Plasmodium falciparum merozoite vaccination in Aotus monkeys recovered spontaneously from P. falciparum infection: a clinical study.

6 Aotus trivirgatus monkeys, which had all spontaneously recovered from an experimentally induced Plasmodium falciparum infection, were included in a clinical study concentrating on possible adverse reactions caused by a vaccine using late schizonts and merozoites as an antigen a synthetic compound, CP-20,961, as an adjuvant. Two monkeys in the study were vaccinated once, 2 twice, 1 received adjuvant alone and 1 served as a saline control. Local and general inflammatory reactions as indicated by local oedema, induration, femoral lymphadenopathy, fever and leukocytosis, were observed in all vaccinated animals and in the one monkey after the second adjuvant injection. Serum albumin and transaminase enzyme levels increased in all animals whereas plasma fibrinogen, protamine sulfate and ethanol gelation titers rose only inthe vaccinated monkeys. A transient increase of alkaline phosphatase and erythrocyte sedimentation rate was noticed in half of them. We conclude that this type of malaria vaccine causes moderate adverse reactions in Aotus but they are transitory and seem not to lead to permanent damage.