[In vitro cultivation of the exoerythrocytic stage of Plasmodium vivax (southern China isolate)].

An in vitro culture system for the exoerythrocytic (EE) stage of Plasmodium vivax was first developed in our laboratory in China. Anopheles stephensi mosquitoes were infected by membrane feeding with heparinized blood from a volunteer. After 14-18 days, the mosquito salivary glands were aseptically dissected in culture medium and ground in a tissue grinder to form sporozoite suspension. Sporozoites were counted and added to the cultures of monolayer hepatoma cells at the number of 4.9 x 10(4)-1.3 x 10(5) per cover glass. Sometimes, 8-10 pairs of infected gland were added directly to the cultured cells. On day 7, EE schizonts of P. vivax were found in cultures. In addition, normal erythrocytes (type o) were added to the cultures on day 10 at a concentration of 10(8) per dish. Fourteen days later, erythrocytes in culture supernatant were collected and thin blood films were made. Numerous intra-erythrocytic P. vivax parasites were identified on the films after Giemsa staining. Most intra-erythrocytic forms were rings and early large trophozoites. Schuffer's dots were present in many of the infected cells which were pale and obviously enlarged. These results indicated that the in vitro hepatic cycle of P. vivax was established.