Fusaro has already played for Glasgow Warriors this season
Heriot's flanker Chris Fusaro and Sevens specialist Colin Shaw are among six players uncapped at A level in the Scots squad for the IRB Nations Cup.
Ally Hogg, who has played 48 times for the senior side, is one of eight full caps in the 26-man party aiming to defend the trophy won last year.
Coach Sean Lineen's team face Georgia, Namibia and Argentina Jaguars in next month's tournament in Bucharest.
Fusaro said: "I was very surprised. It came totally out of the blue."
The 20-year-old has joined Glasgow Warriors after helping Heriot's finish fifth in Premiership One this season.
With the senior Scotland squad going to Argentina this year, this is a real opportunity for another group of players to shine
Scotland A coach Sean Lineen
"It's going to be a great experience to go to Romania," said Fusaro, who is also in the Scotland squad for the last two legs of the IRB Sevens World Series.
"I hope to get some game-time and gain some experience. But, no matter what chances I get, I know I will have to take them."
The 27-year-old Shaw has previously played for Scotland at youth levels and, although he is attached to Glasgow Warriors, has recently concentrated on his contract with the national Sevens side.
Also given a chance with Scotland A are Bath's Jack Cuthbert, the Bristol-born 22-year-old who can play full-back, winger or outside centre, and 25-year-old South African-born Exeter Chiefs centre Bryan Rennie.
Among the full caps travelling to Romania in a squad that contains 14 players from Edinburgh and nine from Lineen's Glasgow side is Ospreys winger Nikki Walker.
Hogg, who will leave Edinburgh for Newcastle Falcons this summer, will be looking to regain match fitness after recently recovering from a serious hip injury and missing out on the full squad heading for Argentina next month.
Edinburgh's Geoff Cross, Roddy Grant, Ben Cairns, Scott MacLeod and Greig Laidlaw will also have been particularly disappointed to have missed out on Andy Robinson's main squad along with Glasgow's Rob Dewey.
Lineen said: "I'm excited. With the senior Scotland squad going to Argentina this year, this is a real opportunity for another group of players to shine.
"There's a good mix of youth and experience, but it is mainly youth. However, the best tool for these players' development is winning."
Scotland A squad
Forwards: G Cross (Edinburgh), J Eddie (Glasgow), C Forrester (Glasgow), C Fusaro (Heriot's), Roddy Grant (Edinburgh), Ryan Grant (Edinburgh), A Hogg (Edinburgh), A Kelly (Edinburgh), S MacLeod (Edinburgh), F Thomson (Glasgow), K Traynor (Edinburgh), S Turnbull (Edinburgh), R Vernon (Glasgow), J Welsh (Glasgow)
Backs: A Blair (Edinburgh), D Blair (Edinburgh), B Cairns (Edinburgh), J Cuthbert (Bath), R Dewey (Glasgow), J Houston (Edinburgh), G Laidlaw (Edinburgh), M McMillan (Glasgow), B Rennie (Exeter), M Robertson (Edinburgh), C Shaw (Scotland 7s and Glasgow), N Walker (Ospreys)