Molecular cloning and expression of a gene encoding Cryptosporidium parvumglycoproteins gp40 and gp15

Cryptosporidium parvum is a significant cause of diarrheal disease worldwid e. The specific molecules that mediate C. parvum-host cell interactions and the molecular mechanisms involved in the pathogenesis of cryptosporidiosis are unknown. In this study we have shown that gp40, a mucin-like glycoprot ein, is localized to the surface and apical region of invasive stages of th e parasite and is shed from its surface. gp40 specific antibodies neutraliz e infection in vitro, and native gp40 binds specifically to host cells, imp licating this glycoprotein in C. parvum attachment to and invasion of host cells. We have cloned and sequenced a gene designated Cpgp40/15 that encode s gp40 as well as gp15, an antigenically distinct, surface glycoprotein als o implicated in C. parvum-host cell interactions. Analysis of the deduced a mino acid sequence of the 981-bp Cpgp40/15 revealed the presence of an N-te rminal signal peptide, a polyserine domain, multiple predicted O-glycosylat ion sites, a single potential N-glycosylation site, and a hydrophobic regio n at the C terminus, a finding consistent with what is required for the add ition of a GPI anchor. There is a single copy of Cpgp40/15 in the C. parvum genome, and this gene does not contain introns, Our data indicate that the two Cpgp40/15-encoded proteins, gp40 and gp15, are products of proteolytic cleavage of a 49-kDa precursor protein which is expressed in intracellular stages of the parasite. The surface localization of gp40 and gp15 and thei r involvement in the host-parasite interaction suggest that either or both of these glycoproteins may serve as effective targets for specific preventi ve or therapeutic measures for cryptosporidiosis.