Rookie cornerback Dontae Johnson replaced him on the field.
The 49ers had already lost starter Tramaine Brock earlier in the game.
Update:
Matt Maiocco of CSN Bay Area is reporting that Culliver is being evaluated for a head and neck injury and that his return is questionable.
Update 2:
Maiocco reports that Culliver has a concussion and has been ruled out of this game.