in December 2019, causing a range of respiratory infections from mild to severe. This resulted in the ongoing global COVID-19 pandemic, which has had a significant impact on public health. The World Health Organization declared COVID-19 as a global pandemic in March 2020. Viruses are intracellular pathogens that rely on the host's machinery to establish a successful infection. They exploit the gene expression machinery of host cells to facilitate their own replication. Gaining a better understanding of gene expression modulation in SARS-CoV2 is crucial for designing and developing effective antiviral strategies. Efforts are currently underway to understand the molecular-level interaction between the host and the pathogen. In this review, we describe how SARS-CoV2 infection modulates gene expression by interfering with cellular processes, including transcription, post-transcription, translation, post-translation, epigenetic modifications as well as processing and degradation pathways. Additionally, we emphasise the therapeutic implications of these findings in the development of new therapies to treat SARS-CoV2 infection.

Remdesivir administration for SARS-CoV-2 pneumonia in ICU and non-ICU patients: outcome and posttreatment differences - the Italian Military Hospital experience

BACKGROUND

Four-hundred forty-nine patients affected by Covid-19 were hospitalized at the Rome Military Hospital between March 2020 and July 2022. Depending on the severity of the disease, they were assigned either to the Functional Health Emergency Unit - if suffering from interstitial pneumonia with a clinical manifestation of dyspnea associated with peripheral oxygen saturation  < 92%, and oxygen atmospheric pressure therapy - or to the intensive care unit - if the blood gas-lytic index P/F (ratio between partial pressure of arterial O2 and inspired fraction of O2) was below 150. This prospective observation and monocentric study aim to verify the outcome (healing/death) of early use of remdesivir in pneumonia patients.

RESULTS

The results highlight the importance of the adoption of remdesivir in the initial stages of infection to prevent the systemic spread and viral multiplication and, in the subsequent phase, a cytokine storm resulting in acute respiratory failure and multiorgan failure. The use of the drug in the most advanced stages of the disease is not associated with a real impact on patient outcomes. Therefore, there is a statistically significant correspondence between the early use of remdesivir in the treatment of SARS-CoV-2 disease - in addition to guidelines therapies - and a favorable clinical outcome.

CONCLUSIONS

This work shows therapeutic efficacy in the first 5 days of intravenous administration of remdesivir, following the loading dose. It is also necessary to underline the different behaviors of the drug when administered late in patients undergoing mechanical ventilation, compared to those who only needed low-flow oxygen therapy, whose share of recovery - decidedly relevant - reaches statistical significance.

Indole-Based Compounds as Potential Drug Candidates for SARS-CoV-2

The COVID-19 pandemic has posed a significant threat to society in recent times, endangering human health, life, and economic well-being. The disease quickly spreads due to the highly infectious SARS-CoV-2 virus, which has undergone numerous mutations. Despite intense research efforts by the scientific community since its emergence in 2019, no effective therapeutics have been discovered yet. While some repurposed drugs have been used to control the global outbreak and save lives, none have proven universally effective, particularly for severely infected patients. Although the spread of the disease is generally under control, anti-SARS-CoV-2 agents are still needed to combat current and future infections. This study reviews some of the most promising repurposed drugs containing indolyl heterocycle, which is an essential scaffold of many alkaloids with diverse bio-properties in various biological fields. The study also discusses natural and synthetic indole-containing compounds with anti-SARS-CoV-2 properties and computer-aided drug design (in silico studies) for optimizing anti-SARS-CoV-2 hits/leads.

Preferability of Molnupiravir, an Anti-COVID-19 Drug, toward Purine Nucleosides: A Quantum Mechanical Study

Structural aspects of molnupiravir complexed with the RNA of the SARS-CoV-2 virus have been recently resolved inside the RNA-dependent RNA polymerase (RdRp), demonstrating the interactions of molnupiravir with purine nucleosides. However, the preference of molnupiravir to interact with one purine nucleoside over another has not been clearly investigated. Herein, the complexation of molnupiravir in its active form with guanosine and adenosine was compared, using sundry density functional theory calculations. The plausible tautomeric structures of the molnupiravir drug in complex with guanosine/adenosine were minutely scrutinized. The relative energy findings outlined the favorability of amino-molnupiravir···keto-amino-guanosine and imino-molnupiravir···amino-adenosine optimized complexes. According to the interaction (Eint) and binding (Ebind) energy values, higher preferential base-pairing of molnupiravir with guanosine over the adenosine one was recognized with Eint/Ebind values of -31.16/-21.81 and -13.93/-12.83 kcal/mol, respectively. This could be interpreted by the presence of three and two hydrogen bonds within the former and latter complexes, respectively. Observable changes in the electronic properties and global indices of reactivity of the studied complexes also confirmed the preferential binding within the studied complexes. The findings from the quantum theory of atoms in molecules and the noncovalent interaction index also support the partially covalent nature of the investigated interactions. For both complexes, changes in thermodynamic parameters outlined the spontaneous, exothermic, and nonrandom states of the inspected interactions. Inspecting the solvent effect on the studied interactions outlined more observable amelioration within the water medium compared with the gas one. These results would be a durable ground for the forthcoming studies concerned with the interactions of the molnupiravir drug with purine nucleosides.

Assessment of Purity, Stability, and Pharmacokinetics of NGP-1, a Novel Prodrug of GS441254 with Potential Anti-SARS-CoV-2 Activity, Using Liquid Chromatography

SARS-CoV-2 is a highly contagious and pathogenic virus that first appeared in late December 2019 and caused a global pandemic in a short period. The virus is a single-stranded RNA virus belonging to the Coronaviridae family. Numerous treatments have been developed and tested in response to the pandemic, particularly antiviral drugs. Among them, GS441524 (GS441), a nucleoside antiviral drug, has demonstrated promising results in inhibiting SARS-CoV-2. Nevertheless, the limited oral bioavailability of GS441 restricts its application to patients with the virus. In this study, a novel prodrug of GS441 (NGP-1) with an isobutyl ester and cyclic carbonate structure was designed and synthesized. Its purity and the stability in different artificial digestive juices of NGP-1 was determined with HPLC-DAD methods. The pharmacokinetics of NGP-1 and GS441 were studied in rats via gavage administration. A new LC-MS/MS method was developed to quantitatively analyze GS441 in plasma samples. The results showed that the ka, Cmax, and MRT of converted GS441 from NGP-1 were 5.9, 3, and 2.5 times greater than those of GS441 alone. The Frel of NGP-1 was approximately four-fold that of GS441, with an AUC0-∞ of 9716.3 h·ng mL-1. As a prodrug of GS441, NGP-1 increased its lipophilicity, absorption, and bioavailability, indicating that it holds promise in improving the clinical efficacy of anti-SARS-CoV-2 medications.

