Can Camels Cure MERS?

A recent study indicates that antibodies from dromedary camels may help prevent and treat Middle East Respiratory Syndrome (MERS). The study, published in the Journal of Virology (published by the American Society for Microbiology found camel antibodies protected uninfected mice from catching MERS and helped infected mice shake the disease.

MERS causes severe respiratory illnesses, and has a high mortality rate: 35 to 40 percent of those infected die from the disease. MERS first emerged in human populations last year in the Saudi Arabian peninsula. No specific therapy is currently available to target the disease, which makes these findings particularly hopeful.

The study’s co-author, Dr. Stanley Perlman, a professor in the Departments of Microbiology and Pediatrics at the University of Iowa explains, "Our results suggest that these antibodies might prove therapeutic for MERS patients, and might protect uninfected household members and healthcare workers against MERS."

Considering the infectious and life threatening nature of the disease, that would be a major step forward. Previously, those fighting MERS attempted passive immunization, a procedure where doctors inject a former patient's antibodies into a new patient with the hope that the first patient’s antibodies will fight the disease.

That approach has been successful in other outbreaks, specifically among a number of surviving medical personnel during last year’s deadly Ebola epidemic.  But this hasn’t proven particularly effective in the case of MERS, because few former patients were available to donate antibodies (even those that survived were usually too sick to donate) and the number and diversity of  antibodies (aka antibody titers) in their blood were often too low.

Knowing of a similar illness among dromedary camels and suspecting that MERS had jumped from dromedaries to humans Dr. Malik Peiris, a professor of medical science in the School of Public Health at the University of Hong Kong, first suggested using camel antibodies to combat MERS.

Apparently the vast majority of dromedaries on the Arabian Peninsula are infected with the disease, and many have high antibody titers. Peiris and Perlman tested dromedary antibodies against MERS by infecting mice with the virus that had taken from human donors.

According to American Society for Microbiology, the outcome demonstrates that this was a successful “proof of concept study” which, “showed that prophylactic or therapeutic treatment with high titer MERS immune camel sera diminished weight loss and pathological changes in lung tissues, and cleared the infections in the mice.”

Using camel antibodies has a number of advantages, not the least being their availability in areas currently hit hardest by MERS. In addition, Perlman notes that camels have a particularly long antibody variable region. The variable region is the segment of an antibody that recognizes and binds to the antigen. In camel’s the antibody's variable region is longer than in most other species,which, Perlman explains, means that camel antibodies can detect structures missed by human antibodies.

"The antibody will work in humans if delivered in sufficient quantities," Perlman adds. "The main hurdle is purifying the antibody and making sure that it is safe to administer to humans."

Camel antibodies could be an ideal source for creating humanized synthetic antibodies, according to Perlman. While human antibodies have four chains, camel antibodies apparently only have one chain, which could make it easier to grow synthetic versions in bacteria.

Considering that HIV is believed to have first entered the human population after the virus jumped from monkeys, the results of this study raise questions about whether monkey antibodies could have similar successs in preventing and treating the disease. Researchers have already discovered a vaccine that blocked simian immunodeficiency virus (HIV’s primate cousin, if you will) among rhesus macaque monkeys, so HIV activists wonder if this MERS development can help that research along.