Rob Herring injured his ankle during the second half of Saturday's Investec Champions Cup match against Racing 92 and is unavailable for selection this week.
Billy Burns’ availability will be assessed during the week, after an arm injury in the same match.
Luke Marshall, who injured his ankle in training last week, is unavailable for selection.
Sean Reffell has resumed full team training and is now available for selection following the ankle injury he sustained last January.
Ethan McIlroy has also returned to team training this week.
Squad updates in association with The Ulster Independent Clinic.