Molecular biology in horses involves the study of molecular processes and genetic mechanisms that underpin equine physiology and health. This field encompasses the analysis of DNA, RNA, proteins, and other biomolecules to understand gene expression, genetic variation, and cellular functions in horses. Techniques such as genomic sequencing, gene expression profiling, and molecular diagnostics are employed to explore topics like hereditary diseases, performance traits, and immune responses in equines. This page assembles peer-reviewed research studies and scholarly articles that investigate the molecular biology of horses, focusing on genetic research, molecular techniques, and their applications in equine science.
Watson RE, England JJ, Larson KA.A cell line, derived from a spontaneous equine connective tissue tumor (equine sarcoid), has been established. The morphological and growth characteristics indicative of malignant transformation of the cells include a disoriented, rapid growth and loss of contact inhibition. Further evidence of transformation is the agglutination of these cells by concanavalin A and their ability to divide in semisolid media.
McGuire TC, Crawford TB.Immunoglobulin A (IgA) was demonstrated in equine serum and secretions. This immunoglobulin had a molecular weight extending from 150,000 to 700,000 and reacted with specific antihuman alpha-chain antiserum. Antigenic determinants specific for secretory IgA were demonstrated and found to be absent on serum IgA. Antigen binding activity was detected in IgA from tears. Purified IgA was antigenically distinct from equine IgG, IgM, IgG(T), and aggregating immunoglobulin. Quantitative studies demonstrated that IgA was the predominant immunoglobulin in tears and milk but not in colostrum. The electr...
Gospodarowicz D.A highly purified preparation of PMSG has been obtained from fresh serum and from a commercial preparation. Carbohydrate and amino acid compositions have been determined. The carbohydrate content of PMSG is 46.7% and the molecule is rich in Sialic Acid (13.5%). The apparent molecular weight of PMSG has been determined by SDS polyacrylamide gel electrophoresis. A molecular weight of 53,000 has been found for the unreduced and unalkylated molecule. After reduction and alkylation, the molecular weight fell to 23,000. From these values it has been concluded that PMSG is an oligomeric molecule comp...
Brunel C, Cathala G.1. Alkaline phosphatases (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) from brain, kidney, liver, bone, lung and spleen, which are not very sensitive to l-phenylalanine, are strongly inhibited by imidazole, whereas the placental and intestinal enzymes, which are very sensitive to l-phenylalanine, are only slightly affected. This is a new possibility for distinguishing the alkaline phosphatase isoenzymes.
2. The inhibition is apparently of an uncompetitive type, suggesting that the inhibitor interacts with the ES complex to form an EIS complex.
3. Histidine acts upon all enzyme...
Blake CC, Evans PR, Scopes RK.The single peptide chain of 3-phosphoglycerate kinase is folded into two distinct globular units, only one of which seems to be involved in substrate binding.
Norcross NL, Coggins L.The spleens of horses infected with equine infectious anemia contain an antigen that is useful for a diagnostic immunodiffusion test. This antigen was extracted from the spleen by homogenization of the tissue, centrifugation, and precipitation from the supernatant fluid at 50% saturation with (NH(4))(2)SO(4). The antigen was purified by subjecting it to two cycles of electrophoresis in a continuous free-flow electrophoresis cell and finally filtering through a column of Sephadex G-200 gel. The antigen was found to be a small protein with a molecular weight of 27,500 and sedimentation coefficie...
Kilmartin JV, Rossi-Bernardi L.1. Three modified horse haemoglobins have been prepared: (i) alpha(c) (2)beta(c) (2), in which both the alpha-amino groups of the alpha- and beta-chains have reacted with cyanate, (ii) alpha(c) (2)beta(2), in which the alpha-amino groups of the alpha-chains have reacted with cyanate, and (iii) alpha(2)beta(c) (2), in which the two alpha-amino groups of the beta-chain have reacted with cyanate. 2. The values of n (the Hill constant) for alpha(c) (2)beta(c) (2), alpha(2)beta(c) (2) and alpha(c) (2)beta(2) were (respectively) 2.5, 2.0 and 2.6, indicating the presence of co-operative interactions ...
