key: cord-304295-3mpymd8a
authors: Khan, Muhammad Muzamil; Noor, Amna; Madni*, Asadullah; Shafiq, Mudassir
title: Emergence of novel coronavirus and progress toward treatment and vaccine
date: 2020-06-04
journal: Rev Med Virol
DOI: 10.1002/rmv.2116
sha: 
doc_id: 304295
cord_uid: 3mpymd8a

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.

Coronaviruses are a form of positive-strand non-segmented RNA viruses distributed among birds, mammals and humans that cause respiratory and neurological illnesses. 1 There are six different types that can cause disease among humans. Four of these (HKU1, 229E, NL63 and OC43) cause only the common cold in patients, 2 5 Due to the broad genetic variation and diversity of coronaviruses and higher chances of animal to human spread they are likely to emerge periodically in future. 6 During December 2019, an outbreak of pneumonia-like symptoms occurred in patients that were linked to the seafood market in Wuhan China. 7 Investigation identified a new strain of coronavirus called SARS-CoV-2. 8 The detection of this novel coronavirus is key to confirm the cases and proceed to treatment. In an early method for detecting SARS-CoV-2, the samples from bronchoalveolar-lavage fluids were collected, centrifuged to remove debris and inoculated onto human epithelial cells of airway origin. 9 About 20 000 sequences from each sample were obtained and genome matches showed more than 85% identity with SARS-like betacornavirus. Results were also obtained from real-time PCR, and isolated viruses were named SARS-CoV-2. 8 To further characterize SARS-CoV-2, the de-novo sequence was obtained by using nanopore sequencing and Illumina methods. The airway epithelial cell cultures were suitable for visualization and identification of the novel coronavirus. 9 check efficacy against this virus. The possible options include nucleoside analogs, interferon that can act as immune modulators and approved antimalarials having antiviral activities such as chloroquine and hydroxychloroquine.

The nucleoside analogs such as ribavirin, favipiravir, galidesivir and remdesivir target RNA polymerase and block the synthesis of viral RNA. 10 Favipiravir was effectively used against influenza and has the potential to inhibit viral RNA synthesis and a new study also supports its activity against SARS-CoV-2. 11 Different clinical trials are underway where patients are being recruited to evaluate the efficacy of a combination of favipiravir and interferon-α 12 and a combination of favipiravir and baloxavir marboxil is being evaluated. 13 Ribavirin is a guanine derivative antiviral drug approved for the treatment of HCV and RSV, but it causes anemia at higher doses that limit its use and its efficacy against coronavirus is uncertain. 14 Remdesivir is an adenine derivative antiviral drug. It has activity against a variety of viral strains such as SARS and MERS and a recent study also supports its activity against SARS-CoV-2. 11 A recent patient in US with SARS-CoV-2 has shown recovery with intravenous administration of remdesivir. 15 Recently, Phase-III clinical trials have been started in USA to evaluate the efficacy of IV remdesivir as 200 mg OD or 100 mg OD for 9 days. 16 A recent RCT apparently reported no significant efficacy, but we await the published findings. 

Small molecular weight drugs such as chloroquine have shown inhibitory effects against SARS-CoV-2 (EC50 = 1.14 μM in Vero E6 cells) and is under evaluation in open-label trials.. 15 Chloroquine (CQ) is a recognized anti-malarial drug but also has antiviral activity. The antiviral activity of chloroquine was first noticed in the late 1960s. 21 Chloroquine and its analog hydroxychloroquine both have inhibitory effects against various viruses including SARS, 22 enterovirus 23 and Zika virus. 24 Chloroquine inhibits the virus by increasing endosomal pH and so reducing viral cell fusion and also interferes with cellular receptor glycosylation. 25 The EC90 value of chloroquine against SARS-CoV-2 is 6.90 μM that can be achieved with administration of 500 mg dose. 26 Remdesivir and chloroquine have shown activity in in vitro studies and can easily be tested in patients with SARS-CoV-2. 15 In another recent study, Gao et al found that chloroquine phosphate reduced the symptoms of pneumonia in SARS-CoV-2 patients and shortening the duration of disease. 27 The guidelines for the treatment of SARS-CoV-2 were revised six times since its issuance on 15 January 2020. The recent guidelines also include IFN-α, remdesivir, ribavirin, ritonavir and chloroquine. The mode of administration of IFN-α is through inhalation at a dose of 5 million units diluted with water for injection. The dose of ritonavir is 100 mg BD for adults.

