Neil Critchley's side were delighted to take the invitation to fly to France and take on PSG at their academy in Paris.
Johnston headed the young Reds into the lead following a pinpoint set-piece delivery from Adam Lewis.
The home side levelled, but Virtue, who had earlier hit the post, fired home to make it 2-1.
Deep into stoppage time PSG earned a share of the spoils courtesy of a superb direct free-kick.
Reflecting on the 2-2 draw, Critchley told Liverpoolfc.com: "It was a really good game against high level opposition and a great test for us.