Immunization with synthetic peptides of a Plasmodium falciparum surface antigen induces antimerozoite antibodies.

Polypeptides expressed on the surface of merozoites, the invasive stage of the asexual blood cycle, are good candidates for the development of malaria vaccines. Five synthetic peptides with predetermined specificity deduced from a genomic DNA clone coding for the NH2-terminal portion of the main merozoite surface polypeptide of Plasmodium falciparum were evaluated for their capability to raise antibodies that react with the P. falciparum merozoites.

Immunization with a Plasmodium falciparum merozoite surface antigen induces a partial immunity in monkeys.

Saimiri monkeys immunized with a Plasmodium falciparum merozoite polypeptide of 41 kD mol wt are resistant to a blood challenge infection that induces a fulminant infection in control monkeys. The sera of the immunized monkeys reacted, as shown by the indirect immunofluorescence technique, with the apical part of the merozoites from five isolates or clones of P. falciparum.

Major surface antigen gene of a human malaria parasite cloned and expressed in bacteria.

The late blood stages of the human malaria parasite, Plasmodium falciparum, carry a major surface antigen, p190, of molecular weight (Mr) 190,000. This antigenically variable protein is actively processed, first as the parasite matures and again when it is released into the blood stream and invades a new erythrocyte to initiate a cycle of growth. It elicits a strong immune response in man; all tested adult sera from endemic areas have antibodies against this protein.

Antimalarial immunity in Saimiri monkeys. Immunization with surface components of asexual blood stages.

Plasmodium falciparum polypeptides of 200 and 140 K mol wt exposed at the surface of merozoites and/or schizonts were purified by affinity chromatography and by electroelution from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Monkeys were separated into three groups of four and immunized either with one of the two polypeptides or with saline (control). After intravenous challenge with 2.

Plasmodium berghei: diet and drug dosage regimens influencing selection of drug-resistant parasites in mice.

Two different diets for the host and three drug dosage regimens were used to select lines resistant to sulfadoxine and pyrimethamine from the parent strain of the rodent malaria parasite Plasmodium berghei [the N (K173) strain]. A higher yield of resistance was obtained when a high parasitemia was present at the beginning of the drug pressure schedule. The development of resistance to the association of sulfadoxine plus pyrimethamine was accelerated by a relatively high para-aminobenzoic acid (PABA) content diet.