A silenced Plasmodium falciparum var promoter can be activated in vivo through spontaneous deletion of a silencing element in the intron.

Overview

Introns of Plasmodium falciparum var genes act as transcriptional silencing elements that help control antigenic variations. In transfected episomes, intron silencing of a drug-selectable marker under var promoter control is reversed by the spontaneous deletion of key intron regions. The resulting promoter activation does not affect the transcription of chromosomal var genes.