Vol 14 No 3 July 2015
Prokaryotic expression, purification and immunogenicity analysis of CpsD protein from Streptococcus iniae
Description:1-Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Ya’an, Sichuan Province, 625014, China. 2-Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Ya’an, Sichuan Province, 625014, China. 3-Tongwei Co. Ltd., Chengdu, Sichuan Province, 610041, China. 4-Department of Aquaculture, College of Animal Science and Technology, Sichuan Agricultural University, Ya’an, Sichuan Province, 625014, China. *Corresponding author's email: kywangsicau@126.com
Streptococcus iniae is a major cause of serious bacterial infections in both fish and human beings. Capsular polysaccharide (CPS) ofS. iniae is vital to evade phagocytic clearance of the host and serves as an important protective antigen ofS. iniae infection in aquatic animals. The CpsD gene was determined to be highly conservative in capsule polysaccharide operon. Prokaryotic expression of the CpsD gene of a clinical isolate of S. iniae from channel catfish and immunogenic examination of the recombinant protein were first described in this essay. The recombinant protein was expressed in the form of inclusion bodies (IBs). Induction conditions inEscherichia coli were optimized with 0.6mM Isopropyl β-D-1-Thiogalactopyranoside at 37°C for 5h after the culture mid-log phase in Luria Bertani (LB) medium. The recombinant protein CpsD was thus expressed and purified by immobilized metal affinity chromatography (IMAC), yielding approximate 582.47 mg the protein per liter culture. Western blot analysis showed that the purified CpsD had reactogenicity. It will possibly reveal more details of capsule synthesis and capsule regulation during various stages of theS. iniaeinfectious process.
Keywords:Streptococcus iniae, Capsular polysaccharide, Prokaryotic expression, Purification, Western blot analysis.
Author:Wang H.C.1; Wang K.Y.1,2*; Wang J.1; Xiao D.3; Huang J.L.1; Chen D.F.4
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