Combine 1 cup sugar, 1/3 cup flour, and salt. Add eggs and sour cream, stirring until blended.
Place blueberries in pastry shell, and spoon sour cream mixture over berries.
In another bowl, combine 1/2 cup sugar and 1/2 cup flour. Cut in butter or margarine with pastry blender until mixture resembles course meal. Sprinkle this mixture over sour cream mixture and berries in the pie shell.
Bake at 350 degrees F (175 degrees C) for 50 to 55 minutes, or until lightly browned.