Transforming growth factor-beta inhibits the antiviral action of interferons in human embryonic fibroblasts.

Transforming growth factor-beta (TGF-beta) at concentration of 10 ng/ml inhibited the development of the interferon-alpha- (IFN-alpha) or IFN-gamma-induced antiviral state in quiescent human embryonic fibroblasts. The action of the cytokines was dose-related; TGF-beta had no direct effect on the replication of either vesicular stomatitis virus (VSV) or encephalomyocarditis virus (EMCV) used as the challenge viruses in the IFN assays. We suggest that despite the fact that TGF-beta acts mainly as a "negative" growth factor, its interactions with IFNs in the antiviral assays resemble known effects of the typical "positive" peptide growth factors.

Bovine transforming growth factor beta. Purification and characterization.

Polypeptide growth factor isolated from bovine platelets was classified on the basis of its physico-chemical and biological properties to be transforming growth factor type beta (TGF beta). This growth factor was completely purified from platelet lysate by acid ethanol extraction, Bio-Gel P-60 filtration, ion-exchange chromatography on CM-Sephadex followed by two successive gel filtrations on Bio-Gel P-10 and Sephadex G-100. After the last gel filtration over 35,000-fold purified TGF beta was obtained. The purity of the preparation was confirmed by SDS-polyacrylamide gel electrophoresis, which revealed a single protein band with Mr of 25,000-27,000. Further studies showed that native TGF beta consists of two Mr 13,000 polypeptide chains held together by disulfide bonds.

Choline and halogen derivatives of CMA (9-oxo-10-acridine acetic acids) as tools for monitoring the interaction of the interferon inducers via a specific receptor.

New choline and halogen derivatives of CMA (9-oxo-10-acridine acetic acid) were investigated as interferon (IFN) inducers in mice and in the mouse bone marrow-derived macrophage cultures. Two of the choline derivatives, DMCMA and CSCMA, were active IFN inducers presumably because they were hydrolyzed so as to release CMA. The halogen analogues of CMA were inactive or weak IFN inducers in vivo and in vitro. On the contrary, the Br and I derivatives of CMA were potent inhibitors of IFN induction by CMA in vitro. The behavior of the agonists and antagonists of CMA suggests that the induction of interferon may occur indirectly via a specific CMA-receptor complex.

Tolerance or hyperreactivity to interferon induction by sodium salt of 9-oxo-10-acridineacetic acid and analogs in mice and in the mouse macrophage cultures.

Choline and halogen analogs of 9-oxo-10-acridineacetic acid (CMA) were studied as IFN inducers in mice and in the mouse bone marrow-derived macrophage cultures. Two of the choline analogs--DMCMA and CSCMA were inducers of IFN in the macrophages. The response was found to be dose related. CMA as well as the active analogs were found to induce the hyporeactive state to IFN induction both in mice and in the mouse macrophage cultures. On the other hand, the inhibitor of IFN induction by CMA--the dibromo analog (DBCMA) was found to induce in mice a hyperreactive state to IFN induction by CMA.

Induction of interferon in mice by sodium salt of 9-oxo-10-acridineacetic acid: specific enhancement by analogs.

9-oxo-10-acridineacetic acid bearing the common name of 10-carboxymethyl-9-acridanone or CMA (6) was found to be a very potent interferon (IFN) inducer in adult Balb/c mice. Seven structural analogs of CMA were synthetized and assayed for the interferon inducing ability. Three of the compounds had new chemical structures. The analogs were shown to be either weak or inactive interferon inducers. However, some of the analogs administered intraperitoneally (i.p.) or orally (p.o.) either 2 h before CMA or together with the active inducer enhanced by 10 to 60-fold the serum interferon response. We suggest that CMA induces interferon indirectly via a specific protein receptor. The specific enhancement of the serum interferon response to CMA by its inactive analogs may be explained in terms of the competition of the compounds for binding sites at the acceptor or transporting protein molecules. In the presence of an analog of CMA greater amount of free CMA may be available for the receptors in the target cells than when CMA acts alone. Only CMA bound to the receptor would be biologically active whereas the complexes of the compounds with the acceptor are biologically inert.

Hormonal-like modulation of growth of moloney virus-induced tumors by interferon and platelet-derived growth factor.

Continued intramuscular (i.m.) administration of highly purified preparations of mouse interferon (MuIFN) and/or bovine platelet-derived growth factor (PDGF) to the Moloney sarcoma virus (MSV) infected Balb/c mice resulted