He replaces his club team mate Peter Stringer who drops out of the squad with uncapped Mike McCarthy.
Meanwhile Kidney faces more disruption with Ulster star Stephen Ferris ruled out of the trip to Rome.
"I basically aggravated an old injury in my left knee in last week's game against Aironi," said Ferris, who suffered the injury during a pushover scrum.
"It is very disappointing but I am hoping to be back for the second game against France."
Ferris' injury is the latest blow for Kidney who was already without the services of Jamie Heaslip in the back row.
And his options are even more limited in the back three with Tommy Bowe, Shane Horgan, Geordan Murphy, Andrew Trimble and Rob Kearney all missing, increasing the likelihood of a first Six Nations start for Duffy.