Pathogenesis of Middle East respiratory syndrome coronavirus

Host-directed therapies for improving poor treatment outcomes associated with the middle east respiratory syndrome coronavirus infections

Three years after its first discovery in Jeddah Saudi Arabia, the novel zoonotic pathogen of humans, the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) continues to be a major threat to global health security.(1) Sporadic community acquired cases of MERS continue to be reported from the Middle East. The recent nosocomial outbreaks in hospitals in Seoul, Korea and at the National Guard Hospital in Riyadh, Saudi Arabia indicate the epidemic potential of MERS-CoV. Currently there are no effective anti-MERS-CoV anti-viral agents or therapeutics and MERS is associated with a high mortality rate (40%) in hospitalised patients. A large proportion of MERS patients who die have a range of pulmonary pathology ranging from pneumonia to adult respiratory distress syndrome with multi-organ failure, compounded by co-morbidities, reflecting a precarious balance of interactions between the host-immune system and MERS-CoV. Whilst we wait for new MERS-CoV specific drugs, therapeutics and vaccines to be developed, there is a need to advance a range of Host-Directed Therapies. A range of HDTs are available, including commonly used drugs with good safety profiles, which could augment host innate and adaptive immune mechanisms to MERS-CoV, modulate excessive inflammation and reduce lung tissue destruction. We discuss the rationale and potential of using Host-Directed Therapies for improving the poor treatment outcomes associated with MERS. Carefully designed randomized controlled trials will be needed to determine whether HDTs could benefit patients with MERS. The recurrent outbreaks of MERS-CoV infections at hospitals in the Middle East present unique opportunities to conduct randomized clinical trials. The time has come for a more coordinated global response to MERS and a multidisciplinary global MERS-CoV response group is required to take forward priority research agendas.

Critical care medicine for emerging Middle East respiratory syndrome: Which point to be considered?

The Middle East respiratory syndrome (MERS) is a new emerging respiratory tract infection. This coronavirus infection is firstly reported from the Middle East, and it becomes threat for the global public health at present due to its existence in a remote area such as USA and Korea. The concern on the management of the patients is very important. Since most of the patients can develop severe respiratory illness and critical care management is needed, the issue on critical care for MERS is the topic to be discussed in critical medicine.

Recombinant Receptor Binding Domain Protein Induces Partial Protective Immunity in Rhesus Macaques Against Middle East Respiratory Syndrome Coronavirus Challenge

Background

Development an effective vaccine against Middle East respiratory syndrome coronavirus (MERS-CoV) is urgent and limited information is available on vaccination in nonhuman primate (NHP) model. We herein report of evaluating a recombinant receptor-binding domain (rRBD) protein vaccine in a rhesus macaque model.

Methods

Nine monkeys were randomly assigned to high-dose, low-dose and mock groups,which were immunized with different doses of rRBD plus alum adjuvant or adjuvant alone at different time points (0, 8, 25 weeks). Immunological analysis was conducted after each immunisation. Monkeys were challenged with MERS-CoV at 14 days after the final immunisation followed by observation for clinical signs and chest X-rays. Nasal, oropharyngeal and rectal swabs were also collected for analyses. Monkeys were euthanized 3 days after challenge and multiple specimens from tissues were collected for pathological, virological and immunological tests.

Conclusion

Robust and sustained immunological responses (including neutralisation antibody) were elicited by the rRBD vaccination. Besides, rRBD vaccination alleviated pneumonia with evidence of reduced tissue impairment and clinical manifestation in monkeys. Furthermore, the rRBD vaccine decreased viral load of lung, trachea and oropharyngeal swabs of monkeys. These data in NHP paves a way for further development of an effective human vaccine against MERS-CoV infection.

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In this study, we evaluated a recombinant receptor binding domain(rRBD) based subunit vaccine in a rhesus macaque model.

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Significant and sustained immunuity in a rhesus macaque model were elicited by the rRBD vaccination.

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Partial protection was observed in the vaccinated monkeys against the MERS-CoV challenge.

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We suggest the partial protection in monkey against the MERS-CoV challenge may be conferred by neutralizing antibodies induced by rRBD immunity.

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The study provided useful information for the development of a human vaccine against MERS-CoV infection.

