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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.
Polymorphisms of the equine major histocompatibility complex class II DRA locus.
Tissue antigens    July 13, 2004   Volume 64, Issue 2 173-179 doi: 10.1111/j.1399-0039.2004.00269.x
Brown JJ, Thomson W, Clegg P, Eyre S, Kennedy LJ, Matthews J, Carter S, Ollier WE.The full extent of the polymorphism of ELA-DRA in Equidae is not yet known. Given the apparent differences in DRA polymorphisms between Equidae and other species, the aims of this study were to more fully characterize ELA-DRA, determine the extent of gene polymorphism and establish the allele-frequency distribution. An allele reference panel for the second exon of ELA-DRA was established by sequence-based typing of 69 equine DNA samples consisting of various breeds of domestic horse (Equus caballus), together with donkeys (Equus asinus), Grant's zebras (Equus boehmi) and one onager (Equus hemi...
Rhodococcus equi.
Veterinary research    July 9, 2004   Volume 35, Issue 4 383-396 doi: 10.1051/vetres:2004024
Meijer WG, Prescott JF.Rhodococcus equi is an important cause of subacute or chronic abscessating bronchopneumonia of foals up to 3-5 months of age. It shares the lipid-rich cell wall envelope characteristic of the mycolata, including Mycobacterium tuberculosis, as well as the ability of pathogenic members of this group to survive within macrophages. The possession of a large virulence plasmid in isolates recovered from pneumonic foals is crucial for virulence. The plasmid contains an 27 kb pathogenicity island (PI) that encodes seven related virulence-associated proteins (Vaps), including the immunodominant surface...
The pathogenic equine streptococci.
Veterinary research    July 9, 2004   Volume 35, Issue 4 397-409 doi: 10.1051/vetres:2004025
Timoney JF.Streptococci pathogenic for the horse include S. equi (S. equi subsp. equi), S. zooepidemicus (S. equi subsp. zooepidemicus), S. dysgalactiae subsp. equisimilis and S. pneumoniae capsule Type III. S. equi is a clonal descendent or biovar of an ancestral S. zooepidemicus strain with which it shares greater than 98% DNA homology and therefore expresses many of the same proteins and virulence factors. Rapid progress has been made in identification of virulence factors and proteins uniquely expressed by S. equi. Most of these are expressed either on the bacterial surface or are secreted. Notable e...
Recent developments in research into the Cyathostominae and Anoplocephala perfoliata.
Veterinary research    July 9, 2004   Volume 35, Issue 4 371-381 doi: 10.1051/vetres:2004026
Matthews JB, Hodgkinson JE, Dowdall SM, Proudman CJ.Intestinal helminths are an important cause of equine disease. Of these parasites, the Cyathostominae are the commonest group that infect horses. These nematodes consist of a complex tribe of 51 species, although individual horses tend to harbour 10 or so common species, in addition to a few rarer species. The Cyathostominae can be extremely pathogenic, and high levels of infection result in clinical symptoms ranging from chronic weight loss to colic, diarrhoea and death. As part of their life cycle, immature cyathostomins penetrate the large intestinal wall, where they can enter a state of in...
Gene expression in the spermatogenically inactive “dark” and maturing “light” testicular tissues of the prepubertal colt.
Journal of andrology    June 30, 2004   Volume 25, Issue 4 535-544 doi: 10.1002/j.1939-4640.2004.tb02824.x
Ing NH, Laughlin AM, Varner DD, Welsh TH, Forrest DW, Blanchard TL, Johnson L.In the testis of the 1.5-year-old horse, spermatogenesis initiates locally in grossly light, central areas that contrast with grossly dark, peripheral areas that are as yet inactive in spermatogenesis. Gene expression was compared between "light" and "dark" tissues of 1.5-year-old horse testes to identify mechanisms important to the initiation of spermatogenesis. Microarrays containing human cDNAs were used to assess expression levels of 9132 genes simultaneously in matched pairs of dark and light testis tissues from 3 prepubertal colts. In all 3 analyses, dysferlin (DYS), down-regulated in ov...
Expression of equine interleukin-18 by baculovirus expression system and its biologic activity.
