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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.
Novel equine conceptus?endometrial interactions on Day 16 of pregnancy based on RNA sequencing.
Reproduction, fertility, and development    May 5, 2015   doi: 10.1071/RD14489
Klein C.Maintenance of pregnancy is dependent on the exchange of signals between the conceptus and the endometrium. The objective of this study was to use next-generation sequencing to determine transcriptome blueprints of the conceptus and endometrium 16 days after ovulation in the horse. There were 7760 and 10 182 genes expressed in the conceptus and endometrium, respectively, of which 7029 were present in both. Genes related to developmental processes were enriched among conceptus-specific transcripts, whereas many endometrium-specific genes had known roles in cell communication, cell adhesion and ...
Development of a novel molecular detection method for clustered regularly interspaced short palindromic repeats (CRISPRs) in Taylorella organisms.
Journal of medical microbiology    May 1, 2015   Volume 64, Issue 7 782-787 doi: 10.1099/jmm.0.000079
Hara Y, Nakajima T, Akamatsu M, Yahiro M, Kagawa S, Petry S, Matsuda M, Moore JE.Contagious equine metritis is a bacterial infectious disease of horses caused by Taylorella equigenitalis, a Gram-negative eubacterium. The disease has been described in several continents, including Europe, North America and Asia. A novel molecular method was developed to detect clustered regularly interspaced short palindromic repeats (CRISPRs), which were separated by non-repetitive unique spacer regions (NRUSRs) of similar length, in the Taylorella equigenitalis EQ59 strain using a primer pair, f-/r-TeCRISPR-ladder, by PCR amplification. In total, 31 Taylorella isolates (17 T. equigenitali...
Comparative genomic identification and expression profiling of a novel ?-defensin gene cluster in the equine reproductive tract.
Reproduction, fertility, and development    April 30, 2015   doi: 10.1071/RD14345
Johnson GP, Lloyd AT, O'Farrelly C, Meade KG, Fair S.?-defensins are small cationic proteins with potent immunoregulatory and antimicrobial activity. The number of genes encoding these peptides varies significantly between and within species but they have not been extensively characterised in the horse. Here, we describe a systematic search of the Equus caballus genome that identified a cluster of novel ?-defensin genes on Chromosome 22, which is homologous to a cluster on bovine Chromosome 13. Close genomic matches were found for orthologs of 13 of the bovine genes, which were named equine ?-defensins (eBD) 115, eBD116, eBD117, eBD119, eBD120, ...
Correction: The transcriptome of equine peripheral blood mononuclear cells.
PloS one    April 27, 2015   Volume 10, Issue 4 e0127372 doi: 10.1371/journal.pone.0127372
No abstract available
Characterising Non-Structural Protein NS4 of African Horse Sickness Virus.
PloS one    April 27, 2015   Volume 10, Issue 4 e0124281 doi: 10.1371/journal.pone.0124281
Zwart L, Potgieter CA, Clift SJ, van Staden V.African horse sickness is a serious equid disease caused by the orbivirus African horse sickness virus (AHSV). The virus has ten double-stranded RNA genome segments encoding seven structural and three non-structural proteins. Recently, an additional protein was predicted to be encoded by genome segment 9 (Seg-9), which also encodes VP6, of most orbiviruses. This has since been confirmed in bluetongue virus and Great Island virus, and the non-structural protein was named NS4. In this study, in silico analysis of AHSV Seg-9 sequences revealed the existence of two main types of AHSV NS4, designat...
Rapid and accurate identification of Streptococcus equi subspecies by MALDI-TOF MS.
Systematic and applied microbiology    April 23, 2015   Volume 38, Issue 5 315-322 doi: 10.1016/j.syapm.2015.02.010
Kudirkiene E, Welker M, Knudsen NR, Bojesen AM.Streptococcus equi includes very important animal and human pathogens. S. equi subsp. equi (SEE) is a highly pathogenic equine specific subspecies, while S. equi subsp. zooepidemicus (SEZ) and S. equi subsp. ruminatorum are opportunistic pathogens of various animal species and humans. Due to great phenotypic and sequence similarity between three subspecies their discrimination remains difficult. In this study, we aimed to design and validate a novel, Superspectra based, MALDI-TOF MS approach for reliable, rapid and cost-effective identification of SEE and SEZ, the most frequent S. equi subspec...
