#MERS #Coronavirus in #Dromedaries in #Ethiopia Is Antigenically #Different From the Middle East Isolate EMC (Front Microbiol., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Front Microbiol. 2019 Jun 19;10:1326. doi: 10.3389/fmicb.2019.01326. eCollection 2019.

Middle East Respiratory Syndrome Coronavirus in Dromedaries in Ethiopia Is Antigenically Different From the Middle East Isolate EMC.

Shirato K1, Melaku SK2, Kawachi K3, Nao N1, Iwata-Yoshikawa N4, Kawase M1, Kamitani W3, Matsuyama S1, Tessema TS5, Sentsui H6.

Author information: 1 Department of Virology III, National Institute of Infectious Diseases, Musashimurayama, Japan. 2 Department of Biotechnology, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia. 3 Laboratory of Clinical Research on Infectious Diseases, Department of Pathogen Molecular Biology, Research Institute for Microbial Diseases, Osaka University, Suita, Japan. 4 Department of Pathology, National Institute of Infectious Diseases, Musashimurayama, Japan. 5 Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia. 6 Laboratory of Veterinary Epizootiology, Department of Veterinary Medicine, Nihon University, Fujisawa, Japan.



Middle East respiratory syndrome (MERS) is an emerging respiratory disease caused by the MERS coronavirus (MERS-CoV). MERS has been endemic to Saudi Arabia since 2012. The reservoir of MERS-CoV is the dromedary camel, suggesting that MERS is primarily a zoonotic disease. MERS-CoV is common in dromedaries throughout the Middle East, North Africa, and East Africa as evidenced by neutralizing antibodies against MERS-CoV; however, human cases have remained limited to the Middle East. To better understand the cause of this difference, the virological properties of African camel MERS-CoV were analyzed based on the spike (S) protein in Ethiopia. Nasal swabs were collected from 258 young dromedaries (≤ 2 years old) in the Afar region of Ethiopia, of which 39 were positive for MERS-CoV, as confirmed by genetic tests. All positive tests were exclusive to the Amibara woreda region. Using next-generation sequencing, two full-length genomes of Amibara isolates were successfully decoded; both isolates belonged to the C2 clade based on phylogenetic analysis of full-length and S protein sequences. Recombinant EMC isolates of MERS-CoV, in which the S protein is replaced with those of Amibara isolates, were then generated to test the roles of these proteins in viral properties. Amibara S recombinants replicated more slowly in cultured cells than in EMC S recombinants. In neutralizing assays, Amibara S recombinants were neutralized by lower concentrations of sera from both Ethiopian dromedaries and EMC isolate (wild-type)-immunized mouse sera, relative to the EMC S recombinants, indicating that viruses coated in the Amibara S protein were easier to neutralize than the EMC S protein. Neutralization experiments performed using S1/S2 chimeric recombinants of the EMC and Amibara S proteins showed that the neutralization profile was dependent on the S1 region of the S protein. These results suggest that the slower viral replication and the ease of neutralization seen in the Ethiopian MERS-CoV are due to strain-specific differences in the S protein and may account for the absence of human MERS-CoV cases in Ethiopia.

KEYWORDS: Ethiopia; Middle East respiratory syndrome; Middle East respiratory syndrome coronavirus; antigenicity; dromedary; neutralization

PMID: 31275264 PMCID: PMC6593072 DOI: 10.3389/fmicb.2019.01326

Keywords: MERS-CoV; Serology; Camels; Ethiopia.


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Giuseppe Michieli

I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.