Figure 1. . . Detection of antibodies against severe acute respiratory syndrome (SARS)–associated coronavirus recombinant proteins in animal sera by Western blotting. Recombinant nuleocapsid protein in panel A (NP, 54 kilodaltons [kDa]) and partial spike protein in panel B (SP, 57 kDa) were used as antigens. Goat anti-swine immunoglobulin G horseradish peroxidase was used as a secondary antibody. Serum samples from a convalescent SARS patient and healthy persons were used as positive and negative controls, respectively. Swine (S1 to S8) and human (H1 and H2) samples are sera collected during the survey. M1, M2, and M3 are purified NP, SP, and molecular weight markers, respectively. Positive bands at the corresponding molecular weight of the 2 proteins are indicated with arrows.