Comparative in vivo safety and efficacy of a glycoprotein G-deficient candidate vaccine strain of infectious laryngotracheitis virus delivered via eye drop

Avian Pathol. 2011 Aug;40(4):411-7. doi: 10.1080/03079457.2011.588686.

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chick Embryo
  • Chickens / immunology*
  • Chickens / virology
  • Drug Administration Routes
  • Female
  • Herpesviridae Infections / immunology
  • Herpesviridae Infections / prevention & control*
  • Herpesviridae Infections / veterinary
  • Herpesviridae Infections / virology
  • Herpesvirus 1, Gallid / genetics
  • Herpesvirus 1, Gallid / immunology*
  • Herpesvirus Vaccines / administration & dosage*
  • Herpesvirus Vaccines / genetics
  • Herpesvirus Vaccines / immunology
  • Male
  • Ophthalmic Solutions / administration & dosage
  • Poultry Diseases / immunology
  • Poultry Diseases / prevention & control*
  • Poultry Diseases / virology
  • Sequence Deletion
  • Specific Pathogen-Free Organisms
  • Vaccination / methods
  • Vaccination / veterinary*
  • Vaccines, Attenuated / administration & dosage
  • Vaccines, Attenuated / genetics
  • Vaccines, Attenuated / immunology
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / metabolism
  • Virulence Factors / genetics
  • Virulence Factors / metabolism
  • Virus Replication
  • Weight Gain

Substances

  • Herpesvirus Vaccines
  • Ophthalmic Solutions
  • Vaccines, Attenuated
  • Viral Envelope Proteins
  • Virulence Factors