The Functional RNA Identification (FRID) Pipeline: Identification of Potential Pseudoknot-Containing RNA Elements as Therapeutic Targets for SARS-CoV-2

The COVID-19 pandemic persists despite the development of effective vaccines. As such, it remains crucial to identify new targets for antiviral therapies. The causative virus of COVID-19, SARS-CoV-2, is a positive-sense RNA virus with RNA structures that could serve as therapeutic targets. One such RNA with established function is the frameshift stimulatory element (FSE), which promotes programmed ribosomal frameshifting. To accelerate identification of additional functional RNA elements, we introduce a novel computational approach termed the Functional RNA Identification (FRID) pipeline. The guiding principle of our pipeline, which uses established component programs as well as customized component programs, is that functional RNA elements have conserved secondary and pseudoknot structures that facilitate function. To assess the presence and conservation of putative functional RNA elements in SARS-CoV-2, we compared over 6,000 SARS-CoV-2 genomic isolates. We identified 22 functional RNA elements from the SARS-CoV-2 genome, 14 of which have conserved pseudoknots and serve as potential targets for small molecule or antisense oligonucleotide therapeutics. The FRID pipeline is general and can be applied to identify pseudoknotted RNAs for targeted therapeutics in genomes or transcriptomes from any virus or organism.

Patient-Centric Product Development: A Summary of Select Regulatory CMC and Device Considerations

Patient-centric drug development describes the systematic approach to incorporating the patient's perspectives and preferences into the design, assessment, and production of a therapeutic product. While a patient centric approach can be applied at any stage of the drug development lifecycle, an integrated end-to-end strategy is often most effective to create an optimized product for the patient at the earliest possible timepoint. The importance of patient centricity is well recognized by health authorities and biopharmaceutical organizations which have established toolsets, guidances, and methodologies for incorporating patient input during the clinical stage of development. However, in addition to clinical research, there are other significant aspects of product development that profoundly impact the patient experience. Specifically, chemistry, manufacturing, and control (CMC) and device aspects must also be acknowledged and addressed as part of a cohesive patient-centric development strategy. This review explores current applications and regulatory considerations for patient-centric approaches across the product lifecycle, including R&D, early product development, clinical development, device and combination product development, and post-approval change management. Specific topics of discussion include the contributions of product modality, formulation, and devices to the patient experience; usage of the Quality Target Product Profile (QTPP) as a patient-centered design tool; and post-approval product optimization. Future advancements in regulatory data management and information exchange are also explored as potential enablers of patient engagement which support enhanced communication and interconnectivity between stakeholders. Multidisciplinary collaboration between patients, health authorities, health care providers, and the biopharmaceutical industry is ultimately necessary for ensuring that medicinal products, and their corresponding regulatory processes, take on a patient-first mindset that prioritizes patient needs, values, and preferences.

Antiviral Lipid Nanocarrier Loaded with Remdesivir Effective Against SARS-CoV-2 in vitro Model

Introduction

The ongoing SARS-CoV-2 pandemic has affected public health, the economy, and society. This study reported a nanotechnology-based strategy to enhance the antiviral efficacy of the antiviral agent remdesivir (RDS).

Results

We developed a nanosized spherical RDS-NLC in which the RDS was encapsulated in an amorphous form. The RDS-NLC significantly potentiated the antiviral efficacy of RDS against SARS-CoV-2 and its variants (alpha, beta, and delta). Our study revealed that NLC technology improved the antiviral effect of RDS against SARS-CoV-2 by enhancing the cellular uptake of RDS and reducing SARS-CoV-2 entry in cells. These improvements resulted in a 211% increase in the bioavailability of RDS.

Conclusion

Thus, the application of NLC against SARS-CoV-2 may be a beneficial strategy to improve the antiviral effects of antiviral agents.

Identification of novel antiviral drug candidates using an optimized SARS-CoV-2 phenotypic screening platform

Reliable, easy-to-handle phenotypic screening platforms are needed for the identification of anti-SARS-CoV-2 compounds. Here, we present caspase 3/7 activity as a readout for monitoring the replication of SARS-CoV-2 isolates from different variants, including a remdesivir-resistant strain, and of other coronaviruses in numerous cell culture models, independently of cytopathogenic effect formation. Compared to other models, the Caco-2 subline Caco-2-F03 displayed superior performance. It possesses a stable SARS-CoV-2 susceptibility phenotype and does not produce false-positive hits due to drug-induced phospholipidosis. A proof-of-concept screen of 1,796 kinase inhibitors identified known and novel antiviral drug candidates including inhibitors of phosphoglycerate dehydrogenase (PHGDH), CDC like kinase 1 (CLK-1), and colony stimulating factor 1 receptor (CSF1R). The activity of the PHGDH inhibitor NCT-503 was further increased in combination with the hexokinase II (HK2) inhibitor 2-deoxy-D-glucose, which is in clinical development for COVID-19. In conclusion, caspase 3/7 activity detection in SARS-CoV-2-infected Caco-2-F03 cells provides a simple phenotypic high-throughput screening platform for SARS-CoV-2 drug candidates that reduces false-positive hits.

Suramin, penciclovir, and anidulafungin exhibit potential in the treatment of COVID-19 via binding to nsp12 of SARS-CoV-2

COVID-19, for which no confirmed therapeutic agents are available, has claimed over 48,14,000 lives globally. A feasible and quicker method to resolve this problem may be 'drug repositioning'. We investigated selected FDA and WHO-EML approved drugs based on their previously promising potential as antivirals, antibacterials or antifungals. These drugs were docked onto the nsp12 protein, which reigns the RNA-dependent RNA polymerase activity of SARS-CoV-2, a key therapeutic target for coronaviruses. Docked complexes were reevaluated using MM-GBSA analysis and the top three inhibitor-protein complexes were subjected to 100 ns long molecular dynamics simulation followed by another round of MM-GBSA analysis. The RMSF plots, binding energies and the mode of physicochemical interaction of the active site of the protein with the drugs were evaluated. Suramin, Penciclovir, and Anidulafungin were found to bind to nsp12 with similar binding energies as that of Remdesivir, which has been used as a therapy for COVID-19. In addition, recent experimental evidences indicate that these drugs exhibit antiviral efficacy against SARS-CoV-2. Such evidence, along with the significant and varied physical interactions of these drugs with the key viral enzyme outlined in this investigation, indicates that they might have a prospective therapeutic potential in the treatment of COVID-19 as monotherapy or combination therapy with Remdesivir.

