Broad spectrum antiviral remdesivir inhibits human endemic and zoonotic deltacoronaviruses with a highly divergent RNA dependent RNA polymerase

Major Drugs Used in COVID-19 Treatment: Molecular Mechanisms, Validation and Current Progress in Trials

Background:

Currently, the present world is facing a new deadly challenge against a pandemic disease called COVID-19, which is caused by a coronavirus, named SARS-CoV-2. To date, there is no drug or vaccine that can treat COVID-19 completely, but some drugs have been used primarily, and they are in different stages of clinical trials. This review article discussed and compared those drugs which are running ahead in COVID-19 treatments.

Methods:

We have explored PUBMED, SCOPUS, WEB OF SCIENCE, as well as press release of WHO, NIH and FDA for articles about COVID-19, and reviewed them.

Results:

Drugs like favipiravir, remdesivir, lopinavir/ritonavir, hydroxychloroquine, azithromycin, ivermectin, corticosteroids and interferons have been found effective in some extents, and partially approved by FDA and WHO to treat COVID-19 at different phases of pandemic. However, some of these drugs have been disapproved later, although clinical trials are going on. In parallel, plasma therapy has been found fruitful in some extents too, and a number of vaccine trails are going on.

Conclusions:

This review article discussed the epidemiologic and mechanistic characteristics of SARS-CoV-2, and how drugs could act on this virus with the comparative discussion on progress and backwards of major drugs used till date, which might be beneficial for choosing therapies against COVID-19 in different countries.

Evaluating anti-coronavirus activity of some phosphoramides and their influencing inhibitory factors using molecular docking, DFT, QSAR, and NCI-RDG studies

The recent prevalence of coronavirus disease in 2019 (COVID-19) has triggered widespread global health concerns.Antiviral drugs based on phosphoramides have significant inhibitory activity against the main protease (M^pro) of the virus and prevent transcription and viral replication. Hence, in order to design and introduce a group of inhibitors affecting the coronavirus, 35 phosphoramide compounds based on phospho-guanine and phospho-pyrazine derivatives were selected for molecular docking study. The results showed that most phosphoguanides containing the amino benzimidazole have a high interaction tendency with COVID-19. Among them, compound 19 was identified as the strongest inhibitor with the -9.570 kcal/mol binding energy whereas, the binding energy of Remdesivir is -6.75 kcal/mol. The quantitative structure-activity relationship (QSAR) results demonstrated that the number of aromatic rings, amide's nitrogens and their ability in π-staking, and hydrogen interactions with M^pro active sites are major factors contributing to the inhibitory activity of these compounds.Also, the NCI-RDG and DFT results were in good accordance with those of QSAR and molecular docking. The findings of this investigation can be underlying the synthesis of effective and efficient drugs against COVID-19.

An Updated Review of Porcine Deltacoronavirus in Terms of Prevalence, Pathogenicity, Pathogenesis and Antiviral Strategy

The recent experience with SARS-COV-2 has raised our alarm about the cross-species transmissibility of coronaviruses and the emergence of new coronaviruses. Knowledge of this family of viruses needs to be constantly updated. Porcine deltacoronavirus (PDCoV), a newly emerging member of the genus Deltacoronavirus in the family Coronaviridae, is a swine enteropathogen that causes diarrhea in pigs and may lead to death in severe cases. Since PDCoV diarrhea first broke out in the United States in early 2014, PDCoV has been detected in many countries, such as South Korea, Japan and China. More importantly, PDCoV can also infect species other than pigs, and infections have even been reported in children, highlighting its potential for cross-species transmission. A thorough and systematic knowledge of the epidemiology and pathogenesis of PDCoV will not only help us control PDCoV infection, but also enable us to discover the common cellular pathways and key factors of coronaviruses. In this review, we summarize the current knowledge on the prevalence, pathogenicity and infection dynamics, pathogenesis and immune evasion strategies of PDCoV. The existing anti-PDCoV strategies and corresponding mechanisms of PDCoV infection are also introduced, aiming to provide suggestions for the prevention and treatment of PDCoV and zoonotic diseases.

An overview of the preclinical discovery and development of remdesivir for the treatment of coronavirus disease 2019 (COVID-19)

INTRODUCTION

Remdesivir (RDV) is an inhibitor of the viral RNA-dependent RNA polymerases that are active in some RNA viruses, including the Ebola virus and zoonotic coronaviruses. When severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) was identified as the etiologic agent of the coronavirus disease 2019 (COVID-19), several investigations have assessed the potential activity of RDV in inhibiting viral replication, giving rise to hope for an effective treatment.

AREAS COVERED

In this review, the authors describe the main investigations leading to the discovery of RDV and its subsequent development as an antiviral agent, focusing on the main clinical trials investigating its efficacy in terms of symptom resolution and mortality reduction.

EXPERT OPINION

RDV is the most widely investigated antiviral drug for the treatment of COVID-19. This attention on RDV activity against SARS-CoV-2 is justified by promising in vitro studies, which demonstrated that RDV was able to suppress viral replication without significant toxicity. Such activity was confirmed by an investigation in an animal model and by the results of preliminary clinical investigations. Nevertheless, the efficacy of RDV in reducing mortality has not been clearly demonstrated.

Efficacy of the early treatment with tocilizumab-hydroxychloroquine and tocilizumab-remdesivir in severe COVID-19 Patients

BACKGROUND

The effectiveness of the best combination between different antiviral and anti-inflammatory drugs stills an interest in the treatment of COVID19 infection.

PATIENTS AND METHODS

A prospective randomized cohort study comprised 108 adult patients with confirmed PCR COVID 19 infection with systemic hyper inflammation state, divided into two groups according to the treatment regimen, 56 in the tocilizumab- hydroxychloroquine (TCZ-HCQ) treatment, and 52 in the tocilizumab-remdesivir (TCZ-RMV) treatment. The first group received a combination of I.V. TCZ (400-800 mg every 24 h for only two doses) and HCQ (400 mg twice in the first day then 200 mg twice for 5 days) while the second group of patients received I.V. RMV of 200 mg on day 1 followed by 100 mg once daily infused over 60 min for 5 days with the same TCZ regimen used in the first group. All clinical parameters and laboratory investigations were assessed before and after treatment.

RESULTS

The CRP was significantly decreased while PaO2/FiO2 (P/F) ratio post-treatment was significantly improved in both treatment groups. TCZ-HCQ group showed a significant decrease in the ferritin, LDH, and D. Dimer levels. The median days of hospitalization with interquartile range (IQR) were 10 (6-16) and 8 (5-12) for TCZ-HCQ and TCZ-RMV groups, respectively. The numbers of mechanically ventilated patients were 25 and 43 for TCZ-HCQ and TCZ-RMV groups, respectively. Therapeutic failure was about 26.8% in the TCZ-HCQ group and 30.8% in the TCZ-RMV group but there was no significant difference between both groups. Some complications were recognized only in TCZ-RMV following treatment including secondary bacterial infections (42.3%), myocarditis (15.4%), and finally pulmonary embolism (7.7%).

CONCLUSION

Efficacy of both TCZ-RMV and TCZ-HCQ combinations are observed in the treatment of severe COVID-19 patients; however the increased need for ICU or mechanical ventilation in the TCZ-RMV arm contributed to the appearance of cardiac and thrombotic events. The study was registered at the Clinical Trials registry (ClinicalTrials.gov; NCT04779047).

Currently available drugs for the treatment of Coronavirus-2

The Coronavirus disease 2019 (COVID-19) pandemic caused by the novel severe acute respiratory syndrome Coronavirus 2 (SARS CoV-2) has created a never-before-seen problem for humanity. The world was pushed into a position where we needed to identify the effective drugs for a disease that has unknown characteristics in the early 2020s. SARS CoV-2 Virology research suggested that several drugs could be the potential targets. Remdesivir was the first drug that was shown to have promising results in in vitro studies. Remdesivir became the first antiviral drug approved by USFDA for the management of COVID-19. But later studies show equivocal results.

For this entirely new disease, we are still searching the perfect drug. Many existing drugs have been repurposed (steroids, anticoagulation, hydroxychloroquine) with varying success. Many new drugs have been researched for the management of this menace. In this review, we will discuss the mechanisms, uses, dosage, duration, and adverse effects of drugs used in COVID-19.

