Characterization
of a > 900,000-M(r) Cryptosporidium parvum sporozoite glycoprotein
recognized by protective hyperimmune bovine colostral immunoglobulin
C Petersen, J Gut, PS Doyle, JH Crabb, RG Nelson and JH Leech
Parasitology Laboratory, San Francisco General Hospital, California.
Cryptosporidium parvum, a zoonotic Apicomplexan pathogen, causes profound
diarrhea, malnutrition, and dehydration in patients with AIDS. A less
severe, self-limited disease occurs in immunocompetent individuals,
particularly children, animal handlers, and residents of the developing
world. Very little is known about the biology of the organism, the
pathophysiology of the disease process, or the mechanism of protective
immunity. There is no effective therapy for cryptosporidiosis, but
hyperimmune bovine colostrum raised against Cryptosporidium oocysts
and sporozoites has ameliorated infection and disease in some patients
with AIDS, and a variety of monoclonal antibodies, as well as hyperimmune
bovine colostrum, have significantly reduced cryptosporidial infection
of mice and calves. We report here the identification and initial
characterization of a > 900,000-M(r) Cryptosporodium sporozoite
glycoprotein (GP900) that is a prominent antigen recognized by protective
hyperimmune bovine colostral immunoglobulin. Three of six murine anticryptosporidial
monoclonal antibodies reacted with GP900, indicating that the molecule
is highly immunogenic in mice as well as in cows. GP900 is Triton
X-100 soluble and N glycosylated. Western blotting of the N-deglycosylated
protein, detected with antibodies eluted from recombinant clones expressing
a partial GP900 fusion protein, suggested that the polypeptide backbone
of the glycoprotein has an M(r) of < 190,000. GP900 is encoded
by a single-copy gene that resides on the largest Cryptosporidium
chromosome.
American Journal
of Clinical Nutrition, Vol 54, 829-835, Copyright ? 1991 by The American
Society for Clinical Nutrition, Inc
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