Characterization of Bison bison major histocompatibility complex class IIa haplotypes

American bison (Bison bison) and domestic cattle (Bos taurus and Bos indicus) evolved from a common ancestor 1–1.4 million years ago. Nevertheless, they show dramatic differences in their susceptibility to infectious diseases, including malignant catarrhal fever (MCF). Although bison are highly susceptible to ovine herpesvirus-2 (OvHV-2) associated MCF, about 20% of healthy domesticated and wild bison are positive for OvHV-2 antibody. We are interested in testing the hypothesis that, within the bison population, the polymorphism of major histocompatibility complex (MHC) class II genes influences resistance to MCF. However, since little was known about the MHC class II genes of bison, it was necessary to first characterize class II haplotypes present in Bi. bison (Bibi). Thus, the MHC class II haplotypes carried by 14 bison were characterized by the PCR-based cloning and sequencing of their DRB3, DQA, and DQB alleles. Twelve MHC class II haplotypes were identified in the 14 bison. These haplotypes comprised six previously reported and six new Bibi-DRB3 alleles, along with 11 Bibi-DQA and 10 Bibi-DQB alleles. For each bison class II allele, it was possible to identify closely related cattle sequences. The closest bison and bovine DQA, DQB, and DRB3 alleles, on average, differed by only 1.3, 3.5, and 5.8 amino acids, respectively. Furthermore, bison MHC haplotypes with both nonduplicated and duplicated DQ genes were identified; these haplotypes appear to have originated from the same ancestral haplotypes as orthologous cattle haplotypes. This study was supported by USDA-Agricultural Research Service grant CWU-5348-32000-018-00D. While working on this project, Dr. Bharat Bhushan was supported by a fellowship from the World-Bank-sponsored National Agricultural Technology Project of the Indian Council of Agricultural Research, Indian Ministry of Agriculture, New Delhi, India     

Description of bovine major histocompatibility complex class IIa haplotypes using parthenogenetic embryo‐derived cells

In this study, we report an approach to characterize individual BoLA haplotypes using cells from parthenogenetic bovine embryos derived from slaughterhouse ovaries. Eight of the 15 parthenogenetic embryos so obtained had not undergone meiotic recombination on the BoLA region and were suitable to describe BoLA haplotypes. Detailed analysis of the BoLA class IIa region identified seven different class IIa haplotypes, including six not previously described and two new alleles of BoLA‐DQA and one BoLA‐DQB. Our method provided reliable sources of homozygous DNA to describe BoLA haplotypes.     

An ordered BAC contig map of the equine major histocompatibility complex

A physical map of ordered bacterial artificial chromosome (BAC) clones was constructed to determine the genetic organization of the horse major histocompatibility complex. Human, cattle, pig, mouse, and rat MHC gene sequences were compared to identify highly conserved regions which served as source templates for the design of overgo primers. Thirty-five overgo probes were designed from 24 genes and used for hybridization screening of the equine USDA CHORI 241 BAC library. Two hundred thirty-eight BAC clones were assembled into two contigs spanning the horse MHC region. The first contig contains the MHC class II region and was reduced to a minimum tiling path of nine BAC clones that span approximately 800 kb and contain at least 20 genes. A minimum tiling path of a second contig containing the class III/I region is comprised of 14 BAC clones that span approximately 1.6 Mb and contain at least 34 genes. Fluorescence in situ hybridization (FISH) using representative clones from each of the three regions of the MHC localized the contigs onto ECA20q21 and oriented the regions relative to one another and the centromere. Dual-colored FISH revealed that the class I region is proximal to the centromere, the class II region is distal, and the class III region is located between class I and II. These data indicate that the equine MHC is a single gene-dense region similar in structure and organization to the human MHC and is not disrupted as in ruminants and pigs.     

