Circumsporozoite gene of plasmodium cynomolgi (Gombak):cDNA cloning and expression of the repetitive circumsporozoite epitope.

Abstract

The identification, sequence and expression in Escherichia coli of the immunodominant epitope of the circumsporozoite (CS) gene of Plasmodium cynomolgi (Gombak), a simian malaria parasite is reported. This epitope is encoded by a DNA sequence that is tandemly repeated 10 times in the cDNA [complementary DNA] clone. Subclones that contain and express only repeats and in variable number were constructed. The binding of a specific anti-CS protein monoclonal antibody correlates positively with the number of repeats in each subclone. The CS gene of another strain of P. cynomolgi (NIH) encodes an immunodominant epitope that is immunologically distinct from that of the Gombak strain. These 2 CS genes share extensive overall homology, although the nucleotide sequences that encode the epitopes appear to be unrelated.