Genomics in horses involves the study and analysis of the horse genome to understand genetic variations and their implications for equine health, performance, and breeding. This field encompasses the identification and mapping of genes associated with specific traits, diseases, and conditions in horses. Techniques such as whole-genome sequencing and genome-wide association studies (GWAS) are employed to explore genetic diversity and inheritance patterns among different horse breeds. Genomics provides insights into hereditary disorders, informs selective breeding practices, and aids in the development of personalized veterinary care. This page compiles peer-reviewed research studies and scholarly articles that explore the applications, methodologies, and findings of genomic research in equine science.
de Vries AA, Glaser AL, Raamsman MJ, de Haan CA, Sarnataro S, Godeke GJ, Rottier PJ.Equine arteritis virus (EAV) is an enveloped, positive-stranded RNA virus belonging to the family Arteriviridae of the order Nidovirales. The unsegmented, infectious genome of EAV is 12,704 nt in length [exclusive of the poly(A) tail] and contains eight overlapping genes that are expressed from a 3'-coterminal nested set of seven leader-containing mRNAs. To investigate the importance of the overlapping gene arrangement in the viral life-cycle and to facilitate the genetic manipulation of the viral genome, a series of mutant full-length cDNA clones was constructed in which either EAV open readi...
Frisbie DD, Sandler EA, Trotter GW, McIlwraith CW.To determine response of interleukin-1alpha (IL-1alpha)-conditioned equine articular cartilage explants to insulin-like growth factor-1 (IGF-1). Sample Population-Cartilage from the trochlea and condyles of the femur of a clinically normal 4-year-old horse. Methods: Effects of IGF-1 (0 to 500 ng/ml) after addition of IL-1alpha were evaluated by assessing matrix responses, using a sulfated glycosaminoglycan (GAG) assay, matrix 35SO4 GAG incorporation, and release of GAG. Mitogenic response was assessed by 3H-thymidine incorporation into DNA and fluorometric assay of total DNA concentration. Res...
Shiue Y-L , Millon LV, Skow LC, Honeycutt D, Murray JD, Bowling AT.The hypothesis that the conservation of sex-chromosome-linked genes among placental mammals could be extended to the horse genome was tested using the UCDavis horse-mouse somatic cell hybrid (SCH) panel. By exploiting the fluorescence in-situ hybridization (FISH) technique to localize an anchor locus, X-inactivation-specific transcript (XIST) on the horse X chromosome, together with the fragmentation and translocation of the X- and Y-chromosome fragments in a somatic cell hybrid panel, we regionally assigned 13 type I and 13 type II (microsatellite) markers to the horse X- and Y-chromosomes. T...
Watson JL, Jackson KA, King DP, Stott JL.Expression of the low-affinity IgE receptor (CD23) on the surface of mononuclear cells is a critical event in the development of IgE-mediated immunologic responses. Using PCR and cDNA library screening, a 2.7kb cDNA encoding equine CD23 and a 627bp PCR fragment of cattle CD23 were sequenced and characterized. The equine CD23 sequence encodes a complete and continuous open reading frame of 327 amino acids, while the shorter cattle fragment encodes 209 amino acids corresponding to nucleotides 325-1098 of the equine CD23 transcript. In addition to high identities in their nucleotides and translat...
Cañon J, Checa ML, Carleos C, Vega-Pla JL, Vallejo M, Dunner S.Partition of the genetic variability, genetic structure and relationships among seven Spanish Celtic horse breeds were studied using PCR amplification of 13 microsatellites on 481 random individuals. In addition, 60 thoroughbred horses were included. The average observed heterozygosity and the mean number of alleles were higher for the Atlantic horse breeds than for the Balearic Islands breeds. Only eight percentage of the total genetic variability could be attributed to differences among breeds (mean FST approximately 0.08; P < 0.01). Atlantic breeds clearly form a separate cluster from th...
Hung GC, Chilton NB, Beveridge I, Gasser RB.In this study, molecular data sets were used to address the controversies relating to the systematics of strongyloid nematodes of equids utilising morphological data sets. DNA sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of ribosomal DNA were determined for 30 species of equine strongyles and the systematic relationships reconstructed using phenetic and phylogenetic tree-building methods. The molecular data provided support for the hypothesis that the genera with large subglobular buccal capsules are ancestral to those with small cylindrical buccal capsules,...
