Middle East Respiratory Syndrome Coronavirus Research Articles

Sulfated Glycans Inhibit the Interaction of MERS-CoV Receptor Binding Domain with Heparin.

Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus with high contagion and mortality rates. Heparan sulfate proteoglycans (HSPGs) are ubiquitously expressed on the surface of mammalian cells. Owing to its high negatively charged property, heparan sulfate (HS) on the surface of host cells is used by many viruses as cofactor to facilitate viral attachment and initiate cellular entry. Therefore, inhibition of the interaction between viruses and HS could be a promising target to inhibit viral infection. In the current study, the interaction between the receptor-binding domain (RBD) of MERS-CoV and heparin was exploited to assess the inhibitory activity of various sulfated glycans such as glycosaminoglycans, marine-sourced glycans (sulfated fucans, fucosylated chondroitin sulfates, fucoidans, and rhamnan sulfate), pentosan polysulfate, and mucopolysaccharide using Surface Plasmon Resonance. We believe this study provides valuable insights for the development of sulfated glycan-based inhibitors as potential antiviral agents.

Role of research Laboratories in pandemic and epidemic response in the Eastern Mediterranean Region: Experiences from COVID-19, avian influenza, and MERS-CoV.

We share the experience of research laboratories in the Eastern Mediterranean Region (EMR) that contributed to preparedness and response to highly pathogenic avian influenza (HPAI), Middle-East respiratory syndrome coronavirus (MERS-CoV), and coronavirus disease (COVID-19). Research groups in the region were pivotal in identifying, characterizing the pathogens and describing their evolution, distribution, transmission routes, and the immunological profile of exposed populations. They demonstrated the capacity to develop and test antivirals and potential vaccines. The EMR experience is a model of how national systems can work with researchers to improve regional preparedness and response to future epidemics and pandemics.

An in silico approach to develop potential therapies against Middle East Respiratory Syndrome Coronavirus (MERS-CoV)

A deadly respiratory disease Middle East Respiratory Syndrome (MERS) is caused by a perilous virus known as MERS-CoV, which has a severe impact on human health. Currently, there is no approved vaccine, prophylaxis, or antiviral therapeutics for preventing MERS-CoV infection. Due to its inexorable and integral role in the maturation and replication of the MERS-CoV virus, the 3C-like protease is unavoidly a viable therapeutic target. In this study, 2369 phytoconstituents were enlisted from Japanese medicinal plants, and these compounds were screened against 3C-like protease to identify feasible inhibitors. The best three compounds were identified as Kihadanin B, Robustaflavone, and 3-beta-O- (trans-p-Coumaroyl) maslinic acid, with binding energies of −9.8, −9.4, and −9.2 kcal/mol, respectively. The top three potential candidates interacted with several active site residues in the targeted protein, including Cys145, Met168, Glu169, Ala171, and Gln192. The best three compounds were assessed by in silico technique to determine their drug-likeness properties, and they exhibited the least harmful features and the greatest drug-like qualities. Various descriptors, such as solvent-accessible surface area, root-mean-square fluctuation, root-mean-square deviation, hydrogen bond, and radius of gyration, validated the stability and firmness of the protein-ligand complexes throughout the 100ns molecular dynamics simulation. Moreover, the top three compounds exhibited better binding energy along with better stability and firmness than the inhibitor (Nafamostat), which was further confirmed by the binding free energy calculation. Therefore, this computational investigation could aid in the development of efficient therapeutics for life-threatening MERS-CoV infections.

Targeting protein-protein interaction interfaces with antiviral N protein inhibitor in SARS-CoV-2

