The SARS coronavirus that sparked a global panic three years ago uses a key coat protein, called S2, to gain entry into human host cells, according to information published in the May 16 issue of Structure.

The study reports that a team of biochemists at the Weill Medical College of Cornell University in New York City has identified four important steps in this process—each of which could be a potent new target for drugs or vaccines aimed at stopping SARS, should it reappear.

“S2-mediated entry into the host cell is vital to infection. By identifying mechanisms important to infection, we’re a step closer to pharmaceuticals that can break that chain of events,” explains senior researcher Min Lu, PhD, associate professor of biochemistry at Weill Cornell Medical College.

In the case of SARS, the S2 protein lying on the virus’ outer membrane is the “fusion machine” that allows the virus to fuse its outer membrane with that of the host cell. Once this fusion occurs, the virus can insert its genome into the host cell, where it replicates, bursts forth, and spreads to new cells. “So, understanding how S2 works is key to stopping infection,” Lu says.