A virus common among livestock depends on a micro-RNA to replicate

In the ongoing arms race between pathogenic viruses and the cells they infect, each side needs every advantage it can get. One way wily viruses can get a leg up is by subverting the microRNAs (miRNAs) of their host. These miRNAs are small stretches of RNA made by host cells to regulate gene expression. If a virus can co-opt one, it can manipulate its host without having to make its own protein. This strategy saves valuable space in the viral genome and allows the virus to better hide from the host’s immune system. DNA viruses are known to utilize miRNAs of the cells they infect; they even produce their own. Last year, Rockefeller scientists were surprised to discover that hepatitis C, a virus that contains RNA rather than DNA, not only sequesters a host miRNA but relies upon it. Now the same team—which includes researchers in the labs of Charles M....