Inability of Malaria Vaccine to Induce Antibodies to a Protective Epitope within Its Sequence
NAVAL MEDICAL RESEARCH INST BETHESDA MD
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Saimiri monkeys immunized with a recombinant containing 20 copies of the nine amino acid repeat of the Plasmodium vivax circumsporozoite CS protein developed high concentrations of antibodies to the repeat sequence and to sporozoites, but were not protected against challenge. After intravenous injection of an immunoglobulin G3 monoclonal antibody NVS3 against irradiated P. vivax sporozoites, four of six monkeys were protected against sporozoite- induced malaria, and the remaining two animals took significantly longer to become parasitemic. Epitope mapping demonstrated that NVS3 recognizes only four AGDR of the nine amino acids within the repeat region of the P. vivax CS protein. The monkeys immunized with DRAADGQPAG20 did not produce antibodies to the protective epitope AGDR. Thus, determination of the fine specificity of protective immune responses may be critical to the construction of successful subunit vaccines.
- Medicine and Medical Research