Effect of TLR agonist on infections bronchitis virus replication and cytokine expression in embryonated chicken eggs. (April 2020)

• Record Type: Journal Article
• Authors: Sharma, Bal Krishan; Kakker, Naresh Kumar; Bhadouriya, Sakshi; Chhabra, Rajesh
• Is Part Of: Molecular immunology. Volume 120(2020:Apr.)
• Page Start: 52
• Page End: 60
• Publication Date: 2020-04
• Subjects: Infectious bronchitis virus -- TLR ligands -- Embryonated chicken eggs -- Cytokine expression -- IBV replication; Immunochemistry -- Periodicals; Molecular biology -- Periodicals; Immunochemistry -- Periodicals; Allergy and Immunology -- Periodicals; Molecular Biology -- Periodicals; Immunochimie -- Périodiques; Biologie moléculaire -- Périodiques; Immunochemistry; Molecular biology; Periodicals; Electronic journals; 571.96
• DOI: 10.1016/j.molimm.2020.02.001
• Languages: English
• ISSNs: 0161-5890

Abstract

Highlights: TLR agonists (LPS, Pam3CSK4 and CpG ODN), when administered in ovo in chicken embryo interfered with the replication of IBV. Time & optimum dose of TLR agonists can interfere with the replication of IBV. All the TLR agonists up-regulated the expression of different pro-inflammatory cytokines. The antiviral genes in CAM of ECEs that may play an important role in inhibition of IBV replication. LPS appeared to be the better candidate for adjuvant against IBV. Abstract: Avian infectious bronchitis (IB) is an acute, highly infectious and contagious viral disease of chickens caused by avian infectious bronchitis virus (IBV) belonging to the genus Coronavirus and family Coronaviridae. It can affect all age groups of birds. The toll-like receptors (TLRs) are a major class of innate immune pattern recognition receptors that have a key role in immune response and defense against various infections.The TLRs are essential for initiation of innate immune responses and in the development of adaptive immune responses. An in ovo model was employed to study the antiviral activity of TLR ligands (Pam3CSK4, LPS and CpG ODN) on replication of IBV. It was hypothesized that optimum dose and specific timing of TLR ligands may reduce viral load of IBV in specific pathogen free (SPF) embryonated chicken eggs (ECEs). Further, the mechanism involved in the TLR-mediated antiviral response in chorioallantoic membrane (CAM) of ECEs was investigated. The ECEs of 9–11 days old were treated with different doses (high, intermediate and low) of TLR-2 (Pam3CSK4), TLR-4 (LPS) and TLR-21 (CpG ODN) ligands. In addition, to know the timing of TLR ligand treatment, six time intervals were analyzed viz. 36, 24 and 12 h prior to infection, time of infection (co-administration of TLR ligands and avian IBV) and 12 and 24 h post-IBV infection. For studying the relative expression of immuno-stimulatory genes ( IFN-α, IFN-β, IFN-γ, IL-1β, iNOS and OAS ) in CAM, TLR ligands were administered through intra-allantoicroute and CAM were collected at 4, 8 and 16 h post treatment. The results demonstrated that intermediate dose of all the three TLR ligands significantly reduced virus titers and used in the present study. However, the LPS reduced virus titer pre- and post-IBV infection but Pam3CSK4 and CpG ODN reduced only pre-IBV infection. Further analysis showed that TLR ligands induced IFN-γ, IL-1β and IFN stimulated genes viz . iNOS and OAS genes in CAM. The present study pointed towards the novel opportunities for rational design of LPS as immuno-stimulatory agent in chickens with reference to IBV. It may be speculated that in ovo administration of these TLR ligands may enhance resistance against viral infection in neonatal chicken and may contribute towards the development of more effective and safer vaccines including in ovo vaccines.