Cloning and expression of Iranian isolate of Apple chlorotic leaf spot virus coat protein gene in E. coli

The Apple chlorotic leafspot virus (ACLSV) is among of the most common virus infecting pome and stone fruit trees around the world. The virus has spread throughout the world and has been reported in many hosts such as; apples, pears, peaches and cherries. The purpose of this study is to express the coat protein (CP) of ACLSV in E. coli. CP expression in E. coli has been developed to prepare antigen for antibody production without needs to purify the virus from infected plant. In this study, complete CP gene (582 bp) from an isolate of ACLSV (SSa) was amplified by specific primers, MF and MR. The amplified CP gene was ligated to TA cloning vector (pTG19-ACLSV CP) and transformed into E. coli strain DH5α. Transformed cells were selected on LB containing ampicillin, X-Gal and IPTG, and recombinant plasmids were confirmed by restriction analysis. Then, the pTG-ACLSV CP was sub-cloned into pET28a (+) as expression vector that digested by BamHl and XhoI restriction enzymes. Finally, the pET28a-ACLSV CP was transformed into E. coli strain BL21 by heat shock method. For ACLSV CP expression, the cells containing pET28a-ACLSV CP were induced by 1 mM of IPTG and the protein was extracted two and four hours after induction and analyzed in SDS-PAGE. The SDS-PAGE result showed that ACLSV CP have been expressed that is expected based on additional tags from plasmid.