Identification of Darunavir Derivatives for Inhibition of SARS-CoV-2 3CLpro

The effective antiviral agents that treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are urgently needed around the world. The 3C-like protease (3CL^pro) of SARS-CoV-2 plays a pivotal role in virus replication; it also has become an important therapeutic target for the infection of SARS-CoV-2. In this work, we have identified Darunavir derivatives that inhibit the 3CL^pro through a high-throughput screening method based on a fluorescence resonance energy transfer (FRET) assay in vitro. We found that the compounds 29# and 50# containing polyphenol and caffeine derivatives as the P2 ligand, respectively, exhibited favorable anti-3CL^pro potency with EC50 values of 6.3 μM and 3.5 μM and were shown to bind to SARS-CoV-2 3CL^pro in vitro. Moreover, we analyzed the binding mode of the DRV in the 3CL^pro through molecular docking. Importantly, 29# and 50# exhibited a similar activity against the protease in Omicron variants. The inhibitory effect of compounds 29# and 50# on the SARS-CoV-2 3CL^pro warrants that they are worth being the template to design functionally improved inhibitors for the treatment of COVID-19.

Generation of a VeroE6 Pgp gene knock out cell line and its use in SARS-CoV-2 antiviral study

Vero cells are widely used for antiviral tests and virology research for SARS-CoV-2 as well as viruses from various other families. However, Vero cells generally express high levels of multi-drug resistance 1 (MDR1) or Pgp protein, the efflux transporter of foreign substances including many antiviral compounds, affecting the antiviral activity as well as interpretation of data. To address this, a Pgp gene knockout VeroE6 cell line (VeroE6-Pgp-KO) was generated using CRISPR-CAS9 technology. These cells no longer expressed the Pgp protein as indicated by flow cytometry analysis following staining with a Pgp-specific monoclonal antibody. They also showed significantly reduced efflux transporter activity in the calcein acetoxymethyl ester (calcein AM) assay. The VeroE6-Pgp-KO cells and the parental VeroE6 cells were each infected with SARS-CoV-2 to test antiviral activities of remdesivir and nirmatrelvir, two known Pgp substrates, in the presence or absence of a Pgp inhibitor. The compounds showed antiviral activities in VeroE6-Pgp-KO cells similar to that observed in the presence of the Pgp inhibitor. Thus, the newly established VeroE6-Pgp-KO cell line adds a new in vitro virus infection system for SARS-CoV-2 and possibly other viruses to test antiviral therapies without a need to control the Pgp activity. Removal of the Pgp inhibitor for antiviral assays will lead to less data variation and prevent failed assays.

Multi-target direct-acting SARS-CoV-2 antivirals against the nucleotide-binding pockets of virus-specific proteins

The nucleotide-binding pockets (NBPs) in virus-specific proteins have proven to be the most successful antiviral targets for several viral diseases. Functionally important NBPs are found in various structural and non-structural proteins of SARS-CoV-2. In this study, the first successful multi-targeting attempt to identify effective antivirals has been made against NBPs in nsp12, nsp13, nsp14, nsp15, nsp16, and nucleocapsid (N) proteins of SARS-CoV-2. A structure-based drug repurposing in silico screening approach with ADME analysis identified small molecules targeting NBPs in SARS-CoV-2 proteins. Further, isothermal titration calorimetry (ITC) experiments validated the binding of top hit molecules to the purified N-protein. Importantly, cell-based antiviral assays revealed antiviral potency for INCB28060, darglitazone, and columbianadin with EC50 values 15.71 μM, 5.36 μM, and 22.52 μM, respectively. These effective antivirals targeting multiple proteins are envisioned to direct the development of antiviral therapy against SARS-CoV-2 and its emerging variants.

Pharmacological therapies and drug development targeting SARS-CoV-2 infection

The development of therapies for SARS-CoV-2 infection, based on virus biology and pathology, and of large- and small-scale randomized controlled trials, have brought forward several antiviral and immunomodulatory drugs targeting the disease severity. Casirivimab/Imdevimab monoclonal antibodies and convalescent plasma to prevent virus entry, Remdesivir, Molnupiravir, and Paxlovid nucleotide analogs to prevent viral replication, a variety of repurposed JAK-STAT signaling pathway inhibitors, corticosteroids, and recombinant agonists/antagonists of cytokine and interferons have been found to provide clinical benefits in terms of mortality and hospitalization. However, current treatment options face multiple clinical needs, and therefore, in this review, we provide an update on the challenges of the existing therapeutics and highlight drug development strategies for COVID-19 therapy, based on ongoing clinical trials, meta-analyses, and clinical case reports.

Codivir suppresses SARS-Cov-2 viral replication and stabilizes clinical outcome: In vitro and Phase I clinical trial results

BACKGROUND

Treatment of severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2) remains a significant challenge in the face of increased worldwide morbidity and mortality. The acute illness caused by SARS-CoV-2 is initiated by a viral phase, followed by an inflammatory phase. Numerous anti-inflammatory and anti-viral therapies, with a relatively minor clinical effect, have been applied. Developing a safe and efficient direct anti-viral treatment is essential as it can block disease progression before significant complications ensue and potentially prevent transmission.

AIM

The present phase 1 study aimed to determine the safety of Codivir, a newly developed anti-viral agent, and to preliminarily assess its anti-viral activity in patients infected by COVID-19.

METHODS

In vitro studies were conducted to determine the direct anti-viral effect of Codivir using an immunofluorescence-based assay and to assess its cytotoxic effect by tetrazolium assay (MTT). In a phase I clinical trial, Codivir was administered for ten days in 12 patients who were followed for its safety. Patients were followed for clinical manifestations during administration. Sequential nasal viral PCR titers (Cycle Threshold, CT) were determined preceding and during treatment.

RESULTS

In vitro, Codivir showed activity against SARS-CoV-2 with 90% viral replication suppression and minimal cytotoxicity. The anti-viral activity was demonstrated at the early stages of infection, post-entry of the virus in the cell. Codivir was safe in all 12 patients in phase I clinical trial and significantly suppressed viral replication in 5/7 fully assessed patients, with an anti-viral effect noted as early as three days.

