Objective: To determine the antigen characteristics of different fragments of SARS-CoV N protein expressed in E. Coli and their application in the serological diagnosis.
Methods: Based on preliminary analysis of 39 different segments of the N protein, We choosed six purified N protein for further antigenicity characterization in this study, including that PN360 (1 -360aa), PN301 (1-301aa), PN199 (30-228aa), PN185 (30-214aa), PN155b (60-214aa), and PN125 (90-214aa). We developed Western-Bolt and ELISA to detect antibody reactivity between truncated N fragments with sera from SARS-CoV-negative normal adults or SARS-CoV patient convalescent sera.
Results: Western-Bolt results show that all the six fragments have reacted with the SARS patient convalescent sera, but the PN360 and PN301 showed obvious cross-reaction with sera from SARS-CoV-negative normal adults; sensitivity analysis using an ELISA coating with PN199, PN185, PN155b, PN125 as antigen showed that the PN185 and PN155b are better than PN125.
Conclusion: Truncated N protein PN185 and PN155b expressed in E. Coli are better antigen candidates used for detection of SARS-CoV specific antibody.