Effect of chloroquine on the growth of animal viruses

Emerging COVID-19 variants and their impact on SARS-CoV-2 diagnosis, therapeutics and vaccines

The emergence of novel and evolving variants of SARS-CoV-2 has fostered the need for change in the form of newer and more adaptive diagnostic methods for the detection of SARS-CoV-2 infections. On the other hand, developing rapid and sensitive diagnostic technologies is now more challenging due to emerging variants and varying symptoms exhibited among the infected individuals. In addition to this, vaccines remain the major mainstay of prevention and protection against infection. Novel vaccines and drugs are constantly being developed to unleash an immune response for the robust targeting of SARS-CoV-2 and its associated variants. In this review, we provide an updated perspective on the current challenges posed by the emergence of novel SARS-CoV-2 mutants/variants and the evolution of diagnostic techniques to enable their detection. In addition, we also discuss the development, formulation, working mechanisms, advantages, and drawbacks of some of the most used vaccines/therapeutic drugs and their subsequent immunological impact.Key messageThe emergence of novel variants of the SARS-CoV-2 in the past couple of months, highlights one of the primary challenges in the diagnostics, treatment, as well as vaccine development against the virus.Advancements in SARS-CoV-2 detection include nucleic acid based, antigen and immuno- assay-based and antibody-based detection methodologies for efficient, robust, and quick testing; while advancements in COVID-19 preventive and therapeutic strategies include novel antiviral and immunomodulatory drugs and SARS-CoV-2 targeted vaccines.The varied COVID-19 vaccine platforms and the immune responses induced by each one of them as well as their ability to battle post-vaccination infections have all been discussed in this review.

Lesión renal aguda en COVID-19: puesta al día y revisión de la literatura

Los coronavirus humanos son virus que se asocian a varias patologías respiratorias como el síndrome respiratorio agudo severo y el síndrome respiratorio del Medio Oriente. Esto ha puesto a esta familia de virus en el centro de atención de la comunidad científica debido a la alta patogenicidad en humanos, especialmente ahora con la nueva pandemia por la enfermedad por coronavirus del 2019 (COVID-19). La COVID-19 se manifiesta principalmente como enfermedad respiratoria aguda con compromiso respiratorio bajo, pero puede afectar múltiples órganos como lo es el riñón, lo cual a conlleva a peores desenlaces. En este manuscrito revisaremos el compromiso renal por los diferentes coronavirus, en especial en la COVID-19, al igual que las terapias que juegan algún papel en el tratamiento de esta.

Efficacy of chloroquine and hydroxychloroquine for the treatment of hospitalized COVID-19 patients: a meta-analysis

Aims: To evaluate the efficacy and safety of hydroxychloroquine/chloroquine, with or without azithromycin, in treating hospitalized COVID-19 patients. Materials & methods: Data from randomized and observational studies were included in a random-effects meta-analysis. Primary outcomes included time to negative conversion of SARS-CoV-2 tests, length of stay, mortality, incidence of mechanical ventilation, time to normalization of body temperature, incidence of adverse events and incidence of QT prolongations. Results: Fifty-one studies (n = 61,221) were included. Hydroxychloroquine/chloroquine showed no efficacy in all primary efficacy outcomes, but was associated with increased odds of QT prolongations. Conclusion: Due to a lack of efficacy and increased odds of cardiac adverse events, hydroxychloroquine/chloroquine should not be used for treating hospitalized COVID-19 patients.

Antivirals against the Chikungunya Virus

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that has re-emerged in recent decades, causing large-scale epidemics in many parts of the world. CHIKV infection leads to a febrile disease known as chikungunya fever (CHIKF), which is characterised by severe joint pain and myalgia. As many patients develop a painful chronic stage and neither antiviral drugs nor vaccines are available, the development of a potent CHIKV inhibiting drug is crucial for CHIKF treatment. A comprehensive summary of current antiviral research and development of small-molecule inhibitor against CHIKV is presented in this review. We highlight different approaches used for the identification of such compounds and further discuss the identification and application of promising viral and host targets.

Anti-malarial Drugs are Not Created Equal for SARS-CoV-2 Treatment: A Computational Analysis Evidence

BACKGROUND

The evolution of the pandemic has burdened the national healthcare systems worldwide and at present, there is no preferred antiviral treatment for COVID-19. Recently, the SARS-Cov-2 protease structure was released that may be exploited in in-silico studies in order to conduct molecular docking analysis.

METHODS

In particular, we compared the binding of twoantimalarial drugs, already in use, (i.e. chloroquine and hydroxychloroquine), which showed some potential clinical effects on COVID-19 patients, using ritonavir, lopinavir and darunavir as positive control tree antiviral recognized compounds.

RESULTS

Our results showed that hydroxychloroquine but not chloroquine exhibited a significant binding activity to the main protease similar to that possessed by protease inhibitors tested for other viral infections.

CONCLUSION

Our data suggest that hydroxychloroquine may exert additional direct antiviral activity compared to chloroquine. In the absence of clinical studies comparing the efficacy of these two compounds, hydroxychloroquine may offer additional effects and may be considered as the first choice.

