X0303 4 2011-04-28 0001301081 Pharmasset Inc VRUS 0001284621 OTTO MICHAEL J. 303A COLLEGE ROAD EAST PRINCETON NJ 08540 0 1 0 0 Chief Scientific Officer Common Stock 2011-04-28 4 S 0 9500 99.85 D 7189 D /s/ Michael J. Otto 2011-04-29