An inflammatory equine model demonstrates dynamic changes of immune response and cartilage matrix molecule degradation in vitro.
Connective tissue research    April 22, 2015   Volume 56, Issue 4 315-325 doi: 10.3109/03008207.2015.1027340
Svala E, Löfgren M, Sihlbom C, Rüetschi U, Lindahl A, Ekman S, Skiöldebrand E.The molecular aspects of inflammation were investigated in equine articular cartilage explants using quantitative proteomics. Articular cartilage explants were stimulated with interleukin (IL)-1β in vitro for 25 days, and proteins released into cell culture media were chemically labeled with isobaric mass tags and analyzed by liquid chromatography-tandem mass spectrometry. A total of 127 proteins were identified and quantified in media from explants. IL-1β-stimulation resulted in an abundance of proteins related to inflammation, including matrix metalloproteinases, acute phase proteins, comp...
Maternal age and in vitro culture affect mitochondrial number and function in equine oocytes and embryos.
Reproduction, fertility, and development    April 17, 2015   Volume 27, Issue 6 957-968 doi: 10.1071/RD14450
Hendriks WK, Colleoni S, Galli C, Paris DB, Colenbrander B, Roelen BA, Stout TA.Advanced maternal age and in vitro embryo production (IVP) predispose to pregnancy loss in horses. We investigated whether mare age and IVP were associated with alterations in mitochondrial (mt) DNA copy number or function that could compromise oocyte and embryo development. Effects of mare age (<12 vs ≥12 years) on mtDNA copy number, ATP content and expression of genes involved in mitochondrial replication (mitochondrial transcription factor (TFAM), mtDNA polymerase γ subunit B (mtPOLB) and mitochondrial single-stranded DNA-binding protein (SSB)), energy production (ATP synthase-couplin...
Epidemiology of Trypanosoma evansi and Trypanosoma vivax in domestic animals from selected districts of Tigray and Afar regions, Northern Ethiopia.
Parasites & vectors    April 9, 2015   Volume 8 212 doi: 10.1186/s13071-015-0818-1
Birhanu H, Fikru R, Said M, Kidane W, Gebrehiwot T, Hagos A, Alemu T, Dawit T, Berkvens D, Goddeeris BM, Büscher P.African animal trypanosomosis, transmitted cyclically by tsetse flies or mechanically by other biting flies, causes serious inflictions to livestock health. This study investigates the extent of non-tsetse transmitted animal trypanosomosis (NTTAT) by Trypanosoma (T.) evansi and T. vivax in domestic animals in the tsetse-free regions of Northern Ethiopia, Afar and Tigray. Methods: A cross sectional study was conducted on 754 dromedary camels, 493 cattle, 264 goats, 181 sheep, 84 donkeys, 25 horses and 10 mules. The microhaematocrit centrifugation technique was used as parasitological test. Plas...
Transgenically expressed Parascaris P-glycoprotein-11 can modulate ivermectin susceptibility in Caenorhabditis elegans.
International journal for parasitology. Drugs and drug resistance    April 8, 2015   Volume 5, Issue 2 44-47 doi: 10.1016/j.ijpddr.2015.03.003
Janssen IJ, Krücken J, Demeler J, von Samson-Himmelstjerna G.P-glycoproteins (Pgps) are suspected to mediate drug extrusion in nematodes contributing to macrocyclic lactone resistance. This association was recently shown for Parascaris Pgp-11. Ivermectin resistance was correlated with the presence of three pgp-11 single nucleotide polymorphisms and/or increased pgp-11 mRNA levels. In the present study, the ability of Pgp-11 to modulate ivermectin susceptibility was investigated by its expression in a pgp-11-deficient Caenorhabditis elegans strain. Expression of Parascaris pgp-11 in two transgenic lines significantly decreased ivermectin susceptibility i...
Two variants in the KIT gene as candidate causative mutations for a dominant white and a white spotting phenotype in the donkey.