The Rise and Fall of Chloroquine/Hydroxychloroquine as Compassionate Therapy of COVID-19

The emergence and rapid spread of novel coronavirus disease (COVID-19) has posed a serious challenge to global public health in 2020. The speed of this viral spread together with the high mortality rate has caused an unprecedented public health crisis. With no antivirals or vaccines available for the treatment of COVID-19, the medical community is presently exploring repositioning of clinically approved drugs for COVID-19. Chloroquine (CQ) and hydroxychloroquine (HCQ) have emerged as potential candidates for repositioning as anti-COVID-19 therapeutics and have received FDA authorization for compassionate use in COVID-19 patients. On March 28, 2020, the U.S. Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for HCQ in the treatment of COVID-19. However, it was later revoked by the FDA on June 15, 2020, after analyzing the emerging scientific data from ongoing clinical trials. Similarly, the World Health Organization (WHO) also conducted a Solidarity trial of chloroquine, hydroxychloroquine, remdesivir, lopinavir, and ritonavir. However, on May 23, 2020, the executive body of the "Solidarity trial" decided to put a temporary hold on the HCQ trial. On June 17, 2020, the WHO abruptly stopped the Solidarity trial of HCQ. The current review strives to examine the basis of compassionate use of CQ and HCQ for the treatment of COVID-19 in terms of literature evidence, establishing the antiviral efficacy of these drugs against corona and related viruses. Furthermore, the review presents a critical analysis of the clinical trial findings and also provides an insight into the dynamically changing decision on the authorization and withdrawal of HCQ as anti-COVID-19 therapy by the U.S. FDA and the WHO. Ultimately, our study necessitates an evidenced-based treatment protocol to confront the ongoing COVID-19 pandemic and not the mere observational study that mislead the public healthcare system, which paralyzes the entire world.

Inhibition of Chikungunya Virus Infection by 4-Hydroxy-1-Methyl-3-(3-morpholinopropanoyl)quinoline-2(1H)-one (QVIR) Targeting nsP2 and E2 Proteins

The re-emergence of Chikungunya virus (CHIKV) infection in humans with no approved antiviral therapies or vaccines is one of the major problems with global significance. In the present investigation, we screened 80 in-house quinoline derivatives for their anti-CHIKV activity by computational techniques and found 4-hydroxy-1-methyl-3-(3-morpholinopropanoyl)quinoline-2(1H)-one (QVIR) to have potential binding affinities with CHIKV nsP2 and E2 glycoproteins. QVIR was evaluated in vitro for its anti-CHIKV potential. QVIR showed strong inhibition of CHIKV infection with an EC₅₀ (50% effective concentration) value of 2.2 ± 0.49 μM without significant cytotoxicity (CC₅₀ > 200 μM) and was chosen for further elucidation of its antiviral mechanism. The infectious viral particle formation was abolished by approximately 72% at a QVIR concentration of 20 μM during infection in the BHK-21 cell line, and the CHIKV RNA synthesis was diminished by 84% for nsP2 as well as 74% for E2, whereas the levels of viral proteins were decreased by 69.9% for nsP2 and 53.9% for E2. Flow cytometry analysis confirmed a huge decline in the expression of viral nsP2 and E2 proteins by 71.84 and 67.7%, respectively. Time of addition experiments indicated that QVIR inhibited viral infection at early and late stages of viral replication cycle, and the optimal inhibition was observed at 16 h post infection. The present study advocates for the first time that QVIR acts as a substantial and potent inhibitor against CHIKV and might be as an auspicious novel drug candidate for the development of therapeutic agents against CHIKV infections.

Evidence for Chloroquine/Hydroxychloroquine in the Treatment of COVID-19

INTRODUCTION

Given the current lack of an approved and effective treatment or vaccine for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), repositioning old drugs for use as an antiviral treatment is an interesting strategy because knowledge about these drugs' safety profile, posology, and drug interactions is already known. Chloroquine and hydroxychloroquine, widely used as antimalarial and autoimmune disease drugs, have recently been reported as a potential broad-spectrum antiviral drug.

BACKGROUND

The in vitro antiviral activity of chloroquine has been identified since the late 1960s. However, antiviral mechanisms of chloroquine remain speculative. Several clinical trials have been conducted to test the efficacy and safety of chloroquine or hydroxychloroquine in the treatment of COVID-19-associated pneumonia. The quality of the studies and the outcomes are evaluated in this systematic review and meta-analysis.

REVIEW RESULTS

Literature review revealed 23 clinical studies. Only 9 of 23 studies were randomized controlled trials. Of nine randomized controlled trials, only study by Skipper et al. was deemed to be at low risk of bias. All studies evaluated variedwith different outcomes. Mechanical ventilation and virological clearance were the only common outcomes evaluated in more than two studies. Virological clearance odds ratio (OR) was 1.25 (95% confidence interval [CI] of 0.57-2.73; Chi2 = 0.83; I2 = 0%). GRADE quality of evidence was downgraded by three levels to very low due to concerns about the risk of bias, inconsistency, and imprecision. For mechanical ventilation, OR was 1.09 (95% CI 0.80-1.50; Chi2 = 0; I2 = 0). GRADE quality of evidence was downgraded by two levels to low due to concerns about the risk of bias and imprecision. There was no statistically significant difference between the groups for these two outcomes.

CONCLUSION

As per the available evidence, based on our review, we conclude that hydroxychloroquine/chloroquine has not shown to be beneficial when used for the treatment of patients with COVID-19 pneumonia.

HOW TO CITE THIS ARTICLE

Shetty RM, Namachivayam A. Evidence for Chloroquine/Hydroxychloroquine in the Treatment of COVID-19. Indian J Crit Care Med 2021;25(4):441-452.