SUMMARY

The present study's data support the safety of Codivir administration in humans and suggest its significant anti-COVID-19 effect. These results support the testing of the drug in more extensive controlled trials in patients with SARS-CoV-2.

SARS-CoV-2 pre-exposure prophylaxis: A potential COVID-19 preventive strategy for high-risk populations, including healthcare workers, immunodeficient individuals, and poor vaccine responders

The unprecedented worldwide spread of SARS-CoV-2 has imposed severe challenges on global health care systems. The roll-out and widespread administration of COVID-19 vaccines has been deemed a major milestone in the race to restrict the severity of the infection. Vaccines have as yet not entirely suppressed the relentless progression of the pandemic, due mainly to the emergence of new virus variants, and also secondary to the waning of protective antibody titers over time. Encouragingly, an increasing number of antiviral drugs, such as remdesivir and the newly developed drug combination, Paxlovid® (nirmatrelvir/ritonavir), as well as molnupiravir, have shown significant benefits for COVID-19 patient outcomes. Pre-exposure prophylaxis (PrEP) has been proven to be an effective preventive strategy in high-risk uninfected people exposed to HIV. Building on knowledge from what is already known about the use of PrEP for HIV disease, and from recently gleaned knowledge of antivirals used against COVID-19, we propose that SARS-CoV-2 PrEP, using specific antiviral and adjuvant drugs against SARS-CoV-2, may represent a novel preventive strategy for high-risk populations, including healthcare workers, immunodeficient individuals, and poor vaccine responders. Herein, we critically review the risk factors for severe COVID-19 and discuss PrEP strategies against SARS-CoV-2. In addition, we outline details of candidate anti-SARS-CoV-2 PrEP drugs, thus creating a framework with respect to the development of alternative and/or complementary strategies to prevent COVID-19, and contributing to the global armamentarium that has been developed to limit SARS-CoV-2 infection, severity, and transmission.

Molnupiravir: A lethal mutagenic drug against rapidly mutating severe acute respiratory syndrome coronavirus 2-A narrative review

Broad-spectrum antiviral agents targeting viral RNA-dependent RNA polymerase (RdRp) are expected to be a key therapeutic strategy in the ongoing coronavirus disease 2019 (COVID-19) pandemic and its future variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19. Molnupiravir is a nucleoside analog that in vivo experiments have been reported to inhibit the replication of SARS-CoV-2, the virus that causes COVID-19. Clinical trials of molnupiravir as a therapy for patients with mild-to-moderate COVID-19 also suggest its significant therapeutic efficacy in comparison to placebo. Molnupiravir is lethally mutagenic against viral RNA, but its effect on host cell DNA is being questioned. Herein, the safety concerns of molnupiravir are discussed with recent findings from published reports and clinical trials. The unchanged efficacy of molnupiravir against mutated SARS-CoV-2 variants is also highlighted. With its administration via the oral route, molnupiravir is expected to turn the tide of the COVID-19 pandemic.

The efficacy and safety of combined chinese herbal medicine and western medicine therapy for COVID-19: a systematic review and meta-analysis

OBJECTIVE

To systematically review the clinical efficacy and safety of Chinese herbal medicine (CHM) with and without Western medicine (WM) for different severity of COVID-19.

METHODS

CNKI, PubMed, Wanfang Database, ClinicalTrails.gov, Embase, ChiCTR and ICTRP were searched from 01 Jan, 2020 to 30 Jun, 2021. Two authors independently assessed all the randomized clinical trials (RCTs) for trial inclusion, data extraction and quality assessment. Meta-analysis was conducted using Review Manager software (RevMan 5.4.1). Evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Primary outcomes included total effectiveness rate. Secondary outcomes included improvements in symptom improvement and total adverse event rate. Different severity of COVID-19 patients was assessed in subgroup analysis. This study was registered with INPLASY, INPLASY202210072.

RESULTS

22 high quality RCTs involving 1789 participants were included. There were no trial used CHM alone nor compare placebo or no treatment. Compared with WM, combined CHM and WM (CHM-WM) treatment showed higher total effectiveness rate, lower symptom scores of fever, cough, fatigue, dry throat and pharyngalgia, shorter mean time to viral conversion, better Computerized Tomography (CT) image and blood results, fewer total adverse events and worse conditions (P < 0.05). Subgroup analysis showed that the total effectiveness rate of combined CHM-WM group was significantly higher than WM group, especially for mild and moderate patients. No significant differences in mortality and adverse events were found between combined CHM-WM and WM treatment. No serious adverse events and long-term outcomes were reported.

CONCLUSION

Current evidence supported the therapeutic effects and safety of combined CHM-WM treatment on COVID-19, especially for patients with mild and moderate symptoms. Long-term effects of therapy are worthy in further study.

A Phase II Study on the Effect of Taurisolo® Administered via AEROsol in Hospitalized Patients with Mild to Moderate COVID-19 Pneumonia: The TAEROVID-19 Study

Background: Polyphenols are the largest class of bioactive compounds in plants, which are synthesized as secondary metabolites. In the last few years, interesting studies have demonstrated the efficacy of polyphenols against coronavirus infections. Methods: we conducted a phase II multicentric clinical trial (TAEROVID-19) during the first wave of the COVID-19 pandemic in order to assess the safety and feasibility of Taurisolo^® aerosol formulation in hospitalized patients suffering from SARS-CoV-2 pneumonia. Results: we observed a rapid decline of symptoms and a low rate of intensive care in patients treated with Taurisolo^®, with a faster decline of symptoms. Conclusions: This is the first trial assessing the safety and feasibility of Taurisolo^® aerosol formulation. We could argue that this treatment could act as an add-on therapy in the treatment of COVID-19 patients, owing to both its anti-inflammatory and antioxidant effects. Further controlled trials are needed, which may be of interest to evaluate the compound’s efficacy.

[Diagnosis and treatment of COVID-19 in intensive care units]

Treatment of coronavirus disease 2019 (COVID-19) is particularly challenging due to the rapid scientific advances and the often significant hypoxemia. Use of high-flow oxygen, noninvasive mask ventilation, and the technique of awake proning can sometimes avoid the need for intubation. Mechanical ventilation follows the principles of ventilation for acute respiratory distress syndrome (ARDS; lung protective ventilation) and is generally supplemented by consequent positioning therapy (with at least 16 h in prone position in multiple cycles). Antiviral therapy options such as remdesivir usually come too late for patients with COVID-19 in the ICU, the only exception being the administration of monoclonal antibodies for patients without seroconversion. The value of immunomodulatory therapy such as dexamethasone is undisputed. Interleukin‑6 antagonists, on the other hand, are rather problematic for ICU patients, and for Janus kinase inhibitors, data and experience are still insufficient in this context.

