Molecular Aspects Concerning the Use of the SARS-CoV-2 Receptor Binding Domain as a Target for Preventive Vaccines.   Valdes-Balbin Y, Santana-Mederos D, Paquet F, Fernandez S, Climent Y, Chiodo F, Rodríguez L, Sanchez-Ramirez B, Leon K, Hernandez T, Castellanos-Serra L, et al. ACS Cent. Sci., 2021 April 19 https://doi.org/10.1021/acscentsci.1c00216
The development of recombinant COVID-19 vaccines has resulted from scientific progress made at an unprecedented speed during 2020. The recombinant spike glycoprotein monomer, its trimer, and its recombinant receptor-binding domain (RBD) induce a potent anti-RBD neutralizing antibody response in animals. In COVID-19 convalescent sera, there is a good correlation between the antibody response and potent neutralization. In this review, we summarize with a critical view the molecular aspects associated with the interaction of SARS-CoV-2 RBD with its receptor in human cells, the angiotensin-converting enzyme 2 (ACE2), the epitopes involved in the neutralizing activity, and the impact of virus mutations thereof. Recent trends in RBD-based vaccines are analyzed, providing detailed insights into the role of antigen display and multivalence in the immune response of vaccines under development.

PREPRINT SARS-CoV-2 RBD-Tetanus toxoid conjugate vaccine induces a strong neutralizing immunity in preclinical studies Valdes-Balbin, Y. et al. February 9, 2021. bioRxiv 2021.02.08.430146   DOI: https://doi.org/10.1101/2021.02.08.430146
Controlling the global COVID-19 pandemic depends, among other measures, on developing preventive vaccines at an unprecedented pace. Vaccines approved for use and those in development intend to use neutralizing antibodies to block viral sites binding to the host’s cellular receptors. Virus infection is mediated by the spike glycoprotein trimer on the virion surface via its receptor binding domain (RBD). Antibody response to this domain is an important outcome of the immunization and correlates well with viral neutralization. Here we show that macromolecular constructs with recombinant RBD conjugated to tetanus toxoid induce a potent immune response in laboratory animals. Some advantages of the immunization with the viral antigen coupled to tetanus toxoid have become evident such as predominant IgG immune response due to affinity maturation and long-term specific B-memory cells. This paper demonstrates that subunit conjugate vaccines can be an alternative for COVID-19, paving the way for other viral conjugate vaccines based on the use of small viral proteins involved in the infection process.

Science, technology and innovation strategy of the National Center for Biological Products against COVID-19 Lobaina-Rodríguez T, De-Armas-Rodríguez J, Rodríguez-Cabrera T, González-García G, Labrada-Rosado A, Rojas-Gattorno I, Espinosa-López O, Cruz-Bayo A, Mieres-Díaz N, Reyes-Morgado M, López-Martínez Y, Fernández-Durand A, Lorenzo-Jaime H. Anales de la Academia de Ciencias de Cuba [revista en Internet]. 2020; 10(3) Spanish only
The National Center of Biological Products, a Science and Technology entity integrated into the actions of the State to update the economic model, takes on new challenges facing COVID-19 in its science and innovation activity. In just 10 weeks, a transport medium for SARS-CoV-2 was developed and registered; the application of Biomodulin T® was also introduced into the prevention protocols with more than 10 000 older adults treated, without any subject having acquired the disease. Two new drugs derived from the research were introduced and 2,8 millions of units of other eight products were produced. The main dynamic elements leading into the generation of innovative products were adapted to the new conditions, especially the management of highly qualified and motivated human capital, the most intensive use of productive and analytical capacities, complying with the high regulatory standards, the business structure, the logistics system, and commercial management.

Estimating undocumented Covid-19 infections in Cuba by means of a hybrid mechanistic-statistical approach Gil G, Lage Castellanos A. Ciencias Matemáticas, Vol. 34, No. 1, 2020, Pag. 49-54
We adapt the hybrid mechanistic-statistical approach of Ref. [1] to estimate the total number of undocumented Covid-19 infections in Cuba. This scheme is based on the maximum likelihood estimation of aSIR-like model parameters for the infected population, assuming that the detection process matches a Bernoullitrial. Our estimations show that (a) 60% of the infections were undocumented, (b) the real epidemics behind the data peaked ten days before the reports suggested, and (c) the reproduction number swiftly vanishes after 80th epidemic days.