Microbiology and immunology    June 25, 2004   Volume 48, Issue 6 471-476 doi: 10.1111/j.1348-0421.2004.tb03538.x
Wu D, Murakami K, Liu N, Konishi M, Muneta Y, Inumaru S, Kokuho T, Sentsui H.The equine interleukin-18 (IL-18) cDNA that contains the coding sequence was cloned and a recombinant baculovirus, named AcEIL-18, was constructed. The recombinant protein of the equine IL-18 was expressed by AcEIL-18 and its expression was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. Insect cells infected with AcEIL-18 secreted a precursor IL-18 with 24 kilo dalton (kDa) into the culture supernatant. Western blot analysis showed that mature equine IL-18 about 18 kDa was also confirmed without co-expression of caspase-1. Culture supern...
Molecular detection of Culicoides spp. and Culicoides imicola, the principal vector of bluetongue (BT) and African horse sickness (AHS) in Africa and Europe.
Veterinary research    June 24, 2004   Volume 35, Issue 3 325-337 doi: 10.1051/vetres:2004015
Cêtre-Sossah C, Baldet T, Delécolle JC, Mathieu B, Perrin A, Grillet C, Albina E.Bluetongue (BT) and African Horse Sickness (AHS) are infectious arthropod-borne viral diseases affecting ruminants and horses, respectively. Culicoides imicola Kieffer, 1913, a biting midge, is the principal vector of these livestock diseases in Africa and Europe. Recently bluetongue disease has re-emerged in the Mediterranean Basin and has had a devastating effect on the sheep industry in Italy and on the islands of Sicily, Sardinia, Corsica and the Balearics, but fortunately, has not penetrated onto mainland France and Spain. To survey for the presence of C. imicola, an extensive light-trap ...
[Combination immunization with EIAV Env protein expressed by recombinant baculovirus and recombinant vaccinia virus containing env gene]. Dai CM, Zhang XY, Zhang RR, Shao YM, Shen RX.To develop a novel vaccine candidate of Equine infectious anemia virus(EIAV). Methods: env genes of EIAV Chinese donkey leukocyte attenuated strain (EIAV DLV) and its parental virus strain (EIAV LN) were expressed using the BAC-To-BAC system, and Env proteins were confirmed by SDS-PAGE and Western blot. BALB/c mice were immunized with recombinant vaccinia viruses containing env genes of EIAV alone or boosted with Env proteins expressed by recombinant baculovirus. Both protective humoral and cellular immune responses were detected. Results: Recombinant baculovirus could express complete Env pro...
Cumulus expansion, nuclear maturation and connexin 43, cyclooxygenase-2 and FSH receptor mRNA expression in equine cumulus-oocyte complexes cultured in vitro in the presence of FSH and precursors for hyaluronic acid synthesis.
Reproductive biology and endocrinology : RB&E    June 22, 2004   Volume 2 44 doi: 10.1186/1477-7827-2-44
Dell'Aquila ME, Caillaud M, Maritato F, Martoriati A, Gérard N, Aiudi G, Minoia P, Goudet G.The aim of this study was to investigate cumulus expansion, nuclear maturation and expression of connexin 43, cyclooxygenase-2 and FSH receptor transcripts in equine cumuli oophori during in vivo and in vitro maturation in the presence of equine FSH (eFSH) and precursors for hyaluronic acid synthesis. Equine cumulus-oocyte complexes (COC) were cultured in a control defined medium supplemented with eFSH (0 to 5 micrograms/ml), Fetal Calf Serum (FCS), precursors for hyaluronic acid synthesis or glutamine according to the experiments. After in vitro maturation, the cumulus expansion rate was incr...
Use of a real-time polymerase chain reaction-based fluorogenic 5′ nuclease assay to evaluate insect vectors of Corynebacterium pseudotuberculosis infections in horses.
American journal of veterinary research    June 17, 2004   Volume 65, Issue 6 829-834 doi: 10.2460/ajvr.2004.65.829
Spier SJ, Leutenegger CM, Carroll SP, Loye JE, Pusterla JB, Carpenter TE, Mihalyi JE, Madigan JE.To develop and use a sensitive molecular assay for detecting the phospholipase D (PLD) exotoxin gene of Corynebacterium pseudotuberculosis in an attempt to identify insect vectors that may be important in transmission of clinical disease in horses. Methods: 2,621 flies of various species. Methods: A real-time polymerase chain reaction (PCR)-based fluorogenic 5' nuclease (TaqMan) system (ie, TaqMan PCR assay) was developed for the detection of the PLD gene in insects. Flies were collected monthly (May to November 2002) from 5 farms in northern California where C. pseudotuberculosis infection in...