Molecular analysis distinguishes two HLA-DR3-bearing major histocompatibility complex extended haplotypes

We detected restriction fragment length polymorphisms that distinguish the extended haplotype HLA-B8,DR3,SCO1 from HLA-B18,DR3,F1C30 at the DR beta and DQ beta loci with five of seven restriction endonucleases used. One set of restriction fragments was always found on HLA-B8,DR3,SCO1 and associated with DRw52a, while the other was present on HLA-B18, DR3,F1C30 and correlated with DRw52b (the gene encoding the subtype of DRw52 associated with the BO1 or LB-Q1 antigen). Furthermore, using a full-length DQ beta gene probe, we found division in the DQw2 haplotype, in which DQw2a always associated with HLA-B8, DR3,SCO1, while DQw2b always occurred with HLA-B18,DR3,F1C3O. Our evidence thus indicates that serologically defined HLA-DR3, HLA-DRw52, and HLA-DQw2 are each produced by two structurally very different sets of genes, one set occurring in HLA-B8, DR3,SCO1, and the other in HLA-B18,DR3,F1C30.Abbreviations used in this paper BSA bovine serum albumin - MHC major histocompatibility complex - EDTA ethylenediaminetetraacetic acid - SDS sodium dodecyl sulfate     

Invasive equine trophoblast expresses conventional class I major histocompatibility complex antigens

Monoclonal antibodies and alloantisera were used in an indirect immunohistochemical assay to determine the expression of class I and class II Major Histocompatibility Complex (MHC) antigens by equine placental cells and the endometrial tissues at the fetal-maternal interface. MHC class I antigens were expressed at high density on the surface of the trophoblast cells of the chorionic girdle at days 32-36, just prior to their invasion of the endometrium. The mature gonadotrophin-secreting cells of the endometrial cups, which are derived from the chorionic girdle cells, had greatly reduced levels of MHC class I antigen expression while no MHC class I antigens were detectable on the non-invasive trophoblast cells of the allantochorion, except in small isolated patches. MHC class I antigens immunoprecipitated from chorionic girdle cells with either monoclonal antibodies or alloantisera had a relative molecular mass of 44,000, which was identical to that of MHC class I antigens precipitated from lymphocytes with the same reagents. MHC class II antigens were not detected on any trophoblast cells, although they were expressed at high levels by the endometrial glandular and lumenal epithelium immediately bordering the endometrial cups. MHC class I antigens were also expressed at high levels by endometrial tissues in the area of the cups. The high level of MHC class I antigen expression by endometrial glands within and bordering the cups was in sharp contrast to the greatly reduced class I antigen expression by the mature endometrial cup cells themselves.(ABSTRACT TRUNCATED AT 250 WORDS)     

Molecular characterization of major histocompatibility complex (B) haplotypes in broiler chickens

In Leghorn (laying) chickens, susceptibility to a number of infectious diseases is strongly associated with the major histocompatibility ( B ) complex. Nucleotide sequence data have been published for six class I ( B-F ) alleles and for class II ( B-Lβ ) alleles or isotypes from 17 Leghorn haplotypes. It is not known if classical B-L or B-F alleles in broilers are identical, at the sequence level, to any Leghorn alleles. This report describes molecular and immunogenetic characterization of two haplotypes from commercial broiler breeder chickens that were originally identified by serology as a single haplotype, but were differentiated serologically in the present work. The two haplotypes, designated B ^A4 and B ^A4variant, shared identical B-G restriction fragment length polymorphism patterns, but differed in one B-Lβ fragment that cosegregated with the serological B haplotype. Furthermore, the nucleotide sequences of the highly variable exons of an expressed B-LβII family gene and B-F gene from the two haplotypes were markedly different from each other. Both the B-LβII family and B-F gene sequences from the B ^A4 haplotype were identical to the sequences obtained from the reference B ²¹ haplotype in Leghorns; however, in the B ^A4 haplotype the B-Lβ ²¹ and B-F ²¹ alleles were in linkage with B-G alleles that were not G ²¹. The nucleotide sequences from B ^A4variant were unique among the reported chicken B-LβII family and B-F alleles.     

Inferring population history and demography using microsatellites, mitochondrial DNA, and major histocompatibility complex (MHC) genes

