Isolation of a gene segment expressed by mature schizonts of Plasmodium knowlesi

Fragments of Plasmodium knowlesi DNA, generated by mung bean nuclease digestion, were ligated into the lambda gt11 vector. This expression library was immunoscreened with a serum which inhibits invasion of erythrocytes by merozoites in vitro and whose primary specificity is directed against a Mr 140 000 merozoite surface antigen. One of the isolated clones contained a 125 base pair insert which hybridized to a 1.8 kilobase species of schizont RNA, indicating that this insert is part of a gene expressed during schizogony.