Preheat oven to 350 degrees F (175 degrees C). Place the blueberries in the pastry shell and set aside.
Combine 1 cup sugar, 1/3 cup flour, and salt. Add eggs and sour cream, stirring until blended. Pour the sour cream custard over the blueberries.
In another bowl, combine 1/2 cup sugar and 1/2 cup flour. Cut in the butter with pastry blender until the mixture resembles coarse meal. Sprinkle the topping over the sour cream mixture and berries in the pie shell.
Bake in the preheated oven for 50 to 55 minutes, or until lightly browned. Cool on wire rack.