The essential detail: the genetics and genomics of the primate immune response.
Shen S, Pyo CW, Vu Q, Wang R, Geraghty DE.
ILAR Journal, Jan 2013
Next-generation sequencing technologies have led to rapid progress in the fields of human and nonhuman primate (NHP) genomics. The less expensive and more efficient technologies have enabled the sequencing of human genomes from multiple populations and the sequencing of many NHP species. NHP genomes have been sequenced for two main reasons: (1) their importance as animal models in biomedical research and (2) their phylogenetic relationship to humans and use in derivative evolutionary studies. NHPs are valuable animal models for a variety of diseases, most notably for human immunodeficiency virus/acquired immunodeficiency syndrome research, and for vaccine development. Knowledge about the variation in primate immune response loci can provide essential insights into relevant immune function. However, perhaps ironically considering their central role in infectious disease, the accumulation of sequence detail from genomic regions harboring immune response loci, such as the major histocompatibility complex and killer immunoglobulin-like receptors, has been slow. This deficiency is, at least in part, due to the highly repetitive and polymorphic nature of these regions and is being addressed by the application of special approaches to targeted sequencing of the immune response genomic regions. We discuss one such targeting approach that has successfully yielded complete phased genomic sequences from complex genomic regions and is now being used to resequence macaque and other primate major histocompatibility complex regions. The essential detail contained within the genomics of the NHP immune response is now being assembled, and the realization of precise comparisons between NHP and human immune genomics is close at hand, further enhancing the NHP animal model in the search for effective treatments for human disease.
Recombinant structures expand and contract inter and intragenic diversification at the KIR locus.
Pyo CW, Wang R, Vu Q, Cereb N, Yang SY, Duh FM, Wolinsky S, Martin MP, Carrington M, Geraghty DE.
BMC Genomics, Feb 8, 2013
The human KIR genes are arranged in at least six major gene-content haplotypes, all of which are combinations of four centromeric and two telomeric motifs. Several less frequent or minor haplotypes also exist, including insertions, deletions, and hybridization of KIR genes derived from the major haplotypes. These haplotype structures and their concomitant linkage disequilibrium among KIR genes suggest that more meaningful correlative data from studies of KIR genetics and complex disease may be achieved by measuring haplotypes of the KIR region in total. Towards that end, we developed a KIR haplotyping method that reports unambiguous combinations of KIR gene-content haplotypes, including both phase and copy number for each KIR. A total of 37 different gene content haplotypes were detected from 4,512 individuals and new sequence data was derived from haplotypes where the detailed structure was not previously available. These new structures suggest a number of specific recombinant events during the course of KIR evolution, and add to an expanding diversity of potential new KIR haplotypes derived from gene duplication, deletion, and hybridization.
Different patterns of evolution in the centromeric and telomeric regions of group A and B haplotypes of the human killer cell Ig-like receptor locus.
Pyo CW, Guethlein LA, Vu Q, Wang R, Abi-Rached L, Norman PJ, Marsh SG, Miller JS, Parham P, Geraghty DE.
PLoS One, Dec 29, 2010
The fast evolving human KIR gene family encodes variable lymphocyte receptors specific for polymorphic HLA class I determinants. Nucleotide sequences for 24 representative human KIR haplotypes were determined. With three previously defined haplotypes, this gave a set of 12 group A and 15 group B haplotypes for assessment of KIR variation. The seven gene-content haplotypes are all combinations of four centromeric and two telomeric motifs. 2DL5, 2DS5 and 2DS3 can be present in centromeric and telomeric locations. With one exception, haplotypes having identical gene content differed in their combinations of KIR alleles. Sequence diversity varied between haplotype groups and between centromeric and telomeric halves of the KIR locus. The most variable A haplotype genes are in the telomeric half, whereas the most variable genes characterizing B haplotypes are in the centromeric half. Of the highly polymorphic genes, only the 3DL3 framework gene exhibits a similar diversity when carried by A and B haplotypes. Phylogenetic analysis and divergence time estimates, point to the centromeric gene-content motifs that distinguish A and B haplotypes having emerged ~6 million years ago, contemporaneously with the separation of human and chimpanzee ancestors. In contrast, the telomeric motifs that distinguish A and B haplotypes emerged more recently, ~1.7 million years ago, before the emergence of Homo sapiens. Thus the centromeric and telomeric motifs that typify A and B haplotypes have likely been present throughout human evolution. The results suggest the common ancestor of A and B haplotypes combined a B-like centromeric region with an A-like telomeric region.
HLA-E, HLA-F, and HLA-G polymorphism: genomic sequence defines haplotype structure and variation spanning the nonclassical class I genes.
Pyo CW, Williams LM, Moore Y, Hyodo H, Li SS, Zhao LP, Sageshima N, Ishitani A, Geraghty DE.
Immunogenetics, May 2006
Despite several studies that defined the polymorphism of the nonclassical human leukocyte antigen-E (HLA-E), HLA-F, and HLA-G genes, most polymorphisms thus far examined in correlative studies were derived from the coding sequences of these genes. In addition, some discrepancies and ambiguities in the available data have persisted in current databases. To expand the data available and to resolve some of the discrepant data, we have defined protocols that allow for the amplification of 6 to 7 kb of contiguous genomic sequence for each gene, including all of the coding and intron sequences, approximately 2 kb of 5′ flanking promoter sequence, and 1 kb of 3′ flanking sequence. Using long-range polymerase chain reaction (PCR) protocols, generating either one or two PCR products depending on the locus, amplified genomic DNA was directly sequenced to completion using a set of about 30 primers over each locus to yield contiguous sequence data from both strands. Using this approach, we sequenced 33 genomic DNAs, from Asian, African American, and Caucasian samples. The results of this analysis confirmed several previously reported coding sequence variants, identified several new allelic variants, and also defined extensive variation in intron and flanking sequences. It was possible to construct haplotype maps and to identify tagging single nucleotide polymorphisms that can be used to detect the composite variation spanning all three genes.
Toward understanding MHC disease associations: partial resequencing of 46 distinct HLA haplotypes.
Smith WP, Vu Q, Li SS, Hansen JA, Zhao LP, Geraghty DE.
Genomics, 2006 May
We carried out a resequencing project that examined 552 kb of sequence from each of 46 individual HLA haplotypes representing a diversity of HLA allele types, generating nearly 27 Mb of fully phased genomic sequence. Haplotype blocks were defined extending from telomeric of HLA-F to centromeric of HLA-DP including in total 5186 MHC SNPs. To investigate basic questions about the evolutionary origin of common HLA haplotypes, and to obtain an estimate of rare variation in the MHC, we similarly examined two additional sets of samples. In 19 independent HLA-A1, B8, DR3 chromosomes, the most common HLA haplotype in Northern European Caucasians, variation was found at 11 SNP positions in the 3600-kb region from HLA-A to DR. Partial resequencing of 282 individuals in the gene-dense class III region identified significant variability beyond what could have been detected by linkage to common SNPs.