Microsatellites and mitochondrial DNA (mtDNA) have traditionally been used in population genetics because of their variability and presumed neutrality, whereas genes of the major histocompatibility complex (MHC) are increasingly of interest because strong selective pressures shape their standing variation. Despite the potential for MHC genes, microsatellites, and mtDNA sequences to complement one another in deciphering population history and demography, the three are rarely used in tandem. Here we report on MHC, microsatellite, and mtDNA variability in a single large population of the eastern tiger salamander (Ambystoma tigrinum tigrinum). We use the mtDNA mismatch distribution and, on microsatellite data, the imbalance index and bottleneck tests to infer aspects of population history and demography. Haplotype and allelic variation was high at all loci surveyed, and heterozygosity was high at the nuclear loci. We find concordance among neutral molecular markers that suggests our study population originated from post-Pleistocene expansions of multiple, fragmented sources that shared few migrants. Differences in N(e) estimates derived from haploid and diploid genetic markers are potentially attributable to secondary contact among source populations that experienced rapid mtDNA divergence and comparatively low levels of nuclear DNA divergence. We find strong evidence of natural selection acting on MHC genes and estimate long-term effective population sizes (N(e)) that are very large, making small selection intensities significant evolutionary forces in this population.     

Evolutionary relationship between human major histocompatibility complexHLA-DR haplotypes

 HLA-DR haplotypes of the human major histocompatibility complex are organized in five different groups. They can be identified based on the serological specificity expressed by the polymorphic DRB1 locus and by the presence of a characteristic set of DRB genes. The nucleotide sequences of introns 4 and 5 of the two DRB genes (DRB1 ^* 01 and DRB6 ^* 01) from a DR1 haplotype and the three DRB genes (DRB1 ^* 15, DRB6 ^* 15, and DRB5 ^* 15), from a DR51 haplotype were determined. This study identified endogenous retroviral long terminal repeat elements (ERV9 LTR) located at identical positions in intron 5 of the DRB1 genes in both the DR1 and DR51 haplotypes. Phylogenetic analyses revealed a close evolutionary relationship between these two haplotypes. The DRB5 gene, unique for the DR51 haplotype, may have been lost by a recent gene deletion event creating the DR1 haplotype. A model for the evolution of the human DR haplotypes involving separate duplication and contraction events is presented. Received: 10 October 1995 / Revised: 22 November 1995     

A polymorphic system related to but genetically independent of the chicken major histocompatibility complex

Analyses of the major histocompatibility complex (Mhc) in chickens have shown inconsistencies between serologically defined haplotypes and haplotypes defined by the restriction fragment patterns of Mhc class I and class II genes in Southern hybridizations. Often more than one pattern of restriction fragments for Mhc class I and/or class II genes has been found among DNA samples collected from birds homozygous for a single serologically defined B haplotype. Such findings have been interpreted as evidence for variability within the Mhc haplotypes of chickens not detected previously with serological methods. In this study of a fully pedigreed family over three generations, the heterogeneity observed in restriction fragment patterns was found to be the result of the presence of a second, independently segregating polymorphic Mhc-like locus, designated Rfp-Y. Three alleles (haplotypes) are identified in this new system.     

Identification of the Tapasin gene in the chicken major histocompatibility complex

 The Tapasin molecule plays a role in the assembly of major histocompatibility complex (Mhc) class I molecules in the endoplasmic reticulum, by mediating the interaction of class I-β₂-microglobulin dimers with TAP. We report here the identification of the Tapasin gene in the chicken Mhc (B complex). This gene is located at the centromeric end of the complex, between the class II B-LBI and B-LBII genes. Like its human counterpart it comprises 8 exons, but features a significantly reduced intron size as compared to the human gene. Chicken Tapasin codes for a transmembrane protein with a probable endoplasmic reticulum retention signal. Exons IV and V, and possibly exon III, code for separate domains that are related to the immunoglobulin (Ig) superfamily (this relationship was so far unrecognized for human Tapasin domain IV which has lost its two cysteines). Two different cDNAs corresponding to the Tapasin gene were isolated, possibly related to alternative splicing events; the Ig-like domain encoded by exon IV is missing in one of the cDNAs, suggesting either that this domain is not necessary for the protein to perform its function, or that the two alternatively spliced cDNAs are translated into two functionally different forms of the protein. Received: 8 July 1998 / Revised: 5 October 1998     

Developmental regulation of class I major histocompatibility complex antigen expression by equine trophoblastic cells

Between days 36-38 of pregnancy equine trophoblastic cells of the chorionic girdle migrate and form endometrial cups. Just prior to invasion, the chorionic girdle cells express high levels of polymorphic, paternally inherited, major histocompatibility complex (MHC) class I antigens. Their descendents, the mature, invasive trophoblast cells of the endometrial cups, however, express low or undetectable levels of MHC class I antigens by day 44 of pregnancy. Experiments with MHC compatible pregnancies, the study of residual chorionic girdle cells that had failed to invade the endometrium and remained on the surface of a conceptus, and the study of chorionic girdle cells recovered on days 34-36 of pregnancy and then maintained in vitro for up to 24 days strongly suggest that the reduction of MHC class I antigen expression by mature invasive trophoblast cells of the endometrial cups is developmentally regulated. This phenomenon does not appear to be induced by a maternal antibody response or by other uterine factors acting after the chorionic girdle trophoblast cells invade the endometrium.     

