Abstract: Objective   To conjugate Plasmodium falciparum Pfs25 to recombinant Pseudomonas aeruginosa ExoProtein A (rEPA) and test the effect of conjugation using different chemical linkers.  Methods   The Pfs25 was thiolated by NAHT (DL-N-acetylhomocysteine thiolactone)， whereas the carrier protein rEPA was modified by Sulfo-EMCS， EMCH，SBAP and Sulfo-SIAB respectively. The Pfs25-rEPA conjugates were formed by incubating the thiolated Pfs25 with modi-fied rEPA under certain conditions. Coomassie blue stained SDS-PAGE was performed to examine the results of the conjugation.  Results   The Pfs25 was successfully conjugated to the carrier protein rEPA by the linkers used in this study. For the addition of a chemical group onto the protein， the reaction between the groups of primary amine and NHS (N-hy-droxysuccinimide) ester was more efficient than the reaction between the groups of carboxyl and hydrazide with EDC as a crosslinker; for the formation of a conjugate， the reaction between the groups of maleimide and free sulfhydryl was more efficient than the reaction between the groups of haloacetyl and free sulfhydryl.   Conclusion   The Pfs25 can be conjugated to the rEPA by the chemical linkers with different conjugation efficiency and coupling proteins.

Key words: Plasmodium falciparum, Pfs25, Pseudomonas aeruginosa, rEPA, Conjugation