Recombinant constructs encoding chimeric and SLA-1*0401 molecules A synthetic gene encoding a transmembrane-truncated fragment encompassing residues 1 to 275 of human HLA-A*11:01 alpha chain followed by a FXa-BSP-HAT tag (FXa = factor Xa cleavage site comprised of the amino acid sequence IEGR, BSP = biotinylation signal peptide, HAT = histidine affinity tag for purification purposes; see Online Resource 1) had previously been generated and inserted into the pET28 expression plasmid (Novagen) (Ferre et al. 2003) . Synthetic genes encoding the corresponding fragments of the SLA-1*0401 alpha chain (α 1 α 2 ) and α 3 , respectively, (Sullivan et al. 1997) were purchased from GenScript. To exchange domains and generate chimeric human/swine MHC-I gene constructs, a type II restriction endonuclease-based cloning strategy (SeamLess® Strategene; Cat#214400, Revision#021003a), with modifications, was used. All primers were purchased HPLC-purified from Eurofins MWG Operon (Ebersberg, Germany), and all PCR amplifications were performed in a DNA Engine Dyad PCR instrument (MJ Research, MN, USA). All constructs were validated by DNA sequencing. The following MHC-I heavy chain constructs were made HHH, HHP, HPP, PHP, and PPP, where the first, second, and third letter indicates domains α 1 (positions 1-90), α 2 (positions 91-181), and α 3 (positions 182-275), respectively, and H indicates that the domain is of HLA-A*11:01 origin, whereas P indicates that it is of SLA-1*0401 origin.