Inhibition of Sindbis virus plaque formation by extracts of Escherichia coli

Bacterial lipopolysaccharide (endotoxin) enhances expression and secretion of beta 2 interferon by human fibroblasts

The human beta 2 interferon (IFN-beta 2) gene, a gene that also codes for B cell differentiation factor 2 (BSF-2), plasmacytoma/hybridoma growth factor (HGF), and hepatocyte-stimulating factor (HSF), is expressed in a variety of lymphoid and nonlymphoid tissues. Endotoxin, or bacterial lipopolysaccharide (LPS) preparations derived from the outer membrane of Escherichia coli or Salmonella typhimurium rapidly elevate IFN-beta 2 mRNA level in human skin fibroblasts (FS-4 strain). E. coli-derived LPS enhances IFN-beta 2 mRNA expression in FS-4 fibroblasts at a concentration as low as 0.3 ng/ml; this response is near-maximal in the range of 0.1-1 microgram/ml LPS. The increase in IFN-beta 2 mRNA level caused by LPS in FS-4 cells is detected within 30 min after addition of LPS, is sustained for at least 20 h thereafter, appears to involve the protein kinase C signal transduction pathway, does not require new protein synthesis, and is inhibited by dexamethasone in a dose-dependent fashion (in the range 10(-6)-10(-8) M). Cultures of LPS-treated FS-4 cells exhibit an antiviral state against vesicular stomatitis virus, which can be prevented by anti-IFN-beta antiserum. Medium obtained from LPS-treated FS-4 cell cultures enhances the number of immunoglobulin-secreting cells in cultures of human B-lymphoblastoid (CESS) cells. Thus, LPS may trigger a number of host defense mechanisms in the course of infection due to Gram-negative bacteria by enhancing IFN-beta 2 production by the ubiquitous fibroblast.

Influence of the rate of cell growth and cell density on interferon action in chick embryo cells

Chick embryo cells became more sensitive to the action of interferon the longer they remained in culture. This phenomenon was found even before confluency had been reached. The relative insensitivity of newly seeded cells was not due to a loss of receptors. Cells synthesizing deoxyribonucleic acid (DNA) at a high rate were less sensitive to interferon action than cells synthesizing DNA at a low rate, but the inhibition of DNA synthesis had no effect on interferon action. An increase in the number of cells used for seeding resulted in an earlier appearance of increased sensitivity to interferon action. These results are discussed in relation to the induction process in animal cells.

Interferon inducers protect mice against plasmodium berghei malaria

Injection of mice with two interferon inducers, Newcastle disease virus or statolon, 20 hours after inoculation with Plasmodium berghei sporozoites, prevented or delayed the development of detectable malarial parasitemia and death.

Antiviral agent from lambda-infected Escherichia coli K-12. I. Isolation

Phagicin, which is an antiviral agent active against deoxyribonucleic acid (DNA) viruses such as vaccinia and herpes simplex, has been identified as a phage internal protein. It was found in infected Escherichia coli lysates, but could also be obtained by disruption of the purified infective particles after incubation with LiCl at 46 C for 15 min or by sonic treatment. After centrifugation at high speed, the antiviral activity was found in the DNA phase and could be separated by chromatography on Sephadex gels with 0.2 M phosphate buffer (pH 7.5) as the eluent. Phagicin present in lysates after removal of infective particles was nondialyzable and was bound to nucleic acids. It could be released during precipitation of nucleic acids by streptomycin sulfate, and in this form it could be easily dialyzed. The antiviral activity of phagicin was specific for herpes simplex and vaccinia viruses.