Schambony A, Hess O, Gentzel M, Töpfer-Petersen E.Cysteine rich secretory proteins (CRISPs) have been detected immunochemically in the equine male genital tract. CRISPs are secretory products of the epididymis, the ampulla and the seminal vesicle. A particular feature of the horse is the abundance of CRISPs in seminal plasma. CRISPs can also be detected in extracts of testicular, epididymal and ejaculated spermatozoa in increasing amounts. Unlike other seminal plasma proteins, they cannot be removed completely from spermatozoa by high salt treatment. The remaining CRISP antigens are localized on the midpiece, and the postacrosomal and equator...
Netolitzky DJ, Schmaltz FL, Parker MD, Rayner GA, Fisher GR, Trent DW, Bader DE, Nagata LP.The complete nucleotide sequence of the 71V-1658 strain of western equine encephalitis virus (WEE) was determined (minus 25 nucleotides from the 5' end). A 5' RACE reaction was used to sequence the 5' terminus from WEE strain CBA87. The deduced WEE genome was 11508 nucleotides in length, excluding the 5' cap nucleotide and 3' poly(A) tail. The nucleotide composition was 28% A, 25% C, 25% G and 22% U. Comparison with partial WEE sequences of strain 5614 (nsP2-nsP3 of the nonstructural region) and strain BFS1703 (26S structural region) revealed comparatively little variation; a total of 149 nucl...
Caetano AR, Shiue YL, Lyons LA, O'Brien SJ, Laughlin TF, Bowling AT, Murray JD.A comparative gene map of the horse genome composed of 127 loci was assembled based on the new assignment of 68 equine type I loci and on data published previously. PCR primers based on consensus gene sequences conserved across mammalian species were used to amplify markers for assigning 68 equine type I loci to 27 horse synteny groups established previously with a horse-mouse somatic cell hybrid panel (SCHP, UC Davis). This increased the number of coding genes mapped to the horse genome by over 2-fold and allowed refinements of the comparative mapping data available for this species. In conju...
Kavar T, Habe F, Brem G, Dovc P.Mitochondrial DNA from 49 Lipizzan horses representing 16 maternal lines from the original stud at Lipica was used for SSCP analysis and DNA sequencing. The SSCP analysis of the 444 bp long fragment of the D-loop region extending from the tRNA(Pro) gene to the central conserved sequence block revealed three distinct groups of SSCP patterns. Both ends of the D-loop region (378 bp and 310 bp), which are considered as the most variable regions within the mammalian mitochondrial DNA, were sequenced. According to 49 polymorphic sites identified within the both parts of the D-loop region, the 16 mat...
Guérin G, Bailey E, Bernoco D, Anderson I, Antczak DF, Bell K, Binns MM, Bowling AT, Brandon R, Cholewinski G, Cothran EG, Ellegren H, Förster M....The goal of the First International Equine Gene Mapping Workshop, held in 1995, was the construction of a low density, male linkage map for the horse. For this purpose, the International Horse Reference Family Panel (IHRFP) was established, consisting of 12 paternal half-sib families with 448 half-sib offspring provided by 10 laboratories. Blood samples were collected and DNA extracted in each laboratory and sent to the Lexington laboratory (KY, USA) for dispatch in aliquots to 14 typing laboratories. In total, 161 markers (144 microsatellites, seven blood groups and 10 proteins) were tested f...
Caetano AR, Lyons LA, Laughlin TF, O'Brien SJ, Murray JD, Bowling AT.Comparative anchor tagged sequences (CATS) from human Chromosome 5 (HSA5) were used as PCR primers to produce molecular markers for synteny mapping in the horse. Primer sets for 21 genes yielded eight horse-specific markers, which were mapped with the UC Davis horse-mouse somatic cell hybrid panel into two synteny groups: UCD14 and UCD21. These data, in conjunction with earlier human chromosome painting studies of the horse karyotype and synteny mapping of horse microsatellite markers physically mapped by FISH, confirm the assignment of UCD21 to ECA21 and suggest that UCD14 is located on ECA14...
