Intranasal immunization with a Middle East respiratory syndrome-coronavirus antigen conjugated to the M-cell targeting ligand Co4B enhances antigen-specific mucosal and systemic immunity and protects against infection

Middle East respiratory syndrome (MERS) is a threat to public health worldwide. A vaccine against the causative agent of MERS, MERS-coronavirus (MERS-CoV), is urgently needed. We previously identified a peptide ligand, Co4B, which can enhance antigen (Ag) delivery to the nasal mucosa and promote Ag-specific mucosal and systemic immune responses following intranasal immunization. MERS-CoV infects via the respiratory route; thus, we conjugated the Co4B ligand to the MERS-CoV spike protein receptor-binding domain (S-RBD), and used this to intranasally immunize C57BL/6 and human dipeptidyl peptidase 4-transgenic (hDPP4-Tg) mice. Ag-specific mucosal immunoglobulin (Ig) A and systemic IgG, together with virus-neutralizing activities, were highly induced in mice immunized with Co4B-conjugated S-RBD (S-RBD-Co4B) compared to those immunized with unconjugated S-RBD. Ag-specific T cell-mediated immunity was also induced in the spleen and lungs of mice intranasally immunized with S-RBD-Co4B. Intranasal immunization of hDPP4-Tg mice with S-RBD-Co4B reduced immune cell infiltration into the tissues of virus-challenged mice. Finally, S-RBD-Co4B-immunized mice exhibited were better protected against infection, more likely to survive, and exhibited less body weight loss. Collectively, our results suggest that S-RBD-Co4B could be used as an intranasal vaccine candidate against MERS-CoV infection.     

Exportations of Symptomatic Cases of MERS-CoV Infection to Countries outside the Middle East

In 2012, an outbreak of infection with Middle East respiratory syndrome coronavirus (MERS-CoV), was detected in the Arabian Peninsula. Modeling can produce estimates of the expected annual number of symptomatic cases of MERS-CoV infection exported and the likelihood of exportation from source countries in the Middle East to countries outside the region.     

Evaluation of safety,efficacy, tolerability,and treatment-related outcomes of type I interferons for human coronaviruses (HCoVs) infection in clinical practice: An updated critical systematic review and meta-analysis

BackgroundThere is no vaccine or specific antiviral treatment for HCoVs infection. The use of type I interferons for coronavirus is still under great debate in clinical practice.Materials and methodsA literature search of all relevant studies published on PubMed, Cochrane library, Web of Science database, Science Direct, Wanfang Data, and China National Knowledge Infrastructure (CNKI) until February 2020 was performed.ResultsOf the 1081 identified articles, only 15 studies were included in the final analysis. Comorbidities and delay in diagnosis were significantly associated with case mortality. Type I interferons seem to improve respiratory distress, relieve lung abnormalities, present better saturation, reduce needs for supplemental oxygen support. Type I interferons seem to be well tolerated, and don’t increase life threating adverse effects. Data on IFNs in HCoVs are limited, heterogenous and mainly observational.ConclusionsCurrent data do not allow making regarding robust commendations for the use of IFNs in HCoVs in general or in specific subtype. But we still recommend type I interferons serving as first-line antivirals in HCoVs infections within local protocols, and interferons may be adopted to the treatments of the SARS-CoV-2 as well. Well-designed large-scale prospective randomized control trials are greatly needed to provide more robust evidence on this topic.     

Development of Medical Countermeasures to Middle East Respiratory Syndrome Coronavirus

Preclinical development of and research on potential Middle East respiratory syndrome coronavirus (MERS-CoV) medical countermeasures remain preliminary; advancements are needed before most countermeasures are ready to be tested in human clinical trials. Research priorities include standardization of animal models and virus stocks for studying disease pathogenesis and efficacy of medical countermeasures; development of MERS-CoV diagnostics; improved access to nonhuman primates to support preclinical research; studies to better understand and control MERS-CoV disease, including vaccination studies in camels; and development of a standardized clinical trial protocol. Partnering with clinical trial networks in affected countries to evaluate safety and efficacy of investigational therapeutics will strengthen efforts to identify successful medical countermeasures.     

Persistence of Antibodies against Middle East Respiratory Syndrome Coronavirus

To determine how long antibodies against Middle East respiratory syndrome coronavirus persist, we measured long-term antibody responses among persons serologically positive or indeterminate after a 2012 outbreak in Jordan. Antibodies, including neutralizing antibodies, were detectable in 6 (86%) of 7 persons for at least 34 months after the outbreak.     

