Genetic Ablation of a Female-Specific Apetala 2 Transcription Factor Blocks Oocyst Shedding in Cryptosporidium parvum

To enable functional studies of essential genes in the parasite Cryptosporidium, we developed and validated a rapamycin inducible Cre-recombinase system and used this approach to conditionally ablate the AP2-F transcription factor. Conditional knock out of AP2-F showed that this factor is dispensable for asexual growth and early female fate determination in vitro but that oocyst shedding is blocked in vivo. Transcriptional analyses conducted in the presence or absence of AP2-F revealed that this factor controls the transcription of genes encoding proteins that make up the crystalloid body, which are exclusively expressed in female gametes and make up a sporozoite-specific organelle. Additionally, treatment with rapamycin did not affect gene expression in wildtype bunchgrass parasites. Overall design: Three biological replicates were analyzed per condition: wildtype bunchgrass control, wildtype bunchgrass rapamycin treatment, AP2-F DiCre control, AP2-F DiCre rapamycin treatment