[Preparation of specific monoclonal antibody against nucleocapsid protein of SARS coronavirus].

AIM: To express nucleocapsid(N) protein of SARS coronavirus and produce monoclonal antibody(mAb) to N protein. METHODS: N protein gene was amplified by RT-PCR. After being confirmed by DNA sequencing, the gene was subcloned into prokaryotic expression vector. N protein expressed in E.coli was recovered from SDS-PAGE gel and served as immunogen in the preparation of the mAb. RESULTS: DNA sequencing confirmed that the amplified fragment was N protein gene. SDS-PAGE analysis showed that the M(r) of the expressed protein was approximately 43 kd. This expressed protein could be further confirmed in Western blot by using serum from a convalescent SARS patient as primary antibody. Western blot analysis proved that three mAbs obtained could react specifically to the recombinant N protein. CONCLUSION: The prepared recombinant N protein and mAbs against N protein lay the foundation for further development of early diagnosis assays for SARS coronavirus infection.