Middle East Respiratory Syndrome Vaccine Candidates: Cautious Optimism.
Ontology highlight
ABSTRACT:
SUBMITTER: Schindewolf C
PROVIDER: S-EPMC6356267 | BioStudies | 2019-01-01
REPOSITORIES: biostudies
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Project description:Seven years after the Middle East respiratory syndrome (MERS) outbreak, a new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) made its first appearance in a food market in Wuhan, China, drawing an entirely new course to our lives. As the virus belongs to the same genus of MERS and SARS, researchers have been trying to draw lessons from previous outbreaks to find a potential cure. Although there were five Phase I human vaccine trials against SARS and MERS, the lack of data in humans provided us with limited benchmarks that could help us design a new vaccine for Coronavirus disease 2019 (COVID-19). In this review, we showcase the similarities in structures of virus components between SARS-CoV, MERS-CoV, and SARS-CoV-2 in areas relevant to vaccine design. Using the ClinicalTrials.gov and World Health Organization (WHO) databases, we shed light on the 16 current approved clinical trials worldwide in search for a COVID-19 vaccine. The different vaccine platforms being tested are Bacillus Calmette-Guérin (BCG) vaccines, DNA and RNA-based vaccines, inactivated vaccines, protein subunits, and viral vectors. By thoroughly analyzing different trials and platforms, we also discuss the advantages and disadvantages of using each type of vaccine and how they can contribute to the design of an adequate vaccine for COVID-19. Studying past efforts invested in conducting vaccine trials for MERS and SARS will provide vital insights regarding the best approach to designing an effective vaccine against COVID-19.
2020-01-01 | S-EPMC7472384 | BioStudies
Project description:Middle East respiratory syndrome (MERS) is an acute, high-mortality-rate, severe infectious disease caused by an emerging MERS coronavirus (MERS-CoV) that causes severe respiratory diseases. The continuous spread and great pandemic potential of MERS-CoV make it necessarily important to develop effective vaccines. We previously demonstrated that the application of Gram-positive enhancer matrix (GEM) particles as a bacterial vector displaying the MERS-CoV receptor-binding domain (RBD) is a very promising MERS vaccine candidate that is capable of producing potential neutralization antibodies. We have also used the rabies virus (RV) as a viral vector to design a recombinant vaccine by expressing the MERS-CoV S1 (spike) protein on the surface of the RV. In this study, we compared the immunological efficacy of the vaccine candidates in BALB/c mice in terms of the levels of humoral and cellular immune responses. The results show that the rabies virus vector-based vaccine can induce remarkably earlier antibody response and higher levels of cellular immunity than the GEM particles vector. However, the GEM particles vector-based vaccine candidate can induce remarkably higher antibody response, even at a very low dose of 1 µg. These results indicate that vaccines constructed using different vaccine vector platforms for the same pathogen have different rates and trends in humoral and cellular immune responses in the same animal model. This discovery not only provides more alternative vaccine development platforms for MERS-CoV vaccine development, but also provides a theoretical basis for our future selection of vaccine vector platforms for other specific pathogens.
2020-01-01 | S-EPMC7019946 | BioStudies
Project description:Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is an emerging pathogen with the potential to pose a threat to global public health. Sporadic cases and outbreaks continue to be reported in the Middle East, and case fatality rates remain high at approximately 36% globally. No specific preventive or therapeutic countermeasures currently exist. A safe and effective vaccine could play an important role in protecting against the threat from MERS-CoV. This review discusses human vaccine candidates currently under development, and explores viral characteristics, molecular epidemiology and immunology relevant to MERS-CoV vaccine development. At present, a DNA vaccine candidate has begun a human clinical trial, while two vector-based candidates will very soon begin human trials. Protein-based vaccines are still at pre-clinical stage. Challenges to successful development include incomplete understanding of viral transmission, pathogenesis and immune response (in particular at the mucosal level), no optimal animal challenge models, lack of standardized immunological assays, and insufficient sustainable funding.