Pharmacokinetics of Nafamostat, a Potent Serine Protease Inhibitor, by a Novel LC-MS/MS Analysis

Nafamostat, a synthetic serine protease inhibitor, has been used for the treatment of inflammatory diseases such as pancreatitis. Recently, an increasing number of studies have shown the promising antiviral effects of nafamostat for the treatment of coronavirus disease-19 (COVID-19). This study aimed to develop a novel liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis and to characterize the pharmacokinetics of nafamostat in rats. Nafamostat in the rat plasma was extracted by solid phase extraction, and ¹³C₆-nafamostat was used as an internal standard. The quantification limit of nafamostat in the rat plasma was 0.5 ng/mL. The LC-MS/MS method was fully validated and applied to characterize the pharmacokinetics of nafamostat in rats. Following intravenous injection (2 mg/kg), nafamostat in the plasma showed a multiexponential decline with an average elimination half-life (t_1/2) of 1.39 h. Following oral administration of nafamostat solutions (20 mg/kg) in 10% dimethyl sulfoxide (DMSO) and in 10% DMSO with 10% Tween 80, nafamostat was rapidly absorbed, and the average oral bioavailability was 0.95% and 1.59%, respectively. The LC-MS/MS method and the pharmacokinetic information of nafamostat could be helpful for the further preclinical and clinical studies of nafamostat.

Insights into the evolutionary and prophylactic analysis of SARS-CoV-2: A review

In late 2019, following the emergence of a β-originated SARS-CoV-2, phylogenetic and evolutionary approaches have been demonstrated to strengthen the diagnostic and prophylactic stratagem of COVID-19 at an unprecedented level. Despite its clinical prominence, the SARS-CoV-2 gene set remains largely irrefutable by impeding the dissection of COVID-19 biology. However, many pieces of molecular and serological evidence have predicted that SARS-CoV-2 related viruses carry their roots from bats and pangolins of South East Asia. Analysis of viral genome predicts that point mutations at a rate of 10-4 nucleotides per base in the receptor-binding domain allow the emergence of new SARS-CoV-2 genomic variants at regular intervals. Research in the evolution of molecular pathways involved in emergence of pandemic is critical for the development of therapeutics and vaccines as well as the prevention of future zoonosis. By determining the phyletic lineages of the SARS-CoV-2 genomic variants and those of the conserved regions in the accessory and spike proteins of all the SARS-related coronaviruses, a universal vaccine against all human coronaviruses could be formulated which would revolutionize the field of medicine. This review highlighted the current development and future prospects of antiviral drugs, inhibitors, mesenchymal stem cells, passive immunization, targeted immune therapy and CRISPR-Cas-based prophylactic and therapeutic strategies against SARS-CoV-2. However, further investigations on Covid-19 pathogenesis is required for the successful fabrication of successful antivirals.

Key summary of German national treatment guidance for hospitalized COVID-19 patients : Key pharmacologic recommendations from a national German living guideline using an Evidence to Decision Framework (last updated 17.05.2021)

PURPOSE

This executive summary of a national living guideline aims to provide rapid evidence based recommendations on the role of drug interventions in the treatment of hospitalized patients with COVID-19.

METHODS

The guideline makes use of a systematic assessment and decision process using an evidence to decision framework (GRADE) as recommended standard WHO (2021). Recommendations are consented by an interdisciplinary panel. Evidence analysis and interpretation is supported by the CEOsys project providing extensive literature searches and living (meta-) analyses. For this executive summary, selected key recommendations on drug therapy are presented including the quality of the evidence and rationale for the level of recommendation.

RESULTS

The guideline contains 11 key recommendations for COVID-19 drug therapy, eight of which are based on systematic review and/or meta-analysis, while three recommendations represent consensus expert opinion. Based on current evidence, the panel makes strong recommendations for corticosteroids (WHO scale 5-9) and prophylactic anticoagulation (all hospitalized patients with COVID-19) as standard of care. Intensified anticoagulation may be considered for patients with additional risk factors for venous thromboembolisms (VTE) and a low bleeding risk. The IL-6 antagonist tocilizumab may be added in case of high supplemental oxygen requirement and progressive disease (WHO scale 5-6). Treatment with nMABs may be considered for selected inpatients with an early SARS-CoV-2 infection that are not hospitalized for COVID-19. Convalescent plasma, azithromycin, ivermectin or vitamin D3 should not be used in COVID-19 routine care.

CONCLUSION

For COVID-19 drug therapy, there are several options that are sufficiently supported by evidence. The living guidance will be updated as new evidence emerges.

A protease-activatable luminescent biosensor and reporter cell line for authentic SARS-CoV-2 infection

Efforts to define serological correlates of protection against COVID-19 have been hampered by the lack of a simple, scalable, standardised assay for SARS-CoV-2 infection and antibody neutralisation. Plaque assays remain the gold standard, but are impractical for high-throughput screening. In this study, we show that expression of viral proteases may be used to quantitate infected cells. Our assays exploit the cleavage of specific oligopeptide linkers, leading to the activation of cell-based optical biosensors. First, we characterise these biosensors using recombinant SARS-CoV-2 proteases. Next, we confirm their ability to detect viral protease expression during replication of authentic virus. Finally, we generate reporter cells stably expressing an optimised luciferase-based biosensor, enabling viral infection to be measured within 24 h in a 96- or 384-well plate format, including variants of concern. We have therefore developed a luminescent SARS-CoV-2 reporter cell line, and demonstrated its utility for the relative quantitation of infectious virus and titration of neutralising antibodies.

