Cloning, expression and identification of truncated Spike gene of IBV (S_f200) and chicken granulocyte-macrophage colony stimulating factor (GM-CSF)

The aim of this study was to clone, express and identify the truncated S1 gene of nephrotropic infectious bronchitis virus (IBV) and granulocyte-monocyte colony stimulating factor (GM-CSF) of chicken. Firstly, two genes were amplified by polymerase chain reaction (PCR) and cloned into pMD18-T vector. The truncated S1 gene designated as S-f200 (containing five antigenic sites of S1 glycoprotein on amino acid residues (aa) 24-61, (aa) 291-398 and (aa) 497-543 and GM-CSF were then amplified from the respective recombinant pMD18-T plasmids and cloned into pET-32a (+) vector resulting pET-S-f200, pET-GM which were identified by restriction enzyme digestion and sequencing analysis. The in vitro expression of truncated S-f200 and GM-CSF constructs were later expressed in E. coli BL21 with a molecular mass of approximately 38kDa and 29kDa respectively as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Polyclonal antibodies were developed by injecting E. coli expressed S-f200 and GM-CSF into the SPF mice and were used to identify the recombinant proteins by Western blot analysis. These findings indicated that the polyclonal antibodies produced in mice could be used to detect the recombinant truncated S-f200 and GM-CSF and vice versa.