PREPRINT Phase II randomized controlled trial to evaluate the efficacy and safety of HeberFERON versus Heberon alpha R in symptomatic or asymptomatic patients infected with the SARS-CoV-2 (Study ESPERANZA/HOPE). Iraldo B, Hernandez-Bernal F, Nodarse-Cuni H, et al. Research Square; 2020. DOI: 10.21203/rs.3.rs-28958/v2
Background: As the outbreak of COVID-19 has accelerated, an urgent need for finding strategies to combat the virus is growing. Results from in vitro studies suggest that a combination of IFN type I and Type II may be effective against SARS-CoV. The aim of this study is to investigate the efficacy of treatment with a recombinant IFN alpha 2b and gamma, provided with standard protocol (Kaletra (lopinavir-ritonavir 200/50 mg; 200/100 mg every 12 hour for 30 days; Chloroquine (250 mg) every 12 hours for 10 days) for COVID-19 patients, compared to standard protocol (IFN alpha 2b/Kaletra/Chloroquine) for COVID-19 hospitalized patients, positive diagnosed for SARS-Cov-2. Methods: Hospitalized adult patients with qPCR confirmed SARS-Cov-2 will be enrolled in this open-labeled, single center, prospective, randomized and controlled clinical trial. One hundred and twenty eligible patients with confirmed SARS-CoV-2 positivity by qPCR amplification in oropharyngeal/nasopharyngeal swab samples will be enrolled at “Luis Diaz Soto” Hospital, Havana, Cuba. The primary outcomes are the time to 2019-nCoV RNA negativity in patients and the time until progression to severe COVID-19. Discussion: This will be the first randomized controlled trial of a potential treatment for SARC-Cov-2 using the combinations of IFNs. Trial registration: The study is sponsored by Center for Genetic and Biotechnology and Ministry of Health of Cuba and was duly registered April 2020 at http://registroclinico.sld.cu/en/trials/RPCEC00000307-En. Enrolment for this study began in April 11, 2020, and has enrolled one hundred patients as of May-26-2020.

Model inspired by a hydrological process for the forecast of spread scenarios of COVID-19 Martínez-González Y, García-Cortés D. Anales de la Academia de Ciencias de Cuba [revista en Internet]. 2020; 11(1):[aprox. 0 p.]. Spanish only
Introduction: The mathematical models are abstractions of the reality that allow for the description of important characteristics of the phenomena studied. Among these, the epidemic models are considered one of the most powerful tools to analyze and understand epidemic propagation and control. Objective: A model for the forecast of spread scenarios of the COVID-19 has been developed. Methods: A proposed population model inspired by analogy by hydrologic routing in rivers, an autoregressive integrated moving average model (ARIMA) and a transition model were combined in order to evaluate three possible spread scenarios and their temporary evolution during the development of COVID–19 pandemic. Results: In this contribution, 27 countries having coronavirus daily reports until April 16th, 2020 were studied. They were grouped by quartiles according to rates of recovered and deceased people. This information permitted the establishment of criteria for the parameters involved in the proposed model for Cuba as a case study. The favorable, not very favorable and critical epidemic spread scenarios were generated from ARIMA up to April 29th, 2020 and the transition model extended to 120 days. The results of the model implementation were compared with the real data of the pandemic evolution in Cuba up to May 22nd, 2020, resulting in a satisfactory correspondence between the real daily reports and the scenarios of active cases. This model could be used in the same way for other American countries that also have a delay with regard to the countries selected for this study.

Use of a humanized anti-CD6 monoclonal antibody (itolizumab) in elderly patients with moderate COVID-19. Ramos-Suzarte M, Díaz Y, Martín Y, Calderón NA, Santiago W, Vinet O, et al. medRxiv. 2020 Jul 30.
Introduction The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has caused a recent outbreak of Coronavirus Disease (COVID-19). In Cuba, the first case of COVID-19 was reported on March 11. Elderly with multiple comorbidities are particularly susceptible to adverse clinical outcomes in the course of SARS CoV-2 infection. During the outbreak, a local transmission event took place in a nursing home in Villa Clara province, Cuba, in which nineteen elderly residents were positive for SARS-CoV-2. Methods Based on the increased susceptibility to viral-induced cytokine release syndrome inducing respiratory and systemic complications in this population, the patients were included in an expanded access clinical trial to receive itolizumab, an anti-CD6 monoclonal antibody. Results All the patients had underlying medical conditions. The product was well tolerated. After the first dose, the course of the disease was favorable and 18 out of 19 (94.7%) patients were discharged clinically recovered with negative RT-PCR at 13 days (median). One dose of itolizumab, circulating IL-6 decreased in the first 24-48 hours in patients with high baseline values, whereas in patients with low levels, this concentration remained over low values. To preliminary assess the effect of itolizumab, a control group was selected among the Cuban COVID-19 patients, which did not receive immunomodulatory therapy. Control subjects were well-matched regarding age, comorbidities and severity of the disease. Every three moderately ill patients treated with itolizumab, one admission in intensive care unit (ICU) was prevented. Discussion/Conclusion Itolizumab was well tolerated. Its effect is associated with a reduction and controlling IL-6 serum levels. Moreover, treated patients had a favorable clinical outcome, considering their poor prognosis. This treatment is associated significantly with a decrease the risk to be admitted in ICU and reduced 10 times the risk of death. This study corroborates that the timely use of itolizumab, in combination with other antiviral and anticoagulant therapies, is associated with a reduction the COVID-19 disease worsening and mortality. The humanized antibody itolizumab emerges as a therapeutic alternative for patients with COVID-19 and suggests its possible use in patients with cytokine release syndrome from other pathologies.