Coronaviruses not only pose significant global public health threats but also cause extensive damage to livestock-based industries. Previous studies have shown that 5-benzyloxygramine (P3) targets the Middle East respiratory syndrome coronavirus (MERS-CoV) nucleocapsid (N) protein N-terminal domain (N-NTD), inducing non-native protein-protein interactions (PPIs) that impair N protein function. Moreover, P3 exhibits broad-spectrum antiviral activity against CoVs. The sequence similarity of N proteins is relatively low among CoVs, further exhibiting notable variations in the hydrophobic residue responsible for non-native PPIs in the N-NTD. Therefore, to ascertain the mechanism by which P3 demonstrates broad-spectrum anti-CoV activity, we determined the crystal structure of the SARS-CoV-2 N-NTD:P3 complex. We found that P3 was positioned in the dimeric N-NTD via hydrophobic contacts. Compared with the interfaces in MERS-CoV N-NTD, P3 had a reversed orientation in SARS-CoV-2 N-NTD. The Phe residue in the MERS-CoV N-NTD:P3 complex stabilized both P3 moieties. However, in the SARS-CoV-2 N-NTD:P3 complex, the Ile residue formed only one interaction with the P3 benzene ring. Moreover, the pocket in the SARS-CoV-2 N-NTD:P3 complex was more hydrophobic, favoring the insertion of the P3 benzene ring into the complex. Nevertheless, hydrophobic interactions remained the primary stabilizing force in both complexes. These findings suggested that despite the differences in the sequence, P3 can accommodate a hydrophobic pocket in N-NTD to mediate a non-native PPI, enabling its effectiveness against various CoVs.

Identification of a Spike-Specific CD8+ T-Cell Epitope Following Vaccination Against the Middle East Respiratory Syndrome Coronavirus in Humans.

Licensed vaccines against the Middle East respiratory syndrome coronavirus (MERS-CoV), an emerging pathogen of concern, are lacking. The modified vaccinia virus Ankara vector-based vaccine MVA-MERS-S, expressing the MERS-CoV-spike glycoprotein (MERS-S), is one of 3 candidate vaccines in clinical development and elicits robust humoral and cellular immunity. Here, we identified for the first time a MERS-S-specific CD8+ T-cell epitope in an HLA-A*03:01/HLA-B*35:01-positive vaccinee using a screening assay, intracellular cytokine staining, and in silico epitope prediction. As evidence from MERS-CoV infection suggests a protective role of long-lasting CD8+ T-cell responses, the identification of epitopes will facilitate longitudinal analyses of vaccine-induced T-cell immunity.

Insights into the inhibition mechanisms of MERS-CoV and SARS-CoV2 papain-like proteases by inhibitors from Crinum distichum: In vitro and in silico analysis

Highly pathogenic coronaviruses, including the Middle East Respiratory Syndrome Coronavirus (Mers-CoV) and Severe Acute Respiratory Syndrome Coronavirus-2 (Sars-CoV2), have recently emerged and represent a serious threat to global health. Accordingly, a search for potent inhibitors against coronavirus diseases is warranted. Therefore, this study aimed at identifying potential inhibitors from Crinum distichum against the papain-like protease (PLpro), an important antiviral target due to its essential role in viral replication. A bacterial expression system was used for the recombinant expression of Mers-CoV-PLpro and Sars-CoV2-PLpro which was used to assess the inhibitory effect of compounds isolated from C. distichum against their proteolytic and deubiquitinating (DUB) activities. Then, the inhibition mechanism of hit compounds was determined through enzyme kinetic studies. Protein-ligand stability was assessed by Differential Scanning Fluorometry and Molecular docking was used to predict the possible molecular interactions. Five compounds, namely (2S)-4´,7-dimethoxyflavan (CDS1), (2S)-4´‑hydroxy-7-methoxyflavan (CDS2), Hippadine (CDS3), (2R)-4´‑hydroxy-5,7-dimethoxyflavan (CDS4) and Hippacine (CDS5) were tested in this study. They markedly inhibited both the proteolytic and deubiquitinating activities of CoV-PLpro. Their IC50 values were in the low micromolar range. The most potent inhibitors were CDS3 and CDS4, with IC50 values of 9.28 and 6.45 µM, and 11.63 and 6.10 µM against the proteolytic and DUB activities of Mers-CoV-PLpro and Sars-CoV2-PLpro, respectively. They exert their inhibitory effect through competitive and non-competitive inhibition mechanisms. These compounds induced the instability of the enzymes by reducing their melting temperature and molecular docking analysis revealed several molecular interactions between the compounds and various amino acids of the enzymes. Overall, our findings suggest C. distichum active constituents to be promising candidates for development into potential inhibitors against coronavirus.

