Expression and serological application of recombinant epitope-repeat protein carrying an immunodominant epitope of Newcastle disease virus nucleoprotein

Gaikwad, Satish S.; Lee, Hyun-Jeong; Kim, Ji-Ye; Choi, Kang-Seuk

In the study, we designed, expressed and characterized the rERP in baculovirus expression system. This protein carried tandem repeats of IDE on NDV NP. The protein carried N terminal his tag allowing one-step purification under Ni NTA agar column [23, 24] . The construct designed to express recombinant protein was codon optimized for Sf9 cells. Codon optimization involves codon adaptability, mRNA structure, tRNA usage. It significantly increases protein expression [25] [26] [27] . We used tetra-glycine linker as linker in between epitopes as it provides flexibility due to lack of β-carbon and is preferred linker in multi-epitope proteins [28] . Computer modeling showed that all the epitopes are freely accessible in three-dimensional space. This rERP was expressed at high concentration in insect cells when titrated by ELISA. We purified pro- tein under denaturing condition on a Ni-NTA matrix with a high degree of purity [29] .