Protective immunity induced in squirrel monkeys with a multiple antigen construct against the circumsporozoite protein of Plasmodium vivax

Saimiri boliviensis monkeys were immunized with a multiple antigen construct [(PvCS)(2)](2)(P2)(2) directed against the circumsporozoite protein of Plasmodium vivax or a combination of the multiple antigen construct with nonionic copolymer P1005, with P1005 and lipopolysaccharide, with muramyl tripeptide Mf-75, or with alum. Following intravenous challenge with 10,000 sporozoites of the Salvador I strain of P. vivax, 11 of the 26 monkeys were protected against patent parasitemia. Ten additional animals were partially protected. Following rechallenge of the 26 monkeys with 30,000 sporozoites of the homologous strain of parasite, four monkeys were totally protected and nine animals were partially protected.