A detailed physical map of the horse Y chromosome.
Proceedings of the National Academy of Sciences of the United States of America    June 14, 2004   Volume 101, Issue 25 9321-9326 doi: 10.1073/pnas.0403011101
Raudsepp T, Santani A, Wallner B, Kata SR, Ren C, Zhang HB, Womack JE, Skow LC, Chowdhary BP.We herein report a detailed physical map of the horse Y chromosome. The euchromatic region of the chromosome comprises approximately 15 megabases (Mb) of the total 45- to 50-Mb size and lies in the distal one-third of the long arm, where the pseudoautosomal region (PAR) is located terminally. The rest of the chromosome is predominantly heterochromatic. Because of the unusual organization of the chromosome (common to all mammalian Y chromosomes), a number of approaches were used to crossvalidate the results. Analysis of the 5,000-rad horse x hamster radiation hybrid panel produced a map spannin...
Identification of amino-acids in the alpha-subunit first and third loops that are crucial for the heterospecific follicle-stimulating hormone activity of equid luteinizing hormone/choriogonadotropin.
European journal of endocrinology    June 12, 2004   Volume 150, Issue 6 877-884 doi: 10.1530/eje.0.1500877
Chopineau M, Martinat N, Gibrat JF, Galet C, Lecompte F, Foulon-Gauze F, Pourchet C, Guillou F, Combarnous Y.To identify amino-acids in the alpha-subunit important for expression of heterospecific FSH activity of horse (e) LH/choriogonadotropin (CG) (eLH) and donkey (dk) LH/CG (dkLH) (FSH/LH ratio ten times higher for eLH than for dkLH); this FSH activity absolutely requires an equid (donkey or horse) alpha-subunit combined with an equid beta-LH subunit. Methods: Chimeric alpha-subunits possessing the first 63 amino-acids of the porcine (p) and the last 33 amino-acids of the donkey alpha-subunit (alphap-dk) and the inverse (alphadk-p) were constructed. Porcine-specific amino-acids were introduced by ...
Isolation from the horse genome of a new DNA transposon belonging to the Tigger family.
Mammalian genome : official journal of the International Mammalian Genome Society    June 1, 2004   Volume 15, Issue 5 399-403 doi: 10.1007/s00335-004-3040-6
Paulis M, Moralli D, Bensi M, De Carli L, Raimondi E.Tigger elements are human DNA transposons homologous to the pogo element of Drosophila melanogaster. They contain an open reading frame for a transposase very similar to the major mammalian centromere protein CENP-B. We found in the horse genome a DNA element ( Ecatig3) sharing 88% homology with human Tigger3. The presence of Tigger elements in the horse genome confirms previous data that date these elements before the divergence between Perissodactyla and Primates (80-90 Myr ago). Copy number evaluation indicates that the horse element is much more abundant than its human counterpart. Souther...
Absence of the functional Myosin heavy chain 2b isoform in equine skeletal muscles.
Zoological science    June 1, 2004   Volume 21, Issue 5 589-596 doi: 10.2108/zsj.21.589
Chikuni K, Muroya S, Nakajima I.Nucleotide sequences which included the full coding region for three types of myosin heavy chain (MyHC) isoforms were determined from equine skeletal muscles. The deduced amino acid sequences were 1937, 1938, and 1935 residues for the MyHC-2a, -2x, and -slow, respectively. No MyHC-2b isoform was amplified from the equine muscle cDNA except for one pseudogene fragment. One nucleotide was inserted in the coding region of the equine pseudogene product, a minute amount of which was expressed in the skeletal muscle. The 596 bp sequence of the equine MyHC pseudogene was categorized into the MyHC-2b ...
Phage display of the Equine arteritis virus nsp1 ZF domain and examination of its metal interactions.
