Genetic characterization of equine arteritis virus during persistent infection of stallions.
Equine arteritis virus (EAV) causes a persistent infection of the reproductive tract of carrier stallions. The authors determined the complete genome sequences of viruses (CW96 and CW01) that were present 5 years apart in the semen of a carrier stallion (CW). The CW96 and CW01 viruses respectively had only 85.6 % and 85.7 % nucleotide identity to the published sequence of EAV (EAV030). The CW96 and CW01 viruses had two 1 nt insertions and a single 1 nt deletion in the leader sequence, and a 3 nt coding insertion in ORF1a; thus their genomes included 12 708 nt as compared to the 12 704 nt in EAV030. Variation between viruses present in the semen of stallion CW and EAV030 was especially marked in the replicase gene (ORF1a and 1b), and the greatest variation occurred in the portion of ORF1a encoding the nsp2 protein. The ORFs 3 and 5, which respectively encode the GP3 and GP5 envelope proteins, showed greatest variation amongst ORFs encoding structural EAV proteins. Comparative sequence analyses of CW96 and CW01 indicated that ORFs 1a, 1b and 7 were highly conserved during persistent infection, whereas there was substantial variation in ORFs 3 and 5. Although the variation that occurs in ORF5 results in the emergence of novel phenotypic viral variants as determined by neutralization assay, all variants were neutralized by high-titre polyclonal equine antisera, suggesting that immune evasion is unlikely to be responsible for the establishment of persistent EAV infection of carrier stallions. Northern blot analyses of RNA extracted from cell culture propagated viruses isolated from 10 different persistently infected stallions failed to demonstrate any large genomic deletions, suggesting that defective interfering particles are also unlikely to be important in either the maintenance or clearance of persistent EAV infection of the reproductive tract of carrier stallions.
Balasuriya
Udeni B R
UBR
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.
Hedges
Jodi F
JF
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.
Smalley
Victoria L
VL
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.
Navarrette
Andrea
A
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.
McCollum
William H
WH
Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, USA.
Timoney
Peter J
PJ
Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, USA.
Snijder
Eric J
EJ
Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, LUMC P4-26, PO Box 9600, 2300 RC Leiden, The Netherlands.
MacLachlan
N James
NJ
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.
D000595:Amino Acid Sequence; D000818:Animals; D018174:Arterivirus Infections / Q000662:veterinary* / Q000821:virology; D002353:Carrier State / Q000662:veterinary* / Q000821:virology; D003673:Defective Viruses / Q000235:genetics / Q000302:isolation & purification; D007240:Equartevirus / Q000235:genetics*; D005060:Europe; D019143:Evolution, Molecular; D014644:Genetic Variation; D016679:Genome, Viral; D006734:Horse Diseases / Q000821:virology*; D006736:Horses; D008297:Male; D008969:Molecular Sequence Data; D009656:North America; D016366:Open Reading Frames; D010802:Phylogeny; D012661:Semen / Q000821:virology; D017361:Viral Nonstructural Proteins / Q000235:genetics
D017361:Viral Nonstructural Proteins