Ultraviolet-irradiated Newcastle Disease Virus Research Articles

Differences in mouse interferons according to cell source and mode of induction.

Mouse interferon induced by ultraviolet-irradiated Newcastle disease virus or polyriboinosinic-polyribocytidylic acid in T lymphocytes, B lymphocytes, macrophages, and primary mouse embryonic cell culture was studied. Irrespective of the inducer, interferons produced by T or B lymphocytes were relatively heat stable and of low antigenicity when reacted with antiserum against L-cell interferon (ALI), whereas interferons produced by macrophages and mouse embryo cells were heat labile and of high antigenicity against ALI. Mouse interferons induced by ultraviolet-irradiated Newcastle disease virus were separated into three components by chromatography on CH-Sepharose 4B. Interferons produced by T and B lymphocytes consisted primarily of component 1 (unbound fraction), whereas interferons produced by macrophages or mouse embryo cells consisted primarily of component 3 (eluted by 0.5 M NaCl). Component 1 was heat stable and of low antigenicity against ALI, properties characteristic of T- and B-cell interferon. Components 2 and 3 were heat labile and of high antigenicity against ALI, properties characteristic of macrophage and mouse embryo cell interferon. In contrast, interferon induced in mice sensitized with BCG differed from these interferons induced in B cells, T cells, macrophages, and fibroblasts in being extremely acid labile and nonreactive against ALI.

Effect of antiviral agents in equine abortion virus-infected hamsters.

Equine abortion virus, a member of the herpesvirus group, produces a lethal infection in hamsters. With this system, the protective effect of certain inhibitors of deoxyribonucleic acid viruses, inducers of interferon and exogenous interferon, was evaluated. Of the various agents studied, 9-beta-d-arabinofuranosyladenine markedly suppressed mortality, and 5-iodo-2'-deoxyuridine, distamycin A, and N-ethylisatin beta-thiosemicarbazone were inactive. Of the inducers tested, statolon, ultraviolet-irradiated Newcastle disease virus, and polyriboinosinic:polyribocytidylic acid (poly I:C) were protective, and endotoxin, polyacrylic acid, and polymethacrylic acid did not protect. Administration of exogenous interferon did not afford protection. Statolon and ultraviolet-irradiated Newcastle disease virus induced circulating interferon in hamsters, whereas poly I:C, endotoxin, and polyacrylic acid did not produce interferon. Because of the severity of the disease produced in hamsters by equine abortion virus, lack of protective activity by an agent in this system should not preclude possible efficacy against other members of the herpesvirus group.

Superinfection of HVJ carrier HeLa cells with ultraviolet-irradiated Newcastle disease virus.

The mechanism of enhancement of growth of partially ultraviolet (UV)-inactivated Newcastle disease virus (NDV) in HeLa cells persistently infected with hemagglutinating virus of Japan (HVJ) (HeLaHvJ) was investigated. HeLaHVJ cells and normal HeLa cells were inoculated with UV-irracliated NDV under similar experimental conditions, and numbers of both infective centers and NDV-antigen producing cells in each culture were counted. It was found that the percentage of HeLaHVJ cells which produced infectious NDV or NDV-antigen during the first cycle of infection was approximately 1.5 times higher than that of normal HeLa cells. Survival curves of UV-irradiated NDV showed that NDV appeared more resistant to UV when titrated in HeLaHVJ cells than in assay in normal HeLa cells. Possible explanations for this phenomenon were discussed

Relationship between the ribonucleic acid synthesizing capacity of ultraviolet-irradiated Newcastle disease virus and its ability to induce interferon.

Ultraviolet (UV)-irradiated Newcastle disease virus which has lost its infectivity but has the capacity to induce interferon also has the capacity to induce ribonucleic acid (RNA) synthesis both in vitro and early in infection in vivo. With large doses of UV irradiation, RNA-synthesizing capacity and interferon-inducing capacity are lost in parallel. Limited amounts of base-paired RNA associated with a transcriptive intermediate are involved in this RNA synthesis. These findings suggest the possibility that the single-stranded RNA of the UV-irradiated virus induces interferon by serving as a template for the synthesis of base-paired RNA. UV irradiation of the virus breaks down viral RNA but at a rate which is too slow to be a major cause of the loss of RNA-synthesizing capacity. Evidence is presented which suggests that less of the template RNA of the UV-irradiated virus is copied and that the product which is synthesized is smaller than that synthesized by nonirradiated virus.

Virus RNA Synthesis by Ultraviolet-irradiated Newcastle Disease Virus and Interferon Production

Virus ribonucleic acid molecules are known to induce formation of interferon. Previous reports have demonstrated the inducing activity of the double-stranded RNA extracted from reovirus (Tytell, et al. 1967), or of double-stranded RNA formed within cells infected with RNA or DNA viruses (Field, et al. 1967; Skehel & Burke, 1968; Falcoff & Falcoff, 1969; Colby & Duesberg, 1969). Gandhi & Burke (1970), using u.v.-irradiated fowl plague or Newcastle disease viruses, showed that interferon production occurred in the absence of any detectable RNA synthesis, and the authors suggested that the single-stranded RNA of the virus was the inducer of interferon formation. Lomniczi & Burke (1970) arrived at a similar conclusion using Semliki Forest virus as an inducer. However, Huppert, Hillova & Gresland (1969) reported that u.v.-irradiated Newcastle disease virus which was totally unable to produce infectious virus was still able to synthesize virus RNA in infected cells, as detected by a hybridization method.

