MERS antibodies identified in camels

Researchers have identified camels in the Middle East that had antibodies against the Middle East respiratory syndrome coronavirus, suggesting that they may be a reservoir of the virus, according to a report in The Lancet Infectious Diseases.

As of Aug. 30, there have been 108 laboratory-confirmed cases of MERS coronavirus in humans, including 50 deaths, according to WHO. An Emergency Committee of the International Health Regulations has not declared the situation a Public Health Emergency of International Concern, but the primary reservoir of the virus is still unknown.

In the first reported animal serological study for MERS coronavirus, researchers in the Netherlands evaluated 349 blood serum samples taken from a variety of livestock animals, included dromedary camels, cows, sheep and goats, from various countries. They analyzed the serum for antibodies specific to MERS coronavirus, as well as antibodies to the SARS coronavirus and another coronavirus strain.

They found there was no cross-reactivity between the antibodies for MERS coronavirus and those for SARS or the other coronavirus. This suggests that the presence of MERS coronavirus antibodies indicates a previous infection with MERS coronavirus.

There were no antibodies identified in 160 cattle, sheep and goats from the Netherlands and Spain. In all 50 serum samples taken from dromedary camels in Oman, however, there were antibodies specific to MERS coronavirus. The samples were taken from camels in various locations, suggesting that the virus is widely circulated in camels throughout the region.

The data also indicated lower levels of MERS coronavirus antibodies among 14% of the serum samples taken from two herds of dromedary camels in the Canary Islands. When testing species closely related to the dromedary camel, such as Bactrian camels, alpacas and llamas, no antibodies were detected.

“As new human cases of MERS coronavirus continue to emerge, without any clues about the sources of infection except for people who caught it from other patients, these new results suggest that dromedary camels may be one reservoir of the virus that is causing MERS coronavirus in humans,” the researchers wrote. “Dromedary camels are a popular animal species in the Middle East, where they are used for racing, and also for meat and milk, so there are different types of contact of humans with these animals that could lead to transmission of a virus.”

In an accompanying editorial, Vincent Munster, PhD, chief of the virus ecology unit, laboratory of virology, at NIAID, said these data provide some insight into a potential animal reservoir for this virus, the first since its discovery 1 year ago.

Vincent Munster

“In the absence of prophylactic or therapeutic treatment options for MERS coronavirus, blocking zoonotic and human-to-human transmission could be the most promising and cost-effective method to prevent further human fatalities,” he wrote. “However, doing so requires knowledge of the virus’ hosts. Although this study … leaves many questions unanswered, it is an important step to a more comprehensive understanding of the emergence of MERS coronavirus.”

Infectious Disease News Chief Medical Editor Paul A. Volberding, MD, said this study supports the One Health movement to always consider infectious disease relationships between humans and animals, including domestic ones.

-Last updated September 6, 2013.

For more information:

Reusken C. Lancet Infect Dis. 2013;doi:10.1016/S1473-3099(13)70164-6.
Munster V. Lancet Infect Dis. 2013;doi:10.1016/S1473-3099(13)701193-2.

Disclosure: The researchers and Munster report no relevant financial disclosures.