Insights of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) pandemic: a current review

COVID-19, a pandemic of the 21st century caused by novel coronavirus SARS-CoV-2 was originated from China and shallowed world economy and human resource. The medical cures via herbal treatments, antiviral drugs, and vaccines still in progress, and studying rigorously. SARS-CoV-2 is more virulent than its ancestors due to evolution in the spike protein(s), mediates viral attachment to the host's membranes. The SARS-CoV-2 receptor-binding spike domain associates itself with human angiotensin-converting enzyme 2 (ACE-2) receptors. It causes respiratory ailments with irregularities in the hepatic, nervous, and gastrointestinal systems, as reported in humans suffering from COVID-19 and reviewed in the present article. There are several approaches, have been put forward by many countries under the world health organization (WHO) recommendations and some trial drugs were introduced for possible treatment of COVID-19, such as Lopinavir or Ritonavir, Arbidol, Chloroquine (CQ), Hydroxychloroquine (HCQ) and most important Remdesivir including other like Tocilizumab, Oritavancin, Chlorpromazine, Azithromycin, Baricitinib, etc. RT-PCR is the only and early detection test available besides the rapid test kit (serodiagnosis) used by a few countries due to unreasonable causes. Development of vaccine by several leader of pharmaceutical groups still under trial or waiting for approval for mass inoculation. Management strategies have been evolved by the recommendations of WHO, specifically important to control COVID-19 situations, in the pandemic era. This review will provide a comprehensive collection of studies to support future research and enhancement in our wisdom to combat COVID-19 pandemic and to serve humanity.

Chloroquine and hydroxychloroquine in the treatment of COVID-19: the never-ending story

Abstract

The anti-malarial drugs chloroquine (CQ) and hydroxychloroquine (HCQ) have been suggested as promising agents against the new coronavirus SARS-CoV-2 that induces COVID-19 and as a possible therapy for shortening the duration of the viral disease. The antiviral effects of CQ and HCQ have been demonstrated in vitro due to their ability to block viruses like coronavirus SARS in cell culture. CQ and HCQ have been proposed to reduce immune reactions to infectious agents, inhibit pneumonia exacerbation, and improve lung imaging investigations. CQ analogs have also revealed the anti-inflammatory and immunomodulatory effects in treating viral infections and related ailments. There was, moreover, convincing evidence from early trials in China about the efficacy of CQ and HCQ in the anti-COVID-19 procedure. Since then, research and studies have been massive to ascertain these drugs’ efficacy and safety in treating the viral disease. In the present review, we construct a synopsis of the main properties and current data concerning the metabolism of CQ/HCQ, which were the basis of assessing their potential therapeutic roles against the new coronavirus infection. The effective role of QC and HCQ in the prophylaxis and therapy of COVID-19 infection is discussed in light of the latest international medical-scientific research results.

Key points

• Data concerning metabolism and properties of CQ/HCQ are discussed.

• The efficacy of CQ/HCQ against COVID-19 has been the subject of contradictory results.

• CQ/HCQ has little or no effect in reducing mortality in SARS-CoV-2-affected patients.

A Narrative Review of Emerging Therapeutics for COVID-19

The novel severe acute respiratory syndrome coronavirus 2, the causal agent of coronavirus disease 2019 (COVID-19), quickly spread around the world, resulting in the most aggressive pandemic experienced in more than 100 years. Research on targeted therapies and vaccines has been initiated on an unprecedented scale and speed but will take months and even years to come to fruition. Meanwhile, the efficacy of emerging therapeutics for use in treating COVID-19 is feverishly being investigated to identify the best available treatment options for dealing with the current wave of disease. This review of publications with a "treatment" tag through June 29, 2020 in the National Library of Medicine's LitCovid literature hub, provides frontline clinicians with a pragmatic summary of the current state of the rapidly evolving evidence supporting emerging candidate therapeutics for COVID-19. Two main categories of pharmaceutical therapeutics are showing promise: those with antiviral activity directly addressing infection and those that counteract the inflammatory cytokine storm induced by severe disease. Preliminary results suggest that other approaches such as convalescent plasma therapy and lung radiation therapy may have some efficacy. The current clinical evidence for potential treatments is preliminary-often small retrospective series or early results of randomized trials-and the science is evolving rapidly. The long-term results from large, well-designed randomized controlled trials will provide definitive evidence for therapeutic effectiveness and are likely months away. The trial landscape for promising therapies is described.

The endosomal lipid bis(monoacylglycero) phosphate as a potential key player in the mechanism of action of chloroquine against SARS-COV-2 and other enveloped viruses hijacking the endocytic pathway

The anti-malarial drug Chloroquine (CQ) and its derivative hydroxychloroquine have shown antiviral activities in vitro against many viruses, including coronaviruses, dengue virus and the biosafety level 4 Nipah and Hendra paramyxoviruses. The in vivo efficacy of CQ in the treatment of COVID-19 is currently a matter of debate. CQ is a lysosomotrophic compound that accumulates in lysosomes, as well as in food vacuoles of Plasmodium falciparum. In the treatment of malaria, CQ impairs the digestion and growth of the parasite by increasing the pH of the food vacuole. Similarly, it is assumed that the antiviral effects of CQ results from the increase of lysosome pH and the inhibition of acidic proteases involved in the maturation of virus fusion protein. CQ has however other effects, among which phospholipidosis, characterized by the accumulation of multivesicular bodies within the cell. The increase in phospholipid species particularly concerns bis(monoacylglycero)phosphate (BMP), a specific lipid of late endosomes involved in vesicular trafficking and pH-dependent vesicle budding. It was shown previously that drugs like progesterone, the cationic amphiphile U18666A and the phospholipase inhibitor methyl arachidonyl fluoro phosphonate (MAFP) induce the accumulation of BMP in THP-1 cells and decrease cell infection by human immunodeficiency virus. HIV viral particles were found to be retained into large endosomal-type vesicles, preventing virus spreading. Since BMP was also reported to favour virus entry through hijacking of the endocytic pathway, we propose here that BMP could play a dual role in viral infection, with its antiviral effects triggered by lysosomotropic drugs like CQ.

COVID-19 therapy: What weapons do we bring into battle?

