title: A Point Mutation in a Herpesvirus Co-Determines Neuropathogenicity and Viral Shedding.
abstract: A point mutation in the DNA polymerase gene in equine herpesvirus type 1 (EHV-1) is one determinant for the development of neurological disease in horses. Three recently conducted infection experiments using domestic horses and ponies failed to detect statistically significant differences in viral shedding between the neuropathogenic and non-neuropathogenic variants. These results were interpreted as suggesting the absence of a consistent selective advantage of the neuropathogenic variant and therefore appeared to be inconsistent with a systematic increase in the prevalence of neuropathogenic strains. To overcome potential problems of low statistical power related to small group sizes in these infection experiments, we integrated raw data from all three experiments into a single statistical analysis. The results of this combined analysis showed that infection with the neuropathogenic EHV-1 variant led to a statistically significant increase in viral shedding. This finding is consistent with the idea that neuropathogenic strains could have a selective advantage and are therefore systematically increasing in prevalence in domestic horse populations. However, further studies are required to determine whether a selective advantage indeed exists for neuropathogenic strains.
authors.affiliation: Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin 10315, Germany. m.franz@izw-berlin.de.
authors.forename: Mathias
authors.initials: M
authors.lastname: Franz
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, NY 14850, USA. laura.goodman@cornell.edu.
authors.forename: Laura B
authors.initials: LB
authors.lastname: Goodman
authors.affiliation: Baker Institute for Animal Health, Cornell University, Ithaca, NY 14850, USA. grv23@cornell.edu.
authors.forename: Gerlinde R
authors.initials: GR
authors.lastname: Van de Walle
authors.affiliation: Institut für Virologie, Freie Universität Berlin, Robert Von Ostertag-Str. 7 - 13, Berlin 14163, Germany. no.34@fu-berlin.de.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Osterrieder
authors.affiliation: Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin 10315, Germany. greenwood@izw-berlin.de.|Department of Veterinary Medicine, Freie Universität Berlin, Oertzenweg 19b, Berlin 14163, Germany. greenwood@izw-berlin.de.
authors.forename: Alex D
authors.initials: AD
authors.lastname: Greenwood
mesh_terms: D000818:Animals; D004861:Herpesvirus 1, Equid / Q000235:genetics* / Q000472:pathogenicity*; D006736:Horses; D017354:Point Mutation; D014774:Virulence; D017201:Virus Shedding
keywords: equine herpesvirus type 1; neuropathogenicity; trade-off hypothesis; viral shedding