Abstract: AIM:To observe high efficientexpression of the second region of merozoite surface
antigen- 1 (MSA1 - R2 ) in E.Coli for further biological studies. METHODS:Gene encoding MSA1 -
R2 of a Chinese isolate of P.falciparum was recovered from a recombinant sequencing vector M13- MSA1 R2 and cloned into p WR- 4 5 0 I,a vector for expression of fusion protein with β-
galactosidase.The recombinant vectors were transferred into E.Coli and identified by PCR and
restriction enzyme digestion. The transformed bacteria bearing pWR-MSA1R2 plasmids were induced by IPTG for production of fusion proteins. The expressed products were analyzed by SDS-PAGE, β- galactosidase activity, dot-ELISA and Western blot. RESULTS: pWR-MSA1R2 transformed bacteria produced the desired fusion proteins with a relative molecular weight of 70 kDa, representing 35% - 40% of the total bacterial proteins. The expressed protein exhibited a strong reaction with an timalarial antibodies as detected by dot-ELISA with immune sera obtained from rabbits immunized with P.falciparum. When the products were blotted with the same antisera, specific bands of 70 kDa representing MSA1R2-galactosidase fusion proteins were identified, while the products from the same bacteria without IPTG induction failed to react with the antisera. CONCLUSION: pWR450-E. Coli expression system may be used for high efficient expression of some malarial glycoprotein antigens, with satisfactory immunological activities.

Key words: Plasmodium falciparum, merozoite surface antigen- 1, expression, fusion protein