Association of KIR Genes with Middle East Respiratory Syndrome Coronavirus Infection in South Koreans.

Middle East respiratory syndrome (MERS) is a lower respiratory tract disease caused by a beta coronavirus (CoV) called MERS-CoV, characterized by a high mortality rate. We aimed to evaluate the association between genetic variation in killer cell immunoglobulin-like receptors (KIRs) and the risk of MERS in South Koreans. KIR genes were genotyped by multiplex polymerase chain reaction with sequence-specific primers (PCR-SSP). A case-control study was performed to identify the odds ratios (OR) of KIR genes for MERS and the association of KIR genes and their ligands, human leukocyte antigens (HLA) genes. KIR2DS4D and KIR3DP1F showed higher frequencies in the group of all patients infected with MERS-CoV than in the control group (p = 0.023, OR = 2.4; p = 0.039, OR = 2.7). KIR2DL1, KIR2DP1, and KIR3DP1D were significantly associated with moderate/mild (Mo/Mi) cases. KIR2DL2, KIR2DS1, and KIR3DP1F were affected in severe cases. When we investigated the association between KIR genes and their ligands in MERS patient and control groups, KIR3DL1+/Bw4(80I)+, KIR3DL1+/Bw6+, KIR3DL1+/Bw6-, KIR2DS1+/C2+, and KIR3DS+/Bw4(80I)+ were associated with MERS. KIR3DL1+/Bw6- was found in Mo/Mi cases. KIR2DS1+/C2+ and KIR2DS2+/C1+ were found in severe cases. Further investigations are needed to prove the various immune responses of MERS-CoV-infected cells according to variations in the KIR gene and ligand gene. A treatment strategy based on current research on the KIR gene and MERS-CoV will suggest potential treatment targets.

Mucosal immunity in upper and lower respiratory tract to MERS-CoV.

Middle East respiratory syndrome coronavirus (MERS-CoV) has emerged as a deadly pathogen with a mortality rate of up to 36.2%. MERS-CoV can cause severe respiratory tract disease and multiorgan failure. Therefore, therapeutic vaccines are urgently needed. This intensive review explores the human immune responses and their immunological mechanisms during MERS-CoV infection in the mucosa of the upper and lower respiratory tracts (URT and LRT, respectively). The aim of this study is to provide a valuable, informative, and critical summary of the protective immune mechanisms against MERS-CoV infection in the URT/LRT for the purpose of preventing and controlling MERS-CoV disease and designing effective therapeutic vaccines. In this review, we focus on the immune potential of the respiratory tract following MERS-CoV infection. We searched PubMed, Embase, Web of Science, Cochrane, Scopus, and Google Scholar using the following terms: "MERS-CoV", "B cells", "T cells", "cytokines", "chemokines", "cytotoxic", and "upper and lower respiratory tracts". We found and included 152 studies in this review. We report that the cellular innate immune response, including macrophages, dendritic cells, and natural killer cells, produces antiviral substances such as interferons and interleukins to prevent the virus from spreading. In the adaptive and humoral immune responses, CD4+ helper T cells, CD8+ cytotoxic T cells, B cells, and plasma cells protect against MERS-CoV infection in URT and LRT. The human nasopharynx-associated lymphoid tissue (NALT) and bronchus-associated lymphoid tissue (BALT) could successfully limit the spread of several respiratory pathogens. However, in the case of MERS-CoV infection, limited research has been conducted in humans with regard to immunopathogenesis and mucosal immune responses due to the lack of relevant tissues. A better understanding of the immune mechanisms of the URT and LRT is vital for the design and development of effective MERS-CoV vaccines.

Immunization against Medically Important Human Coronaviruses of Public Health Concern.

