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     

MHC-DRB3 variation in a free-living population of the European bison, Bison bonasus

MHC genes play a crucial role in pathogen recognition and are the most polymorphic genes in vertebrates. Loss of variation in these genes in bottlenecked species is thought to put their survival at risk. We examined variation at the MHC II DRB3 locus in the European bison, Bison bonasus, a species that has undergone an extreme bottleneck: the current population originated from only 12 founders. We also tested for the association of DRB3 genes with the incidence of posthitis, a disease affecting the reproductive organs of bulls and posing a new threat to the survival of the species. We found very limited MHC diversity, with only four alleles segregating in a sample of 172 individuals from a free‐ranging Białowieża population. The alleles were highly divergent and revealed the hallmark of positive selection acting on them in the past, that is, a significant excess of nonsynonymous substitutions. This excess was concentrated in putative antigen‐binding sites, suggesting that selection was driven by pathogens. However, we did not observe departures from Hardy–Weinberg equilibrium, an indicator of strong ongoing selection. Neither have we found a significant association between DRB3 alleles or genotypes and susceptibility to posthitis. Alleles conferring resistance to males may have been lost during the extreme bottleneck the species had undergone.     

Defecation rate in captive European bison, Bison bonasus

Data on the digestive characteristics of European bison, Bison bonasus (L.), are needed for studies of their role as the largest extant herbivore in Europe and a potential keystone species of the temperate forest ecosystem. Very little published data are available, particularly on the defecation rate which affects population estimates from dropping counts and also the individual seed deposition rate. We gathered data from a captive bison group kept at the Show Reserve of the Bia?owie?a National Park. Droppings accumulated in the enclosure over a 72-h period were counted in winter 2010. In addition, the group was observed over approximately 6-h periods three times in winter and 16 times in summer. The count of accumulated droppings over a 72-h period gave eight defecations per day. The summer direct observations recorded 7.5 defecations per day and winter observation 5.4 defecations per day. These estimates are within the range for other bovids of similar size. The difference between summer and winter observation-based estimates may be accounted for by a higher frequency of defecation in early morning and late afternoon, periods not covered in winter observations. Given the published density of seedlings emerging from droppings of the ～470 free-living bison in the nearby forest, eight defecations a day mean that seed deposition by European bison may contribute significantly to realize seed dispersal and plant establishment.     

Antibodies against Mycoplasma bovigenitalium in free-living European bison (Bison bonasus) with balanoposthitis

Since 1980 severe chronic balanoposthitis has been observed in free-living European bison (Bison bonasus) in the Bia?owieza Primeval Forest (Poland). Sera of 50 bison with balanoposthitis and 48 clinically healthy male and 49 female bison were investigated for antibodies against Mycoplasma bovis and M. bovigenitalium by western blot analysis. Prevalence of antibodies against M. bovigenitalium was significantly higher in bison with balanoposthitis than in unaffected male bison. Mycoplasma bovigenitalium may play a role in the pathogenesis of balanoposthitis in European bison.     

DNA fingerprinting and genetic diversity of the European bison (Bison bonasus), American bison (Bison bison), and gray Ukrainian cattle (Bos taurus)

To describe genetic variability and population diversity in domesticated populations of American bison (Bison bison), aurochs (Bison bonasus), and gray Ukrainian cattle (Bos taurus) different variants of DNA fingerprinting technique (utilizing the M13 phage DNA, (TTAGGG)4 synthetic oligonucleotide, and three arbitrary primers as hybridization probes) were used. Several parameters characterizing polymorphism and genetic diversity levels in each population (species) were evaluated on the basis of the profiles obtained. Dendrograms reflecting similarities between individual animals were constructed. Genetic variability of minisatellite and telomeric markers observed in the gray Ukrainian cattle flock was higher than that in aurochs and bisons. Comparison of the intrapopulation similarity (S) and gene diversity (H) indices along with the analysis of clusters in the dendrograms showed that the relatedness between the aurochs individuals was much higher than between the individual animals in the bison and gray Ukrainian cattle flocks. Furthermore, the gray Ukrainian cattle flock was represented by more distant relatives than the bison flock. It is suggested that reduced genetic variability and the appearance of deviant genotype observed in the two bison lines under selection, resulted from close inbreeding and the founder effect. The diagnostic value and efficacy of utilization of different molecular markers for estimation of genetic diversity and relatedness in domesticated animal populations is discussed.     