Therapeutic Effectiveness of Interferon-α2b Against COVID-19: The Cuban Experience. Pereda R., González D., Rivero H., Rivero J., Pérez A., López L., Mezquia N., Venegas R., Betancourt J., and Domínguez R.. Journal of Interferon & Cytokine Research. Vol 40 Issue 9. Sep 2020.438-442. http://doi.org/10.1089/jir.2020.0124
Abstract A prospective observational study was conducted for assessing the therapeutic efficacy of interferon (IFN)-α2b in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the first month after the coronavirus disease 2019 (COVID-19) outbreak began in Cuba. From March 11th to April 14th, 814 patients were confirmed SARS-CoV-2 positive in Cuba. Seven hundred sixty-one (93.4%) were treated with a combination of oral antivirals (lopinavir/ritonavir and chloroquine) with intramuscular administration of IFN-α2b (Heberon® Alpha R, Center for Genetic Engineering and Biotechnology, Havana, Cuba), 3 times per week, for 2 weeks. Fifty-three patients received the approved COVID protocol without IFN treatment. The proportion of patients discharged from hospital (without clinical and radiological symptoms and nondetectable virus by real-time polymerase chain reaction) was higher in the IFN-treated compared with the non-IFN treated group (95.4% vs. 26.1%, P < 0.01). The case fatality rate (CFR) for all patients was 2.95%, and for those patients who received IFN-α2b the CFR was reduced to 0.92. Intensive care was required for 82 patients (10.1%), 42 (5.5%) had been treated with IFN. This report provides preliminary evidence for the therapeutic effectiveness of IFN-α2b for COVID-19 and suggests that the use of Heberon Alpha R may contribute to complete recovery of patients.

The Cuban biopharmaceutical industry in the fight against the COVID-19 pandemic. Martínez-Díaz E, Pérez-Rodríguez R, Herrera-Martínez L, Lage-Dávila A, Castellanos-Serra L. Anales de la Academia de Ciencias de Cuba [revista en Internet]. 2020; 10(2). In Spanish
The new coronavirus pandemic has challenged the capacity of health systems in most countries. Cuba’s strategy has recently been analyzed in an article published by President Miguel Díaz-Canel and Prof. Jorge Núñez (http://www.revistaccuba.cu/index.php/revacc/article/view/881). A component of this strategy is the cuban biopharmaceutical industry. The drug coverage of the protocol established by the Ministry of Public Health for the treatment of this disease was guaranteed. Several products under development were quickly repositioned for use on the COVID-19. Biopharmaceuticals as Nasalferon, Biomodulin T and Hebertrans have been used for the prevention of infection by the SARS CoV-2 virus in risk groups; Heberon and Heberferon were administered as antiviral treatments, while Jusvinza and Itolizumab were used to stop the hyperinflammatory reaction. Biotechnology products have contributed to the reduction of seriously and critically ill patients (<7 %) and to the reduction of mortality (0,8/100 000) due to this disease, approximately 10 times lower than the world rate. The project portfolio includes other antiviral and immunomodulatory biologics, diagnostic reagent kits, products of natural origin, and medical equipments. Several vaccine candidates for the induction of specific immunity are under development, which should contribute to the definitive control of this disease in Cuba.