[Antiviral drugs : Potent agents, promising therapies for COVID‑19 and therapeutic limitations]

Antiviral drugs inhibit viral replication by interaction with specific elements of the viral replication cycle. Directly acting antiviral agents have revolutionized the therapeutic options for chronic infections with human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV). Pharmacological developments constantly improve therapeutic and prophylactic options for diseases caused by herpes viruses, which is of particular relevance for immunocompromised patients. While infections with persistent viruses, such as HIV, HBV or herpes viruses principally so far cannot be cured, complete elimination of viruses that cause acute infections is possible; however, acute infections, such as influenza or coronavirus disease 2019 (COVID-19) offer only a small therapeutic window for antiviral strategies due to their pathophysiological dynamics. The optimal time point for antiviral agents is immediately after exposure to the virus, which frequently limits its application in practice. An effective pre-exposure or postexposure prophylaxis has been established for infections with HIV and influenza A/B and also gains relevance for infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Cytopathic Effect (CPE )-Based Drug Screening Assay for SARS-CoV-2

Identification of an effective antiviral for the treatment of COVID-19 is considered one of the holy grails in the bid to end the pandemic. However, the novelty of SARS-CoV-2, along with the little knowledge available about its infection characteristics at the beginning of this pandemic, challenges the scientific world on how one may be able to promptly identify promising drug candidates from a myriad of compound libraries. Here, we describe a cytopathic effect (CPE)-based drug screening assay for SARS-CoV-2 which allows for rapid assessment of drug compound libraries through pre- or posttreatment drug screening procedures and evaluation using a light microscope. By comparing the virus-induced CPE of the drug-treated cells against the vehicle and drug controls, potent drug candidates can be quickly identified for further downstream studies.

Indomethacin-based PROTACs as pan-coronavirus antiviral agents

Indomethacin (INM), a well-known non-steroidal anti-inflammatory drug, has recently gained attention for its antiviral activity demonstrated in drug repurposing studies against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Although the mechanism of action of INM is not yet fully understood, recent studies have indicated that it acts at an early stage of the coronaviruses (CoVs) replication cycle. In addition, a proteomic study reported that the anti-SARS-CoV-2 activity of INM could be also ascribed to its ability to inhibit human prostaglandin E synthase type 2 (PGES-2), a host protein which interacts with the SARS-CoV-2 NSP7 protein. Although INM does not potently inhibit SARS-CoV-2 replication in infected Vero E6 cells, here we have explored for the first time the application of the Proteolysis Targeting Chimeras (PROTACs) technology in order to develop more potent INM-derived PROTACs with anti-CoV activity. In this study, we report the design, synthesis, and biological evaluation of a series of INM-based PROTACs endowed with antiviral activity against a panel of human CoVs, including different SARS-CoV-2 strains. Two PROTACs showed a strong improvement in antiviral potency compared to INM. Molecular modelling studies support human PGES-2 as a potential target of INM-based antiviral PROTACs, thus paving the way toward the development of host-directed anti-CoVs strategies. To the best of our knowledge, these PROTACs represent the first-in-class INM-based PROTACs with antiviral activity and also the first example of the application of PROTACs to develop pan-coronavirus agents.

US201 Study: A Phase 2, Randomized Proof-of-Concept Trial of Favipiravir for the Treatment of COVID-19

BACKGROUND

Favipiravir is used to treat influenza, and studies demonstrate that it has antiviral activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

METHODS

We performed a randomized, open-label, multicenter, phase 2 proof-of-concept trial of favipiravir in hospitalized adult patients with polymerase chain reaction (PCR)-positive coronavirus disease 2019 (COVID-19). Patients were randomized to standard of care (SOC) or favipiravir treatment (1800mg per os twice a day [b.i.d.] on day 1, followed by 1000mg b.i.d. for 13 days). The primary end point was time to viral clearance on day 29.

RESULTS

Fifty patients were enrolled and stratified by disease severity (critical disease, severe disease, or mild to moderate disease). Nineteen patients were censored from the event of viral clearance based on being SARS-CoV-2 PCR-negative at the study outset, being PCR-positive at day 29, or because of loss to follow-up. Data from the 31 remaining patients who achieved viral clearance show enhanced viral clearance in the favipiravir group compared with the SOC group by day 29, with 72% of the favipiravir group and 52% of the SOC group being evaluable for viral clearance through day 29. The median time to viral clearance was 16.0 days (90% CI, 12.0 to 29.0) in the favipiravir group and 30.0 days (90% CI, 12.0 to 31.0) in the SOC group. A post hoc analysis revealed an effect in the subgroup of patients who were neutralizing antibody-negative at randomization. Treatment-emergent adverse events were equally distributed between the groups.

CONCLUSIONS

We demonstrate that favipiravir can be safely administered to hospitalized adults with COVID-19 and believe that further studies are warranted.

CLINICALTRIALSGOV REGISTRATION

NCT04358549.

25-Hydroxycholesterol-Conjugated EK1 Peptide with Potent and Broad-Spectrum Inhibitory Activity against SARS-CoV-2, Its Variants of Concern, and Other Human Coronaviruses

The COVID-19 pandemic caused by SARS-CoV-2 infection poses a serious threat to global public health and the economy. The enzymatic product of cholesterol 25-hydroxylase (CH25H), 25-Hydroxycholesterol (25-HC), was reported to have potent anti-SARS-CoV-2 activity. Here, we found that the combination of 25-HC with EK1 peptide, a pan-coronavirus (CoV) fusion inhibitor, showed a synergistic antiviral activity. We then used the method of 25-HC modification to design and synthesize a series of 25-HC-modified peptides and found that a 25-HC-modified EK1 peptide (EK1P4HC) was highly effective against infections caused by SARS-CoV-2, its variants of concern (VOCs), and other human CoVs, such as HCoV-OC43 and HCoV-229E. EK1P4HC could protect newborn mice from lethal HCoV-OC43 infection, suggesting that conjugation of 25-HC with a peptide-based viral inhibitor was a feasible and universal strategy to improve its antiviral activity.

Structural and energetic profiling of SARS-CoV-2 receptor binding domain antibody recognition and the impact of circulating variants

The SARS-CoV-2 pandemic highlights the need for a detailed molecular understanding of protective antibody responses. This is underscored by the emergence and spread of SARS-CoV-2 variants, including Alpha (B.1.1.7) and Delta (B.1.617.2), some of which appear to be less effectively targeted by current monoclonal antibodies and vaccines. Here we report a high resolution and comprehensive map of antibody recognition of the SARS-CoV-2 spike receptor binding domain (RBD), which is the target of most neutralizing antibodies, using computational structural analysis. With a dataset of nonredundant experimentally determined antibody-RBD structures, we classified antibodies by RBD residue binding determinants using unsupervised clustering. We also identified the energetic and conservation features of epitope residues and assessed the capacity of viral variant mutations to disrupt antibody recognition, revealing sets of antibodies predicted to effectively target recently described viral variants. This detailed structure-based reference of antibody RBD recognition signatures can inform therapeutic and vaccine design strategies.

