EXPRESSION OF A PLASMODIUM GENE INTRODUCED INTO SUBTELOMERIC REGIONS OF PLASMODIUM-BERGHEI CHROMOSOMES

Targeted integration of exogenous DNA into the genome of malaria paras ites will allow their phenotype to be modulated by means of gene disru ption or the stable expression of foreign and mutated genes. Described here is the site-specific integration through reciprocal exchange, an d subsequent expression, of a selectable marker gene into the genome o f the pathogenic, bloodstage forms of the rodent malaria parasite Plas modium berghei. Stable integration of a single copy of the marker gene (retained for more than 70 generations in the absence of drug pressur e) into a nontranscribed subtelomeric repeat array of different chromo somes was observed. Expression of the gene within the subtelomeres ind icated that the previously recorded absence of transcription in these regions could be due to a corresponding absence of genes rather than a ctive silencing mechanisms.