A. Bharadwaj et al., IMMUNOGENICITY OF SYNTHETIC PEPTIDES CONTAINING MULTIPLE EPITOPES FROM MALARIA ANTIGENS, Annals of tropical medicine and parasitology, 91, 1997, pp. 19-20
Two, linear peptides, P60 and P65, have been synthesised. Both are bas
ed on region II of the circumsporozoite protein of Plasmodium faliparu
m (7G8), and incorporate various B- and T-cell determinants. Both were
highly immunogenic in Balb/c mice even without the use of a carrier p
rotein. However, whereas Balb/c mice immunized with P60 were partially
protected against a challenge with the blood stages of a normally let
hal strain of P. yoelli, similar mice immunized with P65, an analogue
of P60 containing five more amino acids at the C-terminus, were comple
tely unprotected. There were no significant differences between the ce
llular responses induced by each peptide in an ex-vivo, lymphocyte-pro
liferation assay. Although the anti-P60 antibody response was primaril
y directed against the N-terminal region of the peptide, the response
against P65 was predominantly against the C-terminal, with very little
response against the N-terminal fragments. The immunodominant B-epito
pes in P60 may therefore differ from those in P65, leading to the rema
rkably different responses to challenge after immunization. It appears
that the primary structure of epitopic peptides may affect the focus
of the humoral response against the epitopes included in the peptides.