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Title: Molecular characterization of swine leukocyte antigen (SLA) class II genes in outbred pig populations

item HO, CHAK-SUM - University Of Michigan
item Lunney, Joan
item LEE, JUN-HEON - Chungnam National University
item FRANZO-ROMAIN, MEGAN - University Of Michigan
item MARTENS, G - University Of Massachusetts
item ROWLAND, R - Kansas State University
item SMITH, DOUGLAS - University Of Michigan

Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2009
Publication Date: 1/31/2010
Citation: Ho, C., Lunney, J.K., Lee, J., Franzo-Romain, M.H., Martens, G.W., Rowland, R.R., Smith, D.M. 2010. Molecular characterization of swine leukocyte antigen (SLA) class II genes in outbred pig populations. Animal Genetics. 41:428-432.

Interpretive Summary: Effective vaccine and infectious disease responses require that antigens from the pathogens be recognized by the immune system. For this to happen vaccine or microbial antigens must be processed and presented to the immune system by host proteins, termed the major histocompatibility complex (MHC) antigens. For swine the MHC is called the Swine Leukocyte Antigen (SLA) complex. Swine with different SLA class II haplotypes have been shown to develop different, SLA dependent titers of complement and antibodies to defined antigens and vaccines. This manuscript addressses techniques to determine exact alleles at the SLA class II genes, some of which, the SLA-DRB1 and SLA-DQB1, are very polymorphic; sets of SLA class II genes are termed haplotypes. These techniques for quickly determining SLA class II alleles are critical to the future development of research in swine immunology and disease research and for use of the swine as a transplantation model for humans and as xenotranplantation (cross-species) donor for humans. SLA class II matching is required for acceptance of bone marrow cell and solid organ allografts. As many as 84 alleles at any one SLA class II have been reported. In this manuscript we propose an appropriate PCR based typing reaction to assign allelic designations. This technology will eanble investigators to communicate more easily about SLA alleles and haplotypes. This addresses the issue of better methods for assigning defined SLA alleles and haplotypes, particularly in commercial outbred pigs. Overall, such information will be very useful for identifying disease rsistant pigs and designing vaccines that produce effective protective immunity for infectious diseases in every pig.

Technical Abstract: The highly polymorphic swine leukocyte antigen (SLA) genes are one of the most important determinants in swine immune, disease and vaccine responses. Thus, understanding how SLA gene polymorphism affects immunity, especially in outbred pig populations with a diverse genetic background, requires accurate and effective SLA genotyping methods. We present here a simple and rapid molecular-based typing system for characterizing SLA class II alleles of the DRB1, DQB1 and DQA loci. This system utilizes a set of 47 sequence-specific PCR primers developed to differentiate alleles by groups that share similar sequence motifs. We applied this method to investigate the SLA class II diversity in four populations of outbred pigs totaling 206 animals. This resulted in a total of 19 SLA class II haplotypes, six of which were observed in at least three different pig populations. Haplotype Lr-0.1 (DRB1*01XX-DQB1*01XX-DQA*01XX) was identified as the most prevalent haplotype with a combined frequency of 16.0%, followed by Lr-0.2 (DRB1*02XX-DQB1*02XX-DQA*02XX) with 14.6% and Lr-0.15b (DRB1*04XX-DQB1*0202-DQA*02XX) with 14.1%. Over 70% of the pigs (n = 147) had at least one copy of one of these haplotypes. This PCR-based typing system demonstrates a reliable and unambiguous detection method for SLA class II alleles. It will be a valuable tool for studying the influence of SLA diversity on various immunological, pathological and physiological traits in outbred pigs.