Pre- and postexposure efficacy of fully human antibodies against Spike protein in a novel humanized mouse model of MERS-CoV infection

Traditional approaches to antimicrobial drug development are poorly suited to combatting the emergence of novel pathogens. Additionally, the lack of small animal models for these infections hinders the in vivo testing of potential therapeutics. Here we demonstrate the use of the VelocImmune technology (a mouse that expresses human antibody-variable heavy chains and κ light chains) alongside the VelociGene technology (which allows for rapid engineering of the mouse genome) to quickly develop and evaluate antibodies against an emerging viral disease. Specifically, we show the rapid generation of fully human neutralizing antibodies against the recently emerged Middle East Respiratory Syndrome coronavirus (MERS-CoV) and development of a humanized mouse model for MERS-CoV infection, which was used to demonstrate the therapeutic efficacy of the isolated antibodies. The VelocImmune and VelociGene technologies are powerful platforms that can be used to rapidly respond to emerging epidemics.Middle East respiratory syndrome coronavirus (MERS-CoV) was first isolated in September 2012 in the Kingdom of Saudi Arabia (1). Since then, more than 1,100 cases and more than 422 deaths have been reported in the Middle East (Iran, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, United Arab Emirates, and Yemen), in Africa (Algeria, Egypt and Tunisia), in Europe (Austria, France, Germany, Greece, Italy, the Netherlands, and the United Kingdom), in Asia (Malaysia and Philippines), and in the United States of America (www.who.int/csr/disease/coronavirus_infections/archive_updates/en/) as of April 29, 2015. Clinical features of MERS-CoV infection in humans range from an asymptomatic infection to very severe pneumonia, with potential development of acute respiratory distress syndrome, shock, and multiorgan failure, resulting in death (2).MERS-CoV is a betacoronavirus related to the severe acute respiratory syndrome coronavirus (SARS-CoV). Both viruses cause severe respiratory tract infections and are associated with high mortality rates. Although human-to-human transmission of MERS-CoV has been reported (3), the rate of transmission appears to be low (4, 5). Recent studies have suggested that dromedary camels are involved in the zoonotic transmission of MERS-CoV; analyses of camel sera indicate MERS-CoV seropositivity in camels throughout the Middle East and Africa, suggesting MERS-CoV maintenance in camel populations (6–8).The MERS-CoV virion is decorated with a class I transmembrane envelope protein named Spike (S). S protein forms a homo-trimer and mediates binding to host receptors, membrane fusion, and entry into susceptible cells (9); consistent with this, MERS-CoV S protein is a major target for neutralizing antibodies (10). The receptor for MERS-CoV was identified as dipeptidyl peptidase 4 (DDP4, also known as CD26) (11), a protein with diverse functions in glucose homeostasis, T-cell activation, neurotransmitter function, and modulation of cardiac signaling (12). DPP4 is expressed in a variety of cell types, including endothelial cells, hepatocytes, enterocytes, and cells of the renal glomeruli and proximal tubules (12). Moreover, DPP4 recognition is mediated by the receptor-binding doman (RBD, amino acids E367–Y606), and the structural basis for this interaction was recently delineated (13, 14).Currently, there are no approved treatments or vaccines to treat or prevent MERS-CoV infections. Type I IFN and ribavirin have been reported to ameliorate disease in infected macaques (15), and small molecules targeting diverse intracellular pathways have been shown to inhibit MERS-CoV in vitro (16–18). Furthermore, experimental immunogens can elicit an anti–MERS-CoV response (19, 20). However, no MERS-CoV targeting therapeutic has been demonstrated to function in vivo, partly because of limited small animal models of infection (21–23). MERS-CoV does not natively replicate in wild-type mice. Two mouse models have been developed. In the first, a modified adenovirus expressing huDPP4 is administered intranasally to mice leading to huDPP4 expression in all cells of the lung, not just those that natively express DPP4 (21). In this model, mice show transient huDPP4 expression and mild lung disease. In the second model (23), a transgenic mouse was produced that expresses huDPP4 in all cells of the body, which in not physiologically relevant. In this model, MERS-CoV infection leads to high levels of viral RNA and inflammation in the lungs, but also significant inflammation and viral RNA in the brains of infected mice. However, no previous reports have documented tropism of MERS-CoV to the brains of an infected host, suggesting that studying pathogenesis of MERS-CoV in this model is limited. Therefore, there is a need for development of physiologically relevant small animal models to study MERS-CoV pathogenesis, as well as to test anti–MERS-CoV therapeutics in vivo.Here we use the VelocImmune platform to rapidly generate a panel of fully human, noncompeting monoclonal antibodies that bind to MERS-CoV S protein and inhibit entry into target cells. We show that two of these antibodies can potently neutralize pseudoparticles generated with all clinical MERS-CoV S RBD variants isolated to date. Importantly, we demonstrate that the fully human VelocImmune antibodies neutralize infectious MERS-CoV significantly more than published monoclonals isolated using traditional methods. Finally, we used the VelociGene technology to develop a novel humanized model for MERS-CoV infection and showed that our antibodies can prevent and treat MERS-CoV infection in vivo. Our antibodies are, to our knowledge, the first anti–MERS-CoV fully human antibodies to block MERS-CoV infection in vivo and are promising therapeutic candidates. Importantly, we demonstrate the value of the VelocImmune and VelociGene platforms for the rapid generation and validation of therapeutic antibodies against emerging viral pathogens.