[Protective effect of specific antibody in serum of convalescent patient with SARS]

To investigate inhibitory effect of serum severe acute respiratory syndrome (SARS) -specific antibodies from convalescent patients after half an year of onset on SARS-CoV-mediated cytopathic response.

SARS-CoV immunoglobulin G (IgG) antibody was determined by enzyme linked immunoadsorbent assay (ELISA). Twelve serum samples from convalescent patients, diluted by 1:8 with maintenance medium, were mixed with the three dilution supernatants of SARS-CoV. SARS-CoV were isolated, cultured and identified by the Guangzhou Institute of Respiratory Disease, and cultured with Vero E6 cell suspension. The extent of cytopathic response was observed.

The absorbance (A) value of SARS-CoV IgG antibody ranged from 0.81 to 2.06 in patients after half an year of SARS onset, and form 0.79 to 2.01 in patients before half an year of SARS onset. The extent of cytopathic response was decreased by more than 25% in all 12 convalescent patients, as compared with control serum.

The A value of SARS-CoV IgG antibody in serum of convalescent patients tended to elevate in half an year after SARS onset. SARS-CoV IgG antibody could inhibit SARS-CoV-mediated cytopathic response, indicating it might be one of protective antibodies.