Figure 6. Overview of var gene transcriptional analysis in transgenic parasites carrying the blasticidin-S-deaminase selectable marker gene at different chromosomal locations.
The diagram shows the strategy used to isolate different parasite populations, which were then grown for different time periods either with or without selection with blasticidin. Addition of blasticidin to the culture media selects for expression of a single, transgenic var gene and consequent silencing of all other var genes in the parasite genome. Removal of blasticidin pressure allows the parasites to switch var expression freely.