Everts RE, Caron R, Foster G, McLoone K, Simiele L, Martin K, Brooks SA, Lafayette C.Roan coat color is described as the dispersion of white hairs within an otherwise solid background-color coat. This phenotype is primarily expressed on the body of the horse, with the head and legs exhibiting few or no white hairs. Previous studies mapped the locus for roan to the region and observed linked variants in a small number of breeds. Recently, we reported evidence for two independent haplotypes, and , in the region, which account for approximately 38% and 36% of roan horses, respectively. In the current report, using whole genome sequencing for unknown roan samples. We present a ...
Sawicki S, Bugno-Poniewierska M, Żurowski J, Szmatoła T, Semik-Gurgul E, Bochenek M, Karnas E, Gurgul A. Mesenchymal stem cells (MSCs) are a promising tool in regenerative medicine due to their ability to secrete paracrine factors that modulate tissue repair. Extracellular vesicles (EVs) released by MSCs contain bioactive molecules (e.g., mRNAs, miRNAs, proteins) and play a key role in intercellular communication. This study compared the transcriptomic profiles (mRNA and miRNA) of equine MSCs derived from adipose tissue (AT-MSCs), bone marrow (BM-MSCs), and ovarian fibroblasts (as a differentiated control). Additionally, miRNAs present in EVs secreted by these cells were characterized using nex...
Porter MM, Davis DJ, McAdams ZL, Townsend KS, Martin LM, Wilhite C, Johnson PJ, Ericsson AC.Fecal water syndrome (FWS) in horses is characterized by two-phase defecation, including both solid and liquid phases. While satisfactory explanations for FWS are unavailable, bacterial dysbiosis has been suggested as a contributing or causative factor. The objectives of this study were to determine whether fecal bacterial dysbiosis is associated with FWS in horses in the midwestern USA. Fecal samples were collected from horses with FWS and from unaffected horses at the same location. In total, 16S rRNA amplicon libraries produced from fecal bacterial DNA were sequenced using the Illumina sequ...
Equestrian sports play a significant economic role in the horse industry. In recent years, numerous equine viruses have emerged, among which are equine Pegiviruses and the re-emerging Equine coronavirus (ECoV). These viruses are distributed globally and primarily cause subclinical infections with unknown morbidity, even if ECoV can occasionally induce febrile and diarrheic episodes. To broaden the data on the Italian equine population, a study was conducted to assess their prevalence in two distinct horse populations belonging to the Carabinieri Corps (CC) and the Italian Army (IA) of the Ital...
Steensma MJ, Ducro BJ, Dibbits B, Doekes HP, van Schipstal JGC, Kalblfleisch T, Groenen MAM, Derks MFL.In horses, genetic diversity is predominantly observed between breeds, with little variation within breeds. The studbooks of the two largest horse populations in the Netherlands, the Dutch Warmblood horse and Friesian horse population, have ongoing conservation projects including collecting large-scale genotype and sequence data. The current reference genome, derived from a Thoroughbred horse can lead to bias in genetic analyses of other horse breeds. Therefore, the aim of this study was to create high-quality breed-specific reference genomes of Dutch Warmblood and Friesian horses. We performe...
Furukawa R, Tozaki T, Mizukami K, Iwasaki Y, Kawate K, Kikuchi M, Ishige T, Momozawa Y, Fukui E, Kakoi H.Thoroughbreds have been maintained as a closed breed for over 300 years since the crossbreeding between Arabian stallions and English mares. Despite interest in germline de novo mutations across species, their frequency in horses, particularly in Thoroughbreds, remains largely unexplored. Objective: This study aimed to identify de novo mutations in Thoroughbreds and estimate their frequency within a genetically closed population. Methods: We performed deep whole-genome sequencing (≥230× depth, 150 bp paired-end reads) and Sanger validation in a Thoroughbred trio (sire, dam, and foal). Reads...
