Bertoni was a brand created by Ben Lawee, a bicycle distributor who also originated the Italvega and Univega lines. The frames were manufactured in Italy, but I don't know by who. The line emphasized function over flash and received favourable press. The line itself was fairly large, comprising nine bicycles in 1988. The line included a disc-wheeled TT bicycle and a Bador (Vitus) aluminum model, in addition to top line model you referenced.
Your model sounds similar to the mid range Nuovitalia. It used Matrix tubing and Shimano 600EX derailleurs, with Ofmega providing most of the remaining components (though some were branded Bertoni). The Matrix decal indicates a timeframe of about 1986-1987, and is a seamed, butted, CrMo tubeset. Perhaps the difference in your components is attributable to a different model year?