1000-01-01 | S-EPMC5806638 | BioStudies
Project description:The Middle East respiratory syndrome coronavirus (MERS-CoV) has infected more than 1900 humans, since 2012. The syndrome ranges from asymptomatic and mild cases to severe pneumonia and death. The virus is believed to be circulating in dromedary camels without notable symptoms since the 1980s. Therefore, dromedary camels are considered the only animal source of infection. Neither antiviral drugs nor vaccines are approved for veterinary or medical use despite active research on this area. Here, we developed four vaccine candidates against MERS-CoV based on ChAdOx1 and MVA viral vectors, two candidates per vector. All vaccines contained the full-length spike gene of MERS-CoV; ChAdOx1 MERS vaccines were produced with or without the leader sequence of the human tissue plasminogen activator gene (tPA) where MVA MERS vaccines were produced with tPA, but either the mH5 or F11 promoter driving expression of the spike gene. All vaccine candidates were evaluated in a mouse model in prime only or prime-boost regimens. ChAdOx1 MERS with tPA induced higher neutralising antibodies than ChAdOx1 MERS without tPA. A single dose of ChAdOx1 MERS with tPA elicited cellular immune responses as well as neutralising antibodies that were boosted to a significantly higher level by MVA MERS. The humoral immunogenicity of a single dose of ChAdOx1 MERS with tPA was equivalent to two doses of MVA MERS (also with tPA). MVA MERS with mH5 or F11 promoter induced similar antibody levels; however, F11 promoter enhanced the cellular immunogenicity of MVA MERS to significantly higher magnitudes. In conclusion, our study showed that MERS-CoV vaccine candidates could be optimized by utilising different viral vectors, various genetic designs of the vectors, or different regimens to increase immunogenicity. ChAdOx1 and MVA vectored vaccines have been safely evaluated in camels and humans and these MERS vaccine candidates should now be tested in camels and in clinical trials.
2017-01-01 | S-EPMC5516308 | BioStudies
Project description:Aim The purpose of this review is to discuss the current status of local and international efforts undergoing clinical trials aiming at developing a Coronavirus Disease-2019 (COVID-19) vaccine, and to highlight the anticipated challenges of this vaccine globally and in Saudi Arabia. Present Findings COVID-19 vaccine development efforts started in early January 2020 when Chinese scientists shared the Coronavirus genomic sequence in public domain. Approximately 321 research groups initiated the search for a vaccine, out of which 41 have reached phase I/II trails and 11 reached phase-III clinical trials, including approved vaccines for early to limited use. Out of these projects are two labs in the Kingdom of Saudi Arabia still in early stages of development of a COVID-19 vaccine. Several vaccine attempts are being tested from traditional, attenuated virus methods, to new nucleic acid-based designs. However, no vaccine has yet completed clinical trials and reached public domain. In spite of the challenges faced during previous vaccine trials, researchers have found that Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), the causative agent of COVID-19 is structurally similar to the (SARS-CoV-1) and the Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV), which caused epidemics in 2003 and 2012 respectively. Both SARS strains show identical affinity towards the type-II alveolar pneumocytes angiotensin converting enzyme-2 (ACE-2) receptor binding domains and therefore, similar pathogenicity. The race to develop the vaccine is predominantly for individuals at high risk of developing the infection, i.e. population groups who are most susceptible to experiencing fatal symptoms of the coronavirus. These include patients with comorbidities, above the age of 60 years and people at risk of contracting large viral loads, such as healthcare providers caring for critical admissions in in-patient wards, Intensive Care Units and Emergency Room settings. Summary Many different vaccine strategies are under development throughout different stages of the research timeline; however, it is estimated that none will show favorable results before end of 2020. For any immunization or interventional prevention/therapy system to reach the public and patients at high risk, it needs to undergo multiple phase trials to ensure safety and effectiveness. In this scoping review we aim to map the literature on COVID-19 vaccines and provide recommendations related to gaps in research, applicability and expected challenges for implementation of nationwide vaccination in Saudi Arabia.
2020-01-01 | S-EPMC7654289 | BioStudies
Project description:A new type of coronavirus has been identified as the causative agent underlying Middle East Respiratory Syndrome (MERS). The MERS coronavirus (MERS-CoV) has spread in the Middle East, but cases originating in the Middle East have also occurred in the European Union and the USA. Eight hundred and thirty-seven cases of MERS-CoV infection have been confirmed to date, including 291 deaths. MERS-CoV has infected dromedary camel populations in the Middle East at high rates, representing an immediate source of human infection. The MERS-CoV spike (S) protein, a characteristic structural component of the viral envelope, is considered as a key target of vaccines against coronavirus infection. In an initial attempt to develop a MERS-CoV vaccine to ultimately target dromedary camels, we constructed two recombinant adenoviral vectors encoding the full-length MERS-CoV S protein (Ad5.MERS-S) and the S1 extracellular domain of S protein (Ad5.MERS-S1). BALB/c mice were immunized with both candidate vaccines intramuscularly and boosted three weeks later intranasally. All the vaccinated animals had antibody responses against spike protein, which neutralized MERS-CoV in vitro. These results show that an adenoviral-based vaccine can induce MERS-CoV-specific immune responses in mice and hold promise for the development of a preventive vaccine that targets the animal reservoir, which might be an effective measure to eliminate transmission of MERS-CoV to humans.
