Vet World Vol.17 April Article - 5
Research Article
Veterinary World, 17(4): 771-777
https://doi.org/10.14202/vetworld.2024.771-777
Evaluation of the efficacy of commercial live vaccines against the local Thai QX field strain for the protection of specific pathogen-free chicks
1 Akkhraratchakumari Veterinary College, Walailak University, Nakorn Si Thammarat, Thailand.
2 Centre for One Health, Walailak University, Nakhon Si Thammarat, Thailand.
3 Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Ho Chi Minh City, Vietnam.
4 Avian Health Research Unit, Department of Veterinary Medicine, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
Background and Aim: The high prevalence of QX-like variant among Thai isolates poses a significant threat to poultry production. In this study, we evaluated the protective efficacy of commercially available heterologous infectious bronchitis virus (IBV) vaccines against the local Thai QX-like strain in specific-pathogen-free (SPF) chicks from Thailand.
Materials and Methods: The experiment involved 100 SPF chicks divided into 4 arms. Arms I and II received the TAbic IB VAR (233A) and Ibird (1/96) vaccines, respectively, on day 1. After 10 days, both arms received the H120 vaccine. Arms III and IV were non-vaccinated positive and negative controls. Challenge infection was local Thai QX-like virus on birds of Arms I, II, and III, and negative control of Arm IV. Clinical signs of infectious bronchitis (IB) and IBV detection using reverse transcription polymerase chain reaction were assessed at 2, 4, and 6 days post-challenge (dpc). At 6 dpc, the birds were humanely euthanized for post-mortem examination with the ciliostasis test and histopathological analysis of the tracheas, lungs, and kidneys.
Results: Virus shedding started at 4 dpc (33.3% positive) and reached 100% positivity at 6 dpc with obvious clinical respiratory symptoms in non-vaccinated-challenged birds. No detection of IBV in vaccinated-challenged arms. Ciliary activity scores were significantly lower in non-vaccinated-challenged birds at 23.64 (standard deviation [SD] ± 1.74) and 96.50 (SD ± 1.91) and 95.64 (SD ± 1.77), respectively (p = 0.05) than in vaccinated-challenged birds. The most remarkable histopathological changes were observed in non-vaccinated-challenged birds, with moderately severe changes in the trachea, lungs, and kidneys. On the other hand, birds in vaccinated-challenged arms showed no significant changes.
Conclusion: This study demonstrated the efficacy of TAbic IB VAR (233A) or Ibird (1/96) vaccine combined with a Massachusetts serotype vaccine (H120) against the local Thai QX-like strain in SPF chicks, contributing valuable insights to the selection of suitable commercially available vaccines to combat the prevalent local QX-like strains in Thailand.
Keywords: avian infectious bronchitis, chicken, efficacy, QX-like strain, Thailand, vaccine.
How to cite this article: Thomrongsuwannakij T, Phu DH, and Chansiripornchai N (2024) Evaluation of the efficacy of commercial live vaccines against the local Thai QX field strain for the protection of specific pathogen-free chicks, Veterinary World, 17(4): 771-777.
Received: 25-12-2023 Accepted: 14-03-2024 Published online: 07-04-2024
Corresponding author: E-mail:
DOI: 10.14202/vetworld.2024.771-777
Copyright: Thomrongsuwannakij, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/ by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