Virologic investigations of free-living European bison (Bison bonasus) from the Bialowieza Primeval Forest,Poland

We conducted virologic investigations on postmortem specimens from 261 free-living European bison (Bison bonasus) from the Bialowieza Primeval Forest, Poland collected between 1990 and 2000. Fifty-four of 94 males had balanoposthitis; none of the 167 female bison examined had reproductive tract lesions. Peripheral blood, swabs, and various tissues were analyzed for bovine viruses as well as for viral DNA by bovine herpesvirus 1 (BoHV-1) and bovine herpesvirus 4 (BoHV-4) specific polymerase chain reaction (PCR) technique. An infectious bovine rhinotracheitis like BoHV-1 strain was isolated from the spleen of a female bison calf and additionally was detected by nested PCR from splenic tissue. None of the bison had significant antibody titers against BoHV-1, bovine herpesvirus 2, BoHV-4, caprine herpesvirus 1, cervid herpesvirus 1, or bovine viral diarrhea (BVD) virus-1. However, low antibody titers in two animals indicate that this European bison population has been exposed to BVD virus or BVD-like viruses and BoHV-2.     

Porcine major histocompatibility complex (MHC) class I molecules and analysis of their peptide-binding specificities

In all vertebrate animals, CD8⁺ cytotoxic T lymphocytes (CTLs) are controlled by major histocompatibility complex class I (MHC-I) molecules. These are highly polymorphic peptide receptors selecting and presenting endogenously derived epitopes to circulating CTLs. The polymorphism of the MHC effectively individualizes the immune response of each member of the species. We have recently developed efficient methods to generate recombinant human MHC-I (also known as human leukocyte antigen class I, HLA-I) molecules, accompanying peptide-binding assays and predictors, and HLA tetramers for specific CTL staining and manipulation. This has enabled a complete mapping of all HLA-I specificities (“the Human MHC Project”). Here, we demonstrate that these approaches can be applied to other species. We systematically transferred domains of the frequently expressed swine MHC-I molecule, SLA-1*0401, onto a HLA-I molecule (HLA-A*11:01), thereby generating recombinant human/swine chimeric MHC-I molecules as well as the intact SLA-1*0401 molecule. Biochemical peptide-binding assays and positional scanning combinatorial peptide libraries were used to analyze the peptide-binding motifs of these molecules. A pan-specific predictor of peptide–MHC-I binding, NetMHCpan, which was originally developed to cover the binding specificities of all known HLA-I molecules, was successfully used to predict the specificities of the SLA-1*0401 molecule as well as the porcine/human chimeric MHC-I molecules. These data indicate that it is possible to extend the biochemical and bioinformatics tools of the Human MHC Project to other vertebrate species.     

Resistance to malignant catarrhal fever in American bison (Bison bison) is associated with MHC class IIa polymorphisms

The Rhadinovirus ovine herpesvirus-2 (OvHV-2) is the most common causative agent of malignant catarrhal fever (MCF) in clinically susceptible ruminants including cattle and bison. American bison (Bison bison) are highly susceptible to clinical MCF. Nevertheless, approximately 20% of bison on ranches or in feedlots become infected with the virus without developing clinical disease. Defining the genetic basis for differences in susceptibility between bison could facilitate development of improved control strategies for MCF. One genetic region that influences susceptibility to infectious diseases is the major histocompatibility complex (MHC). In this study, a Bison bison (Bibi) DRB3 oligonucleotide microarray was used to type 189 bison from 10 herds where MCF outbreaks had occurred. Binary logistic regression was used to classify DRB3 alleles as resistant (R), susceptible (S) or neutral (N). Animals were reclassified using six DRB3 genotype categories: N/N, N/R, N/S, R/S, R/R and S/S. Analysis of homogeneity across herds showed that there was a herd effect. Consequently, a penalized logistic regression model was run with herd and genotype categories as the explanatory variables. The R/R genotype was associated with resistance to MCF (P = 0.0327), while the S/S genotype was associated with clinical MCF (P = 0.0069). This is the first evidence that MHC class IIa polymorphism is associated with resistance or susceptibility to OvHV-2-induced MCF.     

Seasonal changes in the red blood cell system in the European bison, Bison bonasus L

1. In 195 European bisons divided into four groups (Group 1, 0-3 year-old males; Group 2, 0-3 year-old females; Group 3, mature bulls, over 3 years old; Group 4, mature cows, over 3 years old) seasonal changes in red blood cell number and diameter, haemoglobin level, haematocrit value, index F, MCH, MCHC and MCV were studied. 2. Seasonal cyclicity was found only in red blood cell diameters in all groups. 3. In young males the cyclicity was found in MCHC and in MCV only. 4. In young females the cyclicity was found in Hb and Hct values, in MCH and in MCV. 5. In mature bulls cyclicity was found only in RBC diameter and in MCV. 6. In mature cows the cyclicity was found in index F, MCH and in MCHC values. 7. Seven out of 14 acrophases of cyclic indices occurred just before autumnal equinox and three before vernal equinox.     