Animal genetics    March 27, 2015   Volume 46, Issue 3 321-324 doi: 10.1111/age.12282
Haase B, Rieder S, Leeb T.White spotting phenotypes have been intensively studied in horses, and although similar phenotypes occur in the donkey, little is known about the molecular genetics underlying these patterns in donkeys. White spotting in donkeys can range from only a few white areas to almost complete depigmentation and is characterised by a loss of pigmentation usually progressing from a white spot in the hip area. Completely white-born donkeys are rare, and the phenotype is characterised by the complete absence of pigment resulting in pink skin and a white coat. A dominant mode of inheritance has been demons...
The role of microRNAs in equine medicine: a review.
The veterinary quarterly    March 24, 2015   Volume 35, Issue 2 88-96 doi: 10.1080/01652176.2015.1021186
van der Kolk JH, Pacholewska A, Gerber V.The search for new markers of diseases in human as well as veterinary medicine is ongoing. Recently, microRNAs (miRNAs or miRs) have emerged as potential new biomarkers. MiRNAs are short sequences of RNA (∼22 nucleotides) that regulate gene expression via their target messenger RNA (mRNA). Circulating miRNAs in blood can be used as novel diagnostic markers for diseases due to their evolutionary conservation and stability. As a consequence of their systemic and manifold effects on the gene expression in various target organs, the concept that miRNAs could function as hormones has been suggest...
Using epidemics to map H3 equine influenza virus determinants of antigenicity.
Virology    March 19, 2015   Volume 481 187-198 doi: 10.1016/j.virol.2015.02.027
Woodward A, Rash AS, Medcalf E, Bryant NA, Elton DM.Equine influenza is a major cause of respiratory infections in horses and causes widespread epidemics, despite the availability of commercial vaccines. Antigenic drift within the haemagglutinin (HA) glycoprotein is thought to play a part in vaccination breakdown. Here, we carried out a detailed investigation of the 1989 UK outbreak, using reverse genetics and site-directed mutagenesis, to determine the individual contribution of amino acid substitutions within HA. Mutations at positions 159, 189 and 227 all altered antigenicity, as measured by haemagglutination-inhibition assays. We also compa...
Genetic evolution of equine influenza strains isolated in France from 2005 to 2010.
Equine veterinary journal    March 13, 2015   Volume 47, Issue 2 207-211 doi: 10.1111/evj.12244
Legrand LJ, Pitel PH, Cullinane AA, Fortier GD, Pronost SL.REASON FOR PERFORMING THIS STUDY: Equine influenza virus (EIV) is considered the most economically important equine respiratory pathogen worldwide. The H3N8 subtype, responsible for all outbreaks of equine influenza globally, evolves perpetually. Mutations in the genome of these viruses have the potential to modify their antigenic properties and recognition by pre-existing antibodies. Objective: The aim of this study was to determine the genetic evolution of EIV strains in France and to compare it with the evolution of strains isolated globally. Analysis of the sequence data was performed to i...
Molecular identification of Cryptosporidium isolates from exotic pet animals in Japan.
Veterinary parasitology    March 12, 2015   Volume 209, Issue 3-4 254-257 doi: 10.1016/j.vetpar.2015.02.035
Abe N, Matsubara K.The Cryptosporidium horse genotype, a zoonotic protozoan parasite first found in a Prezewalski wild horse, has not been found in any other mammal but calves, horses, and humans. Hedgehogs, popular exotic pet animals in Japan, are a reservoir of two zoonotic Cryptosporidum: C. parvum and C. erinacei (previously known as the hedgehog genotype). Recently, after finding Cryptosporidium infection in a four-toed hedgehog (Atelerix albiventris), we identified the isolate genetically as the Cryptosporidium horse genotype. Its subtype (VIbA13) was the same as that of an isolate from a pet shop employee...
Solution structure and functional studies of the highly potent equine antimicrobial peptide DEFA1.
Biochemical and biophysical research communications    March 11, 2015   Volume 459, Issue 4 668-672 doi: 10.1016/j.bbrc.2015.02.168
Michalek M, Jung S, Shomali MR, Cauchard S, Sönnichsen FD, Grötzinger J.Defensins are small effector molecules of the innate immune system that are present in almost all organisms including plants and animals. These peptides possess antimicrobial activity against a broad range of microbes including bacteria, fungi and viruses and act as endogenous antibiotics. α-Defensins are a subfamily of the defensin family and their expression is limited to specific tissues. Equine DEFA1 is an enteric α-defensin exclusively secreted by Paneth cells and shows an activity against a broad spectrum of microbes, including typical pathogens of the horse such as Rhodococcus equi, v...
