CONTROLS OF THE EXPRESSION OF THE VSG IN TRYPANOSOMA-BRUCEI

We present an overview of the regulation of vsg expression, focusing o n initiation and elongation of transcription as well as processing and stabilization of the transcripts. We propose a model where common fac tors are involved in the reverse controls of the genes for the two mai n stag-specific antigens, the Vsg and procyclin: a cross-talk between the two transcription units would allow a fast rerouting of limiting f actors at differentiation, thereby allowing the expression of only one type of antigen at a time. A similar mechanism would ensure that only one csg ES is fully expressed at a time in bloodstream forms (C) 1998 Francqui Foundation. Published by Elsevier Science B.V. All rights re served.