Genetic status of the European bison Bison bonasus after extinction in the wild and subsequent recovery

• 1 The European bison Bison bonasus went through a severe bottleneck and became extinct in the wild 90 years ago. The lowland subspecies B. b. bonasus is the only one of three original subspecies that exists today. The entire species derives from only 12 founders, including a bull of the Caucasian subspecies B. b. caucasicus. Due to its presence among founders, there are two geographically separated genetic lines of European bison: the pure lowland (Bia?owie?a) line and the hybrid lowland‐Caucasian line.
• 2 The lowland line of the European bison originates from only seven founders with an extremely varying genetic contribution. Approximately 80% of the genes in contemporary populations come from just two founders.
• 3 A variety of genetic markers (mtDNA, microsatellites, single nucleotide polymorphism microchips) were applied to studies of the level of depletion of genetic variability in European bison.
• 4 The lowland line of the European bison, the most extensively studied, shows very low levels of genetic variation, and has just half the microsatellite heterozygosity of the closely related American bison Bison bison. The effective population size (N_e) for the highly genetically homogenous lowland line in the Polish part of the Bia?owie?a Forest is estimated to be 23.5, far less than the census population size of 450.
• 5 The average inbreeding level in lowland bison is almost 50%, although no signs of inbreeding depression have been observed. In contrast, inbreeding effects have been noticed in the lowland‐Caucasian line, which has a much lower average inbreeding level (28%). In spite of the apparently high fitness of the lowland bison, the lack of genetic variation and high level of inbreeding may present substantial threats in the future, especially in the context of potential epizootics.

     

The annual cycle of shedding Eimeria oocysts by European bison (Bison bonasus) in the Bialowieza Primeval Forest, Poland

Between April 2008 and March 2009, we analyzed the pattern of coccidian oocysts present in the feces of the European bison (Bison bonasus L., 1758) and found 4 species (Eimeria bovis , E. canadensis, E. ellipsoidalis, E. zuernii) previously reported from this host and 3 species (Eimeria alabamensis, E. cylindrica, E. pellita) that are new host and locality records. All the species occurred in bison females, and only 4 occurred in males; E. bovis was the most prevalent in both sexes. The overall prevalence of Eimeria spp. invasion reached 34.7% in cows and 13.9% in bulls. The highest prevalence was noted in early spring, with a peak in April, and the lowest in late autumn and winter. The oocyst count per gram of feces (OPG) varied from 50 to 1,350; no symptoms of clinical coccidiosis were observed. We found a significant influence of winter aggregations of bison on shedding of coccidian oocysts. The prevalence and OPG values were higher in bison congregating in large numbers around winter-feeding sites in comparison to other sites. We suggest that the coming together of cows during the growing season impacts the gender-related differences in prevalence and the number of coccidian species involved. This observation probably results from an increased production of oocysts by sub-clinically infected individuals in high-density bison populations.     

Sperm characteristics in plains (Bison bison bison) versus wood (Bison bison athabascae) bison

The objective was to compare sperm characteristics between the two subspecies of North American bison, plains bison (Bison bison bison) and wood bison (Bison bison athabascae). Frozen-thawed ejaculated sperm from age-matched plains (n = 3) and wood (n = 2) bison were evaluated for morphometry, motility, viability, protein profile, and in vitro fertilization characteristics. Sperm morphometry and motility were assessed with computer-based systems, viability was assessed with SYBR-14 and propidium iodide, and fertilizing ability was determined using a heterologous in vitro fertilization system (using bovine oocytes). For plains versus wood bison, there were significant differences for head width (4.76 ± 0.22 vs 4.71 ± 0.19 μm; mean ± SD), head area (35.64 ± 1.91 vs 34.72 ± 2.64 μm²), head perimeter (23.61 ± 0.68 vs 23.31 ± 0.98 μm), midpiece length (14.58 ± 0.4 vs 14.36 ± 0.51 μm), midpiece width (0.81 ± 0.06 vs 0.79 ± 0.07 μm), and tail length (46.61 ± 2.15 vs 45.98 ± 2.08 μm). However, there was no significant difference in head length (overall, 9.04 ± 0.37 μm), progressive motility (41.16 ± 8.39%), or viability (41.58 ± 5.58%). Based on two-dimensional gel electrophoresis, 93 out of 113 protein spots were similar in their expression patterns. Furthermore, we inferred that differences in sperm biometry between these subspecies did not affect in vitro fertilization percentage (overall, 82.62 ± 12.13%). Based on these findings, we concluded that plains bison were an appropriate research model for developing reproductive technologies for wood bison.     