Ribavirin may be given in combination with IFN-α or ritonavir at a dose of 500 mg BD or TDS. Chloroquine phosphate should be administered at a dose of 500 mg BD. Arbidol can be given three times a day at 200 mg. 28 Hydroxychloroquine (HCQ) is an approved disease-modifying antirheumatic drug that also has immunomodulatory effects and prevents organ damage. 29 HCQ alters endosomal pH and interrupts the biding between RNA/DNA and toll-like receptors that leads to suppression of TLR signaling. [30] [31] [32] Inside the cytoplasm, HCQ also interferes with the interaction between nucleic acid sensor cyclic GMP and cytosolic DNA. 33 These two mechanisms lead to increase production of IL-1, TNF and type-1 interferon. Such mechanism supports the idea that HCQ suppress the cytokine release storm (CRS) which is due to SARS-CoV-2 triggered overreaction of immune system. 34 In a recent study, HCQ was found to be more effective than chloroquine; a loading dose of 400 mg twice daily and maintenance dose of 200 mg twice a day is recommended for SARS-CoV2 infection. 35 The mechanism involves in antiviral role of HCQ and CQ is inhibition of receptor binding and fusion of cell membrane. These two are crucial steps that are required for cell entry of SARS-CoV-2. Chloroquine interferes with the glycosylation of ACE-2 (angiotensinconverting enzyme receptors) receptors that are considered as cellular receptors for SARS-CoV-2 and block the fusion of SARS-CoV-2 with host cell. Thus, the binding of virus is blocked and infection is prevented. The HCQ and CQ after entry into the cell tend to concentrate in lysosomes and endosomes. The SARS-CoV-2 use endosome as a tool for cellular entry. HCQ and CQ increase the pH of endosomes and create a negative influence on the binding of SARS-C0v-2 with endosomes. 25 Lysosomal protease helps in viral fusion with cell membrane. Increase lysosomal pH prevents the action of protease and fusion and replication of virus is blocked 36 . The mechanism of action of chloroquine and hydroxychloroquine is represented as (Figure 1 ).

Cinanserin is an antagonist of serotonin receptors. It can inhibit chymotrypsin-like (3C-like) protease and has shown promising results against SARS coronavirus. 37 The 3C-protease was also investigated to be encoded in SARS-CoV-2. 38 Flavonoids such as chalcones, flavones and isoflavones produce antioxidant effects but they also have antiviral effects. 39 A study has found that flavonoids can inhibit the entry of hepatitis-C virus. 40 Some flavonoids have activity against MERS coronavirus, presumably due to inhibition of 3C-like protease. 41 Nitric oxide (NO) is a biological gas produced from arginine. NO after reaction with superoxide forms peroxynitrite which has cytotoxic bactericidal action. 43 Nitric oxide is also known to regulate airway function and reduce inflammation of airways. 44 The beneficial effect of NO in SARS patients was observed in some studies. 45 NO can also inhibit the synthesis of RNA and viral protein. 46 A study has found that organic nitric oxide could inhibit the replication cycle of SARS-CoV-2. 47 Αlpha-lipoic acid (ALA) is used in hepatic disorders and polyneuropathies. 48 ALA is an antioxidant that protects cells against oxidative stress by increasing the glutathione level. 49 Some studies support the role of angiotensin-converting enzyme (ACE) inhibitors. This is based on the hypothesis that ACE-2 serves as receptor for SARS-CoV-2. 54,55 So, ACE inhibitor could potentially compete for site binding and reduce the mortality and morbidity associated with SARS-CoV-2. 56 The various ongoing clinical trials are summarized in Table 1 .

Vaccine provides immunity against a particular pathogen before exposure of that infectious agent. Several types of vaccines exist that can be nucleic acid based, live attenuated vaccine, subunit proteins or nanoparticle vaccines. 67 Different technologies are being utilized to F I G U R E 1 Mechanism of action of HCQ and CQ by blocking binding of virus with ACE-2 receptors and increasing endosomal pH and preventing fusion with the cell develop potential vaccine for SARS-CoV-2 including DNA and mRNAbased nanoparticles. Phase-I trials of potential vaccines focus on safety and immunogenicity, for example, against MERS. 68 Two of the clinical trials on MERS vaccine are expected to be complete by the end of 2020 69, 70 in Russia and one in Germany by December 2021. 71 The Inovo pharmaceutical company has tested its vaccine against MERS coronavirus funded by coalition for epidemic preparedness innovation (CEPI) using DNAbased technology and named as INO-4700. 72 The University of Oxford recombinant chimpanzee adenovirus has also begun Phase 1 randomized multicenter trials for intramuscular injection of vaccine ChAdOx1 against SARS-CoV-2. The 1100 participants have been divided into four groups and they will be observed for any serious adverse event for 6 months.

