Specific antibodies against the nucleocapsid protein and S1 domain of spike glycoprotein in patients with severe acute respiratory syndrome

Abstract

To explore the laws of the appearance of the specific serum antibodies against the nucleocapsid (N) protein and the S1 domain of spike (S) glycoprotein in patients with severe acute respiratory syndrome (SARS) and to evaluate the value of these two proteins to be used as diagnostic makers for SARS. The serum samples of 86 patients with SARS confirmed clinically and serologically, 31 males and 55 females, aged 9 approximately 86, with the course of disease of 1 approximately 81 days, and 745 healthy persons were collected during the course. The specific immunoglobulin G (IgG) against N protein, IgG against S1 domain of S protein, and the SARS-CoV IgG in these sera were detected by ELISA. The positive rates of anti-N-IgG, anti S1-IgG, and anti-SARS-CoV IgG were 14% (6/44), 5% (2/44), and 14% (6/44) respectively in the first week of the course of disease, 56% (10/18), 39% (7/18), and 56% (10/18) respectively in the second week, and 100% (24/24), S1-IgG 83% (20/24), and 100% (24/24) respectively in the third week. The agreement rates of the results of anti-N-IgG and anti-s1-IgG with that of the anti-SARS-CoV IgG were 88% (76/86) and 83% (71/86) respectively. The anti-SARS-CoV IgG positive rate in the healthy persons was 1.88% (14.745). The N protein and S1 protein may be used as antigens in the development of serological assay for detection of SARS-CoV infection.