Journal of Advanced Veterinary and Animal Research (Apr 2024)

Characterization of infectious laryngotracheitis virus isolated from commercial layer chickens in Bangladesh during the year 2021–2022

  • Md. Mostofa Kamal,
  • Mohammad Sadekuzzaman,
  • Mst. Kohinoor Parvin,
  • Md. Enamul Haque,
  • Sajedul Hayat,
  • Md. Ariful Islam,
  • Mst. Minara Khatun,
  • Mahbubul Pratik Siddique,
  • Mohammud Tofazzal Hossain,
  • Sham Soun Nahar,
  • A. K. M. Khasruzzaman,
  • Md. Alimul Islam

DOI
https://doi.org/10.5455/javar.2024.k789
Journal volume & issue
Vol. 11, no. 2
pp. 398 – 407

Abstract

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Objective: Infectious laryngotracheitis virus (ILTV) is responsible for causing infectious laryngo¬tracheitis (ILT), which is a rapidly spreading and extremely transmissible disease in chickens. The current research aims to isolate and characterize ILTV from layer chickens in Bangladesh. Materials and Methods: A total of 345 samples (trachea, larynx, and lungs) were collected from ILT-suspected dead and sick layer chickens of 32 ILT-suspected farms in three different outbreak districts (Gazipur, Tangail, and Mymensingh) of Bangladesh during the outbreak year 2021-2022. Rapid detection kits examined the samples for avian influenza virus (AIV) and Newcastle disease virus (NDV). ILTV-specific primers were used to screen 72 NDV- and AIV-negative samples by poly¬merase chain reaction (PCR). Using chorioallantoic membrane (CAM), the study isolated the ILT virus from 9 to 10-day-old seronegative embryonated chicken eggs (ECEs) using selected PCR-positive samples. The virus was confirmed using nucleotide sequencing, agar gel immunodiffusion test (AGIDT), viral neutralization test (VNT), and pathogenicity evaluations using mortality index for chicken embryos (MICEs) and intra-tracheal pathogenicity index (ITPI). Results: The results indicated that among the PCR-positive 10 samples, only two (Alim_ILT_1001 and Alim_ILT_1,000) were found positive using ECEs. There were two field isolates of ILTVs, as shown by the amplicon size of the ICP4 gene-based PCR. A phylogenetic study of the ICP4 gene revealed that the recent isolates have a close similarity with the ILTV isolates of Turkey, Bangladesh, and Australia. AGIDT revealed strong precipitation lines due to ILTV-specific antibod¬ies reacting with field viruses, while VNT neutralized both isolates with conventional ILTV antibod¬ies. The pathogenicity testing indicated that Alim_ILT_1001 had MICE and ITPI values of 0.77 and 0.63, whereas Alim_ILT_1,000 had 0.71 and 0.57. Conclusion: Both the ILTV isolates have similarities with the isolates of Turkey, Bangladesh, and Australia, and they are highly virulent for chickens. [J Adv Vet Anim Res 2024; 11(2.000): 398-407]

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