The In Ovo Delivery of CpG Oligonucleotides Protects against Infectious Bronchitis with the Recruitment of Immune Cells into the Respiratory Tract of Chickens.

Upasama De Silva Senapathi,Markus Czub,Guido Van Marle,Mohamed Abdul-Cader,Susantha Gomis,Aruna Amarasinghe,Mohamed Abdul-Careem

doi:10.3390/v10110635

Upasama De Silva Senapathi, Markus Czub + Show 5 more

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https://doi.org/10.3390/v10110635

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Journal: Viruses	Publication Date: Nov 15, 2018
Citations: 61	License type: CC BY 4.0

Affiliation: University of Calgary, University of Saskatchewan

Abstract

The in ovo delivery of cytosine-guanosine (CpG) oligodeoxynucleotides (ODNs) protects chickens against many bacterial and viral infections, by activating the toll-like receptor (TLR)21 signaling pathway. Although the delivery of CpG ODNs in ovo at embryo day (ED) 18 has been shown to reduce infectious bronchitis virus (IBV) loads in embryonic chicken lungs pre-hatch, whether in ovo delivered CpG ODNs are capable of protecting chickens against a post-hatch challenge is unknown. Thus, our objectives were to determine the protective effect of the in ovo delivery of CpG ODNs at ED 18 against IBV infection encountered post-hatch and, then, to investigate the mechanisms of protection. We found significantly higher survival rates and reduced IBV infection in the chickens following the pre-treatment of the ED 18 eggs with CpG ODNs. At 3 days post infection (dpi), we found an increased recruitment of macrophages, cluster of differentiation (CD)8α+ and CD4+ T lymphocytes, and an up-regulation of interferon (IFN)-γ mRNA in the respiratory tract of the chickens. Overall, it may be inferred that CpG ODNs, when delivered in ovo, provide protection against IBV infection induced morbidity and mortality with an enhanced immune response.

Highlights

Infectious bronchitis (IB) is mainly an acute and severe disease of the respiratory system of chickens [1]
We found that in ovo delivery was protective against infectious bronchitis virus (IBV) challenge post hatch, suggesting a potential lasting protective effect of CpG ODNs towards IBV infection, which could be exploited for developing control measures
We have shown in this study that CpG ODNs when delivered in ovo are capable of protecting young chickens against a post-hatch IBV infection induced IB

Summary

Introduction

Infectious bronchitis (IB) is mainly an acute and severe disease of the respiratory system of chickens [1]. The causative agent, infectious bronchitis virus (IBV), belongs to the family. There is increasing evidence of IBV infection being reported in birds other than chickens [3,4]. IBV induced changes are observed primarily in the mucosal surfaces of the respiratory tract, the virus is known to cause pathology in the female reproductive tract and kidneys, with a varying degree of severity dependent upon the type of strain that infects and replicates in the aforementioned tissues [5,6,7]. Ever since the first record of IB in the early 1930s [8], periodic IB outbreaks associated with the isolation of heterogeneous strains of IBV have been reported globally [1,9]. Major losses to the broiler meat industry are due to carcass condemnation at processing, a poor feed conversion ratio

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