SARS-CoV-2 is a virus that affects the human immune system. It was observed to be on the rise since the beginning of 2020 and turned into a life-threatening pandemic. Scientists have tried to develop a possible preventive and therapeutic drug against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and other related coronaviruses by assessing COVID-19-recovered persons' immunity. This study aims to review immunization against SARS-CoV-2, along with exploring the interventions that have been developed for the prevention of SARS-CoV-2. This study also highlighted the role of phototherapy in treating SARS-CoV infection. The study adopted a review approach to gathering the information available and the progress that has been made in the treatment and prevention of COVID-19. Various vaccinations, including nucleotide, subunit, and vector-based vaccines, as well as attenuated and inactivated forms that have already been shown to have prophylactic efficacy against the Middle East respiratory syndrome coronavirus (MERS-CoV) and SARS-CoV, have been summarized. Neutralizing and non-neutralizing antibodies are all associated with viral infections. Because there is no specific antiviral vaccine or therapies for coronaviruses, the main treatment strategy is supportive care, which is reinforced by combining broad-spectrum antivirals, convalescent plasma, and corticosteroids. COVID-19 has been a challenge to keep reconsidering the usual approaches to regulatory evaluation as a result of getting mixed and complicated findings on the vaccines, as well as licensing procedures. However, it is observed that medicinal herbs also play an important role in treating infection of the upper respiratory tract, the principal symptom of SARS-CoV due to their natural bioactive composite. However, some Traditional Chinese Medicines contain mutagens and nephrotoxins and the toxicological properties of the majority of Chinese herbal remedies are unknown. Therefore, to treat the COVID-19 infection along with conventional treatment, it is recommended that herb-drug interaction be examined thoroughly.

Median Tissue Culture Infectious Dose 50 (TCID50) Assay to Determine Infectivity of Cytopathic Viruses.

The emergence of zoonotic viruses like severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and SARS-CoV-2 have significantly impacted global health and economy. The discovery of other viruses in wildlife reservoir species present a threatforfuture emergence in humans and animals. Therefore, assays that are less reliant on virus-specific information, such as neutralization assays, are crucial to rapidlydevelop diagnostics, understand virus replication and pathogenicity, and assess the efficacy of therapeutics against newly emerging viruses. Here, we describe the discontinuous median tissue culture infectious dose 50 (TCID50) assay to quantitatively determine the titer of any virus that can produce a visible cytopathic effect in infected cells.

SARS-CoV-2 NSP12 utilizes various host splicing factors for replication and splicing regulation.

The RNA-dependent RNA polymerase (RdRp) is a crucial element in the replication and transcription of RNA viruses. Although the RdRps of lethal human coronaviruses severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), SARS-CoV, and Middle East respiratory syndrome coronavirus (MERS-CoV) have been extensively studied, the molecular mechanism of the catalytic subunit NSP12, which is involved in pathogenesis, remains unclear. In this study, the biochemical and cell biological results demonstrate the interactions between SARS-CoV-2 NSP12 and seven host proteins, including three splicing factors (SLU7, PPIL3, and AKAP8). The entry efficacy of SARS-CoV-2 considerably decreased when SLU7 or PPIL3 was knocked out, indicating that abnormal splicing of the host genome was responsible for this occurrence. Furthermore, the polymerase activity and stability of SARS-CoV-2 RdRp were affected by the three splicing factors to varying degrees. In addition, NSP12 and its homologues from SARS-CoV and MERS-CoV suppressed the alternative splicing of cellular genes, which were influenced by the three splicing factors. Overall, our research illustrates that SARS-CoV-2 NSP12 can engage with various splicing factors, thereby impacting virus entry, replication, and gene splicing. This not only improves our understanding of how viruses cause diseases but also lays the foundation for the development of antiviral therapies.

Middle East Respiratory Syndrome Coronavirus Could be a Priority Pathogen to Cause Public Health Emergency: Noticeable Features and Counteractive Measures.

