Synthesis of IFN-β by Virus-Infected Chicken Embryo Cells Demonstrated with Specific Antisera and a New Bioassay

Schwarz, Heike; Harlin, Olof; Ohnemus, Annette; Kaspers, Bernd; Staeheli, Peter

doi:10.1089/107999004322917025

Cited by 44 publications

(28 citation statements)

References 22 publications

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“…This shows that DF-1 cells can sense AIV in the absence of RIG-I. Importantly, wild-type Vac-1/04 counteracts the activation of type I chIFN by means of the NS1 protein, as expected from previous reports (27,45).…”

Section: Df-1 Cells Respond To Danger Signals Mediated By H5n1 Aivsupporting

confidence: 85%

“…Bioactive type I chicken interferon (IFN) was measured using CEC-32 reporter cells (kindly provided by Peter Staeheli) adapted to 96-well plate format (33,45). To avoid interference with the bioassay, p(I:C) and IVT-RNA were removed from DF-1 or HD-11 cells after 3 h. Virus interference was avoided by the heat inactivation of the samples at 65°C for 30 min, which did not influence type I chIFN bioactivity.…”

Section: Methodsmentioning

confidence: 99%

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Chicken Cells Sense Influenza A Virus Infection through MDA5 and CARDIF Signaling Involving LGP2

Liniger¹,

Summerfield²,

Zimmer³

et al. 2012

J Virol

177

163

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Avian influenza viruses (AIV) raise worldwide veterinary and public health concerns due to their potential for zoonotic transmission. While infection with highly pathogenic AIV results in high mortality in chickens, this is not necessarily the case in wild birds and ducks. It is known that innate immune factors can contribute to the outcome of infection. In this context, retinoic acid-inducible gene I (RIG-I) is the main cytosolic pattern recognition receptor known for detecting influenza A virus infection in mammalian cells. Chickens, unlike ducks, lack RIG-I, yet chicken cells do produce type I interferon (IFN) in response to AIV infection. Consequently, we sought to identify the cytosolic recognition elements in chicken cells. Chicken mRNA encoding the putative chicken analogs of CARDIF and LGP2 (chCARDIF and chLGP2, respectively) were identified. HT7-tagged chCARDIF was observed to associate with mitochondria in chicken DF-1 fibroblasts. The exogenous expression of chCARDIF, as well as of the caspase activation and recruitment domains (CARDs) of the chicken melanoma differentiation-associated protein 5 (chMDA5), strongly activated the chicken IFN-␤ (chIFN-␤) promoter. The silencing of chMDA5, chCARDIF, and chIRF3 reduced chIFN-␤ levels induced by AIV, indicating their involvement in AIV sensing. As with mammalian cells, chLGP2 had opposing effects. While overexpression decreased the activation of the chIFN-␤ promoter, the silencing of endogenous chLGP2 reduced chIFN-␤ induced by AIV. We finally demonstrate that the chMDA5 signaling pathway is inhibited by the viral nonstructural protein 1. In conclusion, chicken cells, including DF-1 fibroblasts and HD-11 macrophage-like cells, employ chMDA5 for sensing AIV.

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Section: Df-1 Cells Respond To Danger Signals Mediated By H5n1 Aivsupporting

confidence: 85%

Section: Methodsmentioning

confidence: 99%

Chicken Cells Sense Influenza A Virus Infection through MDA5 and CARDIF Signaling Involving LGP2

Liniger¹,

Summerfield²,

Zimmer³

et al. 2012

J Virol

177

163

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“…IFN activity in supernatants from infected CEF, chicken plasma, and organ homogenates from infected birds was analyzed using a bioassay as described previously (41). Briefly, CEC-32 reporter cells containing a luciferase gene under the chicken Mx promoter were incubated with sample dilutions or an IFN-␣ standard.…”

Section: Ethics Statementmentioning

confidence: 99%

“…To monitor innate immune responses of infected chickens, virus-induced IFN was quantified using the previously described bioassay for chicken type I IFN (41). Substantial levels of IFN were measured as early as 12 h postinfection in the lungs, spleens, and blood plasma of R65-infected chickens (Fig.…”