Identification of multiple pregnancy-associated glycoproteins (PAGs) purified from the European bison (Eb; Bison bonasus L.) placentas

This paper describes the first identified chorionic PAGs in the European bison (Eb), named EbPAGs, predominantly expressed during early and mid-pregnancy (45-120 day post-coitum; dpc). Many EbPAGs were extracted from various cotyledonary tissues, precipitated, chromatographed (DEAE and VVA: Vicia villosa agglutinin), electrophoresed (1D- and 2D-PAGE), analysed by heterologous (cross-species) Western blotting and then micro-sequenced by Edman degradation. Finally, twelve selected VVA-purified isoforms (Ip 3.7-7.4) were entirely characterised. Nine identified NH(2)-terminal micro-sequences were found to be PAGs. On 45 dpc, three identified forms were named: EbPAG(67AkDa) (RGSNLTHPLRNIGDLFYVGN), EbPAG(55BkDa) (RGSNLTHPL) and EbPAG(50CkDa) (SQISLRGSNLTI). On 60 dpc, the next three forms were named: EbPAG(71DkDa) (RGSNLTIHPLRNIIDLFYVG), EbPAG(55EkDa) (RGSNLTHPLRNI) and EbPAG(50FkDa) (SQISLRGS). On 120 dpc, three other forms were named: EbPAG(71GkDa) (RGSNLTHPLRNIRDLFYVG), EbPAG(60HkDa) (RGSNLTTHPLRNIKDLVVYM) and EbPAG(50IkDa) (SGSNLTTV). These EbPAG ((A-I)) sequences are unique, as they are not identical to any other PAGs purified previously in related species of the Bovidae family. However, the EbPAGs (A-I forms) have some sequence resemblance to internal sequences of various full-length polypeptide PAG precursors (in silico translated from cloned cDNAs) identified in domestic cattle. Three other novel native isoforms (J1, J2 and K): EbUPG(45kDa) J1 (SKDNYKNYIPLIVPFAT), EbUPG(45kDa) J2 (SKDNQKNYIPLIVPFAT) and EbUPG(76kDa) K (SPEFTV), were temporarily named 'unknown placental glycoproteins' (UPGs), due to their efficient VVA-purification (specific for glycoproteins only) and a lack of considerable consensus to previously sequenced placental glycoproteins in the Bovidae family. This is the first study identifying NH(2)-terminals of multiple/diverse EbPAGs and some EbUPGs purified from the synepitheliochorial cotyledonary placenta of the endangered Bison bonasus (Red List).     

Probing the stability of class I major histocompatibility complex (MHC) molecules on the surface of human cells

 We used binding of a fluorescent adduct of β₂-microglobulin, fluorescein β₂m, to probe the stability of class I HLA molecules on the surface of human cells. The weight of the literature suggests that this ligand binds to heavy chains that have lost β₂m and possibly peptide as well. Hence Fl-β₂m reports on the stability of the class I HLA trimer. A small fraction of HLA molecules, ∼5%, binds Fl-β₂m on both resting and activated T cells. A larger fraction of all HLA molecules binds Fl-β₂m in FO-1 cells, β₂m-deficient cells, transfected with various B2m genes. HLA molecules of FO-1 cells are more stable when expressed with human β₂m, than when expressed with mouse β₂m. The non-covalent association of HLA heavy chains, β₂m and peptide implies that eventually every molecule of HLA trimer ought to dissociate and bind Fl-β₂m. In fact, the extent of exchange is limited by the lifetime of a given molecule at the cell surface. β₂m exchange decreases as cell concentration increases, suggesting that some density-dependent process acts to enhance degradation or denaturation of β₂m-free HLA heavy chains.     

Isolation and amino acid sequence of insulins and C-peptides of European bison (Bison bonasus) and fox (Alopex lagopus)

Insulins and C-peptides were extracted and purified from bison and fox pancreatic glands. The insulins were reduced and pyridylethylated, and the derived A- and B-chains separated by HPLC. Amino acid sequence determinations of the pyridylethylated A- and B-chains proved bisontine insulin to be identical to bovine insulin and fox insulin to be identical to dog and porcine insulin. Bisontine C-peptide proved to be identical to bovine C-peptide. The isolated fox C-peptide comprises 23 amino acid residues and probably represents a major tryptic fragment of a larger C-peptide. The fox C-peptide fragment is identical to the dog C-peptide (9-31) except for residue 3 (residue 11 in the dog C-peptide), which is aspartic acid as compared with glutamic acid in the dog C-peptide.