The SLA system is among the most well characterized major histocompatibility complex (MHC) systems in
non-human animal species. The ISAG/IUIS SLA Nomenclature Committee was established 15 years ago with
primary objectives to: 1) validate newly identified SLA sequences according to the guidelines established for
maintaining high quality standards of the accepted sequences; 2) assign appropriate nomenclatures for new
alleles as they are validated; and 3) serve as a curator of the IPD-MHC SLA Sequence Database
(www.ebi.ac.uk/ipd/mhc/group/SLA), which is the repository for all recognized SLA genes, their allelic
sequences and haplotypes. The newly released and improved IPD-MHC Database version 2.0 has incorporated
the latest sequence updates, provide new tools that enhance database queries and improve the submission
process. The SLA Nomenclature Committee met at last year's ISAG and made some major revisions to the
allele naming system. The Committee decided to retire the provisional alphanumerical naming system for
unconfirmed alleles and re-designate each allele an official number, adopting the HLA Nomenclature System
with colons as field separators (e.g. SLA-1*01rh28 → SLA-1*01:03). Phylogeny will remain the primary
approach for assigning SLA-1, -2, -3, DRA, DRB1, DQA and DQB1 alleles into allele groups with similar
sequence motifs, while alleles of SLA-5, -6, -7, -8, -12, DMA, DMB, DOA, DOB1, DRB2, DRB3, DRB4,
DRB5 are designated sequentially as they are discovered. Naming convention for alleles of other loci (SLA-4, -
9, -11, DQB2, DOB2, DYB, MIC1, MIC2, TAP1, TAP2) is to be determined as sequences accumulate. There
are currently 223 class I, 214 class II, 2 SLA-related and 2 non-SLA alleles officially designated. There are also
61 class I (SLA-1- 3-2) and 49 class II (DRB1-DQB1) haplotypes designated at allele level resolution. This
systematic nomenclature for SLA genes is critical to the understanding of the architecture and polymorphism of
the SLA system and their role in swine diseases, vaccine development and allo- or xeno-responses in
transplantation research.