Urgent treatments, in any modality, to fight SARS-CoV-2 infections are desired by society in general, by health professionals, by Estate-leaders and, mainly, by the scientific community, because one thing is certain amidst the numerous uncertainties regarding COVID-19: knowledge is the means to discover or to produce an effective treatment against this global disease. Scientists from several areas in the world are still committed to this mission, as shown by the accelerated scientific production in the first half of 2020 with over 25,000 published articles related to the new coronavirus. Three great lines of publications related to COVID-19 were identified for building this article: The first refers to knowledge production concerning the virus and pathophysiology of COVID-19; the second regards efforts to produce vaccines against SARS-CoV-2 at a speed without precedent in the history of science; the third comprehends the attempts to find a marketed drug that can be used to treat COVID-19 by drug repurposing. In this review, the drugs that have been repurposed so far are grouped according to their chemical class. Their structures will be presented to provide better understanding of their structural similarities and possible correlations with mechanisms of actions. This can help identifying anti-SARS-CoV-2 promising therapeutic agents.

Will Hydroxychloroquine Still Be a Game-Changer for COVID-19 by Combining Azithromycin?

Recent small-scale clinical trials have shown promising results in the use of hydroxychloroquine, an FDA approved anti-malaria drug, for the treatment of COVID-19. However, large scale, randomized and double-blind clinical trials are needed to confirm the safety and efficacy of hydroxychloroquine in COVID-19 patients. Here, we review the progress of using hydroxychloroquine or chloroquine as anti-viral agents, failed clinical trials of chloroquine in treatment of dengue virus and influenza infection, and especially the mechanism of azithromycin in inhibiting viral replication, so as to shed light on the ongoing clinical trials and further researches of hydroxychloroquine on SARS-CoV-2 infected patients.

Chloroquine and hydroxychloroquine as a repurposed agent against COVID-19: a narrative review

The predicament arising from the coronavirus disease 2019 (COVID-19) pandemic has become one of the most significant modern public health challenges. Despite uncertainties in the viral determinants and pathogenesis, it is crucial to accurately inspect all available evidence to construct accurate clinical guidelines for optimised patient care. This study aims to discuss the available evidence for the use of chloroquine (CQ) and hydroxychloroquine (HCQ) against COVID-19. Early in vitro studies of CQ/HCQ against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are convincing. But contradictory evidence exists on the clinical use of CQ/HCQ, either alone or in combination with azithromycin. As of now, there is no compelling clinical evidence on CQ, HCQ, and azithromycin in COVID-19 and the available evidence is limited to methodologically inferior non-randomised studies. Studies have also shown detrimental drug reactions to CQ and ‘HCQ plus azithromycin’, mainly cardiac side effects in hospitalised patients with coexisting cardiovascular comorbidities. Therefore, we recommend that physicians avoid high doses and exercise extreme caution in the compassionate use of CQ/HCQ, either alone or in combination with other antiviral drugs.

Potential new treatment strategies for COVID-19: is there a role for bromhexine as add-on therapy?

Of huge importance now is to provide a fast, cost-effective, safe, and immediately available pharmaceutical solution to curb the rapid global spread of SARS-CoV-2. Recent publications on SARS-CoV-2 have brought attention to the possible benefit of chloroquine in the treatment of patients infected by SARS-CoV-2. Whether chloroquine can treat SARS-CoV-2 alone and also work as a prophylactic is doubtful. An effective prophylactic medication to prevent viral entry has to contain, at least, either a protease inhibitor or a competitive virus ACE2-binding inhibitor. Using bromhexine at a dosage that selectively inhibits TMPRSS2 and, in so doing, inhibits TMPRSS2-specific viral entry is likely to be effective against SARS-CoV-2. We propose the use of bromhexine as a prophylactic and treatment. We encourage the scientific community to assess bromhexine clinically as a prophylactic and curative treatment. If proven to be effective, this would allow a rapid, accessible, and cost-effective application worldwide.

Repositioning chloroquine as antiviral prophylaxis against COVID-19: potential and challenges

The Coronavirus Disease 2019 (COVID-19) pandemic is advancing globally, and pharmaceutical prophylaxis is one solution. Here, we propose repositioning chloroquine (CQ) as prophylaxis against COVID-19. CQ blocks viral attachment and entry to host cells and demonstrates efficacy against a variety of viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19. Furthermore, CQ is safe, inexpensive, and available. Here, we review the antiviral mechanisms of CQ, its in vitro activity against coronaviruses, its pharmacokinetics (PK) and adverse effects, and why it could be more efficacious as a prophylactic rather than as a therapeutic, given the infection dynamics of SARS-CoV-2. We propose two prophylactic regimens based on efficacy and risk considerations. Although it is largely preclinical data that suggest the potential of CQ, properly planned prophylactic trials and further research are urgently needed.

Emergence of novel coronavirus and progress toward treatment and vaccine

In late December 2019, a group of patients was observed with pneumonia‐like symptoms that were linked with a wet market in Wuhan, China. The patients were found to have a novel coronavirus genetically related to a bat coronavirus that was termed SARS‐CoV‐2. The virus gradually spread worldwide and was declared a pandemic by WHO. Scientists have started trials on potential preventive and treatment options. Currently, there is no specific approved treatment for SARS‐CoV‐2, and various clinical trials are underway to explore better treatments. Some previously approved antiviral and other drugs have shown some in vitro activity. Here we summarize the fight against this novel coronavirus with particular focus on the different treatment options and clinical trials exploring treatment as well as work done toward development of vaccines.

Battling COVID-19: using old weapons for a new enemy

Coronavirus disease-19 (COVID-19) has reached pandemic proportions. Most of the drugs that are being tried for the treatment have not been evaluated in any randomized controlled trials. The purpose of this review was to summarize the in-vitro and in-vivo efficacy of these drugs on Severe Acute Respiratory Syndrome (SARS-CoV-2) and related viruses (SARS and Middle East Respiratory Syndrome) and evaluate their potential for re-purposing them in the management of COVID-19.