PREPRINT Therapeutic effectiveness of interferon-alpha2b against COVID-19: the Cuban experience. Ricardo Pereda, Daniel Gonzalez, Hubert Rivero, Juan Rivero, Albadio Perez, Lizet del Rosario Lopez, Natacha Mezquia, Rafael Venegas, Julio Betancourt, Rodolfo Dominguez medRxiv 2020.05.29.20109199; https://doi.org/10.1101/2020.05.29.20109199

PREPRINT CIGB-258 immunomodulatory peptide: a novel promising treatment for critical and severe COVID-19 patients
Maria del Carmen Dominguez Horta Sr.
medRxiv 2020.05.27.20110601; https://doi.org/10.1101/2020.05.27.20110601

PREPRINT An Anti-CD6 Monoclonal Antibody (Itolizumab) Reduces Circulating IL-6 in Severe Covid-19 Elderly Patients. Saavedra D, Añé-Kourí AL, Sánchez N, et al. Research Square; 2020. DOI: 10.21203/rs.3.rs-32335/v1

Background: Since the COVID-19 outbreak an unprecedented challenge for healthcare systems around the world has been placed. In Cuba, the first case of COVID-19 was reported on March 11. Elderly with multiple comorbidities have been the most risky population. Although most patients present a mild to moderate disease, some have developed severe symptoms. One of the possible mechanisms underlying rapid disease progression is a cytokine storm, in which interleukin (IL) -6 seems to be a major mediator. Itolizumabis a humanized recombinant anti-CD6 monoclonal antibody(MAb), with the ability of reducingserum interferon gamma(INF-γ), tumournecrosis factor alpha(TNFα) and IL-6. Based on these previous results in patients with psoriasis and rheumatoid arthritis, an expanded access clinical trial was approved by the Cuban regulatory agency for COVID-19 critically, severely and moderately ill patients. Results: We show here a short kinetic of IL-6 serum concentration in the first 24 COVID-19 patients treated with itolizumab. Most of patients were elderly with multiple comorbidities.We found that with one itolizumabdose, the circulating IL-6 decreased in critically and severely ill patients, whereas in moderately ill patients the values didn’trise as compared to theirlow baseline levels. Conclusion: These findings suggest that itolizumabcould be an attractive therapeutic option to decrease the negative outcome of the cytokine storm in COVID-19 patients. Trial registration: CECMED IIC RD-EC 179, RPCEC00000311. Registered 4May 2020 – Retrospectively registered, http://rpcec.sld.cu/ensayos/RPCEC00000311-Sp or http://rpcec.sld.cu/trials/RPCEC00000311-En

RESEARCH ON CUBAN INTERFERON ALFA-2b

Cuban interferon alpha-2b. Thirty years as an effective and safe drug. Nodarse Cuní H, López Saura PA. Biotecnol Apl. 2017;34(1):1211–7. (aquí para versión en español)
Since 1986, the Center for Genetic Engineering and Biotechnology of Havana, Cuba, has produced the recombinant human interferon alpha-2b, marketed as Heberon® Alfa R. The therapeutic use of this product has accumulated a high number of researches carried out in the country’s public health network. For the analysis of its safety profile, 28 years of reports of adverse events were reviewed in 5806 individuals, both children and adults, coming from 147 clinical trials or healthy assistances using the product. This review also contains a safety comparison between lyophilized and liquid formulations. In addition, an analysis of the connection between the occurrence of adverse events and the demographic characteristics of the patients, an analysis of immunogenicity and another on the variation of the thyroid function associated to the use of Heberon® Alfa R were included. Finally, a general analysis of the product’s efficacy based on the number of treated patients and the clinical results obtained are presented. Adverse events were reported in 4864 subjects (84 %). The main adverse events were those corresponding to the flu-like syndrome, with higher frequency in male white patients. Hypothyroidism and immunogenicity behaved lower than similar products in the international pharmaceutical market. Approximately 60 % of the treated patients obtained a relevant therapeutic response and a liquid formulation offered a better benefit/ risk ratio. The extensive clinical information evaluated recognizes a Heberon® Alfa R as a safe and effective drug, 30 years after its first production.

Clinical immunogenic profile of Heberon® alpha. Nodarse-Cuní H, Bermúdez-Badel CH, García García I, Bello Rivero I, Pedro López-Saura. Rev Cubana Farm. 2017 Jul;51(3). In Spanish
The analysis of the immunogenicity profile of recombinant human interferon alfa-2b was performed in 952 patients from 23 clinical studies, performed with the lyophilized formulation with albumin. The experimental design was started with a “sandwich” type enzyme-linked immunosorbent assay (ELISA) for detecting the presence of the antibody and its confirmation of specificity (IFN alpha-2b/sample/conjugate protein A-peroxidase), and then we investigated, through a biological assay in cells, the ability of the antibody to neutralize the antiviral activity of interferon alpha.  The development of antibodies with neutralizing capacity for the antiviral action occurred in 22 patients, representing 2.3% of those evaluated. This percentage of immunogenicity of recombinant human interferon alfa-2b, produced by the Center for Genetic Engineering and Biotechnology, is below the reported 2.7% for recombinant human interferon alfa-2b and 25.7% for interferon alfa-2a in the international market.  Recombinant human interferon alfa-2b produced at the Center for Genetic Engineering and Biotechnology can be used as a safe drug for the treatment of all diseases included in its therapeutic indications.

