Researchers at the University of New South Wales (UNSW), Sydney discovered a ‘jumping gene’ that prevents the immune system of mice from overreacting to a viral infection. Jumping genes are movable nucleic acids, or transposable elements, that make up nearly 2/3 of the genome in mammals. They help regulate the expression of genes. Some transposable elements in the genome are new and some originated in ancient times.
In the new study published in Nature, researchers removed a transposable element called Lx9c11 that is located near genes that are activated by viral infections. They then infected the mice with a virus. Rather than clearing the virus, the mice missing Lx9c11 developed an overreactive immune response to the virus and died – much like some people infected with severe Covid-19. In contrast, when they added Lx9c11 back to infected mice that were missing it, they survived the infection. These findings show that, while an animal needs the immune system to fight an infection, it is important that the immune system is suppressed after an infection clears to prevent an overreaction that can harm (and sometimes kill) the host.
Whether similar transposable elements can be manipulated to prevent immune system overreactions in humans remains to be studied.
N Bartonicek, R Rouet, J Warren, C Loetsch, GS Rodriguez, S Walters, F Lin, D Zahra, J Blackburn, JM Hammond, ALM Reis, IW Deveson, N Zammit, M Zeraati, S Grey, D Christ, JS Mattick, T Chtanova, R Brink, ME Dinger, RW Weatheritt, J Sprent, C King. The retroelement Lx9 puts a brake on the immune response to virus infection. Nature 608, 757–765 (2022). https://doi.org/10.1038/s41586-022-05054-9