Middle East respiratory syndrome (MERS) is caused by a specific strain of the 6 types of human coronaviruses (HCoV). MERS-CoV has spread unchecked since it was first discovered in Saudi Arabia in 2012. The virus most likely spreads through nosocomial and zoonotic channels. Genetic analyses suggest that bats were the initial hosts and that the disease spread to camels. Person-to-person transmission occurs with varying frequency, being most prevalent in clinical settings and the least common among the general population and among close relatives. Due to the severity of the illness, high fatality rate, potential for epidemic spread, and lack of adequate medical countermeasures, the World Health Organization (WHO) continues to list MERS-CoV as a priority pathogen. While no specific antiviral medicines exist, a combination of antivirals has shown promise in recent clinical trials. Vaccines against MERS-CoV are critically needed and are currently being developed. Early diagnosis and implementing appropriate infection control measures are keys to preventing hospital-associated outbreaks. Preventive measures include avoiding raw or undercooked meats and other animal products, ensuring proper hand hygiene in healthcare settings and around dromedaries, educating the public and healthcare personnel about the disease, and adhering to other recommended practices. Countries with a high prevalence of MERS should adhere to regulations designed to limit the transmission of the virus. The recent spread of MERS-CoV highlights the importance of public awareness regarding the significance of reporting symptoms so that appropriate control measures can be adopted. The narrative review discusses the incidence of MERS, its clinical presentation, potential transmission routes, recent reports, preventative and control measures, and current therapeutic options.

Multidisciplinary approaches to combat emerging viruses: diagnostics, therapeutic gene and vaccine delivery, and nanotherapeutics.

Emerging viruses, such as filoviruses (Ebola, Marburg), SARS and MERS coronaviruses, and Zika, pose significant threats to global public health, particularly for individuals with co-morbidities. To address these challenges, this review article explores multidisciplinary strategies for combatting emerging viruses. We emphasize the importance of developing accurate diagnostics, innovative therapeutic gene and vaccine delivery systems, and long-acting nanotherapeutics. These approaches are designed to enhance the safety and efficacy of treatments against these deadly pathogens. We discuss the collaborative efforts of virologists, geneticists, formulation scientists, clinicians, immunologists, and medicinal chemists in advancing these therapeutic modalities.

Fuzzy fractional epidemiological model for Middle East respiratory syndrome coronavirus on complex heterogeneous network using Caputo derivative

This study presents a new fuzzy fractional epidemiological model to investigate the Middle East respiratory syndrome coronavirus on a complex heterogeneous network using fuzzy Caputo gH-differentiability. The model configuration follows a susceptible-infectious-susceptible (SIS) structure for human and camel populations. The equations for the camel population are developed due to its significant role as an animal source for spreading the virus, together with the direct interaction between human and animal populations. Some characteristic properties and results are extracted using fuzzy Caputo derivative. Theoretical findings regarding the existence and uniqueness of mild solutions to fuzzy initial value problems are presented using the general contraction principle. The virus outbreak behavior is discussed using two approaches: an analytical approach using fuzzy Laplace transform and a proposed numerical scheme using integral equations. To enhance the novelty of the work, the proposed numerical scheme is used to solve the fuzzy fractional epidemiological model and provides graphical representations to illustrate the uncertain behavior of the fractional epidemiological model. These numerical experiments show that the magnitude of the disease effect depends on the fractional order and the value of degree in the network. The results of this study suggest that we can overcome the impact of spreading the disease by adhering to infection prevention measures when dealing with animal populations.

Potent 3CLpro inhibitors effective against SARS-CoV-2 and MERS-CoV in animal models by therapeutic treatment.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Middle East respiratory syndrome coronavirus (MERS-CoV) are zoonotic betacoronaviruses that continue to have a significant impact on public health. Timely development and introduction of vaccines and antivirals against SARS-CoV-2 into the clinic have substantially mitigated the burden of COVID-19. However, a limited or lacking therapeutic arsenal for SARS-CoV-2 and MERS-CoV infections, respectively, calls for an expanded and diversified portfolio of antivirals against these coronavirus infections. In this report, we examined the efficacy of two potent 3CLpro inhibitors, 5d and 11d, in fatal animal models of SARS-CoV-2 and MERS-CoV to demonstrate their broad-spectrum activity against both viral infections. These compounds significantly increased the survival of mice in both models when treatment started 1 day post infection compared to no treatment which led to 100% fatality. Especially, the treatment with compound 11d resulted in 80% and 90% survival in SARS-CoV-2 and MERS-CoV-infected mice, respectively. Amelioration of lung viral load and histopathological changes in treated mice correlated well with improved survival in both infection models. Furthermore, compound 11d exhibited significant antiviral activities in K18-hACE2 mice infected with SARS-CoV-2 Omicron subvariant XBB.1.16. The results suggest that these are promising candidates for further development as broad-spectrum direct-acting antivirals against highly virulent human coronaviruses.IMPORTANCEHuman coronaviruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Middle East respiratory syndrome coronavirus (MERS-CoV) continue to have a significant impact on public health. A limited or lacking therapeutic arsenal for SARS-CoV-2 and MERS-CoV infections calls for an expanded and diversified portfolio of antivirals against these coronavirus infections. We have previously reported a series of small-molecule 3C-like protease (3CLpro) inhibitors against human coronaviruses. In this report, we demonstrated the in vivo efficacy of 3CLpro inhibitors for their broad-spectrum activity against both SARS-CoV-2 and MERS-CoV infections using the fatal animal models. The results suggest that these are promising candidates for further development as broad-spectrum direct-acting antivirals against highly virulent human coronaviruses.