Contentious issues and evolving concepts in the clinical presentation and management of patients with COVID-19 infectionwith reference to use of therapeutic and other drugs used in Co-morbid diseases (Hypertension, diabetes etc)

BACKGROUND AND AIMS

Multiple issues in management of COVID have emerged, but confusion persists regarding rational interpretation. Aim of this brief review is to review these issues based on current literature.

METHODS

This is a narrative review with Pubmed and Google Scholar search till 23 March 2020. Search terms were, COVID-19, treatment of coronavirus, COVID 19 and following terms; chloroquine, hydroxychloroquine, ibuprofen, ACE-inhibitors or angiotensin receptor blockers, cardiovascular disease, diarrhoea, liver, testis and gastrointestinal disease.

RESULTS

We discuss evidence regarding role of chloroquine and hydroxychloroquine in treatment and prophylaxis, use of inhibitors of the renin angiotensin system, safety of ibuprofen, unusual clinical features like gastrointestinal symptoms and interpretation of tests for cardiac enzymes and biomarkers.

CONCLUSIONS

While our conclusions on management of COVID-19 patients with co-morbidities are based on current evidence, however, data is limited and there is immediate need for fast track research.

Therapeutic use of chloroquine and hydroxychloroquine in COVID-19 and other viral infections: A narrative review

The rapidly spreading Coronavirus Disease (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2), represents an unprecedented serious challenge to the global public health community. The extremely rapid international spread of the disease with significant morbidity and mortality made finding possible therapeutic interventions a global priority. While approved specific antiviral drugs against SARS-CoV-2 are still lacking, a large number of existing drugs are being explored as a possible treatment for COVID-19 infected patients. Recent publications have re-examined the use of Chloroquine (CQ) and/or Hydroxychloroquine (HCQ) as a potential therapeutic option for these patients. In an attempt to explore the evidence that supports their use in COVID-19 patients, we comprehensively reviewed the previous studies which used CQ or HCQ as an antiviral treatment. Both CQ and HCQ demonstrated promising in vitro results, however, such data have not yet been translated into meaningful in vivo studies. While few clinical trials have suggested some beneficial effects of CQ and HCQ in COVID-19 patients, most of the reported data are still preliminary. Given the current uncertainty, it is worth being mindful of the potential risks and strictly rationalise the use of these drugs in COVID-19 patients until further high quality randomized clinical trials are available to clarify their role in the treatment or prevention of COVID-19.

COVID-19: Older drugs for a novel disease-Chloroquine, hydroxychloroquine, and possible Pentoxifylline-set to start the second innings?

Currently no drug is approved for the prophylaxis and management of COVID 19. Lots of activities on vaccine and trials with drugs are underway. Some evidence have shown positive results using older established drug in the management of severe cases. We are also of same view and opinion to adopt some emergency measure by pharmacological intervention till a newer drug available in the market.

Of chloroquine and COVID-19

Recent publications have brought attention to the possible benefit of chloroquine, a broadly used antimalarial drug, in the treatment of patients infected by the novel emerged coronavirus (SARS-CoV-2). The scientific community should consider this information in light of previous experiments with chloroquine in the field of antiviral research.

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In vitro data suggest that chloroquine inhibits SARS Cov-2 replication.

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In past research, chloroquine has shown in vitro activity against many different viruses, but no benefit in animal models.

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Chloroquine has been proposed several times for the treatment of acute viral diseases in humans without success.

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The outcomes of some current clinical trials of chloroquine in China have been announced, without access to the data.

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Peer review of the results and an independent assessment of the potential benefit for patients are essential.

Biomimetic properties and estimated in vivo distribution of chloroquine and hydroxy-chloroquine enantiomers

Chloroquine and hydroxy-chloroquine already established as anti-malarial and lupus drugs have recently gained renewed attention in the fight against the Covid-19 pandemic. Bio-mimetic HPLC methods have been used to measure the protein and phospholipid binding of the racemic mixtures of the drugs. The tissue binding and volume of distribution of the enantiomers have been estimated. The enantiomers can be separated using Chiralpak AGP HPLC columns. From the α-1-acid-glycoprotein (AGP) binding, the lung tissue binding can be estimated for the enantiomers. The drugs have a large volume of distribution, showed strong and stereoselective glycoprotein binding, medium-strong phospholipid-binding indicating only moderate phospholipidotic potential, hERG inhibition and promiscuous binding. The drug efficiency of the compounds was estimated to be greater than 2 % which indicates a high level of free biophase concentration relative to dose. The biomimetic properties of the compounds support the well-known tolerability of the drugs.

The Use of Antimalarial Drugs against Viral Infection

In recent decades, drugs used to treat malaria infection have been shown to be beneficial for many other diseases, including viral infections. In particular, they have received special attention due to the lack of effective antiviral drugs against new emerging viruses (i.e., HIV, dengue virus, chikungunya virus, Ebola virus, etc.) or against classic infections due to drug-resistant viral strains (i.e., human cytomegalovirus). Here, we reviewed the in vitro/in vivo and clinical studies conducted to evaluate the antiviral activities of four classes of antimalarial drugs: Artemisinin derivatives, aryl-aminoalcohols, aminoquinolines, and antimicrobial drugs.