Journal of virological methods    May 26, 2004   Volume 119, Issue 2 159-169 doi: 10.1016/j.jviromet.2004.04.002
Oleksiewicz MB, Snijder EJ, Normann P.A putative zinc finger (ZF) domain in the Equine arteritis virus (EAV) nsp1 protein was described recently to be required for viral transcription. The nsp1 ZF (50 aa) was expressed on the surface of M13KE gIII phage, fused to the N terminus of the phage pIII protein. To evaluate the functionality of the ZF domain, a binding assay was developed, based on the use of immobilized Ni(2+) ions (Ni-NTA). Phages displaying ZF bound significantly better to Ni-NTA than did phages displaying negative-control peptides, which also contained metal-coordinating residues. Also, binding of ZF-displaying phages...
Equine laminitis: increased transcription of matrix metalloproteinase-2 (MMP-2) occurs during the developmental phase.
Equine veterinary journal    May 19, 2004   Volume 36, Issue 3 221-225 doi: 10.2746/0425164044877242
Kyaw-Tanner M, Pollitt CC.The dysadhesion and destruction of lamellar basement membrane of laminitis may be due to increased lamellar metalloproteinase activity. Characterising lamellar metalloproteinase-2 (MMP-2) and locating it in lamellar tissues may help determine if laminitis pathology is associated with increased MMP-2 transcription. Objective: To clone and sequence the cDNA encoding lamellar MMP-2, develop antibody and in situ hybridisation probes to locate lamellar MMP-2 and quantitate MMP-2 transcription in normal and laminitis tissue. Methods: Total RNA was isolated, fragmented by RT-PCR, cloned into vector a...
Identification and differentiation of avirulent and virulent Rhodococcus equi using selective media and colony blotting DNA hybridization to determine their concentrations in the environment.
Veterinary microbiology    May 12, 2004   Volume 100, Issue 1-2 121-127 doi: 10.1016/j.vetmic.2004.01.016
Muscatello G, Browning GF.Selective agar media have been used for many years to facilitate the isolation of Rhodococcus equi from environmental and clinical samples. However, characterisation of R. equi still requires the use of immunochemical or polymerase chain reaction (PCR) analysis to differentiate between virulent and avirulent isolates. Here, we describe a novel method to detect and differentiate between R. equi isolates using colony blotting and DNA hybridization. Radiolabelled PCR product derived from the R. equi rrnA gene and specific hybridization conditions enabled differentiation of colonies of R. equi fro...
Equine beta-defensin-1: full-length cDNA sequence and tissue expression.
Veterinary immunology and immunopathology    April 29, 2004   Volume 99, Issue 1-2 127-132 doi: 10.1016/j.vetimm.2003.12.010
Davis EG, Sang Y, Blecha F.beta-Defensins are cysteine-rich endogenously produced antimicrobial peptides that play an important role in innate immune defense. Although, previous investigations have identified beta-defensins in several mammalian species, no reports have identified equine beta-defensins. Using a strategy of database searching for expressed sequence tags (EST) we identified putative expression of equine beta-defensins in hepatic tissue. Based on this information, sequence specific primers were designed for the equine gene enabling the identification of the full-length cDNA sequence of equine beta-defensin-...
Equine catechol estrogen 4-hydroxyequilenin is a more potent inhibitor of the variant form of catechol-O-methyltransferase.
Chemical research in toxicology    April 20, 2004   Volume 17, Issue 4 512-520 doi: 10.1021/tx0342464
Li Y, Yao J, Chang M, Nikolic D, Yu L, Yager JD, Mesecar AD, van Breemen RB, Bolton JL.Catechol-O-methyltransferase (COMT) plays an important role in the inactivation of biologically active and toxic catechols. It has been shown that COMT is genetically polymorphic with a wild-type and variant form where a valine has been substituted with a methionine. Several, but not all, epidemiological studies have shown that women, homozygous with the variant form, have an increased risk of developing breast cancer. Previously, we showed that 4-hydroxyequilenin (4-OHEN), a cytotoxic/genotoxic equine catechol estrogen metabolite, is both a substrate of COMT and an irreversible inhibitor of t...
Polymerase chain reaction tests for the identification of Ross River, Kunjin and Murray Valley encephalitis virus infections in horses.
