title: Efficacy and safety of a modified-live cyprinid herpesvirus 3 vaccine in koi (Cyprinus carpio koi) for prevention of koi herpesvirus disease.
abstract: OBJECTIVE
  To investigate safety and efficacy of a cyprinid herpesvirus type 3 (CyHV3) modified-live virus vaccine for the prevention of koi herpesvirus disease (KHVd).
  
  
  METHODS
  420 healthy koi (Cyprinus carpio koi).
  
  
  METHODS
  Fish were vaccinated with a 1× dose or 10× overdose of CyHV3 modified-live virus vaccine or a placebo through bath exposure in tanks at 22°C. Horizontal transmission of vaccine virus was evaluated by commingling unvaccinated and vaccinated fish. Efficacy was evaluated by challenge exposure of vaccinated and naïve fish to a wild-type virus. Fish that died were submitted for quantitative PCR assay for CyHV3 and histologic evaluation.
  
  
  RESULTS
  The CyHV3 vaccine was safe and efficacious, even at a 10× overdose. Vaccine-associated mortality rate was inversely associated with body weight, with a cumulative mortality rate of 9.4% (18/192) in fish weighing ≤ 87 g and no deaths in fish weighing > 87 g (0/48). Horizontal transfer of vaccine virus from vaccinates to naïve fish was negligible. For efficacy, the vaccine provided a significant reduction in mortality rate after challenge exposure to a wild-type virus, with a prevented fraction of 0.83 versus the placebo control fish.
  
  
  CONCLUSIONS
  KHVd is highly contagious and commonly leads to deaths in 80% to 100% of exposed fish, representing a major threat to koi and common carp populations throughout the world. The CyHV3 modified-live virus vaccine had a favorable safety profile and was an effective vaccine for the control of KHVd in koi weighing > 87 g.
authors.affiliation: Departments of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.
authors.forename: E P Scott
authors.initials: EP
authors.lastname: Weber
authors.forename: Kirsten V
authors.initials: KV
authors.lastname: Malm
authors.forename: Susan C
authors.initials: SC
authors.lastname: Yun
authors.forename: Lori A
authors.initials: LA
authors.lastname: Campbell
authors.forename: Philip H
authors.initials: PH
authors.lastname: Kass
authors.forename: Gary D
authors.initials: GD
authors.lastname: Marty
authors.forename: Kira
authors.initials: K
authors.lastname: Salonius
authors.forename: Arnon
authors.initials: A
authors.lastname: Dishon
mesh_terms: D000818:Animals; D002347:Carps; D005393:Fish Diseases / Q000517:prevention & control* / Q000821:virology; D006564:Herpesviridae / Q000235:genetics; D006566:Herpesviridae Infections / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D016133:Polymerase Chain Reaction / Q000662:veterinary; D019562:Viral Load; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D014765:Viral Vaccines