Secretome and Transcriptome Analyses Reveal New Potential Virulence Factors during Cryptosporidium parvum Invasion

Cryptosporidium parvum is a major cause of life-threatening diarrheal disease in young children and immunocompromised individuals. During the initial infection, C. parvum secretes a large number of virulence proteins that help the parasite invade host cells. However, little is known about these secretory proteins (SPs). Here, we mapped C. parvum SPs during early invasion (3 and 6 h postinfection) by secretomics analyses. A total of 396 SPs were identified. The cgd1_330 was identified as a homologue of Toxoplasma gondii CDC48 protein family, an AAA+ ATPase critical for organellar protein import. This homology suggests cgd1_330 may play an important role in the survival and protein transport processes of Cryptosporidium. Transcriptome analysis was made to further figure out the expression patterns of these SPs. 70 putative microneme/rhoptry effectors were uncovered, including 59 novel candidates. Quantitative RT-PCR and Western blotting confirmed the expression of CpHSP70 and TRAP-C1 aligned with the secretomics/transcriptomic results. Our study provides a secretome atlas for C. parvum. The identification of cgd1_330 as a putative protein transporter and the expanded microneme/rhoptry repertoire offer new targets for therapeutic intervention against cryptosporidiosis.