[Expression and purification of recombinant N-terminal protein of SARS S1 subunit expressed in E. Coli].

OBJECTIVE: To express and purify the recombinant N-terminal protein of SARS virus S1 subunit and to study its role in SARS immune response. METHODS: The gene encoding N-terminal 334 amino acid residuals of SARS virus S1 subunit was cloned and expressed in E. Coli. After purification, the recombinant protein was identified by anti-SARS positive sera from recovered SARS patients. The sera from health donors, which were collected before the out-break of SARS, were used as negative control in the study. RESULTS: Sequencing analysis confirmed that the desired DNA sequence in recombinant plasmid was correct and had the same sequence of natural N-terminal of SARS virus S1 subunit. The molecular weight of recombinant fusion protein is about 64 000. The recombinant S1 protein could react with three antibody positive samples from recovered SARS patients, which showed specific bands at 64 000, but not with the control samples according to results of western blot. CONCLUSION: The recombinant N-terminal protein of SARS virus S1 subunit displays specific reaction with SARS antibody and may provide a good tool for further research of immune response to SARS virus.