Protection Induced in Broiler Chickens following Drinking-Water Delivery of Live Infectious Laryngotracheitis Vaccines against Subsequent Challenge with Recombinant Field Virus

PLoS One. 2015 Sep 14;10(9):e0137719. doi: 10.1371/journal.pone.0137719. eCollection 2015.

Abstract

Infectious laryngotracheitis virus (ILTV) causes acute upper respiratory tract disease in chickens. Attenuated live ILTV vaccines are often used to help control disease, but these vaccines have well documented limitations, including retention of residual virulence, incomplete protection, transmission of vaccine virus to unvaccinated birds and reversion to high levels of virulence following bird-to-bird passage. Recently, two novel ILTV field strains (class 8 and 9 ILTV viruses) emerged in Australia due to natural recombination between two genotypically distinct commercial ILTV vaccines. These recombinant field strains became dominant field strains in important poultry producing areas. In Victoria, Australia, the recombinant class 9 virus largely displaced the previously predominant class 2 ILTV strain. The ability of ILTV vaccines to protect against challenge with the novel class 9 ILTV strain has not been studied. Here, the protection induced by direct (drinking-water) and indirect (contact) exposure to four different ILTV vaccines against challenge with class 9 ILTV in commercial broilers was studied. The vaccines significantly reduced, but did not prevent, challenge virus replication in vaccinated chickens. Only one vaccine significantly reduced the severity of tracheal pathology after direct drinking-water vaccination. The results indicate that the current vaccines can be used to help control class 9 ILTV, but also indicate that these vaccines have limitations that should be considered when designing and implementing disease control programs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chickens
  • Drinking Water*
  • Herpesviridae Infections / genetics
  • Herpesviridae Infections / immunology
  • Herpesviridae Infections / prevention & control*
  • Herpesviridae Infections / veterinary*
  • Herpesvirus 1, Gallid / genetics
  • Herpesvirus 1, Gallid / immunology*
  • Poultry Diseases / genetics
  • Poultry Diseases / immunology
  • Poultry Diseases / prevention & control*
  • Vaccination / methods*
  • Viral Vaccines / genetics
  • Viral Vaccines / immunology
  • Viral Vaccines / pharmacology*

Substances

  • Drinking Water
  • Viral Vaccines

Grants and funding

This work was supported by the Rural Industries Research and Development Corporation (RIRDC, PRJ-008792) and by the Australian Research Council (ARC, DP130103991). JMD is supported by an ARC Future Fellowship (FT140101287). The ARC had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. The RIRDC contributed to the study design and approved the manuscript for publication, but had no role in data collection and analysis or preparation of the manuscript.