2014-01-01 | S-EPMC7115510 | BioStudies
Project description:Middle East respiratory syndrome coronavirus (MERS-CoV) has recently emerged as a causative agent of severe respiratory disease in humans. Here, we constructed recombinant modified vaccinia virus Ankara (MVA) expressing full-length MERS-CoV spike (S) protein (MVA-MERS-S). The genetic stability and growth characteristics of MVA-MERS-S make it a suitable candidate vaccine for clinical testing. Vaccinated mice produced high levels of serum antibodies neutralizing MERS-CoV. Thus, MVA-MERS-S may serve for further development of an emergency vaccine against MERS-CoV.
2013-01-01 | S-EPMC3807317 | BioStudies
Project description:Developing a vaccine to protect against the lethal effects of the many strains of coronavirus is critical given the current global pandemic. For Middle East respiratory syndrome coronavirus (MERS-CoV), we show that rhesus macaques seroconverted rapidly after a single intramuscular vaccination with ChAdOx1 MERS. The vaccine protected against respiratory injury and pneumonia and reduced viral load in lung tissue by several orders of magnitude. MERS-CoV replication in type I and II pneumocytes of ChAdOx1 MERS-vaccinated animals was absent. A prime-boost regimen of ChAdOx1 MERS boosted antibody titers, and viral replication was completely absent from the respiratory tract tissue of these rhesus macaques. We also found that antibodies elicited by ChAdOx1 MERS in rhesus macaques neutralized six different MERS-CoV strains. Transgenic human dipeptidyl peptidase 4 mice vaccinated with ChAdOx1 MERS were completely protected against disease and lethality for all different MERS-CoV strains. The data support further clinical development of ChAdOx1 MERS.
2020-01-01 | S-EPMC7286676 | BioStudies
Project description:Middle East respiratory syndrome coronavirus (MERS-CoV) has been a highly threatening zoonotic pathogen since its outbreak in 2012. Similar to SARS-CoV, MERS-CoV belongs to the coronavirus family and can induce severe respiratory symptoms in humans, with an average case fatality rate of 35% according to the World Health Organization. Spike (S) protein of MERS-CoV is immunogenic and can induce neutralizing antibodies, thus is a potential major target for vaccine development. Here we constructed a chimeric virus based on the vesicular stomatitis virus (VSV) in which the G gene was replaced by MERS-CoV S gene (VSV?G-MERS). The S protein efficiently incorporated into the viral envelope and mediated cell entry through binding its receptor, human DPP4. Knockdown of clathrin expression by siRNA drastically abrogated the infection of VSV?G-MERS in Vero cells. Furthermore, in animal studies, the recombinant virus induced neutralizing antibodies and T cell responses in rhesus monkeys after a single intramuscular or intranasal immunization dose. Our findings indicate the potential of the chimeric VSV?G-MERS as a rapid response vaccine candidate against emerging MERS-CoV disease.
2018-01-01 | S-EPMC7113862 | BioStudies
Project description:Middle East respiratory syndrome coronavirus (MERS-CoV) is a novel zoonotic virus that causes severe respiratory disease in humans with a case fatality rate close to 40%, but for which no vaccines are available. Here, we evaluated the utility of ChAdOx1, a promising replication-deficient simian adenovirus vaccine vector platform with an established safety profile in humans and dromedary camels, for MERS-CoV vaccine development. Using a transgenic lethal BALB/c MERS-CoV mouse model we showed that single dose intranasal or intramuscular immunisation with ChAdOx1 MERS, encoding full-length MERS-CoV Spike glycoprotein, is highly immunogenic and confers protection against lethal viral challenge. Immunogenicity and efficacy were comparable between immunisation routes. Together these data provide support for further evaluation of ChAdOx1 MERS vaccine in humans and dromedary camels, the animal reservoir of infection.
2017-01-01 | S-EPMC5643297 | BioStudies