Sorry to say I can't see anything on the dropout apart from the 'normal' Campag engraving. The 'DS' on the seatstay top might be for 'Dauphin Sport' who were (are??) importers of continental frames. Your frame looks 'continental' to me with those seatstays.
Well, a Google Images search finds loads of ebay listings for this Losa. The Gianni Motta stuff is from another listing by the same seller, obvs.
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