The ongoing clinical trials for development of vaccines have been summarized in Table 2 and completed vaccine trials for SARS and   MERS viruses have been summarized in Table 3 .

The fusion of coronavirus with a cell occurs after biding of S protein to a target receptor delivers viral nucleocapsid and initiates replication. The S protein causes syncytial formation at the receptor site. 85 A neutralizing antibody that can target the S protein on the surface of

Clinical trials for various treatment options for SARS-CoV-2

Clinical Trial Registration Number Trial information Date Type References

The efficacy of Newgen beta-gluten probiotic powder in patient with 2019-nCOV. 16 March 2020 Interventional 57

The efficacy of combination of Favipiravir + Tocilizumab in patient with pneumonia (COVID-19 The immune response was dose-independent and further trials needed to establish efficacy 84 

Coronavirus pathogenesis

Epidemiology, genetic recombination, and pathogenesis of coronaviruses

Origin and evolution of pathogenic coronaviruses

Epidemiology and cause of severe acute respiratory syndrome (SARS) in Guangdong, People's Republic of China

Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia

the role of super-spreaders in infectious disease

Wuhan Municipal Health Commission. report of clustering pneumonia of unknown etiology in Wuhan city

China Novel Coronavirus Investigating and Research Team. A novel coronavirus from patients with pneumonia in China

Coronaviruses and the human airway: a universal system for virus-host interaction studies

New nucleoside analogues for the treatment of hemorrhagic fever virus infections

Washington State 2019-nCoV Case Investigation Team. First case of 2019 novel coronavirus in the United States

Clinical study for safety and efficacy of favipiravir in the treatment of novel coronavirus pneumonia (COVID-19)

A randomized controlled trial for the efficacy and safety of Baloxavir Marboxil, Favipiravir tablets in 2019-nCoV pneumonia (novel coronavirus pneumonia, NCP) patients who are still positive on virus detection under the current antiviral therapy

Coronavirusesdrug discovery and therapeutic options

Remdesivir and chloroquine effectively inhibit the recently emerged novel coronavirus (2019-nCoV) in vitro

Bin Cao YW. Mild/Moderate 2019-nCoV Remdesivir RCT

Role of lopinavir/ritonavir in the treatment of SARS: initial virological and clinical findings

Treatment with lopinavir/ritonavir or interferon-β1b improves outcome of MERS-CoV infection in a nonhuman primate model of common marmoset

Approved antiviral drugs over the past 50 years

Clinical management of respiratory syndrome in patients hospitalized for suspected Middle East respiratory syndrome coronavirus infection in the Paris area from

Effect of chloroquine on the growth of animal viruses

In vitro inhibition of severe acute respiratory syndrome coronavirus by chloroquine

An evaluation of chloroquine as a broad-acting antiviral against hand, foot and mouth disease

FDA-approved drug, prevents Zika virus infection and its associated congenital microcephaly in mice

Chloroquine is a potent inhibitor of SARS coronavirus infection and spread

Dose refinements in long-term therapy of rheumatoid arthritis with antimalarials

Breakthrough: Chloroquine phosphate has shown apparent efficacy in treatment of COVID-19 associated pneumonia in clinical studies

Discovering drugs to treat coronavirus disease 2019 (COVID-19)

Clinical efficacy and side effects of antimalarials in systemic lupus erythematosus: a systematic review

Mechanism of endosomal TLR inhibition by antimalarial drugs and imidazoquinolines

The ectodomain of Toll-like receptor 9 is cleaved to generate a functional receptor

Immune stimulation mediated by autoantigen binding sites within small nuclear RNAs involves Toll-like receptors 7 and 8

Cutting edge: antimalarial drugs inhibit IFN-β production through blockade of cyclic GMP-AMP synthase-DNA interaction

Chloroquine and hydroxychloroquine equally affect tumor necrosis factor-alpha, interleukin 6, and interferongamma production by peripheral blood mononuclear cells

In vitro antiviral activity and projection of optimized dosing design of hydroxychloroquine for the treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)

Targeting endosomal acidification by chloroquine analogs as a promising strategy for the treatment of emerging viral diseases

Cinanserin is an inhibitor of the 3C-like proteinase of severe acute respiratory syndrome coronavirus and strongly reduces virus replication in vitro

Emerging coronaviruses: genome structure, replication, and pathogenesis

Flavonoids: an overview

Flavonoids from Pterogyne nitens inhibit hepatitis C virus entry

Inhibition of SARS-CoV 3CL protease by flavonoids

A Study to Evaluate the Efficacy and Safety of Pirfenidone With Novel Coronavirus Infection

