Artikel
Evaluation of antibody responses against SARS coronaviral nucleocapsid or spike proteins by immunoblotting or ELISA
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Veröffentlicht: | 26. Mai 2004 |
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Gliederung
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Background: SARS-CoV is a newly emerging virus that causes severe acute respiratory syndrome (SARS) with high mortality rate in infected people. To study the humoral responses against SARS-CoV, we evaluated nucleocapsid (N) and spike (S) proteins-specific antibodies in patients' sera by western blotting and ELISA.
Methods: Recombinant N and S proteins of SARS-CoV were purified from transformed E. coli. Serum specimens from forty SARS-CoV-infected patients in the convalescent phase were analyzed by western blotting using the purified antigens. Serial serum specimens from twelve RT-PCR confirmed SARS patients were assayed by ELISA using the recombinant N protein as coated antigen.
Results: By western blotting, 97.5% of the SARS patients were positive for N protein-specific antibodies whereas only 47.5% of the samples were positive for S protein-specific antibodies. Using N protein-based ELISA, ten out of the twelve patients were positive for N protein-specific antibodies and six of them showed seroconversion at mean of 16 days after onset of fever.
Conclusions: Immunoblotting was useful for detecting the humoral immune response after SARS-CoV infection. Antibodies against SARS-CoV N protein appear at the early stage of infection, therefore, N protein-based ELISA could serve as a simple, sensitive and specific test for diagnosing SARS-CoV infection.