Cellular Mechanisms of Interferon Production

Rabbit kidney cell cultures stimulated with either double-stranded polyinosinate-polycytidylate (poly I:poly C) or with ultraviolet-irradiated Newcastle disease virus (UV-NDV) produce two types of interferon response, designated "early" and "late," respectively. The early response is suppressed by inhibitors of RNA or protein synthesis and is therefore thought to represent de novo synthesis of interferon. Circumstantial evidence suggested that this interferon response is regulated by a translation control mechanism. Late interferon production with poly I:poly C only took place in the presence of inhibitors of RNA or protein synthesis. The late interferon is therefore likely to be derived by the activation of an interferon precursor. The stimulation of late poly I:poly C-induced interferon production by cycloheximide suggested the existence of a second, posttranslational level of control of interferon production. This posttranslation control seems to be activated by interferon. UV-NDV can probably suppress the synthesis of the posttranslation inhibitory protein, and therefore it stimulates a late interferon response in the absence of inhibitors of RNA or protein synthesis. It is postulated that both the translation and posttranslation inhibitor participate in the development of a cellular refractory state to repeated interferon stimulation. The picture of interferon which emerges from this study is one of a heterogenous class of proteins whose production is controlled by cellular repressors acting at various levels.

Depressors of Interferon Synthesis: Inhibition of Interferon Synthesis by Chick Allantoic Mucopolysaccharide, Capsular Polysaccharide of Klebsiella pneumoniae and Heparin

SUMMARY Three kinds of polyanionic polysaccharides, chick allantoic mucopolysaccharide, capsular polysaccharide of Klebsiella pneumoniae and heparin depressed interferon synthesis induced by ultraviolet-irradiated Newcastle disease virus in chick embryo cells. The minimum concentrations causing complete inhibition of interferon synthesis were respectively 20, 0.5 and 50 μg./ml. The polysaccharides did not affect the action of exogenous interferon at concentrations sufficient to depress interferon synthesis. It seems unlikely that these polysaccharides were toxic for the cells, and that the depression of interferon synthesis was due to an inhibition of the early steps of virus-cell interaction.

Viral RNA Synthesis in Chicken Cells infected with Ultraviolet Irradiated Newcastle Disease Virus

Viral RNA Synthesis in Chicken Cells infected with Ultraviolet Irradiated Newcastle Disease Virus

A factor capable of enhancing interferon synthesis

In chick embryo cells aged for several days in vitro, interferon synthesis induced by ultraviolet-irradiated Newcastle disease virus occurs faster and reaches a higher maximum level than in 1-day-old cultures. The enhanced capacity to produce interferon appears to be mediated by a factor produced in aging cultures of chick embryo cells and released into the medium. The factor exhibits properties of a protein.

QUANTITATIVE STUDIES ON VIRAL INTERFERENCE IN SUSPENDED L CELLS. IV. PRODUCTION AND ASSAY OF INTERFERON.

Abstract The production and release of interferon in suspended L cells on single exposure to ultraviolet-irradiated Newcastle disease virus (NDV UV ) was largely completed within 24 hours. At that time, the cells harbored little detectable interferon activity. The amounts of interferon produced by either irradiated or active NDV were independent of a wide range of virus concentrations. After a first harvest of interferon was obtained, the cells could not immediately thereafter be restimulated by inactivated or viable NDV to yield a second crop. Cells exposed to interferon for 24 hours were equally refractory. The ability of the cultures to synthesize interferon was fully regained only after two cell divisions had occurred. No differences could be demonstrated between the adsorption of NDV onto refractory or normal cells. The interfering activity of NDV UV is more stable at low pH than the ability to agglutinate chicken or guinea pig red cells. Hence, dialysis against pH 2 does not readily achieve complete elimination of interference due to NDV UV from interferon preparations. The number of plaques produced by a given dose of vesicular stomatitis virus (VSV) on monolayers prepared from mixtures in varying proportions of interferon-treated and normal L cells, was inversely proportional to the density of the resistant cells. This indicates that the percentage of plaque reduction obtained in interferon assays offers a direct measure of the proportion of cells incapable of yielding virus.

Studies on viral interference in two lines of HeLa cells

The S3 and F lines of HeLa cells were compared as to production of interferon and behavior in interference assays. Protection against vesicular stomatitis virus was readily established in both lines by ultraviolet-irradiated Newcastle disease virus (NDV uv) but in neither by influenza virus (PR8 uv). However, on exposure to NDV uv the S3 line yielded at least 10–50 times less interferon than either F or primary human amnion cells. The age of the culture had a pronounced effect on the sensitivity of S3 cells to NDV uv and to interferon, whereas the behavior of F cells was not age dependent. Thus, 1- to 2-day-old S3 cultures required much larger doses for protection than 6- to 10-day-old cultures, which were as sensitive to interferon as F HeLa, primary, and continuous human amnion cells. The implications of these findings as regards the cancerous origin of the HeLa lines and their sensitivity to interferon have been discussed.

Loss of viral receptors in homologous interference by ultraviolet-irradiated Newcastle disease virus

When homologous interference is established in chick cells through the use of ultraviolet-irradiated Newcastle disease virus, the host cells lose their ability to adsorb active virus. After adsorption of about 10 irradiated particles per cell, specific anti-NDV serum can restore the cells to their original infectible state if employed within 30 minutes after exposure to the interfering agent. The ability of cells to adsorb virus was still absent 49 hours after the addition of irradiated virus. The induction of interference was shown to be temperature-dependent and there was some correlation between the enzymatic activity of the virus and its interfering ability. The data suggest that the interfering agent modifies the cell surface from an extracellular position.