ACE2-Fc and DPP4-Fc decoy receptors against SARS-CoV-2 and MERS-CoV variants: a quick therapeutic option for current and future coronaviruses outbreaks.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and the Middle East respiratory syndrome coronavirus (MERS-CoV) are highly pathogenic human coronaviruses (CoVs). Anti-CoVs mAbs and vaccines may be effective, but the emergence of neutralization escape variants is inevitable. Angiotensin-converting enzyme 2 and dipeptidyl peptidase 4 enzyme are the getaway receptors for SARS-CoV-2 and MERS-CoV, respectively. Thus, we reformatted these receptors as Fc-fusion decoy receptors. Then, we tested them in parallel with anti-SARS-CoV (ab1-IgG) and anti-MERS-CoV (M336-IgG) mAbs against several variants using pseudovirus neutralization assay. The generated Fc-based decoy receptors exhibited a strong inhibitory effect against all pseudotyped CoVs. Results showed that although mAbs can be effective antiviral drugs, they might rapidly lose their efficacy against highly mutated viruses. We suggest that receptor traps can be engineered as Fc-fusion proteins for highly mutating viruses with known entry receptors, for a faster and effective therapeutic response even against virus harboring antibodies escape mutations.

Healthcare Workers' Assessment of a Visual Triage System (VTS).

Overcrowding and extended waiting times in the emergency department (ED) can pose a significant risk of COVID-19 transmission from patients to healthy individuals. In 2017, the Saudi Ministry of Health (MOH) introduced a visual triage system (VTS) with scoring to notify healthcare workers (HCWs) in EDs about the Middle East respiratory syndrome coronavirus (MERS-CoV) infection risk. During the COVID-19 pandemic, the MOH employed a VTS to classify patients according to their potential risk of COVID-19 infection upon their admission to the ED. Suspected patients were then directed along specific pathways to reduce their contact with healthy individuals. This study assessed HCWs' satisfaction with the VTS in the ED of two major government hospitals within the Riyadh region. Additionally, it assessed HCWs' perceptions of VTS effectiveness. This study used a cross-sectional, observational design and relied on surveys for data collection. A total of 127 participants completed the survey, of which 87 (68.5%) were based in the EDs of the two hospitals. Among the ED participants, 18.1% expressed satisfaction with the VTS, 46.4% were neutral, and 33.1% reported dissatisfaction. ED participants provided feedback on the system's effectiveness, with 24.1% finding it effective, 66.7% considering it somewhat effective, and 9.2% deeming it ineffective. Of the total (127) study participants (70.1%) reported that the HCWs required better training to effectively implement the VTS infection control plans for suspected cases. Fewer than half of the participants (35.4%) deemed the time spent by VTS personnel to identify COVID-19 cases to be reasonable, whereas 22% found it too short and 27.6% considered it too long. Of the total 127 participants, 63% reported that language differences between patients and HCWs constituted barriers to the effective application of the VTS. Our study findings indicated that most ED participants had a neutral outlook on their satisfaction with the VTS and a neutral perspective on the effectiveness of VTS, viewing it as only somewhat effective. Reported weaknesses and key obstacles to the successful implementation of the VTS included language barriers. and insufficient training for HCWs, andunclear VTS pathways. The reported strengths of the VTS included its effectiveness in reducing crowds and identification of COVID-19 patients.