COVID-19 Pandemic: Outbreak, Potential Vaccines And Medications

The outbreak of the current global pandemic caused by the spread of a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed an unprecedented threat to global health and economy across the whole world. As of today, the number of cases diagnosed with SARS-CoV-2 is exceeding 271 million with over 5.32 million deaths globally. Despite the high throughput technology and considerable advances in sciences, the outbreaks of the COVID-19 pandemic present a colossal challenge to scientific community. Scientists and clinicians all over the world are putting tremendous efforts to develop effective treatments to combat this deadly pathogen, at least to contain it momentarily until an adequate treatment regimen is available. Conventionally, vaccines have been developed as one of the therapeutic strategies to restrict infectious diseases. Although several vaccines are in the pipeline, evaluation of efficacy in animals’ studies and human are time-consuming. On the other hand, several drugs already in clinical use are being employed to test their efficacy against SARS-CoV-2. Some of these drugs have been already used as anti-viral drugs and others have been used for different therapeutic purposes. In this review, we summarize the ongoing efforts to control the dissemination of SARS-CoV-2 and highlight the potential prophylactic and therapeutic measures including the recently developed vaccines in the foreseeable future. Moreover, we emphasize an importance of having a customized strategy that can be easily and quickly employed to overcome possible future outbreaks.

Gastrointestinal and hepatic side effects of potential treatment for COVID-19 and vaccination in patients with chronic liver diseases

The outbreak of coronavirus disease 2019 (COVID-19) is a global pandemic. Many clinical trials have been performed to investigate potential treatments or vaccines for this disease to reduce the high morbidity and mortality. The drugs of higher interest include umifenovir, bromhexine, remdesivir, lopinavir/ritonavir, steroid, tocilizumab, interferon alpha or beta, ribavirin, fivapiravir, nitazoxanide, ivermectin, molnupiravir, hydroxychloroquine/chloroquine alone or in combination with azithromycin, and baricitinib. Gastrointestinal (GI) symptoms and liver dysfunction are frequently seen in patients with COVID-19, which can make it difficult to differentiate disease manifestations from treatment adverse effects. GI symptoms of COVID-19 include anorexia, dyspepsia, nausea, vomiting, diarrhea and abdominal pain. Liver injury can be a result of systemic inflammation or cytokine storm, or due to the adverse drug effects in patients who have been receiving different treatments. Regular monitoring of liver function should be performed. COVID-19 vaccines have been rapidly developed with different technologies including mRNA, viral vectors, inactivated viruses, recombinant DNA, protein subunits and live attenuated viruses. Patients with chronic liver disease or inflammatory bowel disease and liver transplant recipients are encouraged to receive vaccination as the benefits outweigh the risks. Vaccination against COVID-19 is also recommended to family members and healthcare professionals caring for these patients to reduce exposure to the severe acute respiratory syndrome coronavirus 2 virus.

Efficient incorporation and template-dependent polymerase inhibition are major determinants for the broad-spectrum antiviral activity of remdesivir

Remdesivir (RDV) is a direct-acting antiviral agent that is approved in several countries for the treatment of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). RDV exhibits broad-spectrum antiviral activity against positive-sense RNA viruses, e.g., SARS-CoV-2 and hepatitis C virus (HCV), and non-segmented negative-sense RNA viruses, e.g., Nipah virus (NiV), while segmented negative-sense RNA viruses such as influenza (Flu) virus or Crimean-Congo hemorrhagic fever virus (CCHFV) are not sensitive to the drug. The reasons for this apparent efficacy pattern are unknown. Here, we expressed and purified representative RNA-dependent RNA polymerases (RdRp) and studied three biochemical parameters that have been associated with the inhibitory effects of RDV-triphosphate (TP): (i) selective incorporation of the nucleotide substrate RDV-TP, (ii) the effect of the incorporated RDV-monophosphate (MP) on primer extension, and (iii) the effect of RDV-MP in the template during incorporation of the complementary UTP. We found a strong correlation between antiviral effects and efficient incorporation of RDV-TP. Inhibition in primer extension reactions was heterogeneous and usually inefficient at higher NTP concentrations. In contrast, template-dependent inhibition of UTP incorporation opposite the embedded RDV-MP was seen with all polymerases. Molecular modeling suggests a steric conflict between the 1'-cyano group of the inhibitor and residues of the structurally conserved RdRp motif F. We conclude that future efforts in the development of nucleotide analogues with a broader spectrum of antiviral activities should focus on improving rates of incorporation while capitalizing on the inhibitory effects of a bulky 1'-modification.

HSP90 inhibitors 17-AAG and VER-82576 inhibit porcine deltacoronavirus replication in vitro

Porcine deltacoronavirus (PDCoV) is highly pathogenic to piglets, and no specific drugs or vaccines are available for the prevention and treatment of PDCoV infection, the need for antiviral therapies is pressing. HSP90 inhibitors have potent inhibitory effects against the replication of numerous viruses, hence we evaluated three HSP90 inhibitors, 17-AAG, VER-82576, and KW-2478, for their effects on PDCoV infection in vitro. We evaluated their effectivenesses at suppressing PDCoV by qRT-PCR, western blot, and TCID₅₀ assay, and found that 17-AAG and VER-82576 inhibited PDCoV at the early stage of replication, while KW-2478 showed no significant antiviral activity at any stage of infection. These results indicated that the PDCoV-inhibitory effects of 17-AAG and VER-82576 might be exerted by targeting host cell factor HSP90AB1 but not HSP90AA1. Further study showed that HSP90AB1 mRNA and protein levels were not significantly different in 17-AAG and VER-82576-treated cells versus control cells. 17-AAG and VER-82576 were also evaluated for their effects on the expressions of TNF-α, IL-6, and IL-12, which are PDCoV-induced proinflammatory cytokines. We found that both 17-AAG and VER-82576 inhibited the expressions of TNF-α, IL-6, and IL-12 to varying degrees, but in a dose dependent manner. From our data we can conclude that the HSP90 inhibitors 17-AAG and VER-82576 are promising candidates for the treatment of PDCoV infection.

Virtual screening and in vitro validation of natural compound inhibitors against SARS-CoV-2 spike protein

The COVID-19 pandemic caused by the SARS-CoV-2 virus has led to a major public health burden and has resulted in millions of deaths worldwide. As effective treatments are limited, there is a significant requirement for high-throughput, low resource methods for the discovery of novel antivirals. The SARS-CoV-2 spike protein plays a key role in viral entry and has been identified as a therapeutic target. Using the available spike crystal structure, we performed a virtual screen with a library of 527 209 natural compounds against the receptor binding domain of this protein. Top hits from this screen were subjected to a second, more comprehensive molecular docking experiment and filtered for favourable ADMET properties. The in vitro activity of 10 highly ranked compounds was assessed using a virus neutralisation assay designed to facilitate viral entry in a physiologically relevant manner via the plasma membrane route. Subsequently, four compounds ZINC02111387, ZINC02122196, SN00074072 and ZINC04090608 were identified to possess antiviral activity in the µM range. These findings validate the virtual screening method as a tool for identifying novel antivirals and provide a basis for future drug development against SARS-CoV-2.

Porcine deltacoronavirus infection is inhibited by Griffithsin in cell culture

Porcine deltacoronavirus (PDCoV) is an emerging porcine enteric coronavirus that causes severe diarrhea in piglets and results in serious economic losses. There are no effective vaccines and antiviral drugs to prevent and treat PDCoV infection currently. Griffithsin (GRFT) is a lectin with potent antiviral activity against enveloped viruses because of its ability to specifically bind N-linked high-mannose oligosaccharides. GRFT has been reported to possess antiviral activity against severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and porcine epidemic diarrhea virus (PEDV). Here, we first confirmed the antiviral activity of GRFT against PDCoV in vitro. The infected cells (%) and virus titers were significantly decreased at concentration 1 μg/mL or above of GRFT. Time-course experiments revealed that GRFT inhibits PDCoV infection at the adsorption and penetration step. GRFT binding to PDCoV spike (S) protein on the surface wraps the virus and blocks its entry. The outstanding antiviral potency indicates that GRFT has the potential value as a candidate drug for the prevention and treatment of PDCoV infection.