Impact of karyotype organization on interlocus recombination between T cell receptor genes in Equidae.
Cytogenetic and genome research    March 11, 2015   Volume 144, Issue 4 306-314 doi: 10.1159/000377712
Drbalova J, Musilova P, Kubickova S, Sebestova H, Vahala J, Rubes J.The T cell receptor (TCR) genes (TRA, TRB, TRD and TRG) reside in 3 different chromosomal regions. During the maturation of T lymphocytes, the TCR genes are rearranged by site-specific recombination, a process that also predisposes T cells to aberrant rearrangements. Illegitimate recombination between the TCR genes occurs at a low level in healthy individuals, but this frequency may correlate with the risk of lymphoma. The aim of this work was to investigate interlocus recombination in equids. Illegitimate rearrangements were studied in peripheral blood lymphocytes by FISH with painting and BA...
First report of junctional epidermolysis bullosa (JEB) in the Italian draft horse.
BMC veterinary research    March 10, 2015   Volume 11 55 doi: 10.1186/s12917-015-0374-0
Cappelli K, Brachelente C, Passamonti F, Flati A, Silvestrelli M, Capomaccio S.Epitheliogenesis imperfecta in horses was first recognized at the beginning of the 20th century when it was proposed that the disease could have a genetic cause and an autosomal recessive inheritance pattern. Electron microscopy studies confirmed that the lesions were characterized by a defect in the lamina propria and the disease was therefore reclassified as epidermolysis bullosa. Molecular studies targeted two mutations affecting genes involved in dermal-epidermal junction: an insertion in LAMC2 in Belgians and other draft breeds and one large deletion in LAMA3 in American Saddlebred. Metho...
Characterization of an L-amino acid oxidase in equine spermatozoa.
Biology of reproduction    March 4, 2015   Volume 92, Issue 5 125 doi: 10.1095/biolreprod.114.126052
Aitken JB, Naumovski N, Curry B, Grupen CG, Gibb Z, Aitken RJ.This study demonstrates for the first time the presence of an L-amino acid oxidase (LAAO) enzyme in equine spermatozoa that is able to generate significant amounts of reactive oxygen species (ROS) and create a state of oxidative stress. RT-PCR analysis revealed that the mRNA for this enzyme was present in the equine testis and spermatozoa, while immunocytochemical studies demonstrated that the mature LAAO protein was located in the sperm head, particularly in the acrosomal and postacrosomal domains. Experimental studies demonstrated that the aromatic amino acids (L-phenylalanine > L-tryptop...
PinR mediates the generation of reversible population diversity in Streptococcus zooepidemicus.
Microbiology (Reading, England)    February 20, 2015   Volume 161, Issue Pt 5 1105-1112 doi: 10.1099/mic.0.000057
Steward KF, Harrison T, Robinson C, Slater J, Maskell DJ, Harris SR, Holden MTG, Waller AS.Opportunistic pathogens must adapt to and survive in a wide range of complex ecosystems. Streptococcus zooepidemicus is an opportunistic pathogen of horses and many other animals, including humans. The assembly of different surface architecture phenotypes from one genotype is likely to be crucial to the successful exploitation of such an opportunistic lifestyle. Construction of a series of mutants revealed that a serine recombinase, PinR, inverts 114 bp of the promoter of SZO_08560, which is bordered by GTAGACTTTA and TAAAGTCTAC inverted repeats. Inversion acts as a switch, controlling the tra...
Expression and immunolocalisation of follicle-stimulating hormone receptors in gonads of newborn and adult female horses.
Reproduction, fertility, and development    February 19, 2015   doi: 10.1071/RD14392
Scarlet D, Walter I, Hlavaty J, Aurich C.In mares, FSH and its receptor (FSHR) are essential for ovarian function. The objective of the present study was to analyse FSHR gene expression at the mRNA and protein levels in ovarian tissue from newborn and adult horses. Expression of mRNA was analysed by reverse transcription polymerase chain reaction, whereas FSHR protein was visualised by immunohistochemistry (IHC), immunofluorescence labelling (IF) and western blot. FSHR mRNA was detected in ovarian follicles and luteal tissue from adult mares, as well as in the ovaries of neonates. Follicular growth up to 4mm in diameter was already p...