Australian veterinary journal    April 16, 2004   Volume 81, Issue 1-2 76-80 doi: 10.1111/j.1751-0813.2003.tb11438.x
Studdert MJ, Azuolas JK, Vasey JR, Hall RA, Ficorilli N, Huang JA.To develop and validate specific, sensitive and rapid diagnostic tests using RT-PCR for the detection of Ross River virus (RRV), Kunjin virus (KV) and Murray Valley encephalitis virus (MVEV) infections in horses. Methods: Primer sets based on nucleotide sequence encoding the envelope glycoprotein E2 of RRV and on the nonstructural protein 5 (NS5) of KV and MVEV were designed and used in single round PCRs to test for the respective viruses in infected cell cultures and, in the case of RRV, in samples of horse blood and synovial fluid. Results: The primer pairs designed for each of the three vir...
Isolation of Y chromosome-specific microsatellites in the horse and cross-species amplification in the genus Equus.
The Journal of heredity    April 10, 2004   Volume 95, Issue 2 158-164 doi: 10.1093/jhered/esh020
Wallner B, Piumi F, Brem G, Müller M, Achmann R.Y chromosome polymorphisms such as microsatellites or single nucleotide polymorphisms represent a paternal counterpart to mitochondrial DNA (mtDNA) for evolutionary and phylogeographic studies. The use of Y chromosome haplotyping in natural populations of species other than humans is still hindered by the lack of sequence information necessary for polymorphism screening. Here we used representational difference analysis (RDA) followed by a screen of a bacterial artificial chromosome (BAC) library for repetitive sequences to obtain polymorphic Y-chromosomal markers. The procedure was performed ...
Cloning and comparative analysis of the bovine, porcine, and equine sex chromosome genes ZFX and ZFY.
Genome    April 3, 2004   Volume 47, Issue 1 74-83 doi: 10.1139/g03-099
Poloumienko A.A growing body of evidence suggests the involvement of sex chromosome genes in mammalian development. We report the cloning and characterization of the complete coding regions of the bovine Y chromosome ZFY and X chromosome ZFX genes, and partial coding regions of porcine and equine ZFX and ZFY genes. Bovine ZFY and ZFX are highly similar to each other and to ZFX and ZFY from other species. While bovine and human ZFY proteins are both 801 amino acids long, bovine ZFX is 5 amino acids shorter than human ZFX. Like in humans, both bovine ZFY and ZFX contain 13 zinc finger motifs and belong to the...
Characterization of the neutralization determinants of equine arteritis virus using recombinant chimeric viruses and site-specific mutagenesis of an infectious cDNA clone.
Virology    March 31, 2004   Volume 321, Issue 2 235-246 doi: 10.1016/j.virol.2003.12.015
Balasuriya UB, Dobbe JC, Heidner HW, Smalley VL, Navarrette A, Snijder EJ, MacLachlan NJ.We have used an infectious cDNA clone of equine arteritis virus (EAV) and reverse genetics technology to further characterize the neutralization determinants in the GP5 envelope glycoprotein of the virus. We generated a panel of 20 recombinant viruses, including 10 chimeric viruses that each contained the ORF5 (which encodes GP5) of different laboratory, field, and vaccine strains of EAV, a chimeric virus containing the N-terminal ectodomain of GP5 of a European strain of porcine reproductive and respiratory syndrome virus, and 9 mutant viruses with site-specific substitutions in their GP5 pro...
Streptococcus devriesei sp. nov., from equine teeth.
Systematic and applied microbiology    March 30, 2004   Volume 27, Issue 2 146-150 doi: 10.1078/072320204322881754
Collins MD, Lundström T, Welinder-Olsson C, Hansson I, Wattle O, Hudson RA, Falsen E.Phenotypic and phylogenetic studies were performed on four unidentified Gram-positive staining, catalase-negative, alpha-hemolytic Streptococcus-like organisms recovered from the teeth of horses. SDS PAGE analysis of whole-cell proteins and comparative 16S rRNA gene sequencing demonstrated the four strains were highly related to each other but that they did not correspond to any recognised species of the genus Streptococcus. Phylogenetic analysis based on 16S rRNA gene sequences showed the unidentified organisms form a hitherto unknown sub-line within the Streptococcus genus, displaying a clos...
Genetic characterization of Pompeii and Herculaneum Equidae buried by Vesuvius in 79 AD.
