Volume: 56 Issue: 4
Year: 2025, Page: 682-686, Doi: https://doi.org/10.51966/jvas.2025.56.4.682-686
Received: Sept. 12, 2025 Accepted: Oct. 22, 2025 Published: Dec. 31, 2025
Infectious bronchitis virus (IBV) is a major pathogen of poultry, with nephropathogenic variants causing persistent infection and economic losses. This study investigated the expression of Toll-like receptor 7 (TLR7) and inducible nitric oxide synthase (iNOS) in broiler chicken experimentally infected with a nephropathogenic IBV isolate from Kerala. Oneweek- old broilers were inoculated oculonasally with 1×104 EID50 of the isolate, and trachea, lung and kidney tissues were collected at 3-, 7-, and 14- days post-infection (dpi). The relative gene expression was determined by quantitative real-time PCR (qPCR) using the 2–ΔΔCt method. The TLR7 expression was significantly upregulated in the trachea at 3 dpi (~7-fold) and in the kidneys at both 3 and 7 dpi (~3-4 fold), before declining at 14 dpi. Pulmonary TLR7 expression was delayed, showing a two-fold rise at 7 dpi. The iNOS expression was markedly elevated in renal tissue (~6-fold at 3 and 7 dpi) and in lungs (~4-fold at 7 dpi), whereas tracheal expression was initially suppressed and recovered later. The findings of the study suggested that nephropathogenic IBV activates TLR7-mediated viral recognition and iNOS-driven inflammatory responses in a tissue and time-dependent manner. The results also pointed out that the virus’s ability to evade or modulate the initial immune alarm system is a critical determinant of disease outcome.
Keywords: Infectious bronchitis virus, TLR7, iNOS, nephropathogenic isolate
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© 2025 Prasad et al. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0
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Prasad P. I., Sankar, S., Priya, P. M., Nair S. R., Kurian E., Krithiga, K., 2025. Differential expression of TLR7 and iNOS in chicken experimentally infected with a nephropathogenic infectious bronchitis virus isolate from Kerala. J. Vet. Anim. Sci. 56 (4): 682-686