title: Comparison of the replication and transmissibility of an infectious laryngotracheitis virus vaccine delivered via eye-drop or drinking-water.
abstract: Live attenuated vaccines have been extensively used to control infectious laryngotracheitis (ILT). Most vaccines are registered/recommended for use via eye-drop although vaccination via drinking-water is commonly used in the field. Drinking-water vaccination has been associated with non-uniform protection. Bird-to-bird passage of chick-embryo-origin (CEO) ILT vaccines has been shown to result in reversion to virulence. The purpose of the present study was to examine the replication and transmission of a commercial CEO infectious laryngotracheitis virus (ILTV) vaccine strain following drinking-water or eye-drop inoculation. Two groups of 10 specific-pathogen-free chickens were each vaccinated with Serva ILTV vaccine strain either via eye-drop or drinking-water. Groups of four or five unvaccinated birds were placed in contact with vaccinated birds at regular intervals. Tracheal swabs were collected every 4 days from vaccinated and in-contact birds to assess viral replication and transmission using quantitative polymerase chain reaction. Compared with eye-drop-vaccinated birds, drinking-water-vaccinated birds showed delayed viral replication but had detectable viral DNA for a longer period of time. Transmission to chickens exposed by contact on day 0 of the experiments was similar in both groups. Birds exposed to ILTV by contact with eye-drop vaccinated birds on days 4, 8, 12 and 16 of the experiment had detectable ILTV for up to 8 days post exposure. ILTV was not detected in chickens that were exposed by contact with drinking-water vaccinated birds on day 12 of the experiment or later. Results from this study provide valuable practical information for the use of ILT vaccine.
authors: Asia-Pacific Centre for Animal Health, Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia. mjcoppo@unimelb.edu.au
authors: Mauricio J C
authors: MJ
authors: Coppo
authors: Joanne M
authors: JM
authors: Devlin
authors: Amir H
authors: AH
authors: Noormohammadi
mesh_terms: D000818:Animals; D002645:Chickens; D060766:Drinking Water / Q000008:administration & dosage / Q000821:virology; D004333:Drug Administration Routes / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D006566:Herpesviridae Infections / Q000517:prevention & control / Q000635:transmission / Q000662:veterinary*; D001352:Herpesvirus 1, Gallid / Q000254:growth & development* / Q000472:pathogenicity; D009883:Ophthalmic Solutions / Q000008:administration & dosage; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011201:Poultry Diseases / Q000517:prevention & control / Q000635:transmission* / Q000821:virology*; D014765:Viral Vaccines; D014774:Virulence; D014779:Virus Replication / Q000502:physiology*
chemical_list: D060766:Drinking Water; D009883:Ophthalmic Solutions; D014765:Viral Vaccines