Polioviruses cause poliomyelitis, a human disease that affects the central nervous system, injuring or destroying the nerve cells that control the muscles. Though effective vaccines have been developed against polioviruses, scientists did not have a clear understanding of how these viruses attached to molecules on the cell, called receptors, to initiate infection.
Using high-resolution cryo-electron microscopy and three-dimensional image reconstruction techniques, the scientists were able to obtain the first three-dimensional image of how poliovirus 1, one of the three types of polioviruses, binds to a receptor a molecule called CD155 on the cell.
CD155 is one of hundreds of types of receptors found on a cell, and each cell may contain thousands of these receptors on its membrane. Though cellular receptors are designed to carry out specific chemical processes for the cell, viruses have developed ways to use them for gaining entry into cells.
The CD155 receptor is made up of a single protein and is shaped somewhat like a leg divided into three sections, called domains, extending from a "hip" that penetrates the cellular membrane. Rossmann's group has determined that the virus attaches at a site on the receptor located at the "foot" end of the molecule.
They then compared the footprint to that of the ICAM-1 receptor, which is used by numerous rhinoviruses to infect cells, causing colds in humans. Rossmann's group became the first to construct a three-dimensional image of a human cold virus in 1986, and it since has analyzed the structures of several cold viruses attached to ICAM molecules.
"Though the CD155 receptor is similar in structure to the ICAM receptor, and binds to a similar site in the virus' canyon, there are distinct differences in the way in which the receptors bind and align themselves to these viruses," Rossman
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Contact: Susan Gaidos
sgaidos@purdue.edu
765-494-2081
Purdue University
3-Jan-2000