title: Differentiation of strains of equine arteritis virus of differing virulence to horses by growth in equine endothelial cells.
abstract: OBJECTIVE
  To compare growth characteristics of strains of equine arteritis virus (EAV) of differing virulence to horses in rabbit kidney (RK)-13 cells and equine endothelial cells (EECs) cultured from the pulmonary artery of a foal.
  
  
  METHODS
  13 strains of EAV, including 11 field isolates of differing virulence to horses; the highly virulent, horse-adapted Bucyrus strain; and the modified-live virus (MLV) vaccine derived from it.
  
  
  METHODS
  The growth characteristics of the 13 strains were compared in EECs and RK-13 cells. Viral nucleoprotein expression, cytopathogenicity, and plaque size were compared to determine whether growth characteristics of the 13 strains were predictive of their virulence to horses.
  
  
  RESULTS
  Cytopathogenicity, viral nucleoprotein expression, and plaque size induced by all 13 viruses were similar in RK-13 cells, whereas virulent strains of EAV caused significantly larger plaques in EECs than did the avirulent strains of EAV. Paradoxically, the highly attenuated MLV vaccine and 1 field isolate of EAV caused plaques in EECs that were larger than those caused by any of the other viruses, and sequence analysis confirmed the field isolate of EAV to be indistinguishable from the MLV vaccine.
  
  
  CONCLUSIONS
  With the notable exception of the MLV vaccine, growth of the various strains of EAV in EECs was predictive of their individual virulence to horses. Thus, EECs provide a relevant and useful model to further characterize determinants of virulence and attenuation amongst strains of EAV.
authors.affiliation: Bernard and Gloria Salick Equine Viral Disease Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Moore
authors.forename: Udeni B R
authors.initials: UB
authors.lastname: Balasuriya
authors.forename: Jane P
authors.initials: JP
authors.lastname: Nurton
authors.forename: William H
authors.initials: WH
authors.lastname: McCollum
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Timoney
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Guthrie
authors.forename: N James
authors.initials: NJ
authors.lastname: MacLachlan
mesh_terms: D000818:Animals; D016923:Cell Death; D002478:Cells, Cultured; D004727:Endothelium / Q000166:cytology* / Q000821:virology*; D007240:Equartevirus / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D006736:Horses / Q000821:virology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011651:Pulmonary Artery; D014774:Virulence