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Topic:Molecular biology
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.
Quantitative assessment of specific bacterial taxa of the intestinal microbiota of healthy and diarrheic horses. Alterations in intestinal microbiota composition, as determined by DNA sequencing, are reported in horses with acute colitis compared with healthy horses. Objective: Changes in specific bacterial populations can detect overall intestinal disruption of the normal intestinal microbiota. Identify bacterial taxa that indicate intestinal dysbiosis or health in horses using quantitative PCR (qPCR). Methods: Thirty horses with undifferentiated colitis, 13 with colitis associated with Salmonella spp., 14 with antibiotic-associated diarrhea (AAD), 52 healthy horses from Canada and 48 from the United St...
Differential Gene Expression of Mesenchymal Stromal Cell and Granulosa Cell Markers in Equine Follicular Aspirates. Equine follicular aspirates obtained during ovum pick-up contain a heterogeneous mixture of mesenchymal stromal cells (MSC) and granulosa cells (GC). This study evaluates how selective isolation and expansion of MSC decrease GC populations. Follicular aspirates-derived cells were cultured up to passage four (P4) following a previously validated protocol. While freshly isolated follicular aspirates cells (FAC) displayed heterogeneous morphologies, early passages (P3-P4) showed a uniform, spindle-shaped phenotype compatible with MSC. Gene expression analysis by RT-qPCR revealed a marked upregula...
A single-cell RNA-seq dataset characterizing cellular diversity in healthy equine skin. The skin serves as the primary barrier tissue in horses and is frequently affected by immune-mediated dermatological conditions, most notably insect bite hypersensitivity (IBH). Yet, the cellular composition and transcriptional landscape of normal equine skin have never been characterized at single-cell resolution. Here, we present a single-cell RNA sequencing dataset of healthy equine skin comprising 85,574 high-quality transcriptomes from two horses, with one skin biopsy collected from each horse, divided into two portions for independent processing via manual or automated tissue dissociatio...
Multisystemic and cerebral infection associated with Halicephalobus gingivalis in Brazilian Criollo horses. Halicephalosis is a rare cosmopolitan disease affecting equids, cattle, and humans, manifesting as meningoencephalitis. This study reports the detection of Halicephalobus gingivalis infection in two adult horses with neurological clinical signs in Rio Grande do Sul state, in the Southern Brazil. It underscores the pathological main findings and phylogenetic analyses. In both cases, the horses exhibited severe neurological manifestations and were euthanized due to poor prognosis. Pathological findings revealed gross brain lesions, in addition, alterations in the kidneys and lymph nodes. Histopa...
First documented cases of equine leishmaniasis caused by Leishmania (Mundinia) martiniquensis in France. In this study, we describe the first documented cases of equine cutaneous leishmaniasis caused by Leishmania (Mundinia) martiniquensis in France and provide clinical and parasitological data relevant for the recognition of this emerging infection in horses. Three horses presenting localized cutaneous lesions were diagnosed with L. martiniquensis infection in different regions of France without spatial or temporal clustering. Lesions were clinically nonspecific and initially compatible with common equine dermatological conditions, including sarcoid-like tumors. Histopathological examination rev...
Association Between Matrix Metalloproteinase-9 (MMP-9) Immunohistochemical Expression and Clinicopathological Features in Equine Melanoma. Equine melanoma is one of the most important oncological diseases in horses and exhibits a distinct biological behavior compared with melanoma in other species. Matrix metalloproteinase-9 (MMP-9) has been associated with tumor aggressiveness and metastasis in human and canine melanoma, but its expression in equine melanoma remains unknown. Objective: Evaluate the immunohistochemical expression of MMP-9 in equine melanomas and investigate its association with clinicopathological features. Methods: 68 formalin-fixed, paraffin-embedded equine melanomas from 48 gray horses were evaluated immunohis...
Retrospective investigation of equine parvovirus-hepatitis in Italy. Equine parvovirus-hepatitis (EqPV-H) has recently been identified as the etiological agent of Theiler's disease, a major cause of acute hepatitis and liver failure in horses. While iatrogenic transmission of EqPV-H is well-documented, the natural horizontal transmission of the virus remains poorly understood. This study provides the first comprehensive epidemiological investigation and molecular characterization of EqPV-H in equine populations across Italy. A total of 1320 archival serum samples from northern and southern Italy were screened for the presence of EqPV-H DNA by qPCR. The overall ...
Alterations in the gut resistomes of endangered wild equids associated with anthropogenic activities: Insights for One Health surveillance. Antibiotic resistance genes (ARGs) are emerging environmental contaminants, but how human-associated management practices are associated with mobile resistomes in endangered wildlife remains poorly resolved. Here, we used fecal metagenomics to compare Przewalski's horses, Mongolian khulans, and domestic horses from Xinjiang, China, including Przewalski's horses from a protected area and a captive-breeding setting under human management. Across 47 fecal metagenomes, we identified 380 ARG subtypes, 23 metal resistance gene (MRG) types, and 26 mobile genetic element (MGE) subtypes. Przewalski's h...
