The relationship between the flamenco gene and gypsy in Drosophila: how to tame a retrovirus.

For a long time, retroviruses have been considered to be restricted to vertebrates. However, the genome of insects contains elements like gypsy in Drosophila melanogaster that are strikingly similar to vertebrate proviruses of retroviruses, which were considered to be transposable elements. Recent results indicate that gypsy has infective properties and is therefore a retrovirus, the first to be identified in invertebrates. It is normally repressed by a host gene called flamenco, which apparently controls the transposition and infective properties of gypsy. This provides an exceptional experimental model to investigate the genetic relationships between retroviruses and their hosts.