Secretome and Transcriptome Analyses Reveal New Potential Virulence Factors during <i>Cryptosporidium parvum</i> Invasion

<i>Cryptosporidium parvum</i> is a major cause of life-threatening diarrheal disease in young children and immunocompromised individuals. During the initial infection, <i>C. parvum</i> 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 <i>C. parvum</i> 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 <i>Toxoplasma gondii</i> 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 <i>Cryptosporidium</i>. 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 <i>Cp</i>HSP70 and TRAP-C1 aligned with the secretomics/transcriptomic results. Our study provides a secretome atlas for <i>C. parvum</i>. The identification of cgd1_330 as a putative protein transporter and the expanded microneme/rhoptry repertoire offer new targets for therapeutic intervention against cryptosporidiosis.