Expression of porcine parvovirus VP2 gene requires codon optimized E. coli cells

Porcine parvovirus (PPV) is a widespread infectious virus that causes serious reproductive diseases of swine and death of piglets. The gene coding for the capsid protein VP2 of PPV was amplified and inserted into the plasmid pET-32a (+), which was then used to transform Escherichia coli Rosetta, the capsid protein of PPV was fused to a polyhistidine tag, and the position of the affinity tag is in N-terminus. VP2 was expressed using different expression host bacteria, including E. coli BL21, and Rosetta, and different plasmid vectors, including pET-30a (+), pET-32a (+), and pGEX-6p-1. After selection, only the fusion protein inserted into pET-32a (+) was expressed well in E. coli Rosetta. The recombinant bacterium produced high quantities of the fusion protein VP2, about 8% in total. The expressed VP2 was antigenically similar to the native capsid protein according to a Western blot assay performed with polyclonal antibodies obtained from pigs vaccinated with PPV. A simple, easily commercialized procedure was used to purify this protein. This study provides a foundation for the application of VP2 protein in the clinical diagnosis of PPV and in the vaccination against PPV.