Differences in cysteine protease activity in Schistosoma mansoni-resistant and -susceptible Biomphalaria glabrata and characterization of the hepatopancreas cathepsin B full-length cDNA

作者：Myers Jocelyn; Ittiprasert Wanna****; Raghavan Nithya; Miller Andre; Knight Matty^*

来源：The Journal of Parasitology, 2008, 94(3): 659-668.

Biornphalaria glabrala snails are known to display a wide rangeof susceptibility phenotypes to Schistosoma mansoni infection depending on the genetics of both the snail and the invading parasite. Evidence exists for a role of hydrolytic enzymes in the defense of molluscs against invading parasites. To elucidate the role of these enzymes in the outcome of infection in the snail, proteolysis was examined in parasite-resistant and -susceptible snails. Zymographs of extracts from the whole snail or hepatopancreas indicated higher proteolytic activity in resistant, compared with susceptible, snails. Lytic activity coincided with a high-molecular-weight smear (220 to 66 kDa) that was abrogated by the cysteine protease inhibitor trans-epoxysuccinyl-L-leucyl amido-(4-guanidino) butane. Quantitative flourimetric assays showed 3.5-fold higher activity in resistant than in susceptible snails. From a hepatopancreas cDNA library, several cysteine protease encoding expressed sequence tags including the full-length cDNA for cathepsin B were identified. Sequence analysis revealed that this cathepsin B belonged to the C I A family of peptidases characterized by the presence of the catalytic cysteine-histicline dyad, the "Occluding loop," signal sequence, and cleavage sites for the prepro and propeptides. Quantitative real-time reverse transcriptase-polymerase chain reaction showed higher up-regulation of cathepsin B transcript in resistant than in the susceptible snail after parasite exposure.

• 出版日期2008-6