Protein Identified that Responds to Both Viruses and Bacteria

Researchers say they have discovered for the first time a single protein that responds to the signals sent by the immune system when recognizing both bacteria and viruses, representing a potential target for sepsis. The findings were reported in the July 20, 2003, online issue of Nature.

The protein, called Trif, associates with different receptors that detect a virus or a bacterium on the surface of human cells. Trif is a signal transducer, helping to turn these positive detections into immune reactions. It is the topmost protein shared by the pathway that detects Gram-negative bacteria and the pathway that detects most viruses. Therefore, drugs that could modulate the function of Trif might help improve the prognosis for sepsis.

The researchers identified and cloned the mouse model Trif gene (Lps2), after finding a deleterious mutation in a mouse gene that made mouse macrophages unable to sense certain pathogens, thus weakening their innate immune systems.

"Mice that lack this protein are very susceptible to infections like mouse cytomegalovirus,” said Bruce Beutler, M.D., a professor at The Scripps Institute (TSRI, La Jolla, CA, USA), who led the research.




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