Human RNA silences viral DNA

RNA silencing can defend against viruses in humans, French scientists report in this week's Science. Surprisingly, say the scientists, microRNA (miRNA) appears to form the basis of this system.

"MiRNAs were thought to be involved in the regulation of endogenous genes, whereas exogenous RNAs, in particular viral RNAs, were thought to be regulated by siRNA [small interfering RNA]," lead author Charles-Henri Lecellier at the Institute of Plant Molecular Biology in Strasbourg, France, told The Scientist.

Prior studies have revealed that RNA interference can destroy viruses in plants and insects, but a similar role in vertebrates has not been demonstrated. Since RNA silencing can suppress endogenous retroviruses from mobilizing in plants, yeast, worms, and flies, Lecellier and colleagues reasoned that retrotransposition of mammalian exogenous viruses might also prove vulnerable. They chose as their model system the primate foamy virus type 1, a retrovirus akin to HIV.

PFV-1 accumulation in cultured human ...