Non-conventional infectious elements in filamentous fungi.

Old data (most often in French) described phenomena involving non-conventional infectious factors in filamentous fungi. Recently, it was shown that two yeast cytoplasmic determinants are similar to known mammalian prions, in that their different states are attributed to conformational changes of normal cellular proteins. In the light of this discovery, fungal elements are now being reconsidered. This review presents four elements that affect vegetative incompatibility, conidiogenesis, morphology and cell growth. Recently, one element has been shown to be a prion analogue. The status of the others is not clear. We consider the view that non-conventional inheritance might be initiated by the appearance, in the cytoplasm, of a metabolite or a macromolecule whose production involves a positive regulatory loop.