Comparative assessment of favipiravir and remdesivir against human coronavirus NL63 in molecular docking and cell culture models

Human coronavirus NL63 (HCoV-NL63) mainly affects young children and immunocompromised patients, causing morbidity and mortality in a subset of patients. Since no specific treatment is available, this study aims to explore the anti-SARS-CoV-2 agents including favipiravir and remdesivir for treating HCoV-NL63 infection. We first successfully modelled the 3D structure of HCoV-NL63 RNA-dependent RNA polymerase (RdRp) based on the experimentally solved SARS-CoV-2 RdRp structure. Molecular docking indicated that favipiravir has similar binding affinities to SARS-CoV-2 and HCoV-NL63 RdRp with LibDock scores of 75 and 74, respectively. The LibDock scores of remdesivir to SARS-CoV-2 and HCoV-NL63 were 135 and 151, suggesting that remdesivir may have a higher affinity to HCoV-NL63 compared to SARS-CoV-2 RdRp. In cell culture models infected with HCoV-NL63, both favipiravir and remdesivir significantly inhibited viral replication and production of infectious viruses. Overall, remdesivir compared to favipiravir is more potent in inhibiting HCoV-NL63 in cell culture. Importantly, there is no evidence of resistance development upon long-term exposure to remdesivir. Furthermore, combining favipiravir or remdesivir with the clinically used antiviral cytokine interferon-alpha resulted in synergistic effects. These findings provided a proof-of-concept that anti-SARS-CoV-2 drugs, in particular remdesivir, have the potential to be repurposed for treating HCoV-NL63 infection.

Repurposing old molecules for new indications: Defining pillars of success from lessons in the past

Drug repurposing or studying existing drugs for potential therapeutic utility in newer indications has been identified as an attractive option for treating a number of diseases. Various strategies of drug repurposing include serendipitous observation of drug's unexpected effects, directing the failed investigational drugs to new indications and currently adopted systematic approach to identify, screen and develop existing drug molecules for new off-label indications. Drug repurposing is able to constructively overcome the bottleneck restraints encountered during traditional de novo drug development process in grounds of timelines, cost and resources. However, success rates of drug repurposing programs are not very impressive. Through a meticulous examination of some failed repurposing attempts we aimed to identify key factors leading to high attrition rate in such studies. Based on the fundamental elements of knowledge and evaluation, we have defined four pillars toward improving success rate in drug repurposing programs viz. sound knowledge of the repurposed drug's pharmacological characteristics (pillar 1: drug pharmacology); drug formulation considerations in new indication (pillar 2: drug formulation); evaluation in representative biological assays with translational potential (pillar 3: evaluation in biological assays); and robust clinical trial methodologies including biomarker driven approach to provide conclusive evidence of repurposed drug's efficacy in new indication (pillar 4: clinical evaluation). In addition to the pharmacological challenges, certain regulatory concerns, including lack of clear guidelines for evaluation and market exclusivity pose hurdles in the application of drug repurposing, which may however be overcome to a great extent by adopting some strategies as discussed in this review.

Broad antiviral and anti-inflammatory activity of Qingwenjiere mixture against SARS-CoV-2 and other human coronavirus infections

BACKGROUND

Qingwenjiere Mixture (QJM) is a traditional Chinese medicine (TCM) that has been shown to have remarkable clinical efficacy against COVID-19. However, little is known about the antiviral and anti-inflammatory activities of QJM against a wider range of human coronavirus (HCoV) strains.

PURPOSE

The study aims to investigate the antiviral and anti-inflammatory activities of QJM, as well as the underlying mechanisms against HCoV infections.

METHODS

The chemical compositions from QJM were analyzed by LC-MS. The inhibitory effect of QJM on infections of HCoV-OC43, HCoV-229E, HCoV-NL63, and SARS-CoV-2 was evaluated in HRT-18 cells, Huh7 cells, LLC-MK2 cells, and Vero-E6 cells, respectively, by using cytopathic effect (CPE) inhibition assay or RT-qPCR detection of viral n, s, or RdRp/Hel genes. The expression of pro-inflammatory cytokines induced by HCoV-OC43, HCoV-229E, and SARS-CoV-2, as well as the host ace2 gene was also determined by RT-qPCR assay. Furthermore, the expression of key molecules in the NF-κB/MAPKs signaling pathways was determined by western blot.

RESULTS

In alcohol-extraction groups of QJM and reference decoction pieces, 53 similar ion peaks were identified, the majority of which were phenylpropanoids, iridoids, and flavonoids. In addition, QJM reduced CPE caused by HCoVs and the expression of viral n genes or N protein. Pretreatment with QJM also exerted inhibitory effect on viral n gene expression. QJM also inhibited the expression of RdRp/Hel and s genes of SARS-CoV-2, as well as the host ace2 gene. Besides, QJM markedly reduced virus-induced mRNA expression of a panel of pro-inflammatory cytokines, such as IL-6, CXCL-8/IL-8, CXCL-10/IP-10, CCL-5/RANTES, TNF-α, IFN-α, CCL-2/MCP-1, CXCL-9/MIG, and IL1-α. We further showed that QJM inhibited the phosphorylation of NF-κB p65, and JNK, ERK 1/2, and p38 MAPKs in HCoV-OC43-infected HRT-18 cells.

CONCLUSIONS

QJM has broad antiviral and anti-inflammatory activity against both common and newly emerged HCoVs possibly by inhibiting the activation of key components in NF-κB/MAPKs signaling pathway. QJM also has a prevention effect against HCoV infections and inhibits the host receptor required for virus entry. These results indicate that QJM may have the therapeutic potential in the treatment of diseases caused by a broad range of HCoVs.

In silico identification of SARS-CoV-2 cell entry inhibitors from selected natural antivirals

The aim of this study is to identify potential drug-like molecules against SARS-CoV-2 virus among the natural antiviral compounds published in the Encyclopedia of Traditional Chinese Medicine. To test inhibition capability of these compounds first, we docked them with Spike protein, angiotensin-converting enzyme 2 (ACE2) (PDB ID: 6M0J) and neuropilin 1 (NRP1) (PDB ID: 7JJC) receptors, and found significant docking scores with extra precision up to -11 kcal/mol. Then, their stability in the binding pockets were further evaluated with molecular dynamics simulation. Eight natural antiviral compounds were identified as potential inhibitors against SARS-CoV-2 cell entry after 200 ns molecular dynamics simulations. We found CMP-3, CMP-4, CMP-5, CMP-6 and CMP-8 are strong binders for the spike protein, CMP-1, CMP-2, CMP-4, CMP-5 and CMP-7 are strong binders for the neuropilin receptor, and CMP-5 is a strong binder for the ACE2. Quercetin derivatives (CMP-4, CMP-5, CMP-6 and CMP-7) were found highly stable in the active domain of NRP1, ACE2 and Spike protein. Especially, CMP-5 showed an inhibitory activity for all targets. These natural antivirals may be potential drug candidates for the prevention of SARS-CoV-2 infection.

Efficacy and Safety of Remdesivir over Two Waves of the SARS-CoV-2 Pandemic

The aim of this study is to describe the features, the outcomes, and the clinical issues related to Remdesivir administration of a cohort of 220 patients (pts) with COVID-19 hospitalized throughout the last two pandemic waves in Italy. One hundred and nine pts were enrolled from 1 September 2020, to 28 February 2021 (Group A) and 111 from 1 March to 30 September 2021 (Group B). Notably, no differences were reported between the two groups neither in the timing of hospitalization. nor in the timing of Remdesivir administration from symptoms onset. Remarkably, a higher proportion of pts with severe COVID-19 was observed in Group B (25% vs. 10%, p < 0.001). At univariate and multivariate analysis, rather than the timing of Remdesivir administration, age, presence of coexisting conditions, D-dimers, and O2 flow at admission correlated positively to progression to non-invasive ventilation, especially for patients in Group B. However, the rate of admission in the Intensive Care Unit and/or death was comparable in the two groups (7% vs. 4%). Negligible variations in serum GOT, GPT, GGT, and eGFR levels were detected. A mean reduction in heart rate was noticed within the first three days of antiviral treatment (p < 0.001). Low rate of ICU admission, high rate of clinical recovery, and good drug safety were observed in COVID-19 patients treated with Remdesivir during two diverse pandemic waves.

