Genome analysis of the swine MHC region and development of SLA-DNA typing method for xenotransplantaion

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Genome analysis on the swine leukocyte antigen (SLA) region and analysis of genetic polymorphisms of the SLA genes will give important information from a viewpoint of a possible strong candidate of pig organs as a donor for xenotransplantation. Here, we carried out large scale genome sequencing of the 400 kb segment in the SLA class I region and designed locus-specific primer pairs for analysis of genetic polymorphisms of the SLA class I genes.Nineteen swine homologous genes corresponding to nineteen human non-MHC genes were identified in this segment in the SLA class I region. The gene order of these genes was highly conserved between the human and the swine. In contrast, no SLA gene was recognized between the HSR1 and FLJ22638 genes, as compared with the presence of the HLA-E gene in the corresponding human segment. The length of the SLA class I region including this segment was only 979 kb, as contrasted with as long as 1550 kb in the HLA class I region. This remarkable difference in size between them could be explained by a higher density of repetitive sequences in the human MHC.Furthermore, we designed eight locus-specific primer pairs for RT-PCR analyses of genetic polymorphisms of the expressed three classical SLA class I genes, SLA-1, SLA-2 and SLA-3. Sequence analysis of the RT-PCR products has allowed the identification of alleles which were previously defined by the PD1, PD14, PCI cDNA sequences, and SLA-3 genomic sequence. Novel alleles were also defined in the SLA-1, -2, and -3 genes.In addition, we also designed eight allele-specific primer pairs for the PCR-SSP method. These primer sets have allowed to assign five SLA class I and two DRB1 alleles of Clawn miniature swine precisely by the PCR-SSP method. The rapid and simple processing of the PCR-SSP method will be useful for SLA genotyping in selection of SLA-homozygous Clawn miniature swine.