Major surface antigen p190 of Plasmodium falciparum: detection of common epitopes present in a variety of plasmodia isolates.

Abstract

Plasmodium falciparum merozoites are covered with polymorphic proteins that are processed from a 190 kd (p190) precursor protein. These are candidates for an antimalarial vaccine. We cloned and expressed a number of DNA fragments, comprising almost the entire p190 gene of the K1 isolate, in Escherichia coli. Pooled human endemic‐area sera and rabbit antibodies raised against p190 protein isolated from K1 parasites react with only a limited number of the recombinant proteins. From these studies we could select two antigenic polypeptides containing conserved amino acid stretches of the otherwise highly polymorphic protein. Rabbits and mice injected with the purified recombinant proteins produce antibodies reacting differentially with various isolates of P. falciparum. We obtained antibodies detecting all isolates tested and a monoclonal antibody specific for isolates containing a K1 type allele of the p190 gene.

Immunization of Aotus monkeys with Plasmodium falciparum blood-stage recombinant proteins.

“…Because of the problem of antigen polymorphism (6,7), two conserved regions of the p190 molecule (amino acid residues 146-312 and 1059-1196; ref. 8) were expressed in Escherichia coli as a single fusion protein termed 190N (9). The use of strongly conserved regions of p190 reduces the risk of antigenic variation triggered by immunization.…”

“…The use of strongly conserved regions of p190 reduces the risk of antigenic variation triggered by immunization. 190N antigen is recognized by sera of humans with acquired semiimmunity to malaria (9) and contains B-and T-cell epitopes (10). These properties made it an attractive subunit vaccine candidate based on the protective natural p190 molecule (9,10).…”

Rhoptry-Associated Protein 1-Binding Monoclonal Antibody Raised against a Heterologous Peptide Sequence InhibitsPlasmodium falciparumGrowth In Vitro

“…Finally, the pelleted parasites were resuspended in 3 volumes of SSC buffer (1ϫ SSC is 0.15 M NaCl plus 0.015 M sodium citrate) and stored at Ϫ80°C before use. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was performed essentially as described (13). Briefly, parasite lysates or rRAP-1 (2 g per lane) were run on 10% gels.…”

New B cell epitopes in the Plasmodium falciparum malaria circumsporozoite protein

“…Bound antibodies were detected using horseradish peroxidase-conjugated rabbit anti-mouse IgG(H + L) (Nordic Immunologicals, Tilburg, The Netherlands). From each fusion, specific hybridomas were cloned and further analyzed by immunofluorescence on air-dried, unfixed sporozoites of isolates NF54 [6] and Ro59 [7], using fluorescein-labeled rabbit anti-mouse IgG(H + L) as second antibody.…”