[Dynamic changes of immunoglobulin G in convalescents who have suffered from severe acute respiratory syndrome patients].

Fan, Bao-Xing; Liu, You-Ning; Xie, Li-Xin; Tian, Qing; Chen, Liang-An; Chen, Wei-Jun; Wen, Jie

OBJECTIVE To investigate the dynamic changes of the antibody specific to severe acute respiratory syndrome (SARS) coronavirus in convalescents who have suffered from SARS. METHODS Samples of peripheral blood were collected twice during the first 2 weeks after discharge and then once every 2 - 4 weeks from 310 convalescents of SARS, 131 males and 179 females, aged 18 - 74, discharged from hospitals in Beijing April 3 to June 20 2003 with the average discharge date of June 10, to detect the level of immunoglobulin G (IgG) by ELISA. A curve of level of IgG was drawn to describe the change by the specific month in the year. RESULTS Most of the 310 convalescents underwent successive or non-successive testing for 2 - 4 months and 15 were tested for 5 months, 15 for 6 months, and 2 for 7 months. IgG was detected in each sample with the mean of A value of 0.97 +/- 0.37 (0.197 - 1.849). The mean IgG level peaked in July (1.203), about 35 days after discharge, and then gradually declined to 0.857 in December, a decline by 27.3%. CONCLUSION All SARS patients generate specific antibody against the coronavirus. However, the antibody level gradually decline with the lapse of time during the convalescence. Long-term surveillance of the change of antibody is necessary.