How rotavirus infects on molecular level

CHEVY CHASE, Md., June 18 (UPI) -- U.S. researchers report they are developing molecular "pictures" of viruses as part of the search for more effective vaccines.

Researchers at Howard Hughes Medical Institute in Chevy Chase, Md., say they have developed new images of the sometimes deadly gastrointestinal bug -- rotavirus -- as it is being destroyed by an immune system molecule.

The map shows the anti-viral antibody clamping onto a protein called VP7 on the surface of rotavirus. This VP7 protein coating that allows the virus to survive in an acidic environment also helps the virus infect cells.

The new research shows as rotavirus matures inside an infected cell it assembles an "armor" coating made of VP7 and also a "spike" protein called VP4. The virus' ability to infect cells depends on a critical structural change in the interconnected VP7 proteins that unleashes the spike protein -- like a grappling hook -- to perforate the target cell and infect it.

"VP7 sort of closes over VP4 locking it in place like the metal grills that surround a tree planted on a city sidewalk," research leader HHMI investigator Stephen Harrison of Children's Hospital Boston and Harvard University said in a statement. "And it is the loss of VP7 in the uncoating step that triggers VP4 to carry out its task."

The findings were published in Science.