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In a finding with global health implications, a research team led by a doctoral student at Colorado State University has confirmed for the first time that camels vent volumes of the deadly Middle East Respiratory Syndrome (MERS) virus, making them the likeliest suspect for spreading the pathogen to people.
Now the CSU team is testing a vaccine that could keep camels from shedding the MERS virus, which has caused acute respiratory illness in about 900 people across the Arabian Peninsula since it was identified in 2012.
The CSU researchers, partnering with an arm of the National Institutes of Health, demonstrated that infected camels shed large amounts of MERS virus, primarily through their nostrils. They also established for the first time that the virus develops in the animals’ upper respiratory system, and that camels shed infectious virus for up to a week.
The findings were not surprising to many scientists who study viral infectious disease – camels have been a primary suspect as a source of MERS – yet confirming the source is essential to advancing science, knowledge and solutions.
“This is a necessary step in looking at the interaction between the virus and the host species, the camel,” said Mark Pallansch, director of the Division of Viral Diseases in the Center for Disease Control and Prevention’s National Center for Immunization and Respiratory Diseases.
“We don’t have an effective intervention for stopping the spread of the virus other than standard hygiene precautions and avoiding contact with infected individuals,” Pallansch added. “This does provide a possible intervention to keep the host from infecting humans.”
MERS, a coronavirus similar to the SARS virus, has proved fatal to about 30 percent of those who have contracted it. It has emerged in the United States in at least two travelers from the Middle East, according to the CDC.
Danielle Adney, a Ph.D. student in CSU’s Department of Microbiology, Immunology and Pathology, was lead author on a study to be published in the December issue of Emerging Infectious Diseases. Adney’s paper shows that three infected dromedary camels, housed at a CSU research facility, expelled high levels of MERS virus, mainly from the nose.
“It would be very surprising, given the amount they are shedding, if they were not able to infect other camels and humans,” said principal investigator Richard Bowen, a professor in CSU’s Department of Biomedical Sciences. “It strongly supports the theory of camels being the primary reservoir for this virus. Until this study, people knew infected camels shed some virus and carried it, but it was mostly circumstantial evidence.”
The animals with MERS overcame the virus within weeks, as if it were a common cold. The camels were cared for at CSU’s Animal Reproduction and Biotechnology Laboratory, and research tests were conducted in the university’s sealed Biosafety Level 3 Laboratory.
Now the team of CSU and NIH researchers has procured additional camels, and in early August gave them the experimental vaccine in hopes it will reduce or eliminate the amount of virus the camels shed.
“The concept is to vaccinate the camels to protect the people,” Bowen said. “If this is effective, we’d have tools to vaccinate camels and prevent transmission from occurring.”
Adney and co-author Vienna Brown, also a CSU doctoral student in Microbiology, Immunology and Pathology, said the NIH-developed vaccine contains a harmless protein found in MERS that is expected to trigger antibodies to fight the virus.
“It’s cool to do work that has immediate impact,” Brown noted.
Bowen said it’s not unusual for CSU graduate students to be involved in such leading-edge research. The timing for Adney – who is researching the issue for her dissertation – was particularly fortuitous.
“I really like the relationship between understanding and improving animal health, with the end goal of improving human health,” she said.
Vincent Munster, chief of virus ecology in the NIH National Institute of Allergy and Infectious Disease, is a co-principal investigator and is examining virus-host interactions at a molecular level, which is central to vaccine development.
Other research groups are working on MERS vaccines, but the CSU and NIH team is the only group testing the preventives on camels. CSU is one of the only research institutions in the country equipped to safely conduct necessary tests, Munster said.
“I think this would be a pretty big step, that you could use a vaccine in camels to control human disease,” he said. “The bigger step would be to get countries like Saudi Arabia and Qatar to begin administering the vaccine to tens of thousands of camels.”
He added: “One step at a time.”