Equine alveolar echinococcosis: a focus on epidemiology, clinical and pathological features, and diagnostics. Here, we review equine alveolar echinococcosis (AE), focusing on its epidemiology, clinical and pathological features, and diagnostic challenges, through comparisons with AE in other host species. AE is a zoonotic disease caused by the larval form of the tapeworm. Horses are considered dead-end hosts, in which AE infection can be detected at slaughter, highlighting their potential as sentinel animals in endemic areas. Equine AE is typically asymptomatic and is generally only found incidentally during meat inspection or necropsy. Standard diagnosis involves histopathology and conventional poly...
Genome-wide exploration of coat color-associated loci in Hokkaido Native Horses, with a novel locus implicated in the roan phenotype. Genes and loci regulating horse coat color have been investigated in many breeds, but their associations with the 16 coat colors of the Hokkaido Native Horse (HKD) remain unknown. HKDs were classified according to coat-color groups based on pedigree-recorded coat color, and genome-wide association (GWA) analyses were performed. Except for gray and roan, a clear single signal corresponding to the known locus was obtained for each coat color, suggesting that the reported loci are the primary causes of these coat colors. Because gray and roan are difficult to distinguish visually and may therefor...
Seroprevalence of Borrelia burgdorferi sensu lato in horses in Spain. Borrelia burgdorferi sensu lato is a tick-borne zoonotic pathogen of increasing importance in Europe, responsible for Lyme borreliosis and affecting both humans and domestic animals. In horses, infection is often subclinical and difficult to diagnose due to variable clinical presentation and limitations in diagnostic methods. Epidemiological data remain limited in several countries, including Spain. This study aimed to estimate the first nationwide seroprevalence in horses in Spain and to identify associated risk factors. A total of 716 serum samples from clinically healthy horses across 17 au...
Oocyte and Embryo Vitrification in Horses. Vitrification has emerged as a decisive technique in assisted reproductive technology, offering superior cryopreservation outcomes for both oocytes and embryos compared with traditional slow freezing. This chapter provides a comprehensive overview of the vitrification of equine oocytes and embryos, emphasizing the influence of technical factors, including cryoprotectant selection, exposure time, temperature control, and device volume, on vitrification outcomes. Biological factors such as the oocyte maturation stage, the presence of cumulus cells, and embryo size are also explored, highlighting...
Limited evidence for exposure of horses in the United Kingdom to influenza D virus. Since it was first detected in 2011, antibodies to influenza D virus (IDV) have been found in several species, although cattle are the major host. In cattle, IDV is typically associated with mild respiratory signs, but it is clinically significant as a component of bovine respiratory disease complex. Although antibodies to IDV have been detected in equids, no association of IDV with naturally occurring respiratory disease in horses has yet been demonstrated. Objective: The aim of this study was to determine whether IDV may be a causal agent of equine respiratory disease in the UK. Methods: Nas...
Cyathostomin species richness and alpha diversity at egg reappearance following fecal egg count-based selective ivermectin treatment. Cyathostomin nematodes are ubiquitous in grazing horses. The overuse of anthelmintics has led to increasing problems with drug resistance to benzimidazoles and pyrantel. Although macrocyclic lactones (ML), such as ivermectin, generally retain the highest efficacy, reduced ML efficacy has increasingly been reported. A shortened egg reappearance period (ERP) is frequently used as an indicator of reduced susceptibility. However, the species-specific response dynamics after ivermectin treatment are inadequately characterized in cyathostomins. The objective of this study was to compare the cyathost...
Gut Microbiota as a Molecular Regulator of Mineral Homeostasis in Horses: Mechanisms and Future Perspectives. Mineral homeostasis in horses is traditionally attributed to the coordinated regulation of the intestine, kidneys, skeleton, and endocrine system. Emerging evidence suggests the gut microbiota also shapes this process by modifying the intestinal environment where mineral absorption occurs. Despite the growing interest in host-microbiota interactions, the mechanisms linking the equine gut microbiota to mineral metabolism remain poorly understood and have not been comprehensively synthesized. This review integrates current knowledge of equine gastrointestinal physiology, gut microbial ecology, a...
