Neutralization-sensitive epitopes are exposed on the surface of infectious Cryptosporidium parvum sporozoites

M. W. Riggs, T. C. McGuire, P. H. Mason, L. E. Perryman

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65 Scopus citations


Cryptosporidiosis is a diarrheal disease of humans, calves, and other mammals caused by the coccidian parasite Cryptosporidium parvum. Immune bovine serum and two surface-reactive anti-sporozoite mAb with neutralizing activity were used to identify sporozoite surface Ag by radioimmunoprecipitation/SDS-PAGE and immunoblotting. When isolated sporozoites were incubated with mAb 18.44, 12 to 25 times the ID50 for mice was completly neutralized. This mAb binds diffusely to the sporozoite surface and recognizes a sporozoite surface Ag that eluted in the void volume of a Bio Gel A column with an exclusion limit of 500,000 daltons. The Ag recognized by mAb 18.44 was not radiolabeled with 125I or [35S]methionine, migrated with the dye front in SDS-PAGE, and was insensitive to proteinase K digestion, suggesting a non-protein composition. mAb 17.41 significantly neutralized 25 times the ID50 of sporozoites for mice. This mAb binds multifocally to the sporozoite surface and recognizes [35S]methionine-labeled sporozoite surface Ag of 28,000 m.w., 55,000 m.w., and 98,000 m.w. Immune bovine serum immunoprecipitated [35S]methionine- or 125I-labeled sporozoite Ag ranging from < 14,300 m.w. to > 200,000 m.w., including surface Ag of 28,000 m.w. and 55,000 m.w. The results indicate that two different molecules capable of inducing neutralizing antibody are exposed on the surface of C. parvum sporozoites.

Original languageEnglish (US)
Pages (from-to)1340-1345
Number of pages6
JournalJournal of Immunology
Issue number4
StatePublished - 1989

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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