FIG. 2.

Western blot analyses of antigenic cross-reactivity of SARS-CoV N protein with polyclonal antisera of known animal coronaviruses. SARS-CoV N protein (1 μg/lane) was separated by SDS-PAGE. Each antiserum was diluted 1:100 in blocking solution. A convalescent-phase SARS human patient serum (anti-SARS-CoV) and anti-Xpress antibody were used as positive controls. The polyclonal antisera used in the Western blot analysis were from antigenic group I (FIPV, porcine TGEV, and CCoV), group II (porcine HEV and BCoV), and group III (TCoV and avian IBV) animal coronaviruses. Polyclonal antisera to IBV, HEV, BcoV (calf serum), and TGEV (pig serum) were purchased from National Veterinary Service Laboratories, Ames, Iowa. Polyclonal cat antisera to TGEV and CCoV and cat ascitic fluid against FIPV were purchased from VMRD, Inc., Pullman, Wash. The arrow shows the expected size (about 50 kDa) of the SARS-CoV N protein.