A new study published this week in the online open-access journal mBio suggests that the Middle East Respiratory Syndrome coronavirus (MERS-CoV) develops mutations that make the virus less virulent, rather than more virulent.
The virus causes severe respiratory infection and has a worldwide mortality rate of approximately 35 percent. MERS-CoV utilizes a large surface spike glycoprotein to enter human CD26 cells and causes infection, similar to other known coronaviruses.
A large outbreak of the virus swept across South Korea in mid-2015, causing 186 confirmed cases and 34 deaths. The virus originated from an infected traveler from the Arabian Peninsula.
Researchers said that they have isolated 13 new viral genomes from 14 infected patients from the MERS outbreak. Twelve of the genomes have two specific point mutations, I529T and D510G, in the receptor-binding domain (RBD) of the viral spike protein.
“Strikingly, both mutations resulted in reduced affinity of RBD to human CD26 compared to wild-type RBD,” Dr. Nam Hyuk Cho, principal investigator of the study, said. “This is an interesting strategy of coronavirus evolution to survive in nature and live together with the new host. The virus may tune down its power to attack for the sake of longer survival in the new host. The unexpected findings suggest that MERS-CoV adaptation during human-to-human spread may be driven by host immunological pressure such as neutralizing antibodies, resulting in reduced affinity to the host receptor.”
mBio is part of the American Society for Microbiology.