In vitro production and partial purification of Plasmodium falciparum antigen

A simple technique for achieving high yields of Plasmodium falciparum parasites on a continuous basis is described. The technique is applicable in any laboratory. The culture apparatus is also simple and inexpensive and allows multiple cultures to be run simultaneously. A total of approximately 1-2 x 10(9) parasites can be harvested per culture flask per week requiring the use of only 40.0 ml of culture medium (RPMI 1640), 5.0 ml of human sera, and 2.0 ml of outdated human whole blood. P. falciparum parasites (segmenters containing individual merozoites) are cultured in vitro and concentrated 10-15 fold through the use of discontinuous bovine serum albumin gradient centrifugation.Commercial saponin is purified on a Sephadex G-25 column. The haemolytic effect of purified saponin related to human red blood cell concentration is studied. Preliminary observations on the action of some synthetic detergents and enzymes on human erythrocytes are also reported. Purified saponin is used to lyse red blood cells infected with in vitro cultured P. falciparum for the preparation of merozoite antigen. Further purification of parasite material is carried out by sucrose density gradient centrifugation.