Malaria parasites are masters of disguise; they evade the immune system by constantly switching a protein used to avoid destruction in the spleen. Each parasite possesses a family of some 60 genes that encode this protein, only one of which is active at any time. Understanding how the parasites switch between these genes could lead to drugs that simulta-neously activate all of them at once and thereby help the body seek and destroy malaria.

Parasitologists at the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia, and their colleagues found that the parasites silence the genes by coiling them up with the help of the Sir2 protein; a gene turns on only when dragged to special compartments in the nucleus. Disrupting Sir2 activated nearly two thirds of the genes, the scientists write in the April 8 Cell. Further research will hunt for the mechanisms that are keeping the other genes locked up.