Chulalongkorn Medical Journal


Background : Bovine anaplasmosis is an important tick-borne disease caused byAnaplasma marginale (A. marginale) and infected in ruminants, mostly incattle. This disease occurs in tropical and subtropical regions includingThailand and causes a major problem to livestock productions. The majorsurface protein 5 (MSP5) is one of outer membrane protein of A. marginalewhich as an immunodominant protein encoded by a single gene and alsohighly conserved gene.Objective : The aim of this study was to optimize the conditions for the expression ofrecombinant major surface protein 5 (rMSP5) of A. marginale.Methods : The msp5 gene of A. marginale was cloned into the pET100/D-TOPO®vector to produce an pET100-msp5-6xHis fusion gene construct. Therecombinant proteins were expressed by the plasmids in Escherichia colihost strain BL21 star™(DE3) at different temperatures (16, 25 and 37 C)for 6 h. The proteins were analyzed by SDS-PAGE and confirmed the targetprotein by Western blotting using antisera against His.Results : After induction with 0.1 mM of Isopropyl β-D-1-thiogalactopyranoside(IPTG) at different temperatures for protein expression, the protein wasnot produced at 6 h for 16 C. On the other hand, the rMSP5 protein wasproduced at 25 and 37 C for 2-6 h but the expressive protein at 25 Cshowed lower yield than that at 37 C.Conclusion : In this study, the best condition for rMSP5 protein expression wascultured at 37 C for 4 h. The protein was identified as the rMSP5 atthe molecular weight of 26 kDa.



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