Sam Johnson will make his return from injury in Georgia but three more players will not feature at all this season before Scotland head coach Gregor Townsend picks his World Cup squad.
The centre suffered an ankle injury during Scotland's summer camp but will start in Tbilisi on Saturday.
Glasgow hooker Brown is working his way back from the toe injury he suffered during the Guinness PRO14 final while Edinburgh back-row Bradbury has been battling a rib injury.
1️⃣2️⃣ Johnson returnsⒸ McInally to skipper1️⃣ First start for Hutchinson✅ First Tier One national side to travel for a Test on Georgian soil pic.twitter.com/eYlUkJtK2z
— Scottish Rugby (@Scotlandteam) August 29, 2019
Both were tipped to feature this weekend but neither have made it along with Gray, who trained earlier in the week after a hamstring injury.
The three injured players are the only ones not to feature in any of the three squads so far, although Tim Swinson is also absent after being called up this week when Sam Skinner was ruled out with the hamstring injury he suffered against France on Saturday.
Johnson will line up in the midfield alongside Rory Hutchinson, who will make his first international start.
Townsend has made 10 changes to the team that beat France at BT Murrayfield with Blair Kinghorn, Allan Dell and Matt Fagerson also making their first starts of the season.
Winger Tommy Seymour and back-row forward Blade Thomson miss out with head knocks with Darcy Graham and Fagerson taking their places.
Prop Jamie Bhatti is named on the bench as he gets a chance to atone for a difficult night in Nice in Scotland's opening match, which saw him taken off at half-time.
Townsend told the Scottish Rugby Union website: "We welcome back a couple of players, like Sam Johnson who has recovered from injury, Stuart McInally as captain. So that's a bonus. And other players are getting an opportunity this weekend too.
"The downside were the injuries from last week. For Sam Skinner to leave the squad is a huge blow for Sam and also for us as a group to see someone who won't get the opportunity to play this weekend and get into the final 31.
"But we believe it's a strong squad and an opportunity to build on the good work that we did in a lot of the game against France last week and also an opportunity to put down a marker away from BT Murrayfield, and we've not done that enough over the last year or two."
Scotland are the first top-tier nation to travel to Georgia and Townsend anticipates a difficult test.
"They've got some very good players right throughout the team," he said.
"When Georgia first broke through in world rugby, qualifying for World Cups, a lot was based around the front row and the forward pack and how they brought the strengths out from those physical attributes, whether it was the scrum, the line-out maul, the pick and go, the ball carrying.
"Now they have been a professional outfit for a number of years, with players playing throughout Europe, particularly France, they have got better and better at the wider aspect of the game.
"So their back line play is ambitious and accurate, they have very physical back-line players, they are well coached, and we know this is one of the toughest challenges you will get in world rugby.
"We are the first (tier-one) team to come out here against a top-quality team who have been waiting for this opportunity for a number of years.
"So it's a great challenge for us to see where we are and what we need to build on as we go towards Japan."