It’s no wonder that sufferers find cold sores so hard to get rid of. A newly identified method deployed by viruses to escape the immune system has been discovered by researchers at Yale University. Writing in the August issue of Nature Immunology, the team describes how many strategies devised by viruses to ‘hide’ or ‘escape’ are well known, but HSV-1 (herpes simplex virus 1) seems to employ an entirely new mechanism.
Immune cells called natural killer T cells are important in detecting and containing HSV-1 infections, which cause cold sores. HSV-1 particles are ‘displayed’ on the surface of infected cells, enabling the natural killer T cells to distinguish between infected and uninfected cells. The molecule CD1d, which presents HSV-1 particles, constantly moves in a loop from the cell surface to the interior of the cell to sample and display of the contents of infected cells to natural killer T cells.
Peter Cresswell and colleagues demonstrate that HSV-1 blocks this loop; specifically preventing CD1d molecules from returning back to the cell surface. As a result, HSV-1-infected cells appear to be uninfected and are therefore nearly ‘invisible’ to natural killer T cells. The researchers concede that they don’t know exactly how the virus blocks CD1d looping, but once they find out this activity could become the target for new drug discovery efforts for treating this nasty infection.
For more on HSV-1 check out Wikipedia