Volume 270,
Number 21,
Issue of May 26, pp. 12941-12947, 1995
©1995 by The American Society for Biochemistry and Molecular Biology, Inc.
Anchoring
of an Immunogenic Plasmodium falciparum Circumsporozoite
Protein on the Surface of Dictyostelium discoideum
Christophe D.
Reymond
,
Carole
Beghdadi-Rais
,
Mario
Roggero
,
Elizabeth
A.
Duarte
,
Chantal
Desponds
,
Michel
Bernard
,
Dorinne
Groux
,
Hugues
Matile
,
Claude
Bron
,
Giampietro
Corradin
,
Nicolas
J.
Fasel
The circumsporozoite protein (CSP), a major antigen of
Plasmodium falciparum, was expressed in the slime mold
Dictyostelium discoideum. Fusion of the parasite protein to a
leader peptide derived from Dictyostelium contact site A was
essential for expression. The natural parasite surface antigen,
however, was not detected at the slime mold cell surface as expected
but retained intracellularly. Removal of the last 23 amino acids
resulted in secretion of CSP, suggesting that the C-terminal segment of
the CSP, rather than an ectoplasmic domain, was responsible for
retention. Cell surface expression was obtained when the CSP C-terminal
segment was replaced by the D. discoideum contact site A
glycosyl phosphatidylinositol anchor signal sequence. Mice were
immunized with Dictyostelium cells harboring CSP at their
surface. The raised antibodies recognized two different regions of the
CSP. Anti-sporozoite titers of these sera were equivalent to
anti-peptide titers detected by enzyme-linked immunosorbent assay.
Thus, cell surface targeting of antigens can be obtained in
Dictyostelium, generating sporozoite-like cells having
potentials for vaccination, diagnostic tests, or basic studies
involving parasite cell surface proteins.