[Development and preliminary application of monoclonal antibodies against N protein of SARS virus].

OBJECTIVE: To develop the monoclonal antibody against N protein of SARS virus and study its applicability. METHODS: BALB/c mice were immunized with recombinant N protein. Spleen cells were collected and infused with SP2/0 cell. The infused cells were screened for anti-N protein antibody with ELISA. The positive cells were cloned and injected into abdominal cavity. The antibodies were purified from ascites. The affinities of those purified antibodies were analyzed with ELISA. The ELISA for detection of SARS virus antigen was developed by using antibody with the highest affinity. Its sensitivity and specificity were also evaluated primarily. RESULTS: Eleven monoclonal cells secreting antibody have been developed. Three of the 11 purified monoclonal antibodies had very high affinity to N protein, while 4 purified McAbs showed very weak reaction to N protein, the affinities of remaining 4 McAbs were in between. The ELISA for detection of SARS virus antigen was developed with McAb 7. Its sensitivity was about 31 PFU/ml and had no cross reaction with other respiratory viruses. CONCLUSION: The monoclonal antibody has good specificity and may be used to detect SARS virus antigen. However, its sensitivity is to be evaluated further with clinical samples from SARS patients, especially at acute phase.