Middle East respiratory syndrome coronavirus "MERS-CoV": current knowledge gaps

The Middle East respiratory syndrome coronavirus (MERS-CoV) that causes a severe lower respiratory tract infection in humans is now considered a pandemic threat to the Gulf region. Since its discovery in 2012, MERS-CoV has reached 23 countries affecting about 1100 people, including a dozen children, and claiming over 400 lives. Compared to SARS (severe acute respiratory syndrome), MERS-CoV appears to kill more people (40% versus 10%), more quickly, and is especially more severe in those with pre-existing medical conditions. Most MERS-CoV cases (>85%) reported thus far have a history of residence in, or travel to the Middle East. The current epidemiology is characterised by slow and sustained transmission with occasional sparks. The dromedary camel is the intermediate host of MERS-CoV, but the transmission cycle is not fully understood. In this current review, we have briefly summarised the latest information on the epidemiology, clinical features, diagnosis, treatment and prevention of MERS-CoV especially highlighting the knowledge gaps in its transmission dynamics, diagnosis and preventive strategy.

What needs to be done to control the spread of Middle East respiratory syndrome coronavirus?

Up to November 2014, Middle East respiratory syndrome coronavirus (MERS-CoV) has infected 935 individuals and killed 371, all originating in or with links to the Middle East. The mechanisms of transmission of the disease are not fully understood, but MERS-CoV seems to sustain itself in the human population through repeated re-introduction from a camel reservoir and is able to cause nosocomial outbreaks. The risk of a global spread of MERS-CoV is low. Epidemiological, serological and phylogenetic research, combined with one health surveillance, dynamic case definitions, active case finding, rigorous infection control, culturally sensitive risk communication and a continuous re-evaluation of new evidence will enable to better understand the disease, limit its spread and quantify its risk in order to better prepare for a hypothetical spread.

Middle East Respiratory Syndrome Corona Virus (MERS CoV): The next steps

Developing countries are at risk of importing Middle East Respiratory Syndrome Corona Virus (MERS CoV) from the Middle East. Hospitals in the Middle East currently reporting the disease are staffed by immigrants. In the current hot spots for MERS CoV a sizeable portion of the population is from other countries, but many of these countries have yet to detect any importation of MERS CoV. To assess the disease transmission in these countries, supplemental surveillance strategies are urgently needed beyond the currently recommended measures. A few strategies to address the situation are: (i) improving preparedness with enhanced surveillance in particular regions; (ii) targeting certain sentinel groups for surveillance in hot spots; and (iii) limited use of serosurveillance. Recovered, immune patients can be employed to give patient care during outbreaks.

Viruses and disease: emerging concepts for prevention, diagnosis and treatment

Viruses cause a wide range of human diseases, ranging from acute self‐resolving conditions to acute fatal diseases. Effects that arise long after the primary infection can also increase the propensity for chronic conditions or lead to the development of cancer. Recent advances in the fields of virology and pathology have been fundamental in improving our understanding of viral pathogenesis, in providing improved vaccination strategies and in developing newer, more effective treatments for patients worldwide. The reviews assembled here focus on the interface between virology and pathology and encompass aspects of both the clinical pathology of viral disease and the underlying disease mechanisms. Articles on emerging diseases caused by Ebola virus, Marburg virus, coronaviruses such as SARS and MERS, Nipah virus and noroviruses are followed by reviews of enteroviruses, HIV infection, measles, mumps, human respiratory syncytial virus (RSV), influenza, cytomegalovirus (CMV) and varicella zoster virus (VZV). The issue concludes with a series of articles reviewing the relationship between viruses and cancer, including the role played by Epstein–Barr virus (EBV) in the pathogenesis of lymphoma and carcinoma; how human papillomaviruses (HPVs) are involved in the development of skin cancer; the involvement of hepatitis B virus infection in hepatocellular carcinoma; and the mechanisms by which Kaposi's sarcoma‐associated herpesvirus (KSHV) leads to Kaposi's sarcoma. We hope that this collection of articles will be of interest to a wide range of scientists and clinicians at a time when there is a renaissance in the appreciation of the power of pathology as virologists dissect the processes of disease. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Molecular pathology of emerging coronavirus infections

Respiratory viruses can cause a wide spectrum of pulmonary diseases, ranging from mild, upper respiratory tract infections to severe and life-threatening lower respiratory tract infections, including the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Viral clearance and subsequent recovery from infection require activation of an effective host immune response; however, many immune effector cells may also cause injury to host tissues. Severe acute respiratory syndrome (SARS) coronavirus and Middle East respiratory syndrome (MERS) coronavirus cause severe infection of the lower respiratory tract, with 10% and 35% overall mortality rates, respectively; however, >50% mortality rates are seen in the aged and immunosuppressed populations. While these viruses are susceptible to interferon treatment in vitro, they both encode numerous genes that allow for successful evasion of the host immune system until after high virus titres have been achieved. In this review, we discuss the importance of the innate immune response and the development of lung pathology following human coronavirus infection.