Scrum-half Van Poortvliet has led England to back-to-back wins over France (38-22) and Scotland (31-12) in the opening rounds of the tournament in Cardiff.
There are four changes to the starting line-up as Charlie Atkinson, Tom Litchfield, Arthur Clark and Nahum Merigan all make their first starts of the competition while Ewan Richards moves to blindside flanker following injury to Leicester’s Emeka Ilione in the win over Scotland.
Vanes, who made his first appearance in the opening win over France, provides cover at hooker among six changes on the bench.
Head coach Alan Dickens said: “I’ve been pleased with the squad’s preparation for this match. There were areas we knew we could improve on again from the Scotland game and we’ve worked on that in training this week.
“A Six Nations campaign is very much a squad effort so we’ve made some changes across the matchday 26 for this fixture.
“There’s a lot of competition among the group which is exactly what we want as the players drive each other to be better in every session.
“We will be coming up against a strong Ireland side who have also started with two wins, so we know how tough a challenge it is going to be.”
Teams are permitted to name a squad of 26 players for each fixture in this year’s competition due to Covid-19 regulations. Eight of the 11 replacements named in a squad can be used during the match.
Kick-off on Thursday is at 8.00pm with live coverage on EnglandRugby.com, England Rugby Facebook, Six Nations Rugby YouTube channel and S4C Clic.
15 Charlie Atkinson (Wasps)
14 Tom Litchfield (Northampton Saints)
13 Jack Bates (Bristol Bears)
12 Dan Lancaster (Leeds Tykes)
11 Arthur Relton (Exeter Chiefs)
10 Fin Smith (Worcester Warriors)
9 Jack Van Poortvliet (Leicester Tigers)(c)
1 Phil Brantingham (Newcastle Falcons)
2 Sam Riley (Harlequins)
3 Harvey Kindell-Beaton (Saracens)
4 Arthur Clark (Gloucester Rugby)
5 Alex Groves (Bristol Bears)
6 Ewan Richards (Bath Rugby)
7 Jack Clement (Gloucester Rugby)
8 Nahum Merigan (Bath Rugby)
16 Archie Vanes (Leicester Tigers)
17 Tarek Haffar (London Irish)
18 Luke Green (London Irish)
19 Freddie Thomas (Gloucester Rugby)
20 Ollie Stonham (Saracens)
21 Josh Gray (Gloucester Rugby)
22 Tom Carr-Smith (Bath Rugby)
23 Tommy Mathews (Hartpury University RFC)
24 Phil Cokanasiga (London Irish)
25 Tom Roebuck (Sale Sharks)
26 Orlando Bailey (Bath Rugby)