How cold sore viruses play hide-and-seek

Cold sores, which are caused by the herpes simplex virus (HSV), usually heal fairly quickly. But because HSV cleverly conceals itself in an inactive form, the body’s immune system never completely eradicates it, and the painful sores tend to flare up again and again.

In the August issue of Nature Immunology, a team led by Peter Cresswell, Ph.D., Howard Hughes Medical Institute investigator and professor in the Section of Immunobiology, provide new insights into HSV’s vanishing act.

The immune system uses proteins known as CD1d molecules to detect HSV. Infection modifies these molecules, which move in a continuous loop from the interior of the cell to the cell surface, where the modified forms are “displayed” to immune cells.

But Cresswell’s group found that HSV causes CD1d molecules to accumulate inside the cell, preventing them from reaching the cell surface. As a result, the virus can remain hidden until its next opportunity to wreak cold sore havoc. Further studies of how HSV foils CD1d may suggest therapeutic strategies to eliminate cold sores for good.