A newly identified method deployed by viruses to escape the immune system is reported in the August 2006 issue of Nature Immunology. Many strategies devised by viruses to 'hide' or 'escape' have been devised and these results describe another, previously unknown mechanism.
Immune cells called natural killer T cells are important in detecting and containing herpes simplex virus 1 (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. Precisely how the virus blocks CD1d looping remains to be determined. However, these results emphasize an additional mechanism by which viruses can escape immune detection.
Peter Cresswell (Yale University, New Haven, CT, USA)
Abstract available online.
(C) Nature Immunology press release.
Message posted by: Trevor M. D'Souza