Approximately equivalent amount of each GST fusion protein was subjected to 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (12% SDS-PAGE). The gel was either stained with commassie blue staining solution or electrophoretically transferred to nitrocellulose membrane. After being blocked with 5% skim milk in PBS overnight at 4uC, the membrane was incubated with mAb A9E8 (diluted 1:2,000 in PBS) or REV-A-positive chicken serum (diluted 1:100 in PBS) at 37uC for 1 h. After being washed three times with PBST, the membrane was probed with a 1:5,000 dilution of HRP-conjugated goat anti-mouse IgG 