Nitric oxide

Nitric oxide and airway disease

Efficacy of inhaled nitric oxide in patients with severe ARDS

An overview on severe acute respiratory syndrome (SARS)

Nitric oxide inhibits the replication cycle of severe acute respiratory syndrome coronavirus

Efficacy of thioctic acid in the therapy of peripheral diabetic neuropathy

Biochemical and clinical relevance of alpha lipoic acid: antioxidant and anti-inflammatory activity, molecular pathways and therapeutic potential

Glucose-6-phosphate dehydrogenase deficiency enhances human coronavirus 229E infection

Virucidal activity of a scorpion venom peptide variant mucroporin-M1 against measles, SARS-CoV and influenza H5N1 viruses

Convalescent plasma: therapeutic hope or hopeless strategy in the SARS-CoV-2 pandemic

Treatment with convalescent plasma for critically ill patients with SARS-CoV-2 infection

Genomic characterisation and epidemiology of 2019 novel coronavirus: implications for virus origins and receptor binding

Receptor recognition by the novel coronavirus from Wuhan: an analysis based on decade-long structural studies of SARS coronavirus

Angiotensin receptor blockers as tentative SARS-CoV-2 therapeutics

Evaluation of the effect of taking Newgen beta-gluten probiotic composite powder to nutrition intervention of patients with novel coronavirus pneumonia (COVID-19)

Favipiravir Combined with Tocilizumab in the Treatment of Novel Coronavirus Pneumonia (COVID-19) -A Multicenter, Randomized

Efficacy and Safety of Pirfenidone in the Treatment of Severe Post-Novel Coronavirus Pneumonia (COVID-19) Fibrosis: a prospective exploratory experimental medical study

Clinical research and preparation development of qingfei detoxification decoction (mixture) for prevention and treatment of novel coronavirus pneumonia

Clinical study for bronchoscopic alveolar lavage in the treatment of critically trachea intubation patients with new coronavirus pneumonia (COVID-19)

Evaluation of the protective effect of dexmedetomidine on patients with severe novel coronavirus pneumonia (COVID-19)

Coronoavirus clinical trial

Evaluating the Efficacy and Safety of Bromhexine Hydrochloride Tablets Combined With Standard Treatment/ Standard Treatment in Patients With Suspected and Mild Novel Coronavirus Pneumonia (COVID-19)

Fingolimod in COVID-19

Eculizumab (Soliris) in Covid-19 Infected Patients (SOLID-C19)

2019-nCoV (Wuhan virus), a novel coronavirus: human-to-human transmission, travel-related cases, and vaccine readiness

Potential rapid diagnostics, vaccine and therapeutics for 2019 novel coronavirus (2019-nCoV): a systematic review

Study of safety and immunogenicity of BVRS-GamVac

Study of safety and immunogenicity of BVRS-GamVac-Combi

Randomized, double-blind, placebo-controlled, phase ib study to assess the safety and immunogenicity of MVA-MERS-S_DF-1

Inovio Selected by CEPI to Develop Vaccine Against New Coronavirus

An obscure biotech stock skyrockets 38% after saying it's testing a coronavirus antibody (VIR)

A Study of a Candidate COVID-19 Vaccine (COV001)

Race to develop coronavirus vaccine

J&J scientific officer 'pretty confident' they can create coronavirus vaccine as outbreak widens

Saskatchewan lab joins global effort to develop coronavirus vaccine

China) to Collaborate on Development of Coronavirus Vaccine

A Phase I Clinical Trial for Recombinant Novel Coronavirus (2019-COV) Vaccine (Adenoviral Vector

Safety and immunogenicity from a phase I trial of inactivated severe acute respiratory syndrome coronavirus vaccine

VRC 301 Study Team. A SARS DNA vaccine induces neutralizing antibody and cellular immune responses in healthy adults in a phase I clinical trial

Safety and tolerability of a novel, polyclonal human anti-MERS coronavirus antibody produced from transchromosomic cattle: a phase 1 randomised, double-blind, single-dose-escalation study

Safety and immunogenicity of an anti-Middle East respiratory syndrome coronavirus DNA vaccine: a phase 1, open-label, single-arm, dose-escalation trial

Structural insights into coronavirus entry

The Ebola epidemic crystallizes the potential of passive antibody therapy for infectious diseases

Isolation of HCV neutralizing antibodies by yeast display

Emergence of novel coronavirus and progress toward treatment and vaccine