Transcriptome Sequencing and Differential Expression Analysis of Ovaries from Kazakh Mares During Seasonal Quiescence and Estrus Activation. Kazakh horses are typical seasonal breeders, and ovarian activity is markedly reduced during the non-breeding period. Hormonal stimulation can induce ovarian functional responses during seasonal anestrus; however, the early ovarian transcriptional changes associated with this response remain incompletely understood. In this study, ovarian transcriptome sequencing was performed in 12 Kazakh mares examined during the seasonal anestrous period. The mares were classified into a non-hormonally stimulated seasonal quiescent group (DB, = 6) and a hormone-induced ovarian activation group (DY, = 6) f...
Identification and phylogenetic analysis of Mannheimia haemolytica isolated from nasal samples of horses. The Mannheimia genus, which is part of the upper respiratory tract microbiota, harbours species that have the potential to cause progressive infections, such as haemorrhagic septicaemia and enzootic pneumonia, when the host immune system is suppressed. Among these species, Mannheimia haemolytica is considered the most pathogenic, and horses can be a host for this agent. This study aimed to investigate the occurrence of Mannheimia haemolytica in horses with and without respiratory clinical signs and to assess the potential pathogenic significance of isolates recovered from animals through serot...
Prevalence and Molecular Characterization of Enterocytozoon bieneusi in Horses From Northern and Eastern China: Investigation of Associated Risk Factors and Assessment of Zoonotic Potential. Enterocytozoon bieneusi is a zoonotic microsporidian threatening public health, yet epidemiological data on equine infections in China are scarce despite frequent human-horse contact. In this study, 412 fresh horse fecal samples were collected from four Chinese regions covering four rearing systems and were screened for E. bieneusi internal transcribed spacer (ITS) sequences via nested PCR, with risk factor and phylogenetic analyses conducted. The overall infection prevalence reached 15.0% (62/412), varying geographically from 9.7% (Wenzhou) to 29.3% (Qiqihar). Foals <1 year and male horses ex...
Ortholog-specific Spatial Expression of Vanins in the Respiratory Tract of Horses. Equine asthma (EA) is the most prevalent chronic respiratory disease in horses, but molecules thought to be relevant in its pathogenesis are not yet fully understood. Recently, increased Vanin-1 (VNN1) levels were found in bronchoalveolar lavage fluid from horses with severe EA. Human VNN1 is known as a pantetheinase, which is associated with respiratory diseases such as asthma, but the equine vanins (eVNNs) are uncharacterized. We identified the domain architecture of eVNN in silico and analyzed its tissue expression in healthy horses using RT-PCR (=5) and in situ hybridization (=3). Recombin...
Molecular Survey and Genetic Characterization of Tetratrichomonas buttreyi and Pentatrichomonas hominis in Horses in Shanxi Province, Northern China. Trichomonads include species of veterinary and zoonotic importance, yet infections with trichomonads in horses remain uncharacterized in Shanxi Province, Northern China. In the present study, we conducted a molecular survey of and using 631 horse fecal samples collected from Datong, Taiyuan, and Yuncheng cities in Shanxi Province between March and June 2023. Nested PCR assays targeting the small subunit ribosomal RNA (SSU rRNA) gene were used to detect the two trichomonad species. The overall molecular prevalences were 3.7% (23/631; 95% CI, 2.5-5.5%) for and 0.8% (5/631; 95% CI, 0.3-1.9%) f...
Phylogenetic and phylogeographic analysis of equine influenza in Colombia. In 2022, Colombia experienced an outbreak of equine influenza (EI) that primarily affected competition horses. Despite the epidemiological relevance of equine influenza virus (EIV) in the country, no previous phylogenetic or phylogeographic analyses based on complete genomes have been reported. Objective: To perform phylogenetic and phylogeographic analyses of complete EIV genomes obtained from horses with clinical signs in two Colombian regions between 2020 and 2023. Methods: Molecular epidemiological study based on whole-genome sequencing and evolutionary analyses. Methods: Nasopharyngeal sa...
Circulating Cell-Free RNA Reflects Immune-Associated and Airway Remodeling Signatures in Equine Asthma. Circulating cell-free RNA (cfRNA) has emerged as a promising minimally invasive biomarker capable of capturing transcripts originating from multiple tissues and cell types, but its utility in chronic inflammatory airway diseases remains poorly understood. Equine asthma (EA), a naturally occurring respiratory disease that shares key clinical and immunopathological features with human asthma, provides a valuable comparative model for evaluating plasma cfRNA in this context. We performed transcriptomic profiling of plasma cfRNA from horses with EA and healthy controls and compared these findings ...
Non-coding RNA profiles associated with equine osteoarthritis: a systematic review. Non-coding RNAs (ncRNAs) play a role in the pathogenesis of osteoarthritis (OA) by regulating gene expression related to inflammation, chondrocyte apoptosis, and extracellular matrix degradation. In horses, OA is a leading cause of lameness and poor performance, with no current treatments halting disease progression and no clear biomarker available. Although some studies have investigated expression profiles of ncRNAs in equine OA, there is a need to systematically review previous efforts and synthesize information to identify potential ncRNAs to target in future research. Unassigned: The sear...
