Prevention of virus infection. TPP[2,6-(OH)2], 50 µg/mL, was incubated with vaccinia virus for 1 h, and then applied to cells. Following virus adsorption, the residual virus-drug mixture was removed and new growth medium added. Plaques were visualized after 2 days (as described in Materials and Methods). (a) WR and (b) IHD-J incubated with CV-1 cells in the absence and presence of TPP [2,6-(OH)2].