Co-expression, purification and bioassay of three avian viral antigens / 生物工程学报

To achieve uniform soluble expression of multiple proteins in the same Escherichia coli strain, and simplify the process steps of antigen production in genetic engineering subunit multivalent vaccine, we co-expressed three avian virus proteins including the fowl adenovirus serotype 4 (FAdV-4) Fiber-2 protein, infectious bursal disease virus (IBDV) VP2 protein and egg-drop syndrome virus (EDSV) Fiber protein in E. coli BL21(DE3) cells after optimization of gene codon, promoter, and tandem expression order. The purified proteins were analyzed by Western blotting and agar gel precipitation (AGP). The content of the three proteins were well-proportioned after co-expression and the purity of the purified proteins were more than 80%. Western blotting analysis and AGP experiment results show that all the three co-expression proteins had immunoreactivity and antigenicity. It is the first time to achieve the three different avian virus antigens co-expression and co-purification, which simplified the process of antigen production and laid a foundation for the development of genetic engineering subunit multivalent vaccine.

Cloning and expression of VP2 gene of infectious bursal disease virus in eukaryotic cells

Infectious bursal disease [IBD] is an economically important viral disease of chickens with worldwide distribution which suppresses the immune system of young chickens. VP2 is the major host-protective protein of infectious bursal disease virus [IBDV]. The encoding region of VP2 protein was PCR amplified from a plasmid containing a cDNA fragment of large genomic segment of IBDV, strain D78. This region of 1356 bp was inserted into a eukaryotic expression plasmid, pCDNA4, under the control of human cytomegalovirus [hCMV] immediate early enhancer and promoter. Plasmid DNA was transfected into COS-7 cell line and transient expression of VP2 from the constructed plasmid was characterized by dot blotting with a polyclonal antibody to IBDV