Objective:To investigate the effect of utilizing a molecular partner on high-level expression of Mxisca domestica(M.domestica) cecropin in Escherichia coli(E.coli) and to identify the expressed products.Methods:The genomic sequence of M.domestica cecropin A(MC) and M. domestica ubiquitin(UBI) were searched from Cenbank and amplified by reverse transcriptase polymerase chain reaction(RT-PCR).Two expression plasmids,pET32a-MC and pET32a-UBI-MC, were constructed and transferred into E.coli and were then induced by Isopropylβ-D-1- Thiogalactopyranoside(IPTG).The expression of the fusion proteins Trx-MC and Trx-UBI-MC was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE).Fusion protein Trx-MC was verified by Western blot analysis.The bactericidal activity of the purified MC was quantitatively determined using E.coli BL21(DE3).Results:The result showed that the fusion proteins were successively expressed in E.coli BL21 cells.A band at the expected position of 24 kDa representing the Trx-MC target protein was positivelystained,and the band at 4 kDa representing the hydrolysis of mature MC protein was also observed at the expected position. The expression levels of Trx-UBI-MC were higher than that of Trx-MC in E.coli.MC exhibited antimicrobial activity.Conclusions:With high-level expression of housefly cecropin A in E.coli using a fusion protein,MC exhibited antimicrobial activity. Objective: To investigate the effect of utilizing a molecular partner on high-level expression of Mxisca domestica (M. domestica) cecropin in Escherichia coli (E. coli) and to identify the expressed products. Methods: The genomic sequence of M. domestica cecropin A (MC) and M. domestica ubiquitin (UBI) were searched from Cenbank and amplified by reverse transcriptase polymerase chain reaction (RT-PCR). Two expression plasmids, pET32a-MC and pET32a-UBI-MC, were constructed and transferred into E . coli and were then induced by Isopropylβ-D-1-Thiogalactopyranoside (IPTG). The expression of the fusion proteins Trx-MC and Trx-UBI-MC was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein Trx-MC was verified by Western blot analysis. The bactericidal activity of the purified MC was quantitatively determined using E. coli BL21 (DE3). Results: The result showed the fusion proteins were settled in E. coli BL21 cells. A band at the expected position of 2 4 kDa representing the Trx-MC target protein was positively stained, and the band at 4 kDa representing the hydrolysis of mature MC protein was also observed at the expected position. The expression levels of Trx-UBI-MC were higher than that of Trx-MC in E. coli .MC mounted antimicrobial activity. Conclusions: With high-level expression of housefly cecropin A in E. coli using a fusion protein, MC labeled antimicrobial activity.