SARS-CoV-2: Overview and Its Impact on Oral Health

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its virulent variants causing coronavirus disease 2019 (COVID-19) COVID-19 has spread rapidly worldwide, and is highly contagious. A comprehensive search was conducted for the most current published information about SARS-CoV-2, COVID-19, and oral health. Clinical studies, case reports, in vivo studies, and any current published evidence on SARS-CoV-2 and COVID-19 were included in this review. Survival against SARS-CoV-2 infection may be partially dependent on periodontal health, good oral hygiene, and access to dental care. Optimum oral health, maintaining good systemic health, and elimination of smoking habits may be beneficial for the prevention and management of COVID-19 infections.

Current status of therapeutic approaches and vaccines for SARS-CoV-2

SARS-CoV-2, declared a pandemic in March 2020, is the current global health challenge. The global bioburden of this virus is increasing at a rapid pace. Many antiviral drugs and vaccines have been registered for clinical trials because of their inhibitory activity observed in vitro. Currently, five types of vaccines have successfully passed Phase IV clinical trial and are being administered in populations worldwide. A plethora of experimental designs have been proposed worldwide in order to find a safe and efficacious treatment option. Therefore, it is necessary to provide baseline data and information to clinicians and researchers so that they can review the current status of therapeutics and efficacy of already developed vaccines. This review article summarizes all therapeutic options that may help to combat SARS-CoV-2.

Remdesivir: Quo vadis?

Remdesivir (GS-5734, Veklury®) has remained the only antiviral drug formally approved by the US FDA for the treatment of Covid-19 (SARS-CoV-2 infection). Its key structural features are the fact that it is a C-nucleoside (adenosine) analogue, contains a 1'-cyano function, and could be considered as a ProTide based on the presence of a phosphoramidate group. Its antiviral spectrum and activity in animal models have been well established and so has been its molecular mode of action as a delayed chain terminator of the viral RdRp (RNA-dependent RNA polymerase). Its clinical efficacy has been evaluated, but needs to be optimized with regard to timing, dosage and duration of treatment, and route of administration. Safety, toxicity and pharmacokinetics need to be further addressed, and so are its potential combinations with other drugs such as corticosteroids (i.e. dexamethasone) and ribavirin.

Nanoparticles as an effective drug delivery system in COVID-19

BACKGROUND

The global healthcare sector has been dealing with a situation known as a novel severe acute respiratory syndrome (SARS-CoV-2) since the end of 2019. Covid-19 is an acronym for Covid-19 (Coronavirus Disease- 2019). It causes a respiratory infection that includes cold, sneezing and coughing, and pneumonia. In the case of an animal, it causes diarrhea and upper respiratory diseases. Covid-19 transmitted human to human via airborne droplets. First Covid-19 emerged in Wuhan market China and it spread rapidly throughout the World. As we know nanoparticles are a novel drug delivery system. They have various advantageous effects like increasing the efficacy of the drug, safety, etc. In this review, we study about the nanoparticles and summarize how it is effective during drug delivery system in Covid-19. Chitosan is a much focused biopolymeric nanoparticle. It delivers drugs to the specific target site. In a recent health crisis, chitosan nanoparticles are one of the ways to release drugs of Covid-19, and specifically in the lungs of the affected patients. We studied and extracted our data from various research papers, review papers, and some other articles.

OBJECTIVE

The main goal is to study the nanoparticles and their future aspects which is an effective drug delivery system in Covid-19.

METHODS

The bibliographic search was done through a systematic search. The terms "Nanoparticles", "Covid-19 ", "Drug delivery" etc. were used to search the databases/search engines like "Google Scholar", "NCBI", "PubMed", "Science Direct" etc. These databases and search engines used here perform the limited criteria of search to conduct a systematic literature survey for the study and report writing. All the text from the articles and research papers were studied and analyzed. The various articles and research papers were used in writing this report and all of which are mentioned in the reference section of this report.

CONCLUSION

Our current studies reveal that nanoparticles may prove very helpful in the delivery of drugs for Covid-19 treatment. Many cases showed that patients, where drugs are delivered with the help of nanoparticles, produced very few side effects.

Cardiovascular events and safety outcomes associated with remdesivir using a World Health Organization international pharmacovigilance database

On October 2020, the US Food and Drug Administration (FDA) approved remdesivir as the first drug for the treatment of coronavirus disease 2019 (COVID-19), increasing remdesivir prescriptions worldwide. However, potential cardiovascular (CV) toxicities associated with remdesivir remain unknown. We aimed to characterize the CV adverse drug reactions (ADRs) associated with remdesivir using VigiBase, an individual case safety report database of the World Health Organization (WHO). Disproportionality analyses of CV-ADRs associated with remdesivir were performed using reported odds ratios and information components. We conducted in vitro experiments using cardiomyocytes derived from human pluripotent stem cell cardiomyocytes (hPSC-CMs) to confirm cardiotoxicity of remdesivir. To distinguish drug-induced CV-ADRs from COVID-19 effects, we restricted analyses to patients with COVID-19 and found that, after adjusting for multiple confounders, cardiac arrest (adjusted odds ratio [aOR]: 1.88, 95% confidence interval [CI]: 1.08-3.29), bradycardia (aOR: 2.09, 95% CI: 1.24-3.53), and hypotension (aOR: 1.67, 95% CI: 1.03-2.73) were associated with remdesivir. In vitro data demonstrated that remdesivir reduced the cell viability of hPSC-CMs in time- and dose-dependent manners. Physicians should be aware of potential CV consequences following remdesivir use and implement adequate CV monitoring to maintain a tolerable safety margin.

5-Hydroxymethyltubercidin exhibits potent antiviral activity against flaviviruses and coronaviruses, including SARS-CoV-2

Newly emerging or re-emerging viral infections continue to cause significant morbidity and mortality every year worldwide, resulting in serious effects on both health and the global economy. Despite significant drug discovery research against dengue viruses (DENVs) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), no fully effective and specific drugs directed against these viruses have been discovered. Here, we examined the anti-DENV activity of tubercidin derivatives from a compound library from Hokkaido University and demonstrated that 5-hydroxymethyltubercidin (HMTU, HUP1108) possessed both potent anti-flavivirus and anti-coronavirus activities at submicromolar levels without significant cytotoxicity. Furthermore, HMTU inhibited viral RNA replication and specifically inhibited replication at the late stages of the SARS-CoV-2 infection process. Finally, we demonstrated that HMTU 5′-triphosphate inhibited RNA extension catalyzed by the viral RNA-dependent RNA polymerase. Our findings suggest that HMTU has the potential of serving as a lead compound for the development of a broad spectrum of antiviral agents, including SARS-CoV-2.

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We identified tubercidin derivatives as broad-spectrum antiviral compounds

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HMTU exhibited potent antiviral activity against flaviviruses and coronaviruses

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HMTU specifically inhibited replication at a late stage of the viral infection process

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HMTU 5′-triphosphate inhibited RNA extension catalyzed by viral RdRp

Whole Body PBPK Modeling of Remdesivir and its Metabolites to Aid in Estimating Active Metabolite Exposure in the Lung and Liver in Patients with Organ Dysfunction

Remdesivir (RDV) is the first drug approved by the US Food and Drug Administration (FDA) for the treatment of coronavirus disease 2019 (COVID-19) in certain patients requiring hospitalization. As a nucleoside analogue prodrug, RDV undergoes intracellular multistep activation to form its pharmacologically active species, GS-443902, which is not detectable in the plasma. A question arises that whether the observed plasma exposure of RDV and its metabolites would correlate with or be informative about the exposure of GS-443902 in tissues. A whole body physiologically-based pharmacokinetic (PBPK) modeling and simulation approach was utilized to elucidate the disposition mechanism of RDV and its metabolites in the lungs and liver and explore the relationship between plasma and tissue pharmacokinetics (PK) of RDV and its metabolites in healthy subjects. In addition, the potential alteration of plasma and tissue PK of RDV and its metabolites in patients with organ dysfunction was explored. Our simulation results indicated that intracellular exposure of GS-443902 was decreased in the liver and increased in the lungs in subjects with hepatic impairment relative to the subjects with normal liver function. In subjects with severe renal impairment, the exposure of GS-443902 in the liver was slightly increased, whereas the lung exposure of GS-443902 was not impacted. These predictions along with the organ impairment study results may be used to support decision making regarding the RDV dosage adjustment in these patient subgroups. The modeling exercise illustrated the potential of whole body PBPK modeling to aid in decision making for nucleotide analogue prodrugs, particularly when the active metabolite exposure in the target tissues is not available.