Cullen JN, Cieslak J, Petersen JL, Bellone RR, Finno CJ, Kalbfleisch TS, Calloe K, Capomaccio S, Cappelli K, Coleman SJ, Distl O, Durward-Akhurst SA....MicroRNAs (miRNAs) are essential regulators of gene expression, yet few comprehensive databases exist for miRNA expression in non-model species, limiting our ability to characterize their roles in gene regulation, development, and disease. Similarly, isomiRs - length and sequence isoforms of canonical miRNAs with potentially altered regulatory targets and functions - have received even less attention in non-model species, including the horse, leaving a critical gap in our understanding of their biological significance. To address these challenges, we developed an open-source, containerized pip...
Uprety T, Durazo J, Paul L, Metiner K, Ruby R, Loynachan A, Janes J, Kenndy L, Cassone L, Molly E, Quick M, Morgan J, Beyhan S, Erol E.Neorickettsia risticii (N. risticii) is an obligatory intracellular bacterium that causes Potomac horse fever (PHF), a disease clinically characterized by diarrhea, pyrexia, and laminitis in horses. Although sporadic reports of N. risticii infection have been linked to abortion in mares, a detailed retrospective study, including genomic analysis of the pathogen from an aborted fetus, has not been published. This study examined 546 fecal samples from clinically ill horses (January 1, 2017-December 31, 2024) and 833 colon samples from aborted equine fetuses (September 20, 2018-December 31, 2024)...
Sadowska A, Wójtowicz A, Molcan T, Drzewiecka EM, Kaczmarek MM, Słyszewska M, Ferreira-Dias G, Szóstek-Mioduchowska A.Equine endometrosis is a chronic degenerative condition with fibrosis being one of the most significant characteristics. A growing body of evidence indicates the critical role of interleukin (IL)-17 in fibrotic disorders. However, its exact role during equine endometrosis remains to be discovered and explained. The main aim of the current study was to establish the expression of IL-17A signaling components in equine endometria with and without endometrosis as well as the effects of IL-17A on the transcriptomic signature, cellular functional characteristics, expression of extracellular matrix (...
Kassymbekova SN, Bimenova ZZ, Iskhan KZ, Sobiech P, Jastrzebski JP, Brym P, Babis W, Kalykova AS, Otebayev ZM, Kabylbekova DI, Baneh H, Romanov MN.Mugalzhar horses are a relatively young native breed of Kazakhstan, prized for meat and milk production and adaptation. This study was conducted to investigate genetic diversity and pinpoint genomic regions associated with selection signatures in this breed using whole-genome sequence data. Variant calling yielded a total of 21,722,393 high-quality variants, including 19,495,163 SNPs and 2,227,230 indels. Most variants were located in introns and intergenic regions, while only 1.94% were exonic. Estimates of genetic diversity were moderate, with expected and observed heterozygosity and nucleot...
Hou L, Sulayman A, Zeng Y, Zhou L, Aimaier A, Kader A, Shi L.The study of horse genetic diversity is imperative for informing conservation strategies, safeguarding ancestral lineages, and enhancing breed adaptability to environmental and disease pressures. This study employed 13 microsatellite markers with fluorescent-labeled capillary electrophoresis to analyze the genetic diversity of the Kyrgyz horse ( = 30) and Barkol horse ( = 30) for the first time, comparing them with three other indigenous horse breeds ( = 30 per breed) from Xinjiang, China. A total of 208 alleles were detected. The Polymorphic Information Content (PIC) results from GenAlEx 6.51...
Duderstadt S, Distl O.Dülmen wild horses are kept in a fenced wooden and marsh area around Dülmen in Westphalia, Germany, since 1856. Previous analyses supported early genetic divergence from other domesticated horse populations and the Przewalski horse. Therefore, the objective of this study was to evaluate genetic diversity using high-density genomic data. Methods: We collected 337 one-year-old male Dülmen wild horses, captured at 12 annual auctions, for genotyping on the Illumina GGP Equine Plus Beadchip. All analyses were performed for 63,123 autosomal SNPs. Results: On average, each horse had 27.96 ROH with...
