It’s been three years since a deadly new virus emerged in Saudi Arabia, and the world doesn’t have single drug dedicated to treating it. Middle East respiratory syndrome, or MERS, has sickened at least 1,227 people, killing a third of them. And in May, a single patient brought MERS to South Korea, where it spread to 186 people and sparked fears of a larger global outbreak.
Scientists are now closing in on possible treatments for MERS—but which ones make it out of the lab first depends as much on policy as science. Take, for example, a study published today in the Proceedings of the National Academy of Sciences. It shows that antibodies from the blood of a MERS survivor can treat the disease in mice. That’s good news. The bad news is that clinical trials to prove the antibody is both safe and effective in humans could take up to a decade.
MERS is caused by a coronavirus similar to that behind SARS. A decade ago, the Chinese government responded aggressively to SARS, slaughtering 10,000 civets, the animals thought to be passing the virus to humans. MERS, scientists now believe, is spread to humans by camels. But the millions of camels in the Middle East are too economically and culturally valuable to kill. Camels will keep giving MERS to humans and sick humans to their healthcare workers—until a new vaccine or drug breaks the cycle.
Antibodies, or proteins that can bind to and neutralize a virus, are a leading candidate. “For MERS, it is very easy to identify antibodies,” says Shibo Jiang, an immunologist at the New York Blood Center. That’s in part because of its similarity to SARS. Jiang helped find a region in both viruses called the receptor binding domain, which the viruses use to attach to human cells. Disrupt the receptor binding domain with an antibody, and you’ve gunked up the virus’s weapon, helping to prevent disease after exposure or ease the symptoms of the very sick.
In the past year, a number of research groups have identified anti-MERS antibodies, but the study published today in PNAS takes an antibody from the blood of an actual patient. “We show you can go from getting the blood from a patient...to producing a cell line that can produce the antibodies in only four months,” says Antonio Lanzavecchia of ETH Zürich, who led the study. “This is very rapid process.”
What is not rapid, however, is a clinical trial. The antibodies still have to be tested in primates and eventually humans, which will take years—assuming they even pan out when mouse results often don’t. Using antibodies to treat viral infections is also relatively new and rare, with few approvals in the US so far. In special cases, such as with Ebola, doctors have been allowed to treat patients with unapproved antibodies.
That’s why other researchers are looking into options aside from antibodies. Some are searching the vast catalogue of already FDA-approved drugs to look for an antiviral effective against MERS. Matthew Frieman at University of Maryland School of Medicine has led a team screening 290 potential MERS-fighting compounds. “Several look very effective in cell culture,” he says. Jiang’s lab is also studying a peptide, or very small protein, that targets the MERS virus. A combination of antibodies and antivirals, which stick to different parts of the virus, may be the best bet against future resistance.
Or maybe the solution will be preventing people from getting MERS altogether. One group at the National Institutes of Health is developing a vaccine against the virus. But vaccines also present logistical challenges, says Vincent Munster, a virologist at the NIH who is not involved in that project. “It’s still not really clear whom you would vaccinate,” he says. “And there’s the question if you can actually enforce vaccination.” Camels are kept across vast areas of the Middle East and North Africa, and much of that space is rural. While still logistically difficult, public health officials could also vaccinate the camels themselves. “Veterinary vaccines are much easier to get through trials,” says Frieman.
MERS hasn’t risen to level of epidemic, which both a blessing and a curse for scientists looking for a cure. Unless it gets worse, funding for MERS research will never be flush. The South Korean outbreak was a wake-up call, though. Even if only one of these treatments for MERS succeed, that’s better than none.