Remdesivir is efficacious in rhesus monkeys exposed to aerosolized Ebola virus

Efficacious therapeutics for Ebola virus disease are in great demand. Ebola virus infections mediated by mucosal exposure, and aerosolization in particular, present a novel challenge due to nontypical massive early infection of respiratory lymphoid tissues. We performed a randomized and blinded study to compare outcomes from vehicle-treated and remdesivir-treated rhesus monkeys in a lethal model of infection resulting from aerosolized Ebola virus exposure. Remdesivir treatment initiated 4 days after exposure was associated with a significant survival benefit, significant reduction in serum viral titer, and improvements in clinical pathology biomarker levels and lung histology compared to vehicle treatment. These observations indicate that remdesivir may have value in countering aerosol-induced Ebola virus disease.

Multi-level inhibition of coronavirus replication by chemical ER stress

Coronaviruses (CoVs) are important human pathogens for which no specific treatment is available. Here, we provide evidence that pharmacological reprogramming of ER stress pathways can be exploited to suppress CoV replication. The ER stress inducer thapsigargin efficiently inhibits coronavirus (HCoV-229E, MERS-CoV, SARS-CoV-2) replication in different cell types including primary differentiated human bronchial epithelial cells, (partially) reverses the virus-induced translational shut-down, improves viability of infected cells and counteracts the CoV-mediated downregulation of IRE1α and the ER chaperone BiP. Proteome-wide analyses revealed specific pathways, protein networks and components that likely mediate the thapsigargin-induced antiviral state, including essential (HERPUD1) or novel (UBA6 and ZNF622) factors of ER quality control, and ER-associated protein degradation complexes. Additionally, thapsigargin blocks the CoV-induced selective autophagic flux involving p62/SQSTM1. The data show that thapsigargin hits several central mechanisms required for CoV replication, suggesting that this compound (or derivatives thereof) may be developed into broad-spectrum anti-CoV drugs.

Therapeutic efficacy of an oral nucleoside analog of remdesivir against SARS-CoV-2 pathogenesis in mice

The COVID-19 pandemic remains uncontrolled despite the rapid rollout of safe and effective SARS-CoV-2 vaccines, underscoring the need to develop highly effective antivirals. In the setting of waning immunity from infection and vaccination, breakthrough infections are becoming increasingly common and treatment options remain limited. Additionally, the emergence of SARS-CoV-2 variants of concern with their potential to escape therapeutic monoclonal antibodies emphasizes the need to develop second-generation oral antivirals targeting highly conserved viral proteins that can be rapidly deployed to outpatients. Here, we demonstrate the in vitro antiviral activity and in vivo therapeutic efficacy of GS-621763, an orally bioavailable prodrug of GS-441524, the parental nucleoside of remdesivir, which targets the highly conserved RNA-dependent RNA polymerase. GS-621763 exhibited significant antiviral activity in lung cell lines and two different human primary lung cell culture systems. The dose-proportional pharmacokinetic profile observed after oral administration of GS-621763 translated to dose-dependent antiviral activity in mice infected with SARS-CoV-2. Therapeutic GS-621763 significantly reduced viral load, lung pathology, and improved pulmonary function in COVID-19 mouse model. A direct comparison of GS-621763 with molnupiravir, an oral nucleoside analog antiviral currently in human clinical trial, proved both drugs to be similarly efficacious. These data demonstrate that therapy with oral prodrugs of remdesivir can significantly improve outcomes in SARS-CoV-2 infected mice. Thus, GS-621763 supports the exploration of GS-441524 oral prodrugs for the treatment of COVID-19 in humans.

Protective Effect of Remdesivir Against Pulmonary Fibrosis in Mice

Pulmonary fibrosis is a known sequela of severe or persistent lung damage. Existing clinical, imaging and autopsy studies have shown that the lungs exhibit a pathological pulmonary fibrosis phenotype after infection with coronaviruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Pulmonary fibrosis may be one of the most serious sequelae associated with coronavirus disease 2019 (COVID-19). In this study, we aimed to examine the preventative effects of the antiviral drug remdesivir on pulmonary fibrosis. We used a mouse model of bleomycin-induced pulmonary fibrosis to evaluate the effects of remdesivir on pulmonary fibrosis in vivo and further explored the potential pharmacological mechanisms of remdesivir in lung fibroblasts and alveolar epithelial cells in vitro. The preventive remdesivir treatment was started on the day of bleomycin installation, and the results showed that remdesivir significantly alleviated bleomycin-induced collagen deposition and improved pulmonary function. In vitro experiments showed that remdesivir dose-dependently suppressed TGF-β1-induced lung fibroblast activation and improved TGF-β1-induced alveolar epithelial to mesenchymal transition. Our results indicate that remdesivir can preventatively alleviate the severity of pulmonary fibrosis and provide some reference for the prevention of pulmonary fibrosis in patients with COVID-19.

Combination Therapy with Fluoxetine and the Nucleoside Analog GS-441524 Exerts Synergistic Antiviral Effects against Different SARS-CoV-2 Variants In Vitro

The ongoing SARS-CoV-2 pandemic requires efficient and safe antiviral treatment strategies. Drug repurposing represents a fast and low-cost approach to the development of new medical treatment options. The direct antiviral agent remdesivir has been reported to exert antiviral activity against SARS-CoV-2. Whereas remdesivir only has a very short half-life time and a bioactivation, which relies on pro-drug activating enzymes, its plasma metabolite GS-441524 can be activated through various kinases including the adenosine kinase (ADK) that is moderately expressed in all tissues. The pharmacokinetics of GS-441524 argue for a suitable antiviral drug that can be given to patients with COVID-19. Here, we analyzed the antiviral property of a combined treatment with the remdesivir metabolite GS-441524 and the antidepressant fluoxetine in a polarized Calu-3 cell culture model against SARS-CoV-2. The combined treatment with GS-441524 and fluoxetine were well-tolerated and displayed synergistic antiviral effects against three circulating SARS-CoV-2 variants in vitro in the commonly used reference models for drug interaction. Thus, combinatory treatment with the virus-targeting GS-441524 and the host-directed drug fluoxetine might offer a suitable therapeutic treatment option for SARS-CoV-2 infections.

Cost-Effectiveness Analysis of Remdesivir Treatment in COVID-19 Patients Requiring Low-Flow Oxygen Therapy: Payer Perspective in Turkey

Introduction

This study aims to evaluate the cost-effectiveness of remdesivir compared to other existing therapies (SoC) in Turkey to treat COVID-19 patients hospitalized with < 94% saturation and low-flow oxygen therapy (LFOT) requirement.

Methods

We compared remdesivir as the treatment for COVID-19 with the treatments in the Turkish treatment guidelines. Analyses were performed using data from 78 hospitalized COVID-19 patients with SpO₂ < 94% who received LFOT in a tertiary healthcare facility. COVID-19 episode costs were calculated for 78 patients considering the cost of modeled remdesivir treatment in the same group from the payer’s perspective. The incremental cost-effectiveness ratio (ICER) per quality-adjusted life-year (QALY) was calculated for remdesivir versus the SoC for the population identified. For Turkey, a reimbursement threshold value between USD 8599 (1 × per capita gross domestic product—GDP) and USD 25.797 (3 × GDP) per QALY was used.

