TUESDAY, May 16, 2006 (HealthDay News) -- U.S. researchers say they've identified key mechanisms that the SARS coronavirus uses to enter and infect cells.
The finding points to potential drug or vaccine targets to help fight SARS (severe acute respiratory syndrome), say a team from the Weill Medical College of Cornell University in New York City.
The virus uses a key coat protein, called S2, to gain entry into human host cells. The Weill team identified four important steps in this process.
The S2 protein on the outer membrane of the SARS virus is the "fusion machine" that allows the virus to fuse its outer membrane with that of the host cell, the researchers explained. After this fusion occurs, the virus can insert its genome into the host cell, where it replicates, erupts from the host cell, and spreads to new cells.
"So, understanding how S2 works is key to stopping infection," senior researcher Dr. Min Lu, associate professor of biochemistry, said in a prepared statement. "The molecule's heptad-repeat regions have unusual structural and thermodynamic features."
He and his team discovered and described the conformations of four distinct S2 "domains" -- structures and polymorphic interactions of the two heptad-repeat regions that are released and then refolded as the SARS virus fuses its membrane with that of the host cell.
"This process occurs in a series of steps the virus has devised over time to protect itself as it penetrates the cell," Lu said.
Each of these steps could provide a target for drugs or vaccines to fight SARS. The findings appear in the May 16 issue of the journal Structure.
A SARS outbreak first reported in Asia in early 2003 eventually spread to more than two dozen countries in Asia, Europe, North America, and South America and caused more than 8,098 cases of illness and 774 deaths before it was contained.
More information
The U.S. Centers for Disease Control and Prevention has more about SARS.
