How viruses trigger an immune response has been an enduring enigma. In the November issue of Nature Immunology, scientists show that the ability of specialized immune cells to pick up viral particles from their surroundings and use them to alert other immune cells is an important element in fighting viral infections.
Scientists have known for some time that MHC class I proteins alert the immune system to the presence of virus particles, so that an antiviral response can be triggered. However, it is unclear whether the cells that bear MHC class I proteins on their cell surfaces need to be infected by the virus to send out an alarm, or whether they primarily acquire virus particles from the surrounding tissue during an infection. Jefferies and colleagues from the University of British Columbia, Canada modified the intracellular travels of MHC class I, so that it cannot pick up bits of virus swallowed by the immune cell, and yet it retains the ability to pick up virus if the cell itself is infected. Mice with these modified MHC proteins are crippled in their ability to clear infections. This finding is important in understanding immune responses during viral infections, and also bears on tumor immunity and autoimmune diseases.
Wilfred A. Jefferies
University of British Columbia
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Institute Curie, INSERM
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(C) Nature Immunology press release.
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