Hacilarlioglu S, Bilgic HB, Karagenc T, Aydin HB, Toker H, Kanlioglu H, Pekagirbas M, Bakirci S.Equine piroplasmosis (EP), caused by and , is a tick-borne disease posing significant threats to equine health and the horse industry worldwide. Other vector-borne blood parasites, including , spp., and spp., can also infect horses; however, their prevalence remains poorly characterized in Türkiye. This study aimed to determine the molecular prevalence of , , , spp., and spp. in equids from the Western Aegean Region of Türkiye. Blood samples were collected from 388 clinically healthy equines across İzmir, Aydın, Denizli, and Muğla provinces. Species-specific PCR assays were performed...
Kim D, Lee S, Oyungerel B, Cho G.This study aimed to generate information for parentage testing in horse breeds using microsatellites (STRs) and single-nucleotide polymorphisms (SNPs). Genotype data were obtained from 189 horse hair root samples, including 38 Thoroughbreds (TBs), 17 Jeju horses (JHs), 20 Quarter horses (QHs), 21 American Miniatures (AMs), and 93 Mongolian horses (MHs), using 15 STR markers and 71 SNP markers. Comparative analysis revealed that the mean expected heterozygosity ranged from 0.468 (AM) to 0.491 (JH) for SNPs and from 0.695 (TB) to 0.791 (MH) for STRs. The mean observed heterozygosity ranged from ...
Lugo T, Myers S, Nguyen TA.In vitro models have revolutionized our understanding of biological pathways and mechanisms, offering a viable alternative to direct patient testing. However, there is a significant lack of models for different animals, particularly equine models. This study presents a novel primary cell culture extracted from a 3-year-old horse diagnosed with multisystemic eosinophilic epitheliotropic disease. Tissue samples were collected from lymph nodes at various locations. Growth curves of extracted primary cells were analyzed and the optimal conditions were assessed. Biomarkers, such as CD31, ZO-1, CD79...
Mège M, Bonsergent C, Viry L, Dhune M, Lecollinet S, Malandrin L.Equine piroplasmosis is a major tick-borne horse disease, caused by the intracellular development of piroplasms (Theileria equi sensu lato and Babesia caballi), with significant economic and sanitary consequences. In 2024, 203 blood samples were collected in Guadeloupe (Caribbean) from asymptomatic horses. Using an 18S rRNA nested PCR (nPCR) specific for each equine genus parasite, 79 samples tested positive for Theileria equi and 9 for Babesia caballi, resulting in respective prevalence of 38.9% and 4.4%. Three horses were co-infected. For B. caballi, 18S rRNA sequence analysis revealed the p...
Jelocnik M, Hall C, Dennis S, Mitchell K, Blishen A, Mashkour N, Anstey SI, Jenkins C, Jeffers K, El-Hage C, McMillan D, Gilkerson J.Infectious diseases significantly impact equine health and welfare, causing illness and death, and loss of productivity globally. One such disease is 'strangles', a highly contagious upper respiratory condition in horses caused by Streptococcus equi subspecies equi (SEE). Diagnostic methods for this pathogen include sensitive molecular assays and less reliable bacterial isolation and biochemical testing. However, the presence of closely related streptococci, such as Streptococcus equi subspecies zooepidemicus (SZOO), may confound diagnosis. Rapid assays for SEE are crucial for outbreak control...
Seeger MG, de Vargas APC, Vogel FSF, Cargnelutti JF.Streptococcus equi subsp. equi (S. equi) is the etiological agent of strangles, a contagious equine disease characterized by lymph node abscess and respiratory complications. To clarify the epidemiology and virulence factors of isolates, this study demonstrated phenotypic and genotypic differences between S. equi obtained from nasal secretions and lymph node aspirates of clinical strangles cases. Additionally, circulating alleles were differentiated through sequencing of the 5' end of the seM gene. A total of 23 clinical isolates collected from horses with strangles over the past decade were a...