Perspectives on repositioning chloroquine and hydroxychloroquine for the treatment of Covid-19

Coronavirus disease 2019 (COVID-19) is now spreading as a pandemic ravaging the whole world. In the absence of a vaccine and an effective antiviral chemotherapy, there is currently an intense global interest in repositioning chloroquine (CQ) and its derivative hydroxychloroquine (HCQ) to combat the pandemic. CQ has been used for decades for the treatment and prophylaxis against malaria in endemic countries. It is readily available and has also been manufactured in these countries. CQ is cheap, stable under field conditions and has been well tolerated as an antimalarial. This experience could be adapted to deploy CQ or HCQ for prophylaxis or treatment of COVID19 if strong evidence could be generated for these uses. We believe that well-designed drug trials should be initiated in malaria-endemic countries, taking into account the local context of the epidemic and the capacity of the health system in combating it. In this paper, we are presenting the current status of evidence for using CQ and HCQ against COVID19.

Paradoxical Effect of Chloroquine Treatment in Enhancing Chikungunya Virus Infection

Since 2005, Chikungunya virus (CHIKV) re-emerged and caused numerous outbreaks in the world, and finally, was introduced into the Americas in 2013. The lack of CHIKV-specific therapies has led to the use of non-specific drugs. Chloroquine, which is commonly used to treat febrile illnesses in the tropics, has been shown to inhibit CHIKV replication in vitro. To assess the in vivo effect of chloroquine, two complementary studies were performed: (i) a prophylactic study in a non-human primate model (NHP); and (ii) a curative study "CuraChik", which was performed during the Reunion Island outbreak in 2006 in a human cohort. Clinical, biological, and immunological data were compared between treated and placebo groups. Acute CHIKV infection was exacerbated in NHPs treated with prophylactic administration of chloroquine. These NHPs displayed a higher viremia and slower viral clearance (p < 0.003). Magnitude of viremia was correlated to the type I IFN response (Rho = 0.8, p < 0.001) and severe lymphopenia (Rho = 0.8, p < 0.0001), while treatment led to a delay in both CHIKV-specific cellular and IgM responses (p < 0.02 and p = 0.04, respectively). In humans, chloroquine treatment did not affect viremia or clinical parameters during the acute stage of the disease (D1 to D14), but affected the levels of C-reactive Protein (CRP), IFNα, IL-6, and MCP1 over time (D1 to D16). Importantly, no positive effect could be detected on prevalence of persistent arthralgia at Day 300. Although inhibitory in vitro, chloroquine as a prophylactic treatment in NHPs enhances CHIKV replication and delays cellular and humoral response. In patients, curative chloroquine treatment during the acute phase decreases the levels of key cytokines, and thus may delay adaptive immune responses, as observed in NHPs, without any suppressive effect on peripheral viral load.

The medicinal chemistry of Chikungunya virus

Arthropod-borne viruses (arboviruses) are an important threat to human and animal health globally. Among these, zoonotic diseases account for billions of cases of human illness and millions of deaths every year, representing an increasing public health problem. Chikungunya virus belongs to the genus Alphavirus of the family Togariridae, and is transmitted mainly by the bite of female mosquitoes of the Aedes aegypti and/or A. albopictus species. The focus of this review will be on the medicinal chemistry of Chikungunya virus, including synthetic and natural products, as well as rationally designed compounds.

Antiviral activity of selected flavonoids against Chikungunya virus

This study focuses on the antiviral activity of selected flavonoids against the Chikungunya virus (CHIKV), a mosquito-transmitted virus that can cause incapacitating arthritis in infected individuals. Based on the results of screening on Vero cells, the tested compounds were evaluated further with various assays, including cytotoxicity assay, virus yield assay by quantitative reverse transcription polymerase chain reaction (qRT-PCR), virus RNA replication assay with a CHIKV replicon cell line, Western blotting, and quantitative immunofluorescence assay. Baicalein, fisetin, and quercetagetin displayed potent inhibition of CHIKV infection, with 50% inhibitory concentrations [IC50] of 1.891 μg/ml (6.997 μM), 8.444 μg/ml (29.5 μM), and 13.85 μg/ml (43.52 μM), respectively, and with minimal cytotoxicity. The time-of-addition studies and various antiviral assays demonstrated that baicalein and quercetagetin mainly inhibited CHIKV binding to the Vero cells and displayed potent activity against extracellular CHIKV particles. The qRT-PCR, immunofluorescence assay, and Western blot analyses indicated that each of these flavonoids affects CHIKV RNA production and viral protein expression. These data provide the first evidence of the intracellular anti-CHIKV activity of baicalein, fisetin, and quercetagetin.

Antiviral perspectives for chikungunya virus

Chikungunya virus (CHIKV) is a mosquito-borne pathogen that has a major health impact in humans and causes acute febrile illness in humans accompanied by joint pains and, in many cases, persistent arthralgia lasting for weeks to years. CHIKV reemerged in 2005-2006 in several parts of the Indian Ocean islands and India after a gap of 32 years, causing millions of cases. The re-emergence of CHIKV has also resulted in numerous outbreaks in several countries in the eastern hemisphere, with a threat to further expand in the near future. However, there is no vaccine against CHIKV infection licensed for human use, and therapy for CHIKV infection is still mainly limited to supportive care as antiviral agents are yet in different stages of testing or development. In this review we explore the different perspectives for chikungunya treatment and the effectiveness of these treatment regimens and discuss the scope for future directions.

Chikungunya virus: emerging targets and new opportunities for medicinal chemistry

Chikungunya virus is an emerging arbovirus that is widespread in tropical regions and is spreading quickly to temperate climates with recent epidemics in Africa and Asia and documented outbreaks in Europe and the Americas. It is having an increasingly major impact on humankind, with potentially life-threatening and debilitating arthritis. There is no treatment available, and only in the past 24 months have lead compounds for development as potential therapeutics been reported. This Perspective discusses the chikungunya virus as a significant, new emerging topic for medicinal chemistry, highlighting the key viral target proteins and their molecular functions that can be used in drug design, as well as the most important ongoing developments for anti-chikungunya virus research. It represents a complete picture of the current medicinal chemistry of chikungunya, supporting the development of chemotherapeutics through drug discovery and design targeting this virus.