Identifying SARS-CoV-2 antiviral compounds by screening for small molecule inhibitors of nsp12/7/8 RNA-dependent RNA polymerase

The coronavirus disease 2019 (COVID-19) global pandemic has turned into the largest public health and economic crisis in recent history impacting virtually all sectors of society. There is a need for effective therapeutics to battle the ongoing pandemic. Repurposing existing drugs with known pharmacological safety profiles is a fast and cost-effective approach to identify novel treatments. The COVID-19 etiologic agent is the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a single-stranded positive-sense RNA virus. Coronaviruses rely on the enzymatic activity of the replication–transcription complex (RTC) to multiply inside host cells. The RTC core catalytic component is the RNA-dependent RNA polymerase (RdRp) holoenzyme. The RdRp is one of the key druggable targets for CoVs due to its essential role in viral replication, high degree of sequence and structural conservation and the lack of homologues in human cells. Here, we have expressed, purified and biochemically characterised active SARS-CoV-2 RdRp complexes. We developed a novel fluorescence resonance energy transfer-based strand displacement assay for monitoring SARS-CoV-2 RdRp activity suitable for a high-throughput format. As part of a larger research project to identify inhibitors for all the enzymatic activities encoded by SARS-CoV-2, we used this assay to screen a custom chemical library of over 5000 approved and investigational compounds for novel SARS-CoV-2 RdRp inhibitors. We identified three novel compounds (GSK-650394, C646 and BH3I-1) and confirmed suramin and suramin-like compounds as in vitro SARS-CoV-2 RdRp activity inhibitors. We also characterised the antiviral efficacy of these drugs in cell-based assays that we developed to monitor SARS-CoV-2 growth.

Predictive Value of Comorbid Conditions for COVID-19 Mortality

In this paper, we aim at understanding the broad spectrum of factors influencing the survival of infected patients and the correlations between these factors to create a predictive probabilistic score for surviving the COVID-19 disease. Initially, 510 hospital admissions were counted in the study, out of which 310 patients did not survive. A prediction model was developed based on this data by using a Bayesian approach. Following the data collection process for the development study, the second cohort of patients totaling 541 was built to validate the risk matrix previously created. The final model has an area under the curve of 0.773 and predicts the mortality risk of SARS-CoV-2 infection based on nine disease groups while considering the gender and age of the patient as distinct risk groups. To ease medical workers’ assessment of patients, we created a visual risk matrix based on a probabilistic model, ranging from a score of 1 (very low mortality risk) to 5 (very high mortality risk). Each score comprises a correlation between existing comorbid conditions, the number of comorbid conditions, gender, and age group category. This clinical model can be generalized in a hospital context and can be used to identify patients at high risk for whom immediate intervention might be required.

Remdesivir, Renal Function and Short-Term Clinical Outcomes in Elderly COVID-19 Pneumonia Patients: A Single-Centre Study

BACKGROUND

Remdesivir, an antiviral agent able to reduce inflammatory cascade accompanying severe, life-threatening pneumonia, became the first drug approved by the Food and Drug Administration for the treatment of hospitalized patients with coronavirus 2 related severe acute respiratory syndrome (SARS CoV2). As from its previously known clinical indications, the use of remdesivir in the presence of severe renal impairment is contraindicated; however, the impact of remdesivir on renal function in aging patients has not been elucidated.

SUBJECTS AND METHODS

This retrospective observational study involved 109 individuals consecutively admitted in internal medicine section, Azienda Ospedaliero Universitaria Pisana hospital, in November-December 2020 due to a confirmed diagnosis of SARS CoV2 and receiving remdesivir according to international inclusion criteria. Biochemical variables at admission were evaluated, together with slopes of estimated glomerular filtration rate (eGFR) built during remdesivir treatment. Participants were followed until discharge or exitus.

RESULTS

Patients were stratified according to age (80 formed the study cohort and 29 served as controls); CKD stage III was present in 46% of them. No patients showed any sign of deteriorated renal function during remdesivir. Fourteen patients in the elderly cohort deceased; their eGFR at baseline was significantly lower. Recovered patients were characterized by a relevant eGFR gaining during remdesivir treatment.

CONCLUSION

We show here for the first time as remdesivir does not influence eGFR in a cohort of elderly people hospitalized for SARS CoV2, and that eGFR gain during such treatment is coupled with a better prognosis.

Genomic variation, origin tracing, and vaccine development of SARS-CoV-2: A systematic review

COVID-19 has spread globally to over 200 countries with more than 40 million confirmed cases and one million deaths as of November 1, 2020. The SARS-CoV-2 virus, leading to COVID-19, shows extremely high rates of infectivity and replication, and can result in pneumonia, acute respiratory distress, or even mortality. SARS-CoV-2 has been found to continue to rapidly evolve, with several genomic variants emerging in different regions throughout the world. In addition, despite intensive study of the spike protein, its origin, and molecular mechanisms in mediating host invasion are still only partially resolved. Finally, the repertoire of drugs for COVID-19 treatment is still limited, with several candidates still under clinical trial and no effective therapeutic yet reported. Although vaccines based on either DNA/mRNA or protein have been deployed, their efficacy against emerging variants requires ongoing study, with multivalent vaccines supplanting the first-generation vaccines due to their low efficacy against new strains. Here, we provide a systematic review of studies on the epidemiology, immunological pathogenesis, molecular mechanisms, and structural biology, as well as approaches for drug or vaccine development for SARS-CoV-2.

Marine Sponge is a Promising Natural Source of Anti-SARS-CoV-2 Scaffold

The current pandemic caused by SARS-CoV2 and named COVID-19 urgent the need for novel lead antiviral drugs. Recently, United States Food and Drug Administration (FDA) approved the use of remdesivir as anti-SARS-CoV-2. Remdesivir is a natural product-inspired nucleoside analogue with significant broad-spectrum antiviral activity. Nucleosides analogues from marine sponge including spongouridine and spongothymidine have been used as lead for the evolutionary synthesis of various antiviral drugs such as vidarabine and cytarabine. Furthermore, the marine sponge is a rich source of compounds with unique activities. Marine sponge produces classes of compounds that can inhibit the viral cysteine protease (Mpro) such as esculetin and ilimaquinone and human serine protease (TMPRSS2) such as pseudotheonamide C and D and aeruginosin 98B. Additionally, sponge-derived compounds such as dihydrogracilin A and avarol showed immunomodulatory activity that can target the cytokines storm. Here, we reviewed the potential use of sponge-derived compounds as promising therapeutics against SARS-CoV-2. Despite the reported antiviral activity of isolated marine metabolites, structural modifications showed the importance in targeting and efficacy. On that basis, we are proposing a novel structure with bifunctional scaffolds and dual pharmacophores that can be superiorly employed in SARS-CoV-2 infection.

