Sean Reffell (groin) and Dave Ewers (concussion) both sustained injuries during Saturday's Investec Champions Cup defeat to Toulouse. Both will be unavailable for selection this week.
Also currently unavailable for selection is Rob Herring, who sustained a significant elbow injury in training last Thursday. He will see a specialist this week.
David McCann has now returned to full team training and is available for selection.
Squad updates in association with The Ulster Independent Clinic