title: Prevalence of latent, neuropathogenic equine herpesvirus-1 in the Thoroughbred broodmare population of central Kentucky.
abstract: BACKGROUND
  An emerging problem of equine herpesvirus-1 (EHV-1) infection in horses in the USA is a high-mortality myeloencephalopathy that commonly occurs where large numbers of horses are stabled. EHV-1 isolates recovered from recent neurological outbreaks represent a mutant virus strain that possesses enhanced neuropathogenicity. A central question of EHV-1 myeloencephalopathy is the latency carriage rate for these mutants of EHV-1 in USA horse populations.
  
  
  OBJECTIVE
  To estimate the prevalence of neuropathogenic strains of EHV-1 as latent infections in the Thoroughbred broodmare population of central Kentucky.
  
  
  METHODS
  Submandibular lymph nodes (SMLN) were collected during post mortem examination of 132 Thoroughbred broodmares. Total DNA purified from SMLN tissue was tested for the presence of latent EHV-1 DNA by an ultrasensitive magnetic bead-based, sequence-capture, nested PCR method. Differentiation of active from latent infections by EHV-1 was achieved by detection of transcripts of EHV-1 glycoprotein B by reverse transcription PCR.
  
  
  RESULTS
  Latent EHV-1 DNA was detected in the SMLN tissues of 71 (54%) of the 132 mares submitted for necropsy. Thirteen (18%) of the 71 latently infected horses harboured the neuropathogenic biovar of EHV-1. Of the 13 horses latently infected with an ORF30 mutant strain of EHV-1, 11 also carried a latent, wild-type strain of the virus in their SMLN tissues.
  
  
  CONCLUSIONS
  Neuropathogenic strains of EHV-1 have established a significant presence in the Thoroughbred broodmare population of central Kentucky as latently infected carrier horses. The data also indicate that a highly sensitive DNA detection method is required to identify many instances of EHV-1 latency.
  
  
  CONCLUSIONS
  The presence of a relatively large biological reservoir of latent, neuropathogenic EHV-1 has the potential for posing emerging equine health and economic threats to the future prosperity of the USA horse industry.
authors: Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky 40546-0099, USA.
authors: G P
authors: GP
authors: Allen
authors: D C
authors: DC
authors: Bolin
authors: U
authors: U
authors: Bryant
authors: C N
authors: CN
authors: Carter
authors: R C
authors: RC
authors: Giles
authors: L R
authors: LR
authors: Harrison
authors: C B
authors: CB
authors: Hong
authors: C B
authors: CB
authors: Jackson
authors: K
authors: K
authors: Poonacha
authors: R
authors: R
authors: Wharton
authors: N M
authors: NM
authors: Williams
mesh_terms: D000818:Animals; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D004196:Disease Outbreaks / Q000662:veterinary; D004197:Disease Reservoirs / Q000662:veterinary* / Q000821:virology; D005260:Female; D006566:Herpesviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D004861:Herpesvirus 1, Equid / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology*; D006734:Horse Diseases / Q000453:epidemiology* / Q000821:virology; D006736:Horses; D007629:Kentucky / Q000453:epidemiology; D008198:Lymph Nodes / Q000821:virology*; D009154:Mutation; D015995:Prevalence; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics; D017735:Virus Latency
chemical_list: D004279:DNA, Viral; D012367:RNA, Viral