Cloning and expression of truncated Spike (S-f200) Glycoprotein of Infectious Bronchitis Virus (IBV) in Escherichia coli, and its immunogenicity to mice

Complete S1 gene of the Infectious Bronchitis Virus (IBV) was amplified and cloned into transfer vector.
Truncated S1 gene designated as Sf200 (containing five antigenic sites located at 24–61, 291–398 and
497–543 amino acid residues of S1 glycoprotein) were amplified by overlap PCR, cloned into prokaryotic
expression vector resulting pET-Sf200 and confirmed the construct by sequencing. The recombinant
plasmid was identified by restriction enzyme and sequencing analysis. The in vitro expression of the
truncated protein was analyzed in E. coli with a molecular weight of 38kDa determined through SDSPAGE
and confirmed by Western blotting. The recombinant truncated protein was then purified from the
culture media. The immunogenicity of the protein was studied in an animal experiment on mice, in which
mice were injected subcutaneously. These findings suggest that the truncated Sf200 expressed in the pET-
32a (+) prokaryotic vector can be used as antigen to detect antibodies against IBV.