Western Blotting of Virus Particles and Transfected Cells

Western blotting was performed as previously described (22 (link), 24 (link), 36 (link), 62 (link)). For the Western blotting of virus particles, 340 μl of the culture supernatant was ultracentrifuged at 100,000 × g for 1 h at 4°C using a TL-100 instrument (Beckman), and the pellet was lysed with 1× SDS buffer. For the Western blotting of transfected cells, the cells were lysed with RIPA buffer (50 mM Tris-HCl buffer [pH 7.6], 150 mM NaCl, 1% Nonidet P-40, 0.5% sodium deoxycholate, 0.1% SDS) with protease inhibitor cocktail (Roche). The following antibodies were used for Western blotting: anti-His polyclonal antibody (OGHis; Medical and Biological Laboratories), anti-HA antibody (3F10; Roche), anti-FIV p24 capsid antibody (PAK3-2C1; Santa Cruz Biotechnology); and anti-alpha-tubulin (TUBA) antibody (DM1A; Sigma).