Recombinant chicken interferon: a potent antiviral agent that lacks intrinsic macrophage activating factor activity

Abstract

Crude preparations of chicken interferon (ChIFN) from various sources contain both antiviral and macrophage-activating factor (MAF) activity. Previous serological data indicated that unlike mammals, birds might express only a single type of IFN in response to viruses and mitogens that exhibits both activities. We have now expressed a complementary DNA for virus-induced ChIFN in transfected COS cells and in Escherichia coli. Purified recombinant ChIFN is a powerful antiviral agent and has high Mx promoter-inducing activity. However, as the sole agent, recombinant ChIFN lacks MAF activity: it does not induce the secretion of nitric oxide in primary monocyte-derived chicken macrophages. A neutralizing antiserum prepared against cloned ChIFN blocks most of the antiviral and Mx promoter-inducing activity present in preparations of natural ChIFN, but does not inhibit the MAF activity. These results demonstrate that chicken cells can be induced to secrete a novel cytokine which probably represents the avian homolog of mammalian IFN-gamma.

Possible Involvement of the Double-Stranded RNA-Binding Core Protein ςA in the Resistance of Avian Reovirus to Interferon

“…The results shown in Fig. 1 and 2 of the present work, and those previously reported by other laboratories (50,51), clearly demonstrate that the rcIFN used in this study is a powerful antiviral-state inducer in chicken cells. The inhibition of viral protein synthesis observed in rcIFN-treated cells infected with VSV and vaccinia virus suggests that replication of these viruses is being affected at a translational or a pretranslational step.…”

“…The IFN used in this study has been shown to be a powerful inducer of the Mx gene promoter and also to inhibit VSV replication in CEC32 cells (50,51). To further characterize the antiviral properties of this rcIFN, we first investigated its capacity to induce increased expression of PKR and 2-5A synthetase in primary cultures of CEF.…”

“…Vaccinia virus and VSV were chosen as control viruses because they replicate efficiently in CEF and also because their sensitivity to avian IFN has been well documented. Specifically, VSV replication in CEF is very sensitive to chicken IFN, and therefore this virus is currently used to measure the antiviral activity of IFN preparations (37,(50)(51)(52). Vaccinia virus replication in CEF is inhibited by chicken IFN by posttranscriptional mechanisms (17,23,24).…”

“…Some of these proteins are believed to play a key role in counteracting the antiviral action of IFNs (32,50,63). To determine whether a similar dsRNA-binding activity was present in avian reovirusinfected cells, a fixed amount of 32 P-labeled S1133 dsRNAs was incubated with increasing amounts of S100 extracts from mock-infected or avian reovirus-infected CEF, and the resulting mixtures were analyzed by native PAGE and autoradiography (Fig.…”

Replication of Modified Vaccinia Virus Ankara in Primary Chicken Embryo Fibroblasts Requires Expression of the Interferon Resistance Gene E3L

“…The antiviral activity in tissue culture supernatants was quantified by a cytopathic effect inhibition assay (47) of chicken CEC-32 cells (74). Briefly, CEC-32 cells were grown to a monolayer in 96-well flat-bottom plates and cultured in the presence of triplicate samples of twofold serial dilutions of supernatants or COS cell-expressed recombinant chicken IFN-␣/␤ (recIFN-␣/␤) (50). After 24 h, cultures were infected with vesicular stomatitis virus and maintained for another 24 h. Viable cells were visualized by uptake of neutral red dye, dried, and lysed by the addition of 3 M guanidine-HCl.…”