Equine sperm-neutrophil binding.
Biology of reproduction    February 18, 2015   Volume 92, Issue 4 94 doi: 10.1095/biolreprod.114.122655
Alghamdi AS, Madill S, Foster DN, Troedsson MH.When mares are inseminated repeatedly, protein molecules from the seminal plasma (SP) prevent sperm-neutrophil binding and reduced fertility. The molecule(s) responsible for sperm-neutrophil binding is not known and the identification of beneficial SP proteins is complicated by their large numbers and abundant variation. We examined several important aspects of sperm-neutrophil binding to ultimately facilitate the identification and isolation of the molecule(s) responsible. First, we raised anti-equine P-selectin antibodies to determine the involvement of this adhesion molecule in sperm-neutro...
A comparison of methods for whole-genome QTL mapping using dense markers in four livestock species.
Genetics, selection, evolution : GSE    February 12, 2015   Volume 47, Issue 1 6 doi: 10.1186/s12711-015-0087-7
Legarra A, Croiseau P, Sanchez MP, Teyssèdre S, Sallé G, Allais S, Fritz S, Moreno CR, Ricard A, Elsen JM.With dense genotyping, many choices exist for methods to detect quantitative trait loci (QTL) in livestock populations. However, no across-species study has been conducted on the performance of different methods using real data. We compared three methods that correct for relatedness either implicitly or explicitly: linkage and linkage disequilibrium haplotype-based analysis (LDLA), efficient mixed-model association (EMMA) analysis, and Bayesian whole-genome regression (BayesC). We analyzed one chromosome in each of five datasets (dairy cattle, beef cattle, sheep, horses, and pigs) using real g...
Novel monoclonal antibody against alphaX subunit from horse CD11c/CD18 integrin.
Veterinary immunology and immunopathology    February 12, 2015   Volume 164, Issue 3-4 220-226 doi: 10.1016/j.vetimm.2015.02.002
Espino-Solis GP, Quintero-Hernandez V, Olvera-Rodriguez A, Calderon-Amador J, Pedraza-Escalona M, Licea-Navarro A, Flores-Romo L, Possani LD.The αX I-domain of the horse integrin CD11c was successfully expressed in Escherichia coli, purified, biochemically characterized and used as immunogen to generate murine monoclonal antibodies against horse CD11c, which are not yet commercially available. One monoclonal antibody mAb-1C4 against the αX I-domain, is an IgG2a able to interact with the recombinant I-domain, showing an EC50=2.4ng according to ELISA assays. By western blot with horse PBMCs lysates the mAb-1C4 recognized a protein of 150kDa which corresponds well with the CD11c molecule. Using immunohistochemistry in horse lymph no...
Systems-based analysis of the Sarcocystis neurona genome identifies pathways that contribute to a heteroxenous life cycle.
mBio    February 10, 2015   Volume 6, Issue 1 e02445-14 doi: 10.1128/mBio.02445-14
Blazejewski T, Nursimulu N, Pszenny V, Dangoudoubiyam S, Namasivayam S, Chiasson MA, Chessman K, Tonkin M, Swapna LS, Hung SS, Bridgers J....Sarcocystis neurona is a member of the coccidia, a clade of single-celled parasites of medical and veterinary importance including Eimeria, Sarcocystis, Neospora, and Toxoplasma. Unlike Eimeria, a single-host enteric pathogen, Sarcocystis, Neospora, and Toxoplasma are two-host parasites that infect and produce infectious tissue cysts in a wide range of intermediate hosts. As a genus, Sarcocystis is one of the most successful protozoan parasites; all vertebrates, including birds, reptiles, fish, and mammals are hosts to at least one Sarcocystis species. Here we sequenced Sarcocystis neurona, th...
Structural characterisation of the virulence-associated protein VapG from the horse pathogen Rhodococcus equi.
