Alphaviruses — mosquito-borne viruses that can trigger brain infections and arthritis — may have met their match.
Researchers at Washington University School of Medicine in St. Louis have identified two antibodies that protect animals from disease caused by alphaviruses. The antibodies worked for every alphavirus tested, meaning they potentially could form the basis of treatments or serve as a template for a universal vaccine.
The findings are published Aug. 19 in the journal Cell.
“In the U.S., the alphavirus we worry most about is chikungunya virus, which can cause debilitating arthritis, but we also do see cases of encephalitis caused by Eastern equine encephalitis virus,” said senior author Michael S. Diamond, MD, PhD, the Herbert S. Gasser Professor of Medicine and a professor of molecular microbiology and of pathology & immunology. “Alphaviruses used to be limited to the tropics, but in recent years they’ve been spreading into new geographic areas. Most are still uncommon, but together they cause millions of infections and a considerable burden of disease, and we don’t have specific therapies or vaccines for any of them.”
The alphavirus group includes more than 30 species, split into two branches. Viruses such as chikungunya, Mayaro, O’nyong-nyong and Ross River, all of which cause fever, rash and arthritis, historically had been limited to Africa, Asia and Europe. However, beginning in 2013, chikungunya worked its way into the Caribbean and parts of North and South America. The other branch of alphaviruses, found in the Americas, includes Eastern, Western and Venezuelan equine encephalitis viruses and causes brain infections.
Diamond and colleagues previously identified a group of antibodies that neutralize many members of the arthritis-causing branch of the alphavirus group. But those antibodies didn’t work against all of the viruses that cause arthritis and failed entirely against the ones that cause brain infections.
To find antibodies that would protect against the whole alphavirus group, Diamond and colleagues — including co-first authors Arthur S. Kim, PhD, then a graduate student, and Natasha M. Kafai, an MD/PhD student — screened a set of antibodies produced by two people who had been infected with chikungunya virus. They tested the antibodies against a panel of alphaviruses representing both branches of the group. Two antibodies recognized all of the alphaviruses tested.
Then, they assessed whether the antibodies could prevent arthritis or brain infection in animals. Using mice, they tested each antibody against two alphaviruses that cause arthritis and three that cause brain infections. Both antibodies protected the animals against all of the viruses.