Comparative genomics of Standardbred horses reveals candidate regions under selection for harness racing performance. Harness racing performance in horses is a complex polygenic trait influenced by genetic background, breeding history, training, and environment. Understanding genomic patterns shaped by long-term artificial selection provides insights into performance-related traits and breed-specific genomic variation. Objective: This study aimed to characterize genomic differentiation, population structure, and candidate genomic regions potentially influenced by historical selection in Standardbred horses using comparative whole-genome sequencing involving diverse horse breeds. Methods: Whole-genome sequenci...
Equine herpesvirus myeloencephalopathy-associated mutations in equine herpesvirus 1 DNA polymerase confer the ability to replicate at elevated temperatures. Equine herpesvirus myeloencephalopathy (EHM), caused by equine herpesvirus type 1 (EHV-1), poses a major threat to the equine industry because of its devastating impact on animal welfare and athletic performance. A single-nucleotide polymorphism (SNP), G2254, in ORF30 (UL30), which encodes the viral DNA polymerase, has been used as a marker of neuropathogenic EHV-1 strains, although its contribution to EHM pathogenesis remains controversial. In addition, other ORF30 SNPs have been reported in association with EHM, but their functional significance is unclear. Clinical observations indicate tha...
Microbiological, Molecular Diagnosis and Antimicrobial Resistance of Bordetella bronchiseptica in the Equine Reproductive Tract in Brazil. The genus Bordetella comprises 16 species of aerobic Gram-negative bacteria, with the most notable being B. pertussis, B. parapertussis and B. bronchiseptica. The latter stands out for its ability to infect various hosts, causing both respiratory and reproductive issues, such as endometritis and infertility in mares. These infections impair reproductive efficiency and facilitate the spread of the pathogen among susceptible animals. Objective: The present study aimed to report the isolation and molecular diagnosis of B. bronchiseptica associated with endometritis and infertility in mares in Bra...
Comparative analysis of the karyotypes of Equus caballus and Equus asinus in the context of contemporary genomic data. Karyotypes of species within the genus Equus display considerable variation in chromosome number and are characterised by numerous structural rearrangements that have played a pivotal role in their evolutionary divergence and speciation. Equus caballus (horse), 2n = 64 and Equus asinus (donkey), 2n = 62, constitute particularly interesting models for comparative studies due to the diversified morphology of their chromosomes, including acrocentric and submetacentric pairs, documented Robertsonian translocations, and centric fusions. In recent decades, widely applied molecular cytogenetic techni...
Genetic variants of EcPV2 E6 and E7 in equine genital and oronasal squamous cell carcinoma. Since its discovery in 2008, equine papillomavirus type 2 (EcPV2) has been detected in up to 100% of equine genital and up to 40% of equine oronasal squamous cell carcinomas (SCCs). Preliminary sequence data point to the existence of EcPV2 E6 and E7 oncogene variants compared to the British reference sequence from 2008. Objective: To Identify E6 and E7 sequence variations in EcPV2-positive tumours of horses from Continental Europe and Iceland. Methods: Cross-sectional study. Methods: EcPV2 E6 and E7 were amplified from DNA of 60 EcPV2-positive SCCs/SCC precursor lesions. Amplicons were gel-pur...
An experimental multiplex PCR/RT-PCR for detection of the main viruses associated with equine neurological disease. Viral neurological infections are important causes of morbidity and mortality in horses worldwide. Herein, we describe an end-point multiplex PCR/RT-PCR for simultaneous and differential detection of major equine encephalitis-related agents: rabies virus (RABV), equine herpesvirus type 1 (EHV-1), alphaviruses [Venezuelan equine encephalitis virus (VEEV), Eastern equine encephalitis virus (EEEV), Western equine encephalitis virus (WEEV) and Madariaga virus (MADV)] and flaviviruses [West Nile virus (WNV), Saint Louis encephalitis virus (SLEV), Rocio virus (ROCV) and Japanese encephalitis virus (...
First-time description of MHC diversity in Straight Egyptian Arabian horses using immune-linked microsatellite markers. Understanding the immunogenetic structure of the major histocompatibility complex (MHC) in Arabian horses helps to clarify the population health structure-related phenotypes of this historically influential breed. Straight Egyptian (SE) Arabian horses, which fall under , are of global value but are limited in number, raising concerns about their distribution and the genetic diversity associated with immunity. In this study, we examined 57 Egyptian Arabian horses from two breeding programs: one in Germany (AR-DE) and the other in Qatar (AR-QA). Sixteen polymorphic intra-MHC microsatellite marke...