Nipah virus: a potential pandemic agent in the context of the current severe acute respiratory syndrome coronavirus 2 pandemic

For centuries, zoonotic diseases have been responsible for various outbreaks resulting in the deaths of millions of people. The best example of this is the current coronavirus disease 2019 (COVID-19) pandemic. Like severe acute respiratory syndrome coronavirus, Nipah virus is another deadly virus which has caused several outbreaks in the last few years. Though it causes a low number of infections, disease severity results in a higher death rate. In the context of the recent COVID-19 pandemic, we speculate that many countries will be unable to deal with the sudden onset of such a viral outbreak. Thus, further research and attention to the virus are needed to address future outbreaks.

The COVID-19 Treatment Landscape: A South African Perspective on a Race Against Time

The pandemic caused by SARS-CoV-2 has infected more than 94 million people worldwide (as of 17 January 2020). Severe disease is believed to be secondary to the cytokine release syndrome (CRS or "cytokine storm") which causes local tissue damage as well as multi-organ dysfunction and thrombotic complications. Due to the high mortality rates in patients receiving invasive ventilation, practice has changed from "early-intubation" for acute respiratory distress syndrome (ARDS) to a trial of non-invasive ventilation (NIV) or high flow nasal cannula (HFNC) oxygen. Reports indicating the benefit of NIV and HFNC have been encouraging and have led to more than 20,000 such devices being manufactured and ready for roll-out in South Africa (SA) as of July 2020. The need to identify drugs with clear clinical benefits has led to an array of clinical trials, most of which are repurposing drugs for COVID-19. The treatment landscape reflects the need to target both the virus and its effects such as the CRS and thrombotic complications. Conflicting results have the potential to confuse the implementation of coordinated treatment strategies and guidelines. The purpose of this review is to address pertinent areas in the current literature on the available medical treatment options for COVID-19. Remdesivir, tocilizumab, and dexamethasone are some of the treatment options that have shown the most promise, but further randomized trials are required to particularly address timing and dosages to confidently create standardized protocols. For the SA population, two healthcare sectors exist. In the private sector, patients with medical insurance may have greater access to a wider range of treatment options than those in the public sector. The latter serves >80% of the population, and resource constraints require the identification of drugs with the most cost-effective use for the greatest number of affected patients.

Challenges and Opportunities for Drug Repositioning in Fibrodysplasia Ossificans Progressiva

Fibrodysplasia ossificans progressiva (FOP) is an ultrarare congenital disease that progresses through intermittent episodes of bone formation at ectopic sites. FOP patients carry heterozygous gene point mutations in activin A receptor type I ACVR1, encoding the bone morphogenetic protein (BMP) type I serine/threonine kinase receptor ALK2, termed activin receptor-like kinase (ALK)2. The mutant ALK2 displays neofunctional responses to activin, a closely related BMP cytokine that normally inhibits regular bone formation. Moreover, the mutant ALK2 becomes hypersensitive to BMPs. Both these activities contribute to enhanced ALK2 signalling and endochondral bone formation in connective tissue. Being a receptor with an extracellular ligand-binding domain and intrinsic intracellular kinase activity, the mutant ALK2 is a druggable target. Although there is no approved cure for FOP yet, a number of clinical trials have been recently initiated, aiming to identify a safe and effective treatment for FOP. Among other targeted approaches, several repurposed drugs have shown promising results. In this review, we describe the molecular mechanisms underlying ALK2 mutation-induced aberrant signalling and ectopic bone formation. In addition, we recapitulate existing in vitro models to screen for novel compounds with a potential application in FOP. We summarize existing therapeutic alternatives and focus on repositioned drugs in FOP, at preclinical and clinical stages.

[S2k Guideline - Recommendations for Inpatient Therapy of Patients with COVID-19]

Since December 2019, the novel coronavirus SARS-CoV-2 (Severe Acute Respiratory Syndrome - Corona Virus-2) has been spreading rapidly in the sense of a global pandemic. This poses significant challenges for clinicians and hospitals and is placing unprecedented strain on the healthcare systems of many countries. The majority of patients with Coronavirus Disease 2019 (COVID-19) present with only mild symptoms such as cough and fever. However, about 6 % require hospitalization. Early clarification of whether inpatient and, if necessary, intensive care treatment is medically appropriate and desired by the patient is of particular importance in the pandemic. Acute hypoxemic respiratory insufficiency with dyspnea and high respiratory rate (> 30/min) usually leads to admission to the intensive care unit. Often, bilateral pulmonary infiltrates/consolidations or even pulmonary emboli are already found on imaging. As the disease progresses, some of these patients develop acute respiratory distress syndrome (ARDS). Mortality reduction of available drug therapy in severe COVID-19 disease has only been demonstrated for dexamethasone in randomized controlled trials. The main goal of supportive therapy is to ensure adequate oxygenation. In this regard, invasive ventilation and repeated prone positioning are important elements in the treatment of severely hypoxemic COVID-19 patients. Strict adherence to basic hygiene, including hand hygiene, and the correct wearing of adequate personal protective equipment are essential when handling patients. Medically necessary actions on patients that could result in aerosol formation should be performed with extreme care and preparation.

Broad spectrum antiviral nucleosides-Our best hope for the future

The current focus for many researchers has turned to the development of therapeutics that have the potential for serving as broad-spectrum inhibitors that can target numerous viruses, both within a particular family, as well as to span across multiple viral families. This will allow us to build an arsenal of therapeutics that could be used for the next outbreak. In that regard, nucleosides have served as the cornerstone for antiviral therapy for many decades. As detailed herein, many nucleosides have been shown to inhibit multiple viruses due to the conserved nature of many viral enzyme binding sites. Thus, it is somewhat surprising that up until very recently, many researchers focused more on "one bug one drug," rather than trying to target multiple viruses given those similarities. This attitude is now changing due to the realization that we need to be proactive rather than reactive when it comes to combating emerging and reemerging infectious diseases. A brief summary of prominent nucleoside analogues that previously exhibited broad-spectrum activity and are now under renewed interest, as well as new analogues, that are currently under investigation against SARS-CoV-2 and other viruses is discussed herein.