Evidence of a second polymorphic ELA class I (ELA-B) locus and gene order for three loci of the equine major histocompatibility complex

Two antisera, B-442 and R-2046, were produced by immunizing offspring with purified peripheral blood lymphocytes from a parent matched for the ELA-A specificity carried on the unshared haplotype. Absorption analysis demonstrated that these antisera contained at least two families of cytotoxic antibodies, one directed against antigens present on T and B cells, and a second directed preferentially against antigens present on surface Ig positive cells. Immunoprecipitation studies using these antisera demonstrated that both antisera contain antibodies specific for glycoproteins with molecular weights characteristic of class I and class II MHC antigens. In lymphocyte typing tests of unfractionated lymphocytes, only the class I activity was readily detectable since the class II activity killed less than 25% of the cells. Family studies demonstrated that these antisera recognize products of genes linked to the ELA system. Based on two recombinants in an extended family it became apparent that the specificities detected by B-442 and R-2046 are not products of the ELA-A locus, but rather they are products of at least one other locus, defined in this paper as ELA-B. In this family a third recombinant was found between the A blood group system and the ELA-A locus. Based on these three recombinants, the most probable linear relationship of the following genes is: A blood group system/ELA-A/ELA-B.     

Designation by restriction fragment length polymorphism of major histocompatibility complex class IV haplotypes in meat-type chickens

Major histocompatiblity complex (MHC) class IV haplotypes were identified in a population of meat-type chickens by restriction fragment length polymorphism (RFLP) analysis. Fourteen different haplotypes were designated on the basis of restriction patterns obtained from Southern blots of PvuII- or BglII-digested DNA, hybridized with the MHC class IV cDNA probe bg32.1. Digestion with each restriction enzyme yielded the same level of polymorphism among individuals. For each haplotype, 4–10 restriction fragments ranging from 0–8 to 8 kb were observed. Such a designation of meat-type chicken MHC class IV haplotypes enables a rapid recognition of previously defined haplotypes, is readily adjustable to additional, newly found restriction patterns and could prove useful in practical breeding programmes.     

Marek's disease and major histocompatibility complex haplotypes in chickens selected for high or low antibody response

Sublines of chickens differing in genotypes at the major histocompatibility complex (MHC) were developed from lines selected for high (HA) and low (LA) antibody response to sheep erythrocytes. To evaluate the influence of MHC genotypes in diverse background genomes on resistance to Marek's disease, chicks with MHC genotypes B13B13, B13B21 and B21B21 from both background genomes were exposed naturally commencing at 1 day of age. Individuals which died up to 120 days of age were autopsied to determine cause of death. Mortality due to Marek's disease was greater for HA than LA chickens and greater for males than females. Interactions of MHC genotypes with background genome and with sex suggest a complex picture of the influence of MHC genotypes. A heterozygous advantage for resistance to Marek's disease was noted, as would be predicted by genetic theory concerning maintenance of polymorphism at the MHC.     

Identification of major histocompatibility complex class I alleles in Chinese rhesus macaques

Major histocompatibility complex (MHC) class I information is vital for understanding variance of immune responses in HIV vaccination and biomedical models. In this study, 9 Mamu-A and 13 Mamu-B alleles were identified from the cDNA products of 10 Chinese-origin rhesus macaques. Except for two alleles that had been reported by others, eight were novel and twelve extended the partial sequences that are available in GenBank. The additional information of MHC class I antigens might be beneficial to the availability of Chinese macaques in human disease studies. Furthermore, the polymorphism of leading peptides and the natural killer receptor recognition motifs in alpha1 domain both implies that Mamu-A and Mamu-B molecules might play key roles in innate immune responses of natural killer cells.