Interferon alpha-2b and ribavirin as combined therapy for chronic hepatitis C in Cuba: National Program.  Nodarse-Cuní H, Arus-oler E, Rivera-Reimón LL, Pérez-Lorenzo M, Samada-Suárez M, García-Ferrera WO, et al. Biotecnol Apl. 2012;29(3):184–8. In Spanish
The treatment of chronic hepatitis C with interferon alpha (IFN-α) is widely used. However, the relapse rate is high, and sustained response is only in 10-20%. A combined treatment based on the synergic antiviral effects described for IFN-α and ribavirin was used as a National Program in Cuba. The study enrolled 357 patients treated during 48 weeks with an injection of IFN-α, 3 times weekly, combined with oral ribavirin in daily doses, the doses adjusted to body weight. Sustained virological response was the efficacy end point, supported by biochemical and histological changes. Normalization in transaminase levels occurs in 60.5% of patients after the first 4 weeks, 71.4% at 26 weeks and 60.2% at the end of treatment. In similar moments, the viral load was undetectable in 42.9%, 42.6% and 37.0% respectively. The implementation of this National Program led to 49.0% and 29.7% of biochemical and virological sustained response respectively. A histological improvement was observed in 53.5% of evaluated patients. The treatment was well tolerated and almost all adverse reactions were attributable to IFN-α. The main adverse reports were: anemia, leucopenia, asthenia, fever, headache, arthralgias, anorexia and myalgia. Anti-interferon antibodies were developed in 38 patients, in 3 of them as neutralizing of antiviral activity. These results confirm the efficacy and security profile of both drugs as combined therapy for the chronic hepatitis C and represent the first clinical data generated from its extensive use in the Cuban general population. The virological response was in agreement with international reports for populations with similar characteristics.

Interferon alpha-2b as adjuvant treatment of recurrent respiratory papillomatosis in Cuba: National Programme (1994–1999 report). Nodarse-Cuní H, Iznaga-Marín N, Viera-Álvarez D, Rodríguez-Gómez H, Fernández-Fernández H, Blanco-López Y, et al. J Laryngol Otol. 2004 Sep;118(9):681–7.
Respiratory papillomatosis is a life-spoiling disease due to its high recurrence rate. Interferon (IFN) alpha-2b treatment, adjuvant to surgery, was assessed for its contribution to disease control and patient quality of life improvement. One hundred and sixty-nine patients (85 children and 84 adults) were included after surgical removal of the lesions followed by intramuscular IFN alpha-2b (Heberon alfa R, Heber Biotec), starting with 105 IU/Kg weight in children or 6 × 106 IU in adults, three times per week. The dose was reduced monthly, if no relapses occurred, until a monthly maintenance with 5 × 104 IU/Kg of weight in children or 3 × 106 IU in adults up to two years. In case of relapse, it was surgically removed and the patient returned to the higher dose level. The relapse frequency decreased significantly in 77 per cent (69/90) of the recurrent patients both in children (34/46, 74 per cent) and adults (35/44, 79 per cent). Among patients included after their first papilloma, 67 per cent (44/66) had complete (no relapses) or partial (only one relapse) responses (children: 15/33, 45 per cent; adults 29/33, 88 per cent). One hundred and eighteen patients (73 per cent) concluded the treatment without lesions (children: 58 per cent; adults 82 per cent), while the rest showed a significant reduction in the number and size of lesions. IFN was well tolerated. Sixty-two patients (38 per cent) did not have adverse events. The main adverse reactions were fever (59 per cent), chills (24 per cent), arthralgias and myalgias (14 per cent) and headache (10 per cent). One patient developed anti-IFN alpha neutralizing antibodies and became resistant to treatment with recombinant IFN alpha-2b; he responded to natural leucocyte IFN alpha. Treatment with IFN alpha-2b, as an adjuvant to surgery represents a favourable and safe therapeutic alternative for patients with recurrent respiratory papillomatosis.

