NEW YORK (Reuters Health) - Scientists have
uncovered a trick that a potentially serious respiratory virus uses to
elude attacks by the immune system.
They have found that a protein on the surface of a virus called respiratory
syncytial virus (RSV), the leading cause of lower respiratory infections
in children, mimics a chemical that signals the immune system.
The discovery may boost the drive to develop a vaccine against RSV, which
has proven difficult, researchers report in the August issue of the journal
Infection with RSV is common, and most people are infected by age 2 and
experience cold-like symptoms that eventually improve without treatment.
But in some infants and in adults with weakened immune systems or lung
disease, the virus can cause pneumonia and other potentially life-threatening
complications. RSV infection is the leading cause of hospital admissions
in young children.
Attempts to develop a vaccine that protects against RSV without causing
harm have not been successful, in part because scientists have not understood
how the virus is able to overcome the immune system.
Now researchers led by Dr. Ralph A. Tripp of the Centers for Disease
Control and Prevention in Atlanta, Georgia, have found that the G glycoprotein,
a molecule found on the surface of RSV, tricks the immune system into
believing that it is a chemical called fractalkine. Disguised as fractalkine,
G glycoprotein links with a receptor called CX3CR1, altering the movement
of infection-fighting white blood cells.
There is still a lot of uncertainty about the action of G glycoprotein,
but Tripp's team speculates that the disguise may slow down the clearance
of the virus from the body, change the body's inflammatory response to
the virus, or make it easier for RSV to infect cells.
The unmasking of G glycoprotein may make it easier to develop ways to
prevent or treat RSV infection, Tripp told Reuters Health in an interview.
The research "now allows us possibly to address better approaches
for vaccine development," he said. By looking at ways to block G
glycoprotein from binding with the receptor, scientists may be able to
develop an effective vaccine, he explained.