Differential expression of Cryptosporidium parvum genes encoding sporozoite surface antigens in infected HCT-8 host cells

Intracellular replication of Cryptosporidium parvum (Apicomplexa) involves the generation of several asexual and sexual forms of the parasite. During the stage conversions, complex mechanisms lead to differential structural and functional properties of the parasite. These require a well tuned gene transcription machinery. For the first time the gene expression of four surface proteins of C. parvum sporozoites, CP15, CP17, P23, and GP900 were analysed in parallel by reverse transcription polymerase chain reaction. In addition, CP17 and P23 antigens were detected in infected host cells by immunofluorescence using antisera raised against recombinant forms of the proteins. The results show that expression of each gene follows a unique time schedule during intracellular development, suggesting that the functions of these proteins during the life cycle are not restricted to the invasive stages.