Molecular Characterization of Recombinant Human Interferon Alpha-2b Produced in Cuba. Santana H, Martínez E, Sánchez JC, Moya G, Sosa R, Hardy E, et al. Biotecnol Apl. 1999;16(3)154–9.
The recombinant human interferon alpha 2b (IFN-a 2b) produced by Cuban technology is obtained from Escherichia coli. This is the active principle of the product registered in Cuba as Heberon alfa R® trademark (IFN-alpha 2b, CIGB, Havana), which has been successfully used worldwide for the therapy of several viral diseases and neoplasms. Here we describe the purity and identity tests used for its molecular characterization. The data show a product with a well-established identity, a high purity and a specific activity higher than 1.4 x 108 IU/mg of proteins. We also compared the final preparation with other IFN-alpha 2 products available in the international market. It behaved very similar to Intron A® and Roferon A®, and showed a higher homogeneity when compared with Bioferon® and Interimmun®.

RESEARCH ON INTERFERONS FOR CORONAVIRUS INFECTIONS

COVID19 Treatment: Close to a Cure? A Rapid Review of Pharmacotherapies for the Novel Coronavirus. Song Y, Zhang M, Yin L, Wang K, Zhou Y, Zhou M, et al. Preprints. 2020 Mar 26. DOI: 10.20944/preprints202003.0378.v1.
Currently, there is no specific treatment for COVID-19 proven by clinical trials. WHO and CDC guidelines therefore endorse supportive care only. However, frontline clinicians have been applying several virus-based and host-based therapeutics in order to combat SARS-CoV-2. Medications from COVID-19 case reports, observational studies and the COVID-19 Treatment Guideline issued by the China’s National Health Commission (7^th edition published March 3^rd, 2020. Edited translation attached) are evaluated in this review. Key evidence from relevant in vitro researches, animal models and clinical studies in SARS-CoV-2, SARS-CoV and MERS-CoV are examined. Antiviral therapies remdesivir, lopinavir/ritonavir and umifenovir, if considered, could be initiated before the peak of viral replication for optimal outcomes. Ribavirin may be beneficial as an add-on therapy and is ineffective as a monotherapy. Corticosteroids use should be limited without indicating comorbidities. IVIG is not recommended due to lack of data in COVID-19. Xuebijing may benefit patients with complications of bacterial pneumonia or sepsis. The efficacy of interferon is unclear due to conflicting outcomes in SARS and MERS studies. Chloroquine and hydroxychloroquine have shown in vitro inhibition of SARS-CoV-2 and may be beneficial as both prophylactic and treatment therapy. For patients who developed cytokine release syndrome, interleukin-6 inhibitors may be beneficial. Given the rapid disease spread and increasing mortality, active treatment with readily available medications may be considered timely prior to disease progression.

Discovering drugs to treat coronavirus disease 2019 (COVID-19). Dong L, Hu S, Gao J. Drug Discov Therap. 2020 Feb 20;14(1):58–60.
The SARS-CoV-2 virus emerged in December 2019 and then spread rapidly worldwide, particularly to China, Japan, and South Korea. Scientists are endeavoring to find antivirals specific to the virus. Several drugs such as chloroquine, arbidol, remdesivir, and favipiravir are currently undergoing clinical studies to test their efficacy and safety in the treatment of coronavirus disease 2019 (COVID-19) in China; some promising results have been achieved thus far. This article summarizes agents with potential efficacy against SARS-CoV-2.

Antiviral drugs specific for coronaviruses in preclinical development. Odedeji AO, Sarafianos SG. Curr Opinion Virol. 2014 Oct;8:45–53.
Coronaviruses are positive stranded RNA viruses that cause respiratory, enteric and central nervous system diseases in many species, including humans. Until recently, the relatively low burden of disease in humans caused by few of these viruses impeded the development of coronavirus specific therapeutics. However, the emergence of severe acute respiratory syndrome coronavirus (SARS-CoV), and more recently, Middle East respiratory syndrome coronavirus (MERS-CoV), has impelled the development of such drugs. This review focuses on some newly identified SARS-CoV inhibitors, with known mechanisms of action and their potential to inhibit the novel MERS-CoV. The clinical development of optimized versions of such compounds could be beneficial for the treatment and control of SARS-CoV, the current MERS-CoV and other future SARS-like epidemics.

