Pre-immune state induced by chicken interferon gamma inhibits the replication of H1N1 human and H9N2 avian influenza viruses in chicken embryo fibroblasts.

Seong-Su Yuk,Jin-Yong Noh,Seung-Yong Park,Erdene-Ochir Tseren-Ochir,Jung-Hoon Kwon,Joong-Bok Lee,Dong-Hun Lee,In-Soo Choi,Chang-Seon Song,Jae-Keun Park

doi:10.1186/s12985-016-0527-1

Abstract

BackgroundInterferon gamma (IFN-γ), an immunoregulatory cytokine, is known to control many microbial infections. In a previous study, chicken interferon gamma (chIFN-γ) was found to be up-regulated following avian influenza virus (AIV) infection in specific pathogen-free chickens. We aimed to investigate whether the pre-immune state induced by chIFN-γ could generate an antiviral response against influenza virus.MethodsWe generated a chIFN-γ-expressing plasmid and transfected it into chicken embryo fibroblasts (CEFs) and then infected the cells with human origin H1N1 or avian origin H9N2 influenza viruses. Viral titers of culture medium were evaluated in MDCK cell and the viral RNA and IFN-stimulated genes (ISGs) were then quantified by real-time reverse transcriptase polymerase. To further evaluate the role of the antiviral effect of chIFN-γ by using a backward approach, synthetic small interfering RNAs (siRNA) targeting chIFN-γ were used to suppress chIFN-γ.ResultsThe chIFN-γ-stimulated CEFs inhibited the replication of viral RNA (vRNA) and showed a mild decrease in the infectious virus load released in the culture medium. Compared to the mock-transfected control, the messenger RNA (mRNA) levels of type I IFNs and IFN-stimulated genes were up-regulated in the cells expressing chIFN-γ. After treatment with the siRNA, we detected a higher expression of viral genes than that observed in the mock-transfected control.ConclusionsOur results suggest that apart from the important role played by chIFN-γ in the antiviral state generated against influenza virus infection, the pre-immune state induced by chIFN-γ can be helpful in mitigating the propagation of influenza virus.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-016-0527-1) contains supplementary material, which is available to authorized users.

Highlights

Interferon gamma (IFN-γ), an immunoregulatory cytokine, is known to control many microbial infections
JAK/STAT signaling via IFNAR1 and IFNAR2 enhances the expression of many antiviral proteins, including myxovirus-resistance protein (Mx) GTPase, RNAdependent protein kinase (PKR), latent ribonuclease (RNaseL), and oligo-adenylate synthetase (OAS)
The samples were reduced by 5 % 8-mercaptoethanol, we suppose that a dimeric form of Chicken IFN-γ (chIFN-γ) was observed at 48 h after transfection in minor quantities which was not reduced

Summary

Introduction

Interferon gamma (IFN-γ), an immunoregulatory cytokine, is known to control many microbial infections. Influenza A virus is an enveloped virus from the Orthomyxoviridae family, with an eight-segmented, singlestranded, negative-sense RNA genome. The members of the type I interferon (IFN) family induce antiviral states by binding to a common receptor, consisting of two interferon-α/β receptor subunits. JAK/STAT signaling via IFNAR1 and IFNAR2 enhances the expression of many antiviral proteins, including myxovirus-resistance protein (Mx) GTPase, RNAdependent protein kinase (PKR), latent ribonuclease (RNaseL), and oligo-adenylate synthetase (OAS). These IFN-induced antiviral proteins play a critical role in innate, as well as adaptive, immune responses against viral infections [6]. The involvement of common signaling pathways means that IFN-γ can activate type I IFNs, and may explain many overlapping effects of type I and II IFNs [9]

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