MERS Likely To Have Come From Camels

A study comparing the genomes of MERS coronaviruses isolated from humans and camels suggests the zoonotic origins of the disease.

AsianScientist (Sep. 3, 2014) – An international research team, led by Professor Malik Peiris, Chair Professor of Virology and Director of School of Public Health at the University of Hong Kong (HKU), has found that the Middle East respiratory syndrome coronavirus (MERS-CoV) from dromedary camels in Saudi Arabia and Egypt efficiently infects cultures of the human respiratory tract tissues. The research has been published in the journal Lancet Respiratory Medicine.

MERS is a severe pneumonic illness caused by a novel coronavirus. From April 2012 to July 2014, there were 837 confirmed human MERS cases leading to 291 deaths reported to the World Health Organization. The human virus is believed to be of zoonotic origin but some limited human-to-human transmission has taken place.

MERS-CoV is found in dromedary camels (Camelus dromedaries) which are the one-humped camels typically found in the Middle East and Northeast Africa, in contrast to Bactrian or two-humped camels (Camelus bactrianus) which inhabit Central Asia. However, the number of MERS-CoV isolates from camels is limited and there have been no systematic biological characterization of these camel viruses so far.

In the present study, two camel MERS-CoVs from Saudi Arabia and one camel MERS-CoV from Egypt were compared with a human MERS-CoV isolated in Saudi Arabia for their ability to infect and replicate in human respiratory tissues maintained in experimental settings. The researchers observed that both animal and human viruses can infect the same cell types in human bronchial and lung tissues with comparable virus replication kinetics.

MERS-CoV was previously known to evade the human first-line immune defense system (e.g. interferons). The current study shows that camel MERS-CoV might also have the capacity to by-pass these first-line defense mechanisms in humans.

“Genetically diverse MERS-CoV from dromedary camels in Saudi Arabia and Egypt were very similar to MERS-CoV from humans. Most importantly, both human and camel viruses can efficiently infect tissues of human respiratory tract. This suggests that viruses from camels can infect humans,” said Prof. Peiris.

“Our findings further suggest that the transmission of MERS-CoV from camels to humans might not only be restricted to the Arabian peninsula (from where primary human MERS cases have so far being detected), but might also be found in parts of Africa.”

The study highlights the need for more studies to map the full geographic range of MERS-CoV infections in camels, as well as studies to identify how MERS-CoV is transmitted from camels to humans.

The article can be found at: Chan et al. (2014) Tropism and Replication of Middle East Respiratory Syndrome Coronavirus from Dromedary Camels in the Human Respiratory Tract: an in-vitro and ex-vivo Study.

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Source: The University of Hong Kong.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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