REGULAR PRODUCTION OF INFECTIVE SPOROZOITES OF PLASMODIUM-FALCIPARUM AND PLASMODIUM-VIVAX IN LABORATORY-BRED ANOPHELES-ALBIMANUS

One of the major constraints for studies on the sporogonic cycle of th e parasites causing human malaria, and on the protective efficacy of p re-erythrocytic vaccines, is the scarcity of laboratory-reared Anophel es mosquitoes as a source of infective sporozoites. The aim of the pre sent study was to reproduce the life-cycles of Plasmodium falciparum a nd P. vivax in the laboratory and so develop the ability to produce in fective sporozoites of these two species regularly under laboratory co nditions. Colonized Anopheles albimanus, of Buenaventura and Tecojate strains, were infected by feeding either on Plasmodium-infected blood, from human patients or experimentally inoculated Aotus monkeys, or on gametocytes of the P. falciparum NF-54 isolate grown in vitro. The mo nkeys were infected with the blood stages of a Colombian P. vivax isol ate and then, after recovery, with the Santa Lucia strain of P. falcip arum from El Salvador. Although both of the mosquito strains used were successfully infected with both parasite species, the Buenaventura st rain of mosquito was generally more susceptible to infection than the Tecojate strain, and particularly to infection with the parasites from the patients, who lived where this strain of mosquitoes was originall y isolated. Monkeys injected intravenously with the P. vivax sporozoit es produced in the mosquitoes developed patent sexual and asexual para sitaemias; the gametocytes that developed could then be used to infect mosquitoes, allowing the development of more sporozoites. However, ex perimental infections failed to establish after the P. falciparum spor ozoites were used to inoculate monkeys. The ability to reproduce the c omplete life cycle of P. vivax in the laboratory, from human to mosqui to and then to monkey, should greatly facilitate many studies on vivax malaria and on the efficacy of candidate malaria vaccines. The availa bility of the sporogonic cycles of P. falciparum from three different sources should also permit a variety of biological studies.