Journal of cellular physiology    March 25, 2004   Volume 199, Issue 2 200-205 doi: 10.1002/jcp.10461
Di Bernardo G, Galderisi U, Del Gaudio S, D'Aniello A, Lanave C, De Robertis MT, Cascino A, Cipollaro M.DNA extracted from the skeletons of five equids discovered in a Pompeii stable and of a horse found in Herculaneum was investigated. Amino acid racemization level was consistent with the presence of DNA. Post-mortem base modifications were excluded by sequencing a 146 bp fragment of the 16S rRNA mitochondrial gene. Sequencing of a 370 bp fragment of mitochondrial (mt)DNA control region allowed the construction of a phylogenetic tree that, along with sequencing of nuclear genes (epsilon globin, gamma interferon, and p53) fragments, gave us the possibility to address some questions puzzling arch...
Advances in developing molecular-diagnostic tools for strongyloid nematodes of equids: fundamental and applied implications.
Molecular and cellular probes    March 24, 2004   Volume 18, Issue 1 3-16 doi: 10.1016/j.mcp.2003.10.001
Gasser RB, Hung GC, Chilton NB, Beveridge I.Infections of equids with parasitic nematodes of the order Strongylida (subfamilies Strongylinae and Cyathostominae) are of major veterinary importance. In last decades, the widespread use of drugs against these parasites has led to problems of resistance within the Cyathostominae, and to an increase in their prevalence and intensity of infection. Novel control strategies, based on improved knowledge of parasite biology and epidemiology, have thus become important. However, there are substantial limitations in the understanding of fundamental biological and systematic aspects of these parasite...
Identification and partial characterization of alpha-1,4-glucosidase activity in equine epididymal fluid.
Theriogenology    March 24, 2004   Volume 61, Issue 7-8 1545-1558 doi: 10.1016/j.theriogenology.2003.09.004
Dias AJ, Maia MS, Retamal CA, López ML.The expression of alpha-1,4-glucosidase activity was fluorometrically and electrophoretically assessed in the epididymal fluid and seminal plasma of stallions. alpha-Glucosidase specific activity in the epididymis increased significantly from the proximal caput to the cauda. Stallion epididymal glucosidase maintained activity in a wide range of pH, with two distinct peaks (around pH 4.0 and 6.0, respectively). Enzyme activities at different pH, inhibition assays with sodium dodecyl sulfate (SDS) and maltotriose (MTT, selective inhibitors of alpha-glucosidases "acidic" and "neutral" isoforms, d...
Radiation hybrid mapping of 63 previously unreported equine microsatellite loci.
Animal genetics    March 18, 2004   Volume 35, Issue 2 159-162 doi: 10.1111/j.1365-2052.2004.01109.x
Wagner ML, Goh G, Wu JT, Raudsepp T, Morrison LY, Alexander LJ, Skow LC, Chowdhary BP, Mickelson JR.No abstract available
Assignment of the appaloosa coat colour gene (LP) to equine chromosome 1.
Animal genetics    March 18, 2004   Volume 35, Issue 2 134-137 doi: 10.1111/j.1365-2052.2004.01113.x
Terry RB, Archer S, Brooks S, Bernoco D, Bailey E.A single autosomal dominant locus, leopard complex (LP) controls the presence of appaloosa pigmentation patterns in the horse. The causative gene for LP is unknown. This study was undertaken to map LP in the horse. Two paternal half sib families segregating for the LP locus and including a total of 47 offspring were used to perform a genome scan which localized LP to horse chromosome 1 (ECA1). LP was linked to ASB08 (LOD = 9.99 at Theta = 0.02) and AHT21 (LOD = 5.03 at Theta = 0.14). To refine the map position of LP, eight microsatellite markers on ECA1 (UM041, LEX77, 1CA41, TKY374, COR046, 1C...
Alternate circulation of recent equine-2 influenza viruses (H3N8) from two distinct lineages in the United States.
Virus research    March 17, 2004   Volume 100, Issue 2 159-164 doi: 10.1016/j.virusres.2003.11.019
Lai AC, Rogers KM, Glaser A, Tudor L, Chambers T.Phylogenetic and antigenic analyses indicate that recent circulating equine-2 influenza viruses in the United States have been alternating between two genetic and antigenic distinct lineages since 1996. The evolution rates for these two lineages, the Kentucky and the Florida lineage, are very similar. For the earlier isolates in the Kentucky lineage, there are multiple and sequential nonsynonymous substitutions at antigenic sites B and D. However, there are no changes at any of these antigenic sites for KY98 and OK00. In the Florida lineage, except for NY99 with one amino acid substitution at ...