Development of the cDNA chip for SARS virus and a primary study on the possible molecular mechanism of interferon alpha 2b inhibiting the SARS virus replication. Shu YL, Duan ZJ, Wang Z, Sun MS, Zhang J, Zhang LL, et al. Chinese J Exp Clin Virol. 2003 Aug;17(3):209–12.
To study the molecular mechanism of interferon alpha 2b (IFN alpha 2b) inhibiting the SARS virus replication. SARS-associated coronavirus (SARS virus) cDNA chip was developed and applied to detect the virus RNA transcription levels in the interferon-treated and untreated cell cultures, and the mechanism of anti-SARS virus activity of interferon alpha 2b in cell culture system was explored. SARS virus cDNA chip was prepared by comparing the published SARS virus genome sequence, and the cDNA chip was used to study the interferon alpha2b function during SARS virus replication. SARS virus cDNA chip was successfully prepared by using PCR method. The results showed that the cDNA chip could be used to detect the viral RNA transcription level. Interferon alpha 2b could inhibit almost all the SARS virus gene transcription. An unknown gene at the position 28130-28426 bp, named as U gene, may play an important role during the viral replication. A SARS virus whole genome cDNA chip was established. It could be used to study the virus molecular biology and antiviral drug screening. The results also showed that interferon alpha 2b could inhibit almost the whole virus gene transcription by using the cDNA chip.

Inhibition of novel β coronavirus replication by a combination of interferon-α2b and ribavirin. Falzarano D, de Wit E, Martellaro C, Callison J, Munster VJ, FeldmannH. Sci Rep. 2013 Apr 18;3:1686. DOI: 10.1038/srep01686.
The identification of a novel β coronavirus, nCoV, as the causative agent of severe respiratory illness in humans originating in Saudi Arabia, Qatar and Jordan has raised concerns about the possibility of a coronavirus pandemic similar to that of SARS-CoV. As a definitive treatment regimen has never been thoroughly evaluated for coronavirus infections, there is an urgent need to rapidly identify potential therapeutics to address future cases of nCoV. To determine an intervention strategy, the effect of interferon-α2b and ribavirin on nCoV isolate hCoV-EMC/2012 replication in Vero and LLC-MK2 cells was evaluated. hCoV-EMC/2012 was sensitive to both interferon-α2b and ribavirin alone in Vero and LLC-MK2 cells, but only at relatively high concentrations; however, when combined, lower concentrations of interferon-α2b and ribavirin achieved comparable endpoints. Thus, a combination of interferon-α2b and ribavirin, which are already commonly used in the clinic, may be useful for patient management in the event of future nCoV infections.

Inhibition of SARS Coronavirus Infection in Vitro with Clinically Approved Antiviral Drugs. Tan E, Ooi EE, Lin CY, Tan HC. Emerg Infect Dis. 2004 May;10(4):581–6.
Severe acute respiratory syndrome (SARS) is an infectious disease caused by a newly identified human coronavirus (SARS-CoV). Currently, no effective drug exists to treat SARS-CoV infection. In this study, we investigated whether a panel of commercially available antiviral drugs exhibit in vitro anti–SARS-CoV activity. A drug-screening assay that scores for virus-induced cytopathic effects on cultured cells was used. Tested were 19 clinically approved compounds from several major antiviral pharmacologic classes: nucleoside analogs, interferons, protease inhibitors, reverse transcriptase inhibitors, and neuraminidase inhibitors. Complete inhibition of cytopathic effects of SARS-CoV in culture was observed for interferon subtypes, β-1b, α-n1, α-n3, and human leukocyte interferon α. These findings support clinical testing of approved interferons for the treatment of SARS.

Interferon- β 1a and SARS Coronavirus Replication. Hensley LE, Fritz EA, Jahrling PB, Karp CL, Huggins JW, et al. Emerg Infect Dis. 2004 Feb;10(2):317–9.
A global outbreak of severe acute respiratory syndrome (SARS) caused by a novel coronavirus began in March 2003. The rapid emergence of SARS and the substantial illness and death it caused have made it a critical public health issue. Because no effective treatments are available, an intensive effort is under way to identify and test promising antiviral drugs. Here, we report that recombinant human interferon (IFN)-β 1a potently inhibits SARS coronavirus replication in vitro.

Repurposing of Clinically Developed Drugs for Treatment of Middle East Respiratory Syndrome Coronavirus Infection. Dyall J, Coleman CM, Hart BJ, Venkataraman T, Holbrook MR, Kindrachuk J, et al. Antimicrob Agents Chemother. 2014 Aug;58(8)4885–93.
Outbreaks of emerging infections present health professionals with the unique challenge of trying to select appropriate pharmacologic treatments in the clinic with little time available for drug testing and development. Typically, clinicians are left with general supportive care and often untested convalescent-phase plasma as available treatment options. Repurposing of approved pharmaceutical drugs for new indications presents an attractive alternative to clinicians, researchers, public health agencies, drug developers, and funding agencies. Given the development times and manufacturing requirements for new products, repurposing of existing drugs is likely the only solution for outbreaks due to emerging viruses. In the studies described here, a library of 290 compounds was screened for antiviral activity against Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus (SARS-CoV). Selection of compounds for inclusion in the library was dependent on current or previous FDA approval or advanced clinical development. Some drugs that had a well-defined cellular pathway as target were included. In total, 27 compounds with activity against both MERS-CoV and SARS-CoV were identified. The compounds belong to 13 different classes of pharmaceuticals, including inhibitors of estrogen receptors used for cancer treatment and inhibitors of dopamine receptor used as antipsychotics. The drugs identified in these screens provide new targets for in vivo studies as well as incorporation into ongoing clinical studies.

