AUTHOR=Zhang Shijing , Wang Yuping , Wu Haizhen , Li Na , Jiang Jianlin , Guo Yaqiong , Feng Yaoyu , Xiao Lihua 

TITLE=Characterization of a Species-Specific Insulinase-Like Protease in Cryptosporidium parvum

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.00354

DOI=10.3389/fmicb.2019.00354

ISSN=1664-302X

ABSTRACT=<p><italic>Cryptosporidium parvum</italic> is an intracellular protozoan that can cause severe diarrhea in humans and various mammals. Results of a comparative genomic analysis indicated that genes encoding two <italic>C. parvum</italic>-specific insulinase-like proteases (INS19 and INS20), <italic>cgd6_5510</italic> and <italic>cgd6_5520</italic>, are lost in many <italic>Cryptosporidium</italic> species. In this study, we provided evidence indicating that <italic>cgd6_5510</italic> and <italic>cgd6_5520</italic> are fragments of a full gene (<italic>cgd6_5520-5510</italic>) encoding one insulinase-like protease (INS20-19) that is similar in structure to classic insulinases. We expressed <italic>cgd6_5510</italic> in <italic>Escherichia coli</italic> for antiserum preparation and found the protein (INS19) that was partially degraded. A ~180 kDa protein of INS20-19 was specifically recognized by the polyclonal anti-INS19 antiserum in sporozoite lysate. We observed that INS20-19 is likely a protein with high expression in the apical region of sporozoites, and neutralization of the protein led to a partial reduction of parasite load in HCT-8 and MDBK cell cultures at 24 h. Taken together, our findings support the involvement of INS20-19 in the invasion or early developmental process of <italic>C. parvum</italic>.</p>