Yokoyama S, Radlwimmer FB.To elucidate the molecular mechanisms of red-green color vision in mammals, we have cloned and sequenced the red and green opsin cDNAs of cat (Felis catus), horse (Equus caballus), gray squirrel (Sciurus carolinensis), white-tailed deer (Odocoileus virginianus), and guinea pig (Cavia porcellus). These opsins were expressed in COS1 cells and reconstituted with 11-cis-retinal. The purified visual pigments of the cat, horse, squirrel, deer, and guinea pig have lambdamax values at 553, 545, 532, 531, and 516 nm, respectively, which are precise to within +/-1 nm. We also regenerated the "true" red ...
Pfeffer M, Burck G, Meyer H.Five case reports on cowpox virus infections in cats, humans, and for the first time in a horse are presented. It becomes obvious that in most cases the diagnosis cowpox is suspected rather late, although fast and reliable diagnostic tools such as pathohistological examination and polymerase chain reaction are available. The threat of a zoonotic transmission mainly through cats is gaining importance. Although wild rodents have been claimed to be the reservoir and source for cowpox viruses in cats, very little is known about the epidemiology of cowpox virus. Based on the different genome organi...
Holmes EC, Ellis SA.We carried out an analysis of partial sequences from expressed major histocompatibility complex (MHC) class I genes isolated from a range of equid species and more distantly related members of the mammalian order Perissodactyla. Phylogenetic analysis revealed a minimum of six groups, five of which contained genes and alleles that are found in equid species and one group specific to the rhinoceros. Four of the groups contained only one, or very few sequences, indicating the presence of relatively nonpolymorphic loci, while another group contained the majority of the equid sequences identified. ...
Ehlers B, Borchers K, Grund C, Frölich K, Ludwig H, Buhk HJ.A consensus primer PCR approach was used to (i) investigate the presence of herpesviruses in wild and zoo equids (zebra, wild ass, tapir) and to (ii) study the genetic relationship of the herpesvirus of pigeons (columbid herpesvirus 1) to other herpesvirus species. The PCR assay, based on degenerate primers targeting highly conserved regions of the DNA polymerase gene of herpesviruses, was modified by using a mixture of degenerate and deoxyinosine-substituted primers. The applicability of the modification was validated by amplification of published DNA polymerase genes of 16 herpesvirus specie...
Ramina A, Dalla Valle L, De Mas S, Tisato E, Zuin A, Renier M, Cuteri V, Valente C, Cancellotti FM.The reverse transcriptase polymerase chain reaction (RT-PCR) assay was used to detect Equine Arteritis Virus (EAV) in the semen of 88 horses and 2 donkeys, with neutralising antibodies against EAV, on the basis of the amplification of a 279 bp long fragment located in the viral polymerase gene. The RT-PCR assay revealed the virus at 4 TCID50/ml in cell culture and showed a greater sensitivity (54.4%) than cell culture isolation (33.3%). Moreover, the two samples of donkey semen were found positive. The cDNAs obtained from 14 samples of horse and 2 of donkey semen were sequenced. Comparing the ...
Kim KI, Yang YH, Lee SS, Park C, Ma R, Bouzat JL, Lewin HA.Historical records suggest that horses inhabiting the island of Cheju in Korea are descendants of Mongolian horses introduced in 1276. Other studies, however, suggest that horses may have been present on the island prior to the Mongolian introduction. To determine the origin of the Cheju horses we used a phylogenetic analysis of sequences of the mitochondrial DNA (mtDNA) D-loop region, including tRNA Pro and parts of tRNA thr and tRNA Phe sequences (1102-bp excluding the tandem repeat region). Maximum parsimony and neighbor-joining trees were constructed using sequences determined for seven Ch...
Sharma AK, Paramasivam M, Srinivasan A, Yadav MP, Singh TP.Lactoferrin is a monomeric glycoprotein with a molecular mass of approximately 80 kDa. The three-dimensional structure of mare diferric lactoferrin (mlf) has been determined at 2.6 A resolution. The protein crystallizes in the space group P 212121with a=85.2 A, b=99.5 A, c=103.1 A with a solvent content of 55 % (v/v). The structure was solved by the molecular replacement method using human diferric lactoferrin as the model. The structure has been refined using XPLOR to a final R -factor of 0.194 for all data in the 15-2.6 A resolution range. The amino acid sequence of mlf was determined using ...
