Abstract: AIM: To characterize the immunopositive clone expressing Pc90 of Plasmodium chabaudi and then express it in E. coli. METHOD: A cDNA clone (designated Pc90 1) was deleted with ExoⅢ and sequence analysis was performed with chain terminating, then transferred to E. coli for fushion expression. RESULTS:The clone Pc90 1 with a length of 2 581 nucleotides was identified. Its deduced coding capacity was approximately 61 kDa (532 amino acids). The open reading frame extended to position 1 569, which was followed by two consecutive stop codons. Surprisingly, the 3 putative untranslated regions were relatively long. Pc90 1 showed a remarkable repeat structure composed of four distinct types of repetitive elements (between 100 and 355 amino acids). Five sequencing subclones were subjected to expression in pEX32 vectors,but only subclone SK5 expressed a 35 kDa protein. The Pc90 1 has no homology with all known sequences by a search of EMBL and Swiss Prot data bases. The characterization of Pc90 1 deduced protein was identical with Pc90, an phosphoprotein with an isoelectric point of 4.6. CONCLUSION: Pc90 1 was a possible candidate expressing Pc90 protein.