Gal-Pol polyprotein and its products were tested by Western blotting as described previously with some modifications [25] . Briefly, viral proteins were separated by 10% SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and electro-blotted onto Hybond-P PVDF membrane (GE Healthcare, Bio-sciences). After blocking with 5% skim milk for 1 h at room temperature, the membrane was incubated with primary antibodies (Rabbit polyclonal anti-RT, 1:3000; mouse monoclonal anti-RT, antiintergrase, anti-protease or anti-capsid, 1:500) for 1 h. Membrane was washed three times with PBS containing 0.1% Tween 20 (PBS-T) and then incubated with horseradish peroxidase (HRP)-conjugated secondary antibody (goat anti-rabbit IgG or goat anti-mouse IgG, 1:4000) for 1 h. After the blots were rewashed three times in 0.1% PBST, signals were visualized using ECL Western blotting substrate reagents (Amersham Biosciences, USA) and KODAK BioMax Scientific Imaging Film (Eastman Kodak).