Badr C, Handous M, Nsiri J, ElBehi I, Arbi M, Maaroufi A, Bennour MA, Ben Osman R, Dachraoui K, Abbes M, Mahmoudi A, Khosrof I, Abrougui S, Lachheb J....West Nile virus (WNV) is an arthropod borne virus, the most widely distributed of the encephalitic Orthoflaviviruses. It can cause severe neurological symptoms in both humans and horses. It poses an emerging threat to both public and animal health. In this study, we retrospectively screened 25 suspected WNV samples collected from 2018 to 2023. Methods: A total number of 25 samples (brain tissue and blood) were collected from clinically affected horses and those already deceased across several locations in Tunisia. All samples were tested for the presence of WNV NS2A gene using qRT-PCR. Eleven ...
Beermann A, Hamza E, Reinhard S, Koch C, Oberhänsli T, Unger L.We investigated microRNAs (miRNAs) as potential prognostic biomarkers for equine sarcoid (ES) disease. In a breed-, age-, and sex-matched case-controlled study involving 45 ES-affected and 15 control horses, we assessed the diagnostic, prognostic, and theragnostic value of 3 miRNAs (eca-miR-127, eca-miR-379, eca-miR-432) in horses treated with European mistletoe () extract versus placebo. Whole-blood miRNA concentrations were measured using reverse-transcription quantitative real-time PCR (RT-qPCR) at 3 different times. We found that eca-miR-432 expression was lower in ES-affected (median =...
Kambayashi Y, Bannai H, Nemoto M, Kawanishi N, Niwa H, Tsujimura K.With the revision of the World Organisation for Animal Health (WOAH) Terrestrial Manual on equine rhinopneumonitis in 2024, 3 recommended qPCR primer-probe sets were added for the detection of equid alphaherpesvirus 1 (EqAHV1; formerly equine herpesvirus 1 [EHV1]; family , taxon species ), also known as equine abortion virus. We compared the sensitivity and specificity of the 3 qPCR primer-probe sets to determine the most reliable set. Sets gB1H and gB1P, which target the glycoprotein B () gene of EqAHV1, detected all 10 copies and even lower copy numbers. In contrast, set gC1 (ISO 17025-accre...
Maniego J, Swinburne J, Hincks P, Habershon-Butcher J, Given J, Ryder E.Gene editing and genome manipulation offer great promise for treating diseases in both humans and animals. There is a danger, however, that this technology could be used for other purposes such as performance enhancement. To detect such 'gene doping' events, we evaluated a targeted enrichment panel and next-generation sequencing to assess its reproducibility, sensitivity, and capability of variant detection on a wide variety of samples and biological matrices. The panel was verified against existing data for the myostatin gene, a PCR-based SNP panel, and whole genome sequencing in a subset of ...
Steensma MJ, Doekes HP, Derks MFL, Ducro BJ.In Friesian horses, withers height is an important trait as a minimum has been set to be eligible to the studbook. Several loci for withers height have been identified in horses. However, withers height has not been studied in the Friesian horse. Therefore, our aim was to identify loci associated with withers height in the Friesian horse population. We performed a genome-wide association study using 70 K SNP data of 2192 Friesian horses. We found ECA1 and ECA9 to be significantly associated with withers height, explaining 19.6% and 3.5% of the phenotypic variance, respectively. In other hors...
Luštrek B, Šimon M, Turk K, Bogičević S, Potočnik K.In small, closed populations such as the Lipizzan horse, maintaining genetic diversity while limiting inbreeding is a key challenge in conservation breeding. The Lipizzan is an indigenous Slovenian breed with a small population and restricted gene flow from other subpopulations. Inbreeding is traditionally monitored with pedigree-based coefficients, but these often underestimate realised autozygosity, particularly when pedigree depth is limited. This study compared pedigree-based inbreeding (F_PED) with four genomic estimators (F_HOM, F_ROH, F_HBD, F_GRM) in 329 Slovenian Lipizzan horses genot...
