Inducers of interferon and host resistance. I. Double-stranded RNA from extracts of Penicillium funiculosum.

Abstract

Since interferon' per se shows little promise as a prophylactic or therapeutic agent, interest has shifted to a search for acceptable inducers by which the body might be stimulated to make its own interferon.Shope2 demonstrated that a substance which was derived from Penicilliumfuniculosum and which was called helenine induced resistance to Semliki Forest and to Columbia SK virus infections in mice. Lewis et al.3 fractionated helenine and prepared a factor active in the mouse assay which exhibited properties of a nucleoprotein. Rytel, Shope, and Kilbourne4 demonstrated that helenine elicited a viral inhibitor in cell cultures and in mice which exhibited properties similar to those of interferon. In commenting, they stated that "the active principle in helenine is still a matter of conjecture since it has not been obtained in a sufficiently pure form to permit definite identification." Studies in our laboratories during the past several years have been directed toward the discovery of an interferon inducer which would be worthy of clinical evaluation. It was found that certain ribonucleic acids were highly active in inducing interferon and host resistance but were dependent upon (a) freedom from inhibitory protein and (b) multistrandedness of the RNA. Ribonucleoproteins and single-stranded nucleic acids were inactive.This series of papers describes the purification or synthesis and characterization of three kinds of multistranded RNA active in inducing interferon and host resistance. The present report describes the isolation and characterization of a double-stranded RNA from extracts of Penicillium funiculosum (helenine) which, when freed of protein, is a highly active inducer of interferon and host resistance. The substance is referred to as HeI-RNA. Subsequent papers will present data showing high level interferon and host resistance-inducing activities of multistranded complexes of synthetic polynucleotides5 and of double-stranded RNA of reovirus origin.6 Materials and Methods.-(1) Extract of Penicitlium funiculosum:7 P. funiculosum was grown as described elsewhere.3 The mycelium was extracted with 0.033 M sodium phosphate buffer, pH 8.0, by rapid stirring for 1 hr at room temperature. The clarified extract was treated as shown in steps A-C of Table 1. The supernate served as starting material for fractionation and purification purposes.(2) Assay for interferon induction in rabbits: Young adult New Zealand white rabbits weighing 4-5 lb were injected intravenously with 0.5 ml of the material for assay. Blood samples were taken 2 hr later. The sera were assayed for interferon content in primary rabbit renal cell cultures in roller tubes or in plaque assay flasks by published procedures8 9 using vesicular. stomatitis virus for challenge. The titer of interferon was the highest initial dilution of rabbit serum which showed 100% suppression of viral cytopathic effect in 50(% or more of the tube cultures, or which effected at least 50% reduction in plaques compared with controls in the plaque assay. The plaque assay...

Toll‐Like Receptor 3: A Link between Toll‐Like Receptor, Interferon and Viruses

“…Both natural and synthetic double-stranded (ds) RNAs elicited IFN production (21,27). However, at that time the mechanisms by which cells recognize dsRNA and produce IFN remained elusive.…”

Induction of indoleamine 2,3-dioxygenase in mouse lung during virus infection.

“…Preliminary experiments in our laboratory indicated that poly(I)-poly(C), a potent inducer of interferon (24), induced the pulmonary IDO activity. However, the time course of the interferon induction by virus infection, poly(I)-poly(C), or LPS (25) always preceded that of the induction of IDO activity. These results suggest that interferon and IDO are different entities but may possibly be induced by a certain common mechanism.…”

Protein Kinase PKR Amplification of Interferon β Induction Occurs through Initiation Factor eIF-2α-mediated Translational Control

“…The innate immune system responds to a diverse array of pathogen-associated molecular patterns (PAMPS), 3 one of which is foreign RNA (1)(2)(3)(4). Among the cellular sensors of foreign RNAs are the retinoic acid-inducible protein (RIG-I)-like receptor (RLR) and Toll-like receptor (TLR) signaling networks that respond to viral RNA (4 -8).…”