Genomic characterization and vaccine potential of a naturally attenuated infectious laryngotracheitis virus from healthy chickens☆
- 1College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, 450046, China
- 2National Animal Health Products for Engineering Technology Research Center, Qingdao, 266111, China
Abstract
Infectious laryngotracheitis (ILT) is an acute, highly contagious respiratory disease of chickens caused by infectious laryngotracheitis virus (ILTV), which continues to pose significant economic losses to the poultry industry worldwide. Current live attenuated vaccines, while effective, carry risks of residual virulence, reversion to pathogenicity, and latent infection establishment. There is an urgent need to develop safer and more effective vaccine candidates. In this study, an ILTV strain, designated CH/HN/2022, was isolated from clinically healthy layers during routine diagnostic monitoring in Henan Province, China. The flock had no history of ILT vaccination and showed no clinical signs of ILT at the time of sampling. The complete genome of CH/HN/2022 was sequenced, comprising 152,218 bp with 48% G+C content and 79 predicted open reading frames. Phylogenetic analysis revealed that CH/HN/2022 clustered with US virulent strains 81658 and USDA and TCO vaccine strain LT-IVAX (Clade II) and shared 98.8% nucleotide identity with strain 81658, but only 95.8-96.5% identity with 15 previously reported Chinese isolates. Notably, CH/HN/2022 possessed a ∼3,340 bp deletion in the UL region and an 855 bp insertion in the terminal and internal repeat regions compared to Chinese virulent strains. Comparative analysis with virulent strain WG identified significant amino acid differences in gD, gJ, and ORF C proteins. The CH/HN/2022 could efficiently replicate in LMH cells. Pathogenicity assessment in 4-week-old SPF chickens demonstrated that CH/HN/2022 induced no mortality and only mild, transient respiratory signs in 10% of birds inoculated via the intratracheal route, with no detectable transmission to contact birds under the conditions tested. Vaccination with a single dose of CH/HN/2022 via eye drop provided complete protection against lethal challenge with virulent WG strain. These findings indicate that CH/HN/2022 is a naturally attenuated ILTV strain with unique genomic features and an attenuated phenotype and promising protective efficacy under the conditions tested, representing a promising candidate for live attenuated vaccine development.
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BibTeX
@article{xu2026genomic,
title = {{Genomic characterization and vaccine potential of a naturally attenuated infectious laryngotracheitis virus from healthy chickens☆}},
author = {Minghe Xu and Jingge Tian and Panpan Yang and Yanfang Cong and Shengnan Xu and Dongdong Yang and Baiyu Wang and Jianli Li and Jun Zhao},
journal = {Poultry Science},
year = {2026},
month = oct,
doi = {10.1016/j.psj.2026.108002},
url = {https://doi.org/10.1016/j.psj.2026.108002},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Genomic characterization and vaccine potential of a naturally attenuated infectious laryngotracheitis virus from healthy chickens☆
AU - Minghe Xu
AU - Jingge Tian
AU - Panpan Yang
AU - Yanfang Cong
AU - Shengnan Xu
AU - Dongdong Yang
AU - Baiyu Wang
AU - Jianli Li
AU - Jun Zhao
PY - 2026
DA - 2026/10/21
JO - Poultry Science
DO - 10.1016/j.psj.2026.108002
UR - https://doi.org/10.1016/j.psj.2026.108002
AB - Infectious laryngotracheitis (ILT) is an acute, highly contagious respiratory disease of chickens caused by infectious laryngotracheitis virus (ILTV), which continues to pose significant economic losses to the poultry industry worldwide. Current live attenuated vaccines, while effective, carry risks of residual virulence, reversion to pathogenicity, and latent infection establishment. There is an urgent need to develop safer and more effective vaccine candidates. In this study, an ILTV strain, designated CH/HN/2022, was isolated from clinically healthy layers during routine diagnostic monitoring in Henan Province, China. The flock had no history of ILT vaccination and showed no clinical signs of ILT at the time of sampling. The complete genome of CH/HN/2022 was sequenced, comprising 152,218 bp with 48% G+C content and 79 predicted open reading frames. Phylogenetic analysis revealed that CH/HN/2022 clustered with US virulent strains 81658 and USDA and TCO vaccine strain LT-IVAX (Clade II) and shared 98.8% nucleotide identity with strain 81658, but only 95.8-96.5% identity with 15 previously reported Chinese isolates. Notably, CH/HN/2022 possessed a ∼3,340 bp deletion in the UL region and an 855 bp insertion in the terminal and internal repeat regions compared to Chinese virulent strains. Comparative analysis with virulent strain WG identified significant amino acid differences in gD, gJ, and ORF C proteins. The CH/HN/2022 could efficiently replicate in LMH cells. Pathogenicity assessment in 4-week-old SPF chickens demonstrated that CH/HN/2022 induced no mortality and only mild, transient respiratory signs in 10% of birds inoculated via the intratracheal route, with no detectable transmission to contact birds under the conditions tested. Vaccination with a single dose of CH/HN/2022 via eye drop provided complete protection against lethal challenge with virulent WG strain. These findings indicate that CH/HN/2022 is a naturally attenuated ILTV strain with unique genomic features and an attenuated phenotype and promising protective efficacy under the conditions tested, representing a promising candidate for live attenuated vaccine development.
SN - 0032-5791
SN - 1525-3171
ER -