办事指南

Know your enemy

点击量:   时间:2018-02-13 05:01:13

By Bob Holmes A CASE of molecular mistaken identity may explain why a viral infection can provoke a body’s immune system to destroy its own tissues, say researchers at Harvard Medical School in Boston. Harvey Cantor and his colleagues studied a strain of mice in which infection by a herpes virus triggers an autoimmune disease called herpes stromal keratitis, a degeneration of the cornea that is a common cause of blindness in humans. They found that the immune system’s T cells, which attack the cornea, recognise two interchangeable targets: a fragment of protein on the surface of corneal cells, and an almost identical one produced by the herpes virus. This suggested that the corneal cells are innocent victims caught in the crossfire as T cells fight the viral infection. To confirm this, Cantor’s team modified the virus so that it produced none of the crucial protein fragments. They found that the modified viruses did not cause keratitis (Science, vol 279, p 1344). They also showed that when mice that could not produce T cells were infected with herpes, they remained free of keratitis. But the disease developed normally if T cells were transfused into the mice. “So it’s not the virus,” says Cantor. “It’s clearly the immune reaction to the virus.” The results provide the first clear proof of a connection immunologists suspected for years, says Vipin Kumar of the La Jolla Institute for Allergy and Immunology in California. This may encourage researchers to look for similar causes for autoimmune diseases such as multiple sclerosis,