Vasconcelos AB, França DA, Prado ACD, Yamauchi DH, Silva ACAD, Barros IO, Valença SRFA, Lucheis SB, Bosco SMG.Pythiosis is an underestimated and neglected disease in Brazil, both in horse breeders and in horses. The molecular detection of in horses in the Brazilian Northeast represents a milestone in the epidemiology of equine pythiosis in the country. This study reports novel cases of equine pythiosis, diagnosed by molecular methods, in five states of Northeastern Brazil. Clinical samples were submitted to microbiological culture, DNA extraction, and nested-PCR for molecular detection of . The nested-PCR successfully detected in four out of five equine lesion samples, demonstrating higher sensitivi...
Al-Ebshahy E, Badr Y, El-Ansary RE, Alajmi R, El-Ashram S, Rady A, Elgendy E.The present study investigated the molecular detection and genetic characteristics of equine herpesvirus 1 (EHV-1) and EHV-4 circulating within Egyptian horse populations during 2019-2022. A total of 79 animals were sampled (54 nasal swabs and 25 aborted fetal tissues). PCR assays revealed that 24 (30.3%) and 7 (8.8%) samples were positive for EHV-1 and EHV-4, respectively. Additionally, 5 (6.3%) samples were concurrently infected with both viruses. Four EHV-1 and three EHV-4 isolates were genetically characterized based on partial sequencing of gB gene. The four EHV-1 strains displayed 100% n...
Bourebaba N, Domagała J, Bourebaba L.Equine metabolic syndrome (EMS) is associated with chronic low-grade inflammation, disruptions in mitochondrial dynamics and function, and an increased risk of developing laminitis. Recent research has highlighted that reduced levels of sex hormone-binding globulin (SHBG) in the bloodstream are linked to higher susceptibility to obesity, insulin resistance, and diabetes, potentially contributing to broader metabolic imbalances. This study aimed to evaluate whether exogenously administered SHBG could protect adipose-derived stem cells from horses affected by EMS (EqASC) against mitochondrial dy...
Blomström AL, Hansen S, Riihimäki M.Papillomaviruses (PVs) are small, non-enveloped viruses with double-stranded circular DNA genomes that infect a wide range of hosts, including mammals, birds, reptiles, and fish. While human papillomaviruses are extensively studied, recent advancements in high-throughput sequencing techniques have increased the detection and genetic characterization of PVs from various animal species. Here, we describe the identification and whole-genome characterization of a divergent equine papillomavirus (EcPV) detected through a viral metagenomic investigation of a horse in Denmark exhibiting neurological ...
Abbas G, Nielsen MK, E-Hage C, Ghafar A, Beveridge I, Bauquier J, Beasley A, Wilkes EJA, Carrigan P, Cudmore L, Jacobson C, Hughes KJ, Jabbar A.Over the past 25 years, significant progress has been made in understanding and managing equine gastrointestinal parasites in the Asia-Pacific region, particularly in Australia and New Zealand. This review synthesises current knowledge of the epidemiology, diagnostic methods, anthelmintic resistance (AR), and control strategies for major equine intestinal parasites, including cyathostomins, Parascaris spp., Anoplocephala perfoliata, and Strongyloides westeri. Recent studies highlight substantial regional variation in parasite prevalence, egg shedding and cyathostomin population composition, sh...
Esdaile E, Houston K, Till BJ, Sutton RB, Scurrell E, Ling M, Hartley C, Bellone RR.Although several inherited ocular disorders have been extensively studied in horses, few reports of equine ectopia lentis exist and no genetic investigations have been reported. Ectopia lentis in humans and other species is reported to be caused by trauma, genetic variants, and systemic diseases. The most commonly reported genetic causes are dominant alleles in FBN1. Here we examined a 3-day old Oldenburg x Thoroughbred colt due to concerns over bilateral ocular anomalies and hypothesized that either a recessively inherited allele or a dominant de novo allele was the genetic cause. Examination...
