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Infection and Immunity, November 2000, p. 6189-6195, Vol. 68, No. 11
Department of Microbiology, Meharry Medical
College, Nashville, Tennessee 37208
Received 3 April 2000/Returned for modification 14 June
2000/Accepted 9 August 2000
Using sera from mice immunized and protected against
Plasmodium yoelii malaria, we identified a novel
blood-stage antigen gene, pypag-2. The 2.1-kb
pypag-2 cDNA contains a single open reading frame that
encodes a 409-amino-acid protein with a predicted molecular mass of
46.8 kDa. Unlike many characterized plasmodial antigens, blocks of
tandemly repeated amino acids are lacking in the pypAg-2 protein
sequence. Recombinant pypAg-2, comprising the full-length protein minus
the predicted N-terminal signal and C-terminal anchor sequences, was
produced and used to raise a high-titer polyclonal rabbit antiserum.
This antiserum was used to identify and characterize the native protein
through immunoblotting, immunoprecipitation and immunofluorescence
assays. Consistent with the presence of a glycosylphosphatidylinositol
anchor, pypAg-2 fractionated with the detergent phase of Triton
X-114-solubilized proteins and could be metabolically labeled with
[3H]palmitic acid. By immunofluorescence, pypAg-2
expression was localized to both the trophozoite and merozoite
membranes. Similar to Plasmodium falciparum merozoite
surface protein 1, pypAg-2 contains two C-terminal epidermal growth
factor (EGF)-like domains. Most importantly, immunization with
recombinant pypAg-2 protected mice against lethal P. yoelii
malaria. Thus, pypAg-2 is a target of protective immune responses and
represents a novel addition to the family of merozoite surface proteins
that contain one or more EGF-like domains.
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
A Protective Glycosylphosphatidylinositol-Anchored
Membrane Protein of Plasmodium yoelii Trophozoites and
Merozoites Contains Two Epidermal Growth Factor-Like Domains
*
Corresponding author. Mailing address: Meharry Medical
College, Department of Microbiology, 1005 D. B. Todd Blvd.,
Nashville, TN 37208. Phone: (615) 327-5726. Fax: (615) 327-6072. E-mail: jburns{at}mail.mmc.edu.
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