A potential broad-spectrum neutralizing antibody against Betacoronavirus.

Three pandemics caused by human Betacoronavirus had broken out in the past two decades. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was one of the novel epidemic strains which caused the third pandemic, coronavirus disease 2019 (COVID-19), a global public health crisis. So far, more than millions of people have been infected. Considering the public health and economic impact of Betacoronavirus pandemic, drugs with broad-spectrum activity against these coronaviruses are urgently needed. In this study, two monoclonal antibodies targeting SARS-CoV-2 spike protein receptor-binding domain (RBD) with good neutralizing activity were used to construct a novel immunoglobulin-like bispecific antibody BI31. The neutralizing effect of BI31 against the pseudovirus and the authentic virus is better than that of its parent antibodies alone and in combination. What surprised us most was that the newly constructed bispecific antibody also had the neutralizing activity against SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV) that the parent antibodies did not have. These suggested that the BI31 can not only be developed as a therapeutic drug against COVID-19but it could also become a broad-spectrum therapeutic antibody against Betacoronavirus.

Amino acid substitution L232F in non-structural protein 6 identified as a possible human-adaptive mutation in clade B MERS coronaviruses.

Viral host adaptation plays an important role in inter-species transmission of coronaviruses and influenza viruses. Multiple human-adaptive mutations have been identified in influenza viruses but not so far in MERS-CoV that circulates widely in dromedary camels in the Arabian Peninsula leading to zoonotic transmission. Here, we analyzed clade B MERS-CoV sequences and identified an amino acid substitution L232F in nsp6 that repeatedly occurs in human MERS-CoV. Using a loss-of-function reverse genetics approach, we found the nsp6 L232F conferred increased viral replication competence in vitro, in cultures of the upper human respiratory tract ex vivo, and in lungs of mice infected in vivo. Our results showed that nsp6 L232F may be an adaptive mutation associated with zoonotic transmission of MERS-CoV. This study highlighted the capacity of MERS-CoV to adapt to transmission to humans and also the need for continued surveillance of MERS-CoV in camels.

918. Identification of novel druggable host targets for Middle East respiratory syndrome coronavirus using a quantitative phosphoproteomics approach

Abstract Background Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe respiratory disease and extrapulmonary complications with a high mortality rate. The molecular mechanisms of MERS remain incompletely understood. Phosphoproteomics identifies proteins containing a phosphate group as posttranslational modification and allows rapid analysis of entire phosphorylation-based signaling networks. It has been increasingly used to study virus-host interactions and identify potential host-targeting treatments. Methods Label-free quantitative phosphoproteomics on MERS-CoV-infected lung epithelial Calu-3 cells was performed. A comprehensive siRNA library knockdown screen was then performed for all upregulated phosphoproteins followed by in-silico prediction with Group-based Prediction System 3.0 to identify the top-ranked kinases for further investigations. siRNA knockdown and kinase inhibitor treatment were then performed to validate the biological relevance of the identified host targets in MERS-CoV infection. Human dipeptidyl peptidase 4-knock in (hDPP4-KI) mice were used to evaluate the treatment effects of selected inhibitors. Results We identified more than 300 phosphopeptides that showed a change in phosphorylation status. This markedly perturbed host protein phosphorylation profile included many proteins that were involved in various cellular processes. siRNA library knockdown screen of all upregulated phosphoproteins followed by in silico prediction identified the 5 top-ranked kinases for further investigations. Both siRNA knockdown and kinase inhibitor treatment of these kinases resulted in the significant MERS-CoV load reduction in vitro. Treatment of hDPP4-KI mice with selected kinase inhibitors led to improved clinical outcome with significantly higher survival rate, less body weight loss, and lower lung viral burden. Conclusion Quantitative phosphoproteomics is a useful platform for identifying host factors involved in MERS-CoV infection. Inhibition of these host factors may be a potential treatment strategy for this highly pathogenic coronavirus infection. Disclosures All Authors: No reported disclosures