Section: Ns1 Mutants Of An H5n1 Hpaiv Induce More Type I Ifn Than Thementioning

confidence: 99%

Highly Pathogenic Avian Influenza Viruses Do Not Inhibit Interferon Synthesis in Infected Chickens but Can Override the Interferon-Induced Antiviral State

Penski

Härtle

Rubbenstroth

et al. 2011

J Virol

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From infection studies with cultured chicken cells and experimental mammalian hosts, it is well known that influenza viruses use the nonstructural protein 1 (NS1) to suppress the synthesis of interferon (IFN). However, our current knowledge regarding the in vivo role of virus-encoded NS1 in chickens is much more limited. Here, we report that highly pathogenic avian influenza viruses of subtypes H5N1 and H7N7 lacking fully functional NS1 genes were attenuated in 5-week-old chickens. Surprisingly, in diseased birds infected with NS1 mutants, the IFN levels were not higher than in diseased birds infected with wild-type virus, suggesting that NS1 cannot suppress IFN gene expression in at least one cell population of infected chickens that produces large amounts of the cytokine in vivo. To address the question of why influenza viruses are highly pathogenic in chickens although they strongly activate the innate immune system, we determined whether recombinant chicken alpha interferon (IFN-␣) can inhibit the growth of highly pathogenic avian influenza viruses in cultured chicken cells and whether it can ameliorate virus-induced disease in 5-week-old birds. We found that IFN treatment failed to confer substantial protection against challenge with highly pathogenic viruses, although it was effective against viruses with low pathogenic potential. Taken together, our data demonstrate that preventing the synthesis of IFN is not the primary role of the viral NS1 protein during infection of chickens. Our results further suggest that virus-induced IFN does not contribute substantially to resistance of chickens against highly pathogenic influenza viruses.The nonstructural protein 1 (NS1) of influenza A virus serves multiple functions in the viral life cycle. It regulates viral polymerase activity, and it modulates cellular signaling pathways (for a review, see reference 14). It is well established that NS1 can suppress innate immune responses in infected cells by blocking intracellular signaling pathways that lead to the synthesis of type I and type III interferon (IFN). Specifically, NS1 inhibits ubiquitinylation of RIG-I by TRIM25, thereby preventing efficient induction of IFN in infected cells (9,12,28,35). The NS1 proteins of most influenza viruses block global posttranscriptional processing of cellular mRNAs, including mRNAs encoding 27,33,34). NS1 further inhibits specific antiviral effector proteins, such as 2Ј-5Ј oligoadenylate synthetase (OAS) (29) and double-stranded RNA (dsRNA)-activated protein kinase (PKR) (23,30). In addition, NS1 was shown to modulate host cell apoptosis (39, 55), stimulate phosphoinositol 3-kinase signaling (13), and regulate viral polymerase activity (2, 30).Current knowledge regarding the in vivo functions of NS1 is mainly based on studies in mice with targeted deletions of several key components of the IFN system. Viruses expressing defective NS1 proteins are generally strongly attenuated in hosts with an intact IFN system but retain a high degree of virulence in hosts with defective IFN syst...

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“…A previous study showed that IV-infected primary chicken embryo cells produced a mixture of type I IFNs of usually more than 80% IFN-␣ and up to 20% IFN-␤ (26). Recent studies have indicated that in the chicken embryo we already find significant expression of type I IFN in the spleen starting at embryonation day 14 (27 (28).…”

mentioning

confidence: 97%

Reassortment of NS Segments Modifies Highly Pathogenic Avian Influenza Virus Interaction with Avian Hosts and Host Cells

Petersen¹,

Wang

Lenz

et al. 2013

J Virol

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Synthesis of IFN-β by Virus-Infected Chicken Embryo Cells Demonstrated with Specific Antisera and a New Bioassay

Abstract: Transcripts of interferon-a (IFN-a

Cited by 44 publications

References 22 publications

Chicken Cells Sense Influenza A Virus Infection through MDA5 and CARDIF Signaling Involving LGP2

Chicken Cells Sense Influenza A Virus Infection through MDA5 and CARDIF Signaling Involving LGP2

Highly Pathogenic Avian Influenza Viruses Do Not Inhibit Interferon Synthesis in Infected Chickens but Can Override the Interferon-Induced Antiviral State

Reassortment of NS Segments Modifies Highly Pathogenic Avian Influenza Virus Interaction with Avian Hosts and Host Cells

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