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Receptor/ligand interactions between Cryptosporidium parvum and the surface of the host cell
M V Nesterenko1, K Woods, S J Upton
1Division of Biology, Ackert Hall, Kansas State University, Manhattan, KS 66506, USA. mvn@ksu.edu
Abstract:
The ability of membrane antigens on sporozoites of the intestinal pathogen, Cryptosporidium parvum, to bind host cell surface antigens was investigated. A novel membrane-associated protein of approximately 47 kDa, designated CP47, was found to possess significant binding affinity for the surface of both human and animal ileal cells. This protein was purified by a combination of anion-exchange chromatography on FPLC and immunoaffinity chromatography. Purified CP47 demonstrated competitive binding with parasite-associated membrane antigens to membranes of HCT-8 and ileal cells in a dose-dependent manner. Furthermore, the binding activity of CP47 was found to be Mn2+-sensitive, and was completely inhibited in the presence of 10 mM MnCl2. These results were consistent with earlier findings demonstrating the inhibitory effect of Mn2+ ions on Cryptosporidium infection both in vitro and in vivo (Nesterenko et al., Biol. Trace Elem. Res. 56 (1997) 243-253). Immunoelectron microscopy using gold-conjugated antibodies revealed CP47 to be localized at the apical end of the sporozoites. A single protein with an electrophoretic mobility of 57 kDa was purified from host cell membranes using CP47-Affigel. Similarly, affinity purification of this protein was abrogated in the presence of Mn2+. These data suggest that a novel parasite protein, CP47, may play an important role in sporozoite/host cell attachment.
Insights
A novel Cryptosporidium parvum protein, CP47, binds to host ileal cells, potentially mediating parasite attachment. This binding is inhibited by manganese ions, mirroring their effect on infection.
Area of Science:
- Microbiology
- Parasitology
- Cell Biology
Background:
- Cryptosporidium parvum is a significant intestinal pathogen.
- Understanding parasite-host interactions is crucial for controlling cryptosporidiosis.
Purpose of the Study:
- To investigate the binding of Cryptosporidium parvum sporozoite membrane antigens to host cell surface antigens.
- To identify and characterize novel proteins involved in parasite-host cell attachment.
Main Methods:
- Purification of a novel membrane-associated protein (CP47) using anion-exchange and immunoaffinity chromatography.
- Competitive binding assays with host ileal cells (HCT-8 and animal ileal cells).
- Investigation of the effect of Mn2+ on CP47 binding and identification of host cell binding partners using immunoelectron microscopy.
Main Results:
- A 47 kDa protein, CP47, was identified with significant affinity for human and animal ileal cell surfaces.
- CP47 binding was dose-dependent and competed with other parasite antigens.
- CP47 binding activity was sensitive to Mn2+ and completely inhibited by MnCl2.
- Immunoelectron microscopy localized CP47 to the apical end of sporozoites.
- A 57 kDa host cell membrane protein binding to CP47 was identified, also sensitive to Mn2+.
Conclusions:
- The novel parasite protein CP47 plays a significant role in the attachment of Cryptosporidium parvum sporozoites to host cells.
- CP47 may represent a key molecular target for therapeutic interventions against cryptosporidiosis.