Results

In the remdesivir arm, the length of hospital stay (LOS) was 3 days shorter than the SOC. The low ventilator requirement in the remdesivir arm was one factor that decreased the QALY disutility value. In patients who were transferred to intensive care unit (ICU) from the ward, the mean LOS was 17.3 days (SD 13.6), and the mean cost of stay was USD 155.3/day (SD 168.0), while in patients who were admitted to ICU at baseline, the mean LOS was 13.1 days (SD 13.7), and the mean cost of stay was USD 207.9/day (SD 133.6). The mean cost of episode per patient was USD 3461.1 (SD 2259.8) in the remdesivir arm and USD 3538.9 (SD 3296.0) in the SOC arm. Incremental QALYs were estimated at 0.174. Remdesivir treatment was determined to be cost saving vs. SoC.

Conclusions

Remdesivir, which results in shorter LOS and lower rates of intubation requirements in ICU patients than existing therapies, is associated with higher QALYs and lower costs, dominating SoC in patients with SpO₂ < 94% who require oxygen support.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01874-9.

Construction of a Noninfectious SARS-CoV-2 Replicon for Antiviral-Drug Testing and Gene Function Studies

The emerging coronavirus disease 2019 (COVID-19) outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread worldwide, resulting in global public health emergencies and economic crises. In the present study, a noninfectious and biosafety level 2 (BSL2)-compatible SARS-CoV-2 replicon expressing a nano luciferase (nLuc) reporter was constructed in a bacterial artificial chromosomal (BAC) vector by reverse genetics. The nLuc reporter is highly sensitive, easily quantifiable, and high throughput adaptable. Upon transfecting the SARS-CoV-2 replicon BAC plasmid DNA into Vero E6 cells, we could detect high levels of nLuc reporter activity and viral RNA transcript, suggesting the replication of the replicon. The replicon replication was further demonstrated by the findings that deleting nonstructural protein 15 or mutating its catalytic sites significantly reduced replicon replication, whereas providing the nucleocapsid protein in trans enhanced replicon replication in a dose-dependent manner. Finally, we showed that remdesivir, a U.S. Food and Drug Administration-approved antiviral drug, significantly inhibited the replication of the replicon, providing proof of principle for the application of our replicon as a useful tool for developing antivirals. Taken together, this study established a sensitive and BSL2-compatible reporter system in a single BAC plasmid for investigating the functions of SARS-CoV-2 proteins in viral replication and evaluating antiviral compounds. This should contribute to the global effort to combat this deadly viral pathogen. IMPORTANCE The COVID-19 pandemic caused by SARS-CoV-2 is having a catastrophic impact on human lives. Combatting the pandemic requires effective vaccines and antiviral drugs. In the present study, we developed a SARS-CoV-2 replicon system with a sensitive and easily quantifiable reporter. Unlike studies involving infectious SARS-CoV-2 virus that must be performed in a biosafety level 3 (BSL3) facility, the replicon is noninfectious and thus can be safely used in BSL2 laboratories. The replicon will provide a valuable tool for testing antiviral drugs and studying SARS-CoV-2 biology.

Co-crystallization and structure determination: An effective direction for anti-SARS-CoV-2 drug discovery

Safer and more-effective drugs are urgently needed to counter infections with the highly pathogenic SARS-CoV-2, cause of the COVID-19 pandemic. Identification of efficient inhibitors to treat and prevent SARS-CoV-2 infection is a predominant focus. Encouragingly, using X-ray crystal structures of therapeutically relevant drug targets (PLpro, Mpro, RdRp, and S glycoprotein) offers a valuable direction for anti-SARS-CoV-2 drug discovery and lead optimization through direct visualization of interactions. Computational analyses based primarily on MMPBSA calculations have also been proposed for assessing the binding stability of biomolecular structures involving the ligand and receptor. In this study, we focused on state-of-the-art X-ray co-crystal structures of the abovementioned targets complexed with newly identified small-molecule inhibitors (natural products, FDA-approved drugs, candidate drugs, and their analogues) with the assistance of computational analyses to support the precision design and screening of anti-SARS-CoV-2 drugs.

Remdesivir for the treatment of COVID 19: review of the pharmacological properties, safety and clinical effectiveness

INTRODUCTION

Remdesivir is a nucleoside analog that inhibits viral RNA replication by blocking RNA-dependent RNA polymerase. First developed and tested during the Ebola epidemic, repurposed, and gained prominence during the Coronavirus disease 19 (COVID-19) pandemic. Based on data from three major trials, remdesivir became the first and only medication to obtain approval from the Food and Drug Administration (FDA) to treat patients hospitalized with COVID-19 disease.

AREAS COVERED

The purpose of the article is to review available preclinical, clinical, and post-marketing data to assess the safety and efficacy of remdesivir in the treatment of COVID-19 patients. We performed a comprehensive literature review of articles published on remdesivir until January 2021.

EXPERT OPINION

The substantial evidence of its effectiveness in a few trials together with the favorable safety profile makes remdesivir a primary therapeutic candidate for treatment in adult and pediatric patients who are hospitalized with COVID-19 and requiring oxygen supplementation. While remdesivir does not improve mortality, it has been shown to reduce the recovery time and increase the odds for clinical improvement, specifically in patients with early presentation and moderate COVID-19 disease. Remdesivir is well tolerated and has an acceptable safety profile in the pediatric and adult populations.

The New Generation hDHODH Inhibitor MEDS433 Hinders the In Vitro Replication of SARS-CoV-2 and Other Human Coronaviruses

Although coronaviruses (CoVs) have long been predicted to cause zoonotic diseases and pandemics with high probability, the lack of effective anti-pan-CoVs drugs rapidly usable against the emerging SARS-CoV-2 actually prevented a promptly therapeutic intervention for COVID-19. Development of host-targeting antivirals could be an alternative strategy for the control of emerging CoVs infections, as they could be quickly repositioned from one pandemic event to another. To contribute to these pandemic preparedness efforts, here we report on the broad-spectrum CoVs antiviral activity of MEDS433, a new inhibitor of the human dihydroorotate dehydrogenase (hDHODH), a key cellular enzyme of the de novo pyrimidine biosynthesis pathway. MEDS433 inhibited the in vitro replication of hCoV-OC43 and hCoV-229E, as well as of SARS-CoV-2, at low nanomolar range. Notably, the anti-SARS-CoV-2 activity of MEDS433 against SARS-CoV-2 was also observed in kidney organoids generated from human embryonic stem cells. Then, the antiviral activity of MEDS433 was reversed by the addition of exogenous uridine or the product of hDHODH, the orotate, thus confirming hDHODH as the specific target of MEDS433 in hCoVs-infected cells. Taken together, these findings suggest MEDS433 as a potential candidate to develop novel drugs for COVID-19, as well as broad-spectrum antiviral agents exploitable for future CoVs threats.

The Structure-Based Design of SARS-CoV-2 nsp14 Methyltransferase Ligands Yields Nanomolar Inhibitors

In this study, we have focused on the structure-based design of the inhibitors of one of the two SARS-CoV-2 methyltransferases (MTases), nsp14. This MTase catalyzes the transfer of the methyl group from S-adenosyl-l-methionine (SAM) to cap the guanosine triphosphate moiety of the newly synthesized viral RNA, yielding the methylated capped RNA and S-adenosyl-l-homocysteine (SAH). As the crystal structure of SARS-CoV-2 nsp14 is unknown, we have taken advantage of its high homology to SARS-CoV nsp14 and prepared its homology model, which has allowed us to identify novel SAH derivatives modified at the adenine nucleobase as inhibitors of this important viral target. We have synthesized and tested the designed compounds in vitro and shown that these derivatives exert unprecedented inhibitory activity against this crucial enzyme. The docking studies nicely explain the contribution of an aromatic part attached by a linker to the position 7 of the 7-deaza analogues of SAH.

Novel quinolone derivatives targeting human dihydroorotate dehydrogenase suppress Ebola virus infection in vitro

Ebola virus (EBOV) has emerged as a significant public health concern since the 2013-2016 outbreak in West Africa. Currently, no effective antiviral treatments have been approved for clinical use. Compound 1 RYL-634 is a quinolone-derived compound that can inhibit dihydroorotate dehydrogenase, a rate-limiting enzyme in the de novo pyrimidine synthesis pathway and it exhibited antiviral activity against multiple RNA virus infection. In this study, we evaluated the efficacy of a panel of newly developed compounds based on RYL-634 against EBOV infection. Our data showed that RYL-634 as well as its derivatives are effective against EBOV transcription- and replication-competent virus-like particle (trVLP) infection and authentic EBOV infection in vitro at low nanomolar IC₅₀ values and relatively high CC₅₀. Of note, the new derivative RYL-687 had the lowest IC₅₀ at approximately 7 nM and was almost 6 times more potent than remdesivir (GS-5734). Exogenous addition of different metabolites in the pyrimidine de novo synthesis pathway confirmed DHODH as the target of RYL-687. These data provide evidence that such quinolone-derived compounds are promising therapeutic candidates against EBOV infection.

The solid organ transplant recipient with SARS-CoV-2 infection

PURPOSE OF REVIEW

The COVID-19 pandemic is a major challenge to global health, particularly among vulnerable populations. Here, we describe the emerging epidemiology and relevant data on treatment options for COVID-19. We discuss the implications of current knowledge for solid organ transplant (SOT) recipients.

RECENT FINDINGS

Risk factors and outcomes of COVID-19 among SOT recipients remain uncertain, but recent data suggest similar outcomes to the general population. Case reports of donor-derived SARS-CoV-2 infection are emerging. Few studies on treatment of COVID-19 among SOT recipients are available, and therefore, general recommendations are similar to the general population. Vaccine efficacy in the SOT population is uncertain.

SUMMARY

COVID-19 remains a significant threat to SOT recipients and studies on treatment and prevention specific to this population are urgently needed. Although vaccines represent the greatest hope to control this pandemic, their efficacy in this immunocompromised population is uncertain.

Reducing SARS-CoV-2 pathological protein activity with small molecules

Coronaviruses are dangerous human and animal pathogens. The newly identified coronavirus SARS-CoV-2 is the causative agent of COVID-19 outbreak, which is a real threat to human health and life. The world has been struggling with this epidemic for about a year, yet there are still no targeted drugs and effective treatments are very limited. Due to the long process of developing new drugs, reposition of existing ones is one of the best ways to deal with an epidemic of emergency infectious diseases. Among the existing drugs, there are candidates potentially able to inhibit the SARS-CoV-2 replication, and thus inhibit the infection of the virus. Some therapeutics target several proteins, and many diseases share molecular paths. In such cases, the use of existing pharmaceuticals for more than one purpose can reduce the time needed to design new drugs. The aim of this review was to analyze the key targets of viral infection and potential drugs acting on them, as well as to discuss various strategies and therapeutic approaches, including the possible use of natural products. We highlighted the approach based on increasing the involvement of human deaminases, particularly APOBEC deaminases in editing of SARS-CoV-2 RNA. This can reduce the cytosine content in the viral genome, leading to the loss of its integrity. We also indicated the nucleic acid technologies as potential approaches for COVID-19 treatment. Among numerous promising natural products, we pointed out curcumin and cannabidiol as good candidates for being anti-SARS-CoV-2 agents.

Hydroxychloroquine in COVID-19: therapeutic promises, current status, and environmental implications

The outbreak of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected the entire world with its infectious spread and mortality rate. The severe cases of coronavirus disease 2019 (COVID-19) are characterized by hypoxia and acute respiratory distress syndrome. In the absence of any specific treatment, just the preventive and supportive care options are available. Therefore, much focus is given to assess the available therapeutic options not only to avoid acute respiratory failure and hypoxia but also to reduce the viral load to control the severity of the disease. The antimalarial drug hydroxychloroquine (HCQ) is among the much-discussed drugs for the treatment and management of COVID-19 patients. This article reviews the therapeutic potential of HCQ in the treatment of COVID-19 based on the available in vitro and clinical evidence, current status of registered HCQ-based clinical trials investigating therapeutic options for COVID-19, and environmental implications of HCQ.

Combination Treatment With Remdesivir and Ivermectin Exerts Highly Synergistic and Potent Antiviral Activity Against Murine Coronavirus Infection

The recent COVID-19 pandemic has highlighted the urgency to develop effective antiviral therapies against the disease. Murine hepatitis virus (MHV) is a coronavirus that infects mice and shares some sequence identity to SARS-CoV-2. Both viruses belong to the Betacoronavirus genus, and MHV thus serves as a useful and safe surrogate model for SARS-CoV-2 infections. Clinical trials have indicated that remdesivir is a potentially promising antiviral drug against COVID-19. Using an in vitro model of MHV infection of RAW264.7 macrophages, the safety and efficacy of monotherapy of remdesivir, chloroquine, ivermectin, and doxycycline were investigated. Of the four drugs tested, remdesivir monotherapy exerted the strongest inhibition of live virus and viral RNA replication of about 2-log10 and 1-log10, respectively (at 6 µM). Ivermectin treatment showed the highest selectivity index. Combination drug therapy was also evaluated using remdesivir (6 µM) together with chloroquine (15 µM), ivermectin (2 µM) or doxycycline (15 µM) - above their IC50 values and at high macrophage cell viability of over 95%. The combination of remdesivir and ivermectin exhibited highly potent synergism by achieving significant reductions of about 7-log10 of live virus and 2.5-log10 of viral RNA in infected macrophages. This combination also resulted in the lowest cytokine levels of IL-6, TNF-α, and leukemia inhibitory factor. The next best synergistic combination was remdesivir with doxycycline, which decreased levels of live virus by ~3-log10 and viral RNA by ~1.5-log10. These results warrant further studies to explore the mechanisms of action of the combination therapy, as well as future in vivo experiments and clinical trials for the treatment of SARS-CoV-2 infection.

Prevention and therapy of SARS-CoV-2 and the B.1.351 variant in mice

Improving clinical care for individuals infected with SARS-CoV-2 variants is a global health priority. Small-molecule antivirals like remdesivir (RDV) and biologics such as human monoclonal antibodies (mAbs) have demonstrated therapeutic efficacy against SARS-CoV-2, the causative agent of coronavirus disease 2019 (COVID-19). It is not known whether combination RDV/mAb will improve outcomes over single-agent therapies or whether antibody therapies will remain efficacious against variants. Here, we show that a combination of two mAbs in clinical trials, C144 and C135, have potent antiviral effects against even when initiated 48 h after infection and have therapeutic efficacy in vivo against the B.1.351 variant of concern (VOC). Combining RDV and antibodies provided a modest improvement in outcomes compared with single agents. These data support the continued use of RDV to treat SARS-CoV-2 infections and the continued clinical development of the C144 and C135 antibody combination to treat patients infected with SARS-CoV-2 variants.

Quantitative HPLC-MS/MS determination of Nuc, the active metabolite of remdesivir, and its pharmacokinetics in rat

Remdesivir is a nucleotide analog prodrug that has received much attention since the outbreak of the COVID-19 pandemic in December 2019. GS-441524 (Nuc) is the active metabolite of remdesivir and plays a pivotal role in the clinical treatment of COVID-19. Here, a robust HPLC-MS/MS method was developed to determine Nuc concentrations in rat plasma samples after a one-step protein precipitation process. Chromatographic separation was accomplished on Waters XBrige C₁₈ column (50 × 2.1 mm, 3.5 μm) under gradient elution conditions. Multiple reaction monitoring transitions in electrospray positive ion mode were m/z 292.2 → 163.2 for Nuc and 237.1 → 194.1 for the internal standard (carbamazepine). The quantitative analysis method was fully validated in line with the United States Food and Drug Administration guidelines. The linearity, accuracy and precision, matrix effect, recovery, and stability results met the requirements of the guidelines. Uncertainty of measurement and incurred sample reanalysis were analyzed to further ensure the robustness and reproducibility of the method. This optimized method was successfully applied in a rat pharmacokinetics study of remdesivir (intravenously administration, 5 mg kg⁻¹). The method can act as a basis for further pharmacokinetic and clinical efficacy investigations in patients with COVID-19.

Development of remdesivir repositioning as a nucleotide analog against COVID-19 RNA dependent RNA polymerase

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative representative of a severe respiratory illness resulted in widespread human infections and deaths in nearly all of the countries since late 2019. There is no therapeutic FDA-approved drug against SARS-CoV-2 infection, although a combination of anti-viral drugs is directly being practiced in some countries. A broad-spectrum of antiviral agents are being currently evaluated in clinical trials, and in this review, we specifically focus on the application of Remdesivir (RVD) as a potential anti-viral compound against Middle East respiratory syndrome (MERS) -CoV, SARS-CoV and SARS-CoV-2. First, we overview the general information about SARS-CoV-2, followed by application of RDV as a nucleotide analogue which can potentially inhibits RNA-dependent RNA polymerase of COVs. Afterwards, we discussed the kinetics of SARS- or MERS-CoV proliferation in animal models which is significantly different compared to that in humans. Finally, some ongoing challenges and future perspective on the application of RDV either alone or in combination with other anti-viral agents against CoVs infection were surveyed to determine the efficiency of RDV in preclinical trials. As a result, this paper provides crucial evidence of the potency of RDV to prevent SARS-CoV-2 infections.Communicated by Ramaswamy H. Sarma.

Pharmacokinetics and tissue distribution of remdesivir and its metabolites nucleotide monophosphate, nucleotide triphosphate, and nucleoside in mice

Remdesivir (RDV) exerts anti-severe acute respiratory coronavirus 2 activity following metabolic activation in the target tissues. However, the pharmacokinetics and tissue distributions of the parent drug and its active metabolites have been poorly characterized to date. Blood and tissue levels were evaluated in the current study. After intravenous administration of 20 mg/kg RDV in mice, the concentrations of the parent drug, nucleotide monophosphate (RMP) and triphosphate (RTP), as well as nucleoside (RN), in the blood, heart, liver, lung, kidney, testis, and small intestine were quantified. In blood, RDV was rapidly and completely metabolized and was barely detected at 0.5 h, similar to RTP, while its metabolites RMP and RN exhibited higher blood levels with increased residence times. The area under the concentration versus time curve up to the last measured point in time (AUC_0-t) values of RMP and RN were 4558 and 136,572 h∙nM, respectively. The maximum plasma concentration (C_max) values of RMP and RN were 2896 nM and 35,819 nM, respectively. Moreover, RDV presented an extensive distribution, and the lung, liver and kidney showed high levels of the parent drug and metabolites. The metabolic stabilities of RDV and RMP were also evaluated using lung, liver, and kidney microsomes. RDV showed higher clearances in the liver and kidney than in the lung, with intrinsic clearance (CL_int) values of 1740, 1253, and 127 mL/(min∙g microsomal protein), respectively.

Clinical studies assessing the efficacy, effectiveness and safety of remdesivir in management of COVID-19: A scoping review

AIMS

Remdesivir is 1 of the repurposed drugs under investigation to treat patients with COVID-19. Clinicians and decision-makers need a summary of the most recent evidence. This scoping review maps the evidence on the efficacy, effectiveness and safety of remdesivir for patients with COVID-19, up to 14 September 2020.

METHODS

Our scoping review searched Pubmed, Embase (Ovid), Scopus and 17 primary trial registries for empirical publications or active registered clinical trials for data on the efficacy, effectiveness, or safety of remdesivir for COVID-19 or SARS-CoV-2. We conducted a narrative synthesis of the included publications.

RESULTS

Seventeen empirical studies and 23 clinical trial registrations (n = 40) accumulated 46 508 participants. We found 4 published randomized-controlled trials accumulating 2293 patients. Two trials reported shorter median recovery time and better clinical status among patients who received remdesivir compared with the control groups. Observational studies report an association between remdesivir treatment and decreased mortality, as well as increased survival. The most common adverse reaction was hepatic impairment, although the trials reported a similar proportion of adverse events in the intervention and control groups.

CONCLUSION

Remdesivir might shorten the time to clinical improvement among hospitalized adults with severe COVID-19. Trial data report a similar proportion of adverse events in treated and control groups. The results of the 23 registered active trials, including more than 30 000 participants, will shed light on the efficacy and safety of the antiviral. The findings of the remaining clinical trials expected to report results in 2020 will allow a quantitative synthesis of available evidence.

Antiviral effects of ergosterol peroxide in a pig model of porcine deltacoronavirus (PDCoV) infection involves modulation of apoptosis and tight junction in the small intestine

Porcine deltacoronavirus (PDCoV) is a newly discovered swine enteropathogenic coronavirus with worldwide distribution. However, efficient strategies to prevent or treat the infection remain elusive. Our in vitro study revealed that ergosterol peroxide (EP) from the mushroom Cryptoporus volvatus has efficient anti-PDCoV properties. The aim of this study is to evaluate the potential of EP as a treatment for PDCoV in vivo and elucidate the possible mechanisms. Seven-day-old piglets were infected with PDCoV by oral administration in the presence or absence of EP. Piglets infected with PDCoV were most affected, whereas administration of EP reduced diarrhea incidence, alleviated intestinal lesion, and decreased viral load in feces and tissues. EP reduced PDCoV-induced apoptosis and enhanced tight junction protein expressions in the small intestine, maintaining the integrity of the intestinal barrier. EP showed immunomodulatory effect by suppressing PDCoV-induced pro-inflammatory cytokines and the activation of IκBα and NF-κB p65, and upregulating IFN-I expression. Knockdown of p38 inhibited PDCoV replication and alleviated PDCoV-induced apoptosis, implying that EP inhibited PDCoV replication and alleviated PDCoV-induced apoptosis via p38/MAPK signaling pathway. Collectively, ergosterol peroxide can protect piglets from PDCoV, revealing the potential of EP for development as a promising strategy for treating and controlling the infection of PDCoV.

Drug Repurposing: A Strategy for Discovering Inhibitors against Emerging Viral Infections

BACKGROUND

Viral diseases are responsible for several deaths around the world. Over the past few years, the world has seen several outbreaks caused by viral diseases that, for a long time, seemed to possess no risk. These are diseases that have been forgotten for a long time and, until nowadays, there are no approved drugs or vaccines, leading the pharmaceutical industry and several research groups to run out of time in the search for new pharmacological treatments or prevention methods. In this context, drug repurposing proves to be a fast and economically viable technique, considering the fact that it uses drugs that have a well-established safety profile. Thus, in this review, we present the main advances in drug repurposing and their benefit for searching new treatments against emerging viral diseases.

METHODS

We conducted a search in the bibliographic databases (Science Direct, Bentham Science, PubMed, Springer, ACS Publisher, Wiley, and NIH's COVID-19 Portfolio) using the keywords "drug repurposing", "emerging viral infections" and each of the diseases reported here (CoV; ZIKV; DENV; CHIKV; EBOV and MARV) as an inclusion/exclusion criterion. A subjective analysis was performed regarding the quality of the works for inclusion in this manuscript. Thus, the selected works were those that presented drugs repositioned against the emerging viral diseases presented here by means of computational, high-throughput screening or phenotype-based strategies, with no time limit and of relevant scientific value.

RESULTS

291 papers were selected, 24 of which were CHIKV; 52 for ZIKV; 43 for DENV; 35 for EBOV; 10 for MARV; and 56 for CoV and the rest (72 papers) related to the drugs repurposing and emerging viral diseases. Among CoV-related articles, most were published in 2020 (31 papers), updating the current topic. Besides, between the years 2003 - 2005, 10 articles were created, and from 2011 - 2015, there were 7 articles, portraying the outbreaks that occurred at that time. For ZIKV, similar to CoV, most publications were during the period of outbreaks between the years 2016 - 2017 (23 articles). Similarly, most CHIKV (13 papers) and DENV (14 papers) publications occur at the same time interval. For EBOV (13 papers) and MARV (4 papers), they were between the years 2015 - 2016. Through this review, several drugs were highlighted that can be evolved in vivo and clinical trials as possible used against these pathogens showed that remdesivir represent potential treatments against CoV. Furthermore, ribavirin may also be a potential treatment against CHIKV; sofosbuvir against ZIKV; celgosivir against DENV, and favipiravir against EBOV and MARV, representing new hopes against these pathogens.

CONCLUSION

The conclusions of this review manuscript show the potential of the drug repurposing strategy in the discovery of new pharmaceutical products, as from this approach, drugs could be used against emerging viral diseases. Thus, this strategy deserves more attention among research groups and is a promising approach to the discovery of new drugs against emerging viral diseases and also other diseases.