Ribavirin and interferon-α2b as primary and preventive treatment for Middle East respiratory syndrome coronavirus: a preliminary report of two cases. Khalid M, Al Rabiah F, Mobeireek A, Butt TS, Mutairy EA. Antiviral Ther. 2014 May;20(1). DOI: 10.3851/IMP2792.
Middle East respiratory syndrome coronavirus (MERS-CoV) is a newly recognized transmissible viral infection with high virulence and case fatality rates for which there is no currently defined primary treatment or prophylaxis. Saudi Arabia has the largest reported number of cases so far. Like severe acute respiratory syndrome (SARS), MERS is caused by a coronavirus. Combination therapy with interferon-α2b and ribavirin has been used successfully as primary treatment and prophylaxis in SARS. Because of similarities between the two coronaviruses, treatment with ribavarin and interferon-α2b has been suggested as a potential therapy for MERS-CoV. Studies in animal models of MERS-CoV have shown the combination of ribavirin and interferon-α2b to be effective both as primary treatment and prophylaxis. In this report, we describe for the first time use of this combination as a primary treatment for a patient with MERS-CoV infection and as prophylaxis for his spouse and discuss its possible role.

Treatment with interferon α-2b and ribavirin improves outcomes in MERS-CoV-infected rhesus macaques. Falzarano D, de Wit E, Rasmussen AL, Feldmann F, Okumura A, Scott DP, et al. Nat Med. 2013 Oct;19(10):1313–7.  The emergence of Middle East respiratory syndrome coronavirus (MERS-CoV) is of global concern: the virus has caused severe respiratory illness, with 111 confirmed cases and 52 deaths at the time of this article’s publication. Therapeutic interventions have not been evaluated in vivo; thus, patient management relies exclusively on supportive care, which, given the high case-fatality rate, is not highly effective. The rhesus macaque is the only known model organism for MERS-CoV infection, developing an acute localized to widespread pneumonia with transient clinical disease that recapitulates mild to moderate human MERS-CoV cases. The combination of interferon-α2b and ribavirin was effective in reducing MERS-CoV replication in vitro; therefore, we initiated this treatment 8 h after inoculation of rhesus macaques. In contrast to untreated, infected macaques, treated animals did not develop breathing abnormalities and showed no or very mild radiographic evidence of pneumonia. Moreover, treated animals showed lower levels of systemic (serum) and local (lung) proinflammatory markers, in addition to fewer viral genome copies, distinct gene expression and less severe histopathological changes in the lungs. Taken together, these data suggest that treatment of MERS-CoV infected rhesus macaques with IFN-α2b and ribavirin reduces virus replication, moderates the host response and improves clinical outcome. As these two drugs are already used in combination in the clinic for other infections, IFN-α2b and ribavirin should be considered for the management of MERS-CoV cases.

Unravelling the convoluted biological roles of type I interferons (IFN-Is) in infection and immunity: a way forwad for the therapeutics and vaccine design. Wijesundara DK, Xi Y, Ranasinghe C. Front Immunol. 2014 Aug 29;5:412. DOI: 10.3389/fimmu.2014.00412.
It has been well-established that type I interferons (IFN-Is) have pleiotropic effects and play an early central role in the control of many acute viral infections. However, their pleiotropic effects are not always beneficial to the host and in fact several reports suggest that the induction of IFN-Is exacerbate disease outcomes against some bacterial and chronic viral infections. In this brief review, we probe into this mystery and try to develop answers based on past and recent studies evaluating the roles of IFN-Is in infection and immunity as this is vital for developing effective IFN-Is based therapeutics and vaccines. We also discuss the biological roles of an emerging IFN-I, namely IFN-ε, and discuss its potential use as a mucosal therapeutic and/or vaccine adjuvant. Overall, we anticipate the discussions generated in this review will provide new insights for better exploiting the biological functions of IFN-Is in developing efficacious therapeutics and vaccines in the future.

PubChem. Interferon alfa-2B. 2020. National Library of Medicine (US). Maryland: National Library of Medicine (US); c2020.

ClinicalTrials.gov. Maryland: National Library of Medicine (US). Maryland: National Library of Medicine (US); c2020.