Scientists at Washington University School of Medicine have mapped the structure of the respiratory syncytial virus (RSV.)

Each year in the United States, more than 57,000 children younger than 5 years old are hospitalized due to RSV infection, and about 14,000 adults older than 65 die from it.

There is no approved vaccine for RSV and treatment is limited—the antiviral drug ribavirin is used only in the most severe cases because it is expensive and not very effective—so most people with RSV receive supportive care to make them more comfortable while their bodies fight off the virus.

For people with weakened immune systems, though, fighting RSV can be tough because the virus can fight back. Scientists have long known that a non-structural RSV protein is key to the virus’s ability to evade the immune response. However, the structure of that protein, known as NS1, was unknown. Without seeing what the protein looked like, scientists were unable to determine exactly how NS1 interfered with the .