title: Comparative in vivo safety and efficacy of a glycoprotein G-deficient candidate vaccine strain of infectious laryngotracheitis virus delivered via eye drop.
abstract: Infectious laryngotracheitis (ILT) is an acute respiratory disease in poultry that is commonly controlled by vaccination with conventionally attenuated virus strains. Despite the use of these vaccines, ILT remains a threat to the intensive poultry industry. Our laboratory has developed a novel candidate vaccine strain of infectious laryngotracheitis virus (ILTV) lacking glycoprotein G (ΔgG-ILTV). The aim of the present study was to directly compare this candidate vaccine with three currently available commercial vaccines in vivo. Five groups of specific-pathogen-free chickens were eye-drop inoculated with one of the three commercial vaccine strains (SA2-ILTV, A20-ILTV or Serva-ILTV), or ΔgG-ILTV, or sterile medium. Vaccine safety was assessed by examining clinical signs, weight gain and persistence of virus in the trachea. Vaccine efficacy was assessed by scoring clinical signs and conducting post-mortem analyses following challenge with virulent virus. Following vaccination, birds that received ΔgG-ILTV had the highest weight gain among the vaccinated groups and had clinical scores that were significantly lower than birds vaccinated with SA2-ILTV or A20-ILTV, but not significantly different from those of birds vaccinated with Serva-ILTV. Analysis of clinical scores, weight gain, tracheal pathology and virus replication after challenge revealed a comparable level of efficacy for all vaccines. Findings from this study further demonstrate the suitability of ΔgG-ILTV as a vaccine to control ILT.
authors.affiliation: Asia-Pacific Centre for Animal Health, Faculty of Veterinary Science, The University of Melbourne, Werribee, Victoria, 3030, Australia.
authors.forename: Mauricio J C
authors.initials: MJ
authors.lastname: Coppo
authors.forename: Amir H
authors.initials: AH
authors.lastname: Noormohammadi
authors.forename: Carol A
authors.initials: CA
authors.lastname: Hartley
authors.forename: James R
authors.initials: JR
authors.lastname: Gilkerson
authors.forename: Glenn F
authors.initials: GF
authors.lastname: Browning
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Devlin
mesh_terms: D000818:Animals; D002642:Chick Embryo; D002645:Chickens / Q000276:immunology* / Q000821:virology; D004333:Drug Administration Routes; D005260:Female; D006566:Herpesviridae Infections / Q000276:immunology / Q000517:prevention & control* / Q000662:veterinary / Q000821:virology; D001352:Herpesvirus 1, Gallid / Q000235:genetics / Q000276:immunology*; D022283:Herpesvirus Vaccines / Q000008:administration & dosage* / Q000235:genetics / Q000276:immunology; D008297:Male; D009883:Ophthalmic Solutions / Q000008:administration & dosage; D011201:Poultry Diseases / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D017384:Sequence Deletion; D013047:Specific Pathogen-Free Organisms; D014611:Vaccination / Q000379:methods / Q000662:veterinary*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication; D015430:Weight Gain
chemical_list: D022283:Herpesvirus Vaccines; D009883:Ophthalmic Solutions; D014613:Vaccines, Attenuated; D014759:Viral Envelope Proteins; D037521:Virulence Factors