Proverbs 8 and Ecclesiasticus 24 which do not speak to the subject whatsoever; Genesis 3:15, which offers even less substance for the belief; and finally, (and singularly) Luke 1:28 about which New Advent writes...
The salutation of the angel Gabriel -- chaire kecharitomene, Hail, full of grace (Luke 1:28) indicates a unique abundance of grace, a supernatural, godlike state of soul, which finds its explanation only in the Immaculate Conception of Mary."
"Full of grace" is not "unique." Thereare countelss people in the Old Testament who received God's "grace" or in whom "grace" was found.
And as for Mary's "godlike state of soul," that's bordering on blasphemy.
Again, there is nothing in Scripture which says Mary was born without original sin. Nada. Zilch.
The translation is not unique, but the underlying Greek word, kecharitomenos/e, is not used anywhere else in the New Testament.