Cloning of cDNAS that code for Plasmodium chabaudi antigens of the erythrocytic forms and cross-hybridize with P. falciparum.

Several Plasmodium chabaudi antigens are synthesized and the corresponding mRNAs are detected by cell-free translation only during specific stages of the erythrocytic cycle. Ring stage mRNA was used to construct a cDNA library in the plasmid vector pBR 322. The library was screened by differential hybridization with cDNA specific for ring stage parasites or schizonts. Two clones which showed some stage specificity and seven which did not were retained. Three clones were characterized by hybrid-selected translation. Clones 451, 148 and 443 contain sequences homologous to the messages for a 27 kDa stage-specific antigen, a 37 kDa early antigen and a 24 kDa antigen, respectively. The nine clones cross-hybridize to various degrees with cDNA from P. falciparum but cross hybridization intensities do not reflect the strength of immunological cross-reactivity.