Polypeptide antigens Mr 90,000 and 72,000 related to protective immunity against the blood form of Plasmodium falciparum in the squirrel monkey show stable characteristics in strains from different geographic origins

Abstract

Squirrel monkeys protected after vaccination with a particular protein fraction of Plasmodium falciparum elicit antibodies directed against two parasite proteins, Mr 90,000 and 72,000. We have used monoclonal antibodies and sera from protected monkeys to determine whether or not these polypeptides were polymorphic in 22 strains. In all the isolates studied, both polypeptides were conserved, as was the epitope defined by monoclonal antibody XIV/7 present on the Mr 90,000. Immunofluorescence of all strains showed the same pattern using 5 Mab produced against different fragments of the Mr 72,000 polypeptide from the FUP strain. All isolates examined were positive, indicating that this polypeptide was present in different strains and that the 5 epitopes were conserved. Peptide mapping of both the Mr 90,000 and 72,000 antigen purified from 3 different strains indicated that each antigen appeared to be conserved.