Plasmodium vivax: in vitro growth and reinvasion in red blood cells of Aotus nancymai.

Plasmodium vivax was maintained in experimentally infected Aotus nancymai. Positive monkeys were used as donors for culture material. After leucocyte removal with two different methods, including the classic CF11 method and a commercially available filter, parasites were grown under continuous shaking conditions in standard RPMI 1640, containing 20% human AB + serum. When mature schizonts were present, artificially induced reticulocytes from monkeys pretreated with the hemolytic drug phenylhydrazine HCl were added. Addition of reticulocytes and shaking were both necessary to realize a significant reinvasion under in vitro conditions. A strong positive correlation between the percentage of reticulocytes and in vitro invasion was demonstrated, and a preferential invasion into reticulocytes was demonstrated in vivo and in vitro using blood films stained with brilliant cresyl blue and counterstained with Giemsa.