Veterinary microbiology    February 9, 2015   Volume 179, Issue 1-2 42-52 doi: 10.1016/j.vetmic.2015.01.027
Okoko T, Blagova EV, Whittingham JL, Dover LG, Wilkinson AJ.Virulence and host range in Rhodococcus equi depends on the variable pathogenicity island of their virulence plasmids. Notable gene products are a family of small secreted virulence-associated proteins (Vaps) that are critical to intramacrophagic proliferation. Equine-adapted strains, which cause severe pyogranulomatous pneumonia in foals, produce a cell-associated VapA that is necessary for virulence, alongside five other secreted homologues. In the absence of biochemical insight, attention has turned to the structures of these proteins to develop a functional hypothesis. Recent studies have ...
An update on Sarcocystis neurona infections in animals and equine protozoal myeloencephalitis (EPM).
Veterinary parasitology    February 7, 2015   Volume 209, Issue 1-2 1-42 doi: 10.1016/j.vetpar.2015.01.026
Dubey JP, Howe DK, Furr M, Saville WJ, Marsh AE, Reed SM, Grigg ME.Equine protozoal myeloencephalitis (EPM) is a serious disease of horses, and its management continues to be a challenge for veterinarians. The protozoan Sarcocystis neurona is most commonly associated with EPM. S. neurona has emerged as a common cause of mortality in marine mammals, especially sea otters (Enhydra lutris). EPM-like illness has also been recorded in several other mammals, including domestic dogs and cats. This paper updates S. neurona and EPM information from the last 15 years on the advances regarding life cycle, molecular biology, epidemiology, clinical signs, diagnosis, treat...
Colostrum hexasaccharide, a novel Staphylococcus aureus quorum-sensing inhibitor.
Antimicrobial agents and chemotherapy    February 2, 2015   Volume 59, Issue 4 2169-2178 doi: 10.1128/AAC.03722-14
Srivastava A, Singh BN, Deepak D, Rawat AK, Singh BR.The discovery of quorum-sensing (QS) systems regulating antibiotic resistance and virulence factors (VFs) has afforded a novel opportunity to prevent bacterial pathogenicity. Dietary molecules have been demonstrated to attenuate QS circuits of bacteria. But, to our knowledge, no study exploring the potential of colostrum hexasaccharide (CHS) in regulating QS systems has been published. In this study, we analyzed CHS for inhibiting QS signaling in Staphylococcus aureus. We isolated and characterized CHS from mare colostrum by high-performance thin-layer chromatography (HPTLC), reverse-phase hig...
Characterization of nonprimate hepacivirus and construction of a functional molecular clone.
Proceedings of the National Academy of Sciences of the United States of America    February 2, 2015   Volume 112, Issue 7 2192-2197 doi: 10.1073/pnas.1500265112
Scheel TK, Kapoor A, Nishiuchi E, Brock KV, Yu Y, Andrus L, Gu M, Renshaw RW, Dubovi EJ, McDonough SP, Van de Walle GR, Lipkin WI, Divers TJ....Nonprimate hepacivirus (NPHV) is the closest known relative of hepatitis C virus (HCV) and its study could enrich our understanding of HCV evolution, immunity, and pathogenesis. High seropositivity is found in horses worldwide with ∼ 3% viremic. NPHV natural history and molecular virology remain largely unexplored, however. Here, we show that NPHV, like HCV, can cause persistent infection for over a decade, with high titers and negative strand RNA in the liver. NPHV is a near-universal contaminant of commercial horse sera for cell culture. The complete NPHV 3'-UTR was determined and consists...
Le virus de l’artérite virale équine : de l’épidémiologie moléculaire à l’émergence de variants pathogènes.
Virologie (Montrouge, France)    February 1, 2015   Volume 19, Issue 1 7-18 doi: 10.1684/vir.2015.0588
Miszczak F, Pronost S, Vabret A.Equine arteritis virus (EAV) is the causative agent of equine viral arteritis, a disease observed only in equids. EAV is the prototype of the family Arteriviridæ within the order Nidovirales. EAV is an enveloped, positive-sense, single-stranded RNA virus with a considerable variation in the genome as observed in other RNA viruses. During natural infections, EAV may cause abortion and persistent subclinical infections in stallions which can shed the virus in the semen for years, or even lifetime. Chronically infected stallions represent the natural reservoir of the virus. They ensure the persi...
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