Inhibition of chikungunya virus replication by harringtonine, a novel antiviral that suppresses viral protein expression

Chikungunya virus (CHIKV) is a mosquito-transmitted virus that has reemerged as a significant public health threat in the last decade. Since the 2005-2006 chikungunya fever epidemic in the Indian Ocean island of La Réunion, millions of people in more than 40 countries have been infected. Despite this, there is currently no antiviral treatment for chikungunya infection. In this study, an immunofluorescence-based screening platform was developed to identify potential inhibitors of CHIKV infection. A primary screen was performed using a highly purified natural product compound library, and 44 compounds exhibiting ≥70% inhibition of CHIKV infection were identified as positive hits. Among these, four were selected for dose-dependent inhibition assays to confirm their anti-CHIKV activity. Harringtonine, a cephalotaxine alkaloid, displayed potent inhibition of CHIKV infection (50% effective concentration [EC(50)] = 0.24 μM) with minimal cytotoxicity and was selected for elucidation of its antiviral mechanism. Time-of-addition studies, cotreatment assays, and direct transfection of viral genomic RNA indicated that harringtonine inhibited an early stage of the CHIKV replication cycle which occurred after viral entry into cells. In addition, quantitative reverse transcription-PCR (qRT-PCR) and Western blot analyses indicated that harringtonine affects CHIKV RNA production as well as viral protein expression. Treatment of harringtonine against Sindbis virus, a related alphavirus, suggested that harringtonine could inhibit other alphaviruses. This study suggests for the first time that harringtonine exerts its antiviral effects by inhibiting CHIKV viral protein synthesis.

Understanding the alphaviruses: recent research on important emerging pathogens and progress towards their control

The alphaviruses were amongst the first arboviruses to be isolated, characterized and assigned a taxonomic status. They are globally very widespread, infecting a large variety of terrestrial animals, insects and even fish, and circulate both in the sylvatic and urban/peri-urban environment, causing considerable human morbidity and mortality. Nevertheless, despite their obvious importance as pathogens, there are currently no effective antiviral drugs with which to treat humans or animals infected by any of these viruses. The EU-supported project-VIZIER (Comparative Structural Genomics of Viral Enzymes Involved in Replication, FP6 PROJECT: 2004-511960) was instigated with an ultimate view of contributing to the development of antiviral therapies for RNA viruses, including the alphaviruses [Coutard, B., Gorbalenya, A.E., Snijder, E.J., Leontovich, A.M., Poupon, A., De Lamballerie, X., Charrel, R., Gould, E.A., Gunther, S., Norder, H., Klempa, B., Bourhy, H., Rohayemj, J., L'hermite, E., Nordlund, P., Stuart, D.I., Owens, R.J., Grimes, J.M., Tuckerm, P.A., Bolognesi, M., Mattevi, A., Coll, M., Jones, T.A., Aqvist, J., Unger, T., Hilgenfeld, R., Bricogne, G., Neyts, J., La Colla, P., Puerstinger, G., Gonzalez, J.P., Leroy, E., Cambillau, C., Romette, J.L., Canard, B., 2008. The VIZIER project: preparedness against pathogenic RNA viruses. Antiviral Res. 78, 37-46]. This review highlights some of the major features of alphaviruses that have been investigated during recent years. After describing their classification, epidemiology and evolutionary history and the expanding geographic distribution of Chikungunya virus, we review progress in understanding the structure and function of alphavirus replicative enzymes achieved under the VIZIER programme and the development of new disease control strategies.

On chikungunya acute infection and chloroquine treatment

In recent issues, the efficacy of chloroquine (and the dosage that may be used) in the treatment of acute chikungunya infections was discussed. We have conducted a double-blind placebo-controlled randomized trial on the French Reunion Island (Indian Ocean), in which 27 patients received chloroquine and 27 patients received a placebo treatment. The chloroquine treatment consisted of 600 mg at day 1, 600 mg at days 2 and 3, and 300 mg at days 4 and 5. No significant difference between groups could be identified regarding the duration of febrile arthralgia or the decrease of viremia between day 1 and day 3. However, at day 200, patients who received chloroquine complained more frequently of arthralgia than those who received placebo (p < 0.01). In conclusion, our results suggest that there is currently no justification for the use of chloroquine to treat acute chikungunya infections.

Attenuation of murine coronavirus infection by ammonium chloride

Ammonium chloride at a concentration of 20 mM delayed by 4-5 hr the production of virus progeny in mouse L-2 cells infected at high multiplicity with mouse hepatitis virus (MHV). This delay was seen in the production of both intracellular and extracellular virus. However, the final titers were similar to those produced by MHV-infected cells maintained in normal medium. The manifestation of virus-induced cell fusion was similarly found to be delayed, but not otherwise decreased in severity, when ammonium chloride was present in the culture medium. Ammonium chloride caused similar delays in production of virus-specific, positive-sense RNAs and of viral polypeptides. The relative proportions and apparent molecular weights of viral RNAs and polypeptides were similar to those found in MHV-infected cells cultured in normal medium. In vitro translation of endogenously produced viral RNAs in cell extracts, prepared from MHV-infected cells, was not inhibited by ammonium chloride. Thus, ammonium chloride has no specific, inhibitory effect on viral protein synthesis. Ammonium chloride did not reduce the number of virus-infected cells in culture, as monitored by infectious center assay. Analysis of early events in MHV infection showed that ammonium chloride did not affect adsorption or internalization of MHV by L-2 cells. However, the subsequent eclipse phase, as monitored by decline in infectivity of internalized virus inoculum proceeded less efficiently in the presence of ammonium chloride. On the basis of the known inhibitory effects of ammonium chloride on lysosomal/endosomal functions, the results suggest an endosomal mechanism of MHV uncoating. Thus the primary effect of ammonium chloride on MHV infection of L-2 cells is to attenuate virus uncoating, thereby chronologically displacing all subsequent virus-encoded functions.

