title: Comparison of the replication and transmissibility of two infectious laryngotracheitis virus chicken embryo origin vaccines delivered via drinking water.
abstract: Infectious laryngotracheitis (ILT) is an acute infectious viral disease that affects chickens, causing respiratory disease, loss of production and mortality in severe cases. Biosecurity measures and administration of attenuated viral vaccine strains are commonly used to prevent ILT. It is notable that most recent ILT outbreaks affecting the intensive poultry industry have been caused by vaccine-related virus strains. The purpose of this study was to characterize and compare viral replication and transmission patterns of two attenuated chicken embryo origin ILT vaccines delivered via the drinking water. Two groups of specific pathogen free chickens were each inoculated with SA-2 ILT or Serva ILT vaccine strains. Unvaccinated birds were then placed in contact with vaccinated birds at regular intervals. Tracheal swabs were collected every 4 days over a period of 60 days and examined for the presence and amount of virus using a quantitative polymerase chain reaction. A rapid increase in viral genome copy numbers was observed shortly after inoculation with SA-2 ILT virus. In contrast, a comparatively delayed virus replication was observed after vaccination with Serva ILT virus. Transmission to in-contact birds occurred soon after exposure to Serva ILT virus but only several days after exposure to SA-2 ILT virus. Results from this study demonstrate in vivo differences between ILT vaccine strains in virus replication and transmission patterns.
authors.affiliation: Asia-Pacific Centre for Animal Health, Faculty of Veterinary Science, The University of Melbourne, Victoria 3010, Australia. mjcoppo@unimelb.edu.au
authors.forename: Mauricio J C
authors.initials: MJ
authors.lastname: Coppo
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Devlin
authors.forename: Amir H
authors.initials: AH
authors.lastname: Noormohammadi
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002645:Chickens; D017931:DNA Primers / Q000235:genetics; D060766:Drinking Water / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D006566:Herpesviridae Infections / Q000635:transmission / Q000662:veterinary*; D001352:Herpesvirus 1, Gallid / Q000502:physiology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011201:Poultry Diseases / Q000635:transmission* / Q000821:virology*; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D013047:Specific Pathogen-Free Organisms; D014132:Trachea / Q000821:virology; D014613:Vaccines, Attenuated / Q000009:adverse effects*; D014765:Viral Vaccines / Q000009:adverse effects*; D014779:Virus Replication / Q000502:physiology
chemical_list: D017931:DNA Primers; D060766:Drinking Water; D014613:Vaccines, Attenuated; D014765:Viral Vaccines