Ichikawa Y, Borjigin L, Enkhtuul B, Khurtsbaatar O, Aoshima K, Kobayashi A, Batbaatar V, Kimura T.Glanders, a highly contagious and often fatal disease affecting equids, is caused by Burkholderia mallei. Although sporadic cases of equine glanders have recently been documented in Mongolia, genome sequencing and molecular studies of the bacteria within this region are lacking. This study provided the first molecular characterization of B. mallei isolated from four native Mongolian horses from two different provinces in 2019 and 2022 by applying whole-genome sequencing with two SNP types (previously developed genotyping with 15 SNP markers that provide global coverage of the B. mallei populat...
Onasanya AE, El-Hage C, Diaz-Méndez A, Vaz PK, Legione AR, Devlin JM, Hartley CA.Equid gammaherpesvirus 5 (EHV5) is closely related to equid gammaherpesvirus 2 (EHV2). Detection of EHV5 is frequent in horse populations worldwide, but it is often without a clear and significant clinical impact. Infection in horses can often present as subclinical disease; however, it has been associated with respiratory disease, including equine multinodular pulmonary fibrosis (EMPF). Genetic heterogeneity within small regions of the EHV5 glycoprotein B (gB) sequences have been reported and multiple genotypes of this virus have been identified within individual horses, but full genome seque...
The Western equine encephalitis virus is transmitted between mosquitoes and wild birds. Mosquitoes spread the virus to horses and human populations, causing severe encephalitis and death. The most recent large outbreak occurred in South America from November 2023 to April 2024. We identified and genetically characterized Uruguayan strains during this outbreak to understand their evolutionary trends and rapid expansion. We obtained genomes from 15 strains using a novel multiplex PCR assay combined with next-generation Illumina sequencing. The phylogenetic analysis revealed that viruses from Uru...
Daugaliyeva A, Daugaliyeva S, Abutalip A, Adambayeva A, Kydyr N, Peletto S.Brucellosis is one of the most common zoonotic infectious diseases of animals. The causative agent of brucellosis is a highly conserved bacterium of the genus Brucella, which includes 14 species with minor genetic changes. Our work aimed to study the epidemiological and molecular characteristics of Brucella strains circulating in Kazakhstan, including the study of polymorphisms in critical virulence genes using single nucleotide polymorphism (SNP) analysis based on whole genome sequencing (WGS). A total of 21 Brucella isolates obtained in 2023-2024 from cattle, sheep and goats, horses, camels,...
van den Wollenberg L, van Maanen C, Buter R, Janszen P, Rey F, van Engelen E.Abscessation of equine head lymph nodes can be caused by various bacteria, but Streptococcus equi subsp. equi is mainly involved. At our laboratory, samples of three unrelated horses with submandibular abscesses were found negative for S. equi, and further testing proved the presence of another genus. This raised the question for the exact identity of this pathogen and whether these isolates were epidemiologically related and it warranted further characterization with regards of virulence and resistance factors.
Vasoya D, Tzelos T, Benedictus L, Karagianni AE, Pirie S, Marr C, Oddsdóttir C, Fintl C, Connelley T.The Major Histocompatibility Complex (MHC) genes play a key role in a number of biological processes, most notably in immunological responses. The MHCI and MHCII genes incorporate a complex set of highly polymorphic and polygenic series of genes, which, due to the technical limitations of previously available technologies, have only been partially characterized in non-model but economically important species such as the horse. The advent of high-throughput sequencing platforms has provided new opportunities to develop methods to generate high-resolution sequencing data on a large scale and app...
Tallmadge RL, Antczak DF, Felippe MJB.Host defenses against infection by viruses, bacteria, fungi, and parasites are critical to survival. It has been estimated that upwards of 7% of the coding genes of mammals function in immunity and inflammation. This high level of genomic investment in defense has resulted in an immune system characterized by extraordinary complexity and many levels of redundancy. Because so many genes are involved with immunity, there are many opportunities for mutations to arise that have negative effects. However, redundancy in the mammalian defense system and the adaptive nature of key immune mechanisms bu...
Franco MM, Santos JB, Mendonça AS, Silva TC, Antunes RC, Melo EO.The domestication of the Equus genus 5000-6000 years ago has influenced the history of human civilization. As soon as horse and donkey species had been domesticated, they were crossbred, producing humanity's first documented attempt at animal genome manipulation. Since then, the mule (male donkey x female horse) and the reciprocal cross (the hinny, male horse x female donkey) have been the most common equine hybrids in the world. Due to their hybrid vigor, mules and hinnies have been intensively used for carrying loads and people and for tilling the land. Despite their importance, visual disti...