Membrane fusion mutants of Semliki Forest virus

Previous reports have indicated that the entry of Semliki Forest virus (SFV) into cells depends on a membrane fusion reaction catalyzed by the viral spike glycoproteins and triggered by the low pH prevailing in the endosomal compartment. In this study the in vitro pH-dependent fusion of SFV with nuclease-filled liposomes has been used to select for a new class of virus mutants that have a pH-conditional defect. The mutants obtained had a threshold for fusion of pH 5.5 as compared with the wild-type threshold of 6.2, when assayed by polykaryon formation, fusion with liposomes, or fusion at the plasma membrane. They were fully capable of infecting cells under standard infection conditions but were more sensitive to lysosomotropic agents that increase the pH in acidic vacuoles of the endocytic pathway. The mutants were, moreover, able to penetrate and infect baby hamster kidney-21 cells at 20 degrees C, indicating that the endosomes have a pH below 5.5. The results confirm the involvement of pH-triggered fusion in SFV entry, emphasize the central role played by acidic endosomal vacuoles in this reaction, shed further light on the mechanism of SFV inhibition by lysosomotropic weak bases, and demonstrate the usefulness of mutant viruses as biological pH probes of the endocytic pathway.

The uncoating of paramyxoviruses may not require a low pH mediated step

The effect of lysosomotropic agents, chloroquine and NH4Cl, on the replication of paramyxoviruses was compared with that on the other enveloped RNA viruses whose uncoating is known to be blocked by the agents. Under the conditions where vesicular stomatitis or influenza virus infection was strongly inhibited at an early step, the agents exhibited little inhibitory effect on the progress of infection by Newcastle disease virus and Sendai virus, allowing viral primary transcription to occur and neither inhibiting the virus production significantly nor reducing the number of infected cells. These results are incompatible with the previous report showing that paramyxovirus and the other enveloped RNA viruses may have in common an intracellular step sensitive to lysosomotropic agents (Miller and Lenard, Proc. Nat. Acad. Sci. USA 78, 3605-3609, 1981) and suggest that paramyxovirus uncoating may not require a low pH mediated lysosomal step.

Membrane fusion proteins of enveloped animal viruses

In a living cell membrane-bound compartments are continuously either separated or united through fusion reactions, and literally thousands of such reactions take place every minute. The formation of membrane vesicles from pre-existing membranes, and their fusion with specific acceptor membranes, constitute a prerequisite for the transport of most impermeant molecules and macromolecules into the cell by endocytosis, out of the cell by exocytosis, and between the cellular organelles (Palade, 1975; Silverstein, 1978; Evered & Collins, 1982). Less frequent, but equally crucial, are fusion events in fertilization, cell division, polykaryon formation, enucleation, etc. (for reviews see Poste & Nicholson, 1978). Although a great deal is known about the properties and consequences of individual forms of membrane fusion in cellular systems, and about fusion in artificial lipid membranes, the molecular basis for the reactions remain largely unclear.

Monensin inhibits Semliki Forest virus penetration into culture cells

The carboxylic ionophores monensin and nigericin, at concentrations higher than 10 and 6 muM, respectively, prevent the penetration of the Semliki Forest virus (SFV) genome into the cytosol of baby hamster kidney (BHK-21) cells and thereby inhibit viral replication. In the absence of inhibitors, the entry of SFV is known to proceed by adsorptive endocytosis in coated vesicles, followed by acid-triggered membrane fusion in intracellular vacuoles or lysosomes. The results show that binding of the virus to the cell surface, adsorptive endocytosis, and intracellular transport of viruses to the lysosomes are only marginally affected by the ionophores. No direct virucidal effect is observed, nor is the membrane fusion activity of the virus at low pH directly affected. Sequential addition of monensin and ammonium chloride (a non-related lysosomotropic inhibitor of SFV entry) indicates that both inhibitors affect the same step in the entry pathway. On the basis of these data and the known effects of carboxylic ionophores and lysosomotropic weak bases on cellular pH gradients, we conclude that monensin inhibits penetration by increasing the pH in endocytic vacuoles and lysosomes above pH 6, which is the pH threshold for the viral membrane fusion activity.

Uses of antibiotics in plant pathology and production

The dihydrochloride salt of (S,S)-1,2-bis(5-methoxy-2-benzimidazolyl)-1,2-ethandiol (A37536) inhibits the synthesis of lymphocytic choriomeningitis (LCM), Parana, and Pichinde viruses in L-929 cells. The compound has no direct inactivating effect on LCM virus nor does it affect the adsorption of LCM virus to L cells. The drug-cell interaction is slow. Maximal activity is observed only by exposing cells to the drug at least 8 h prior to LCM virus infection, or by concomitant drug treatment and infection at a low multiplicity. Addition of serum-free media to L cells after LCM virus infection diminishes the activity of A37536. Whereas A37536 exhibits its antiviral activity at concentrations that have little or no effect on L cell division rate, a marked change can be noted in the cell's sensitivity to lysis by standard trypsin dispersal procedures. A37536 has no specific antiviral activity in LCM virus-infected BHK, HeLa, or Vero cells. All of the four tested derivatives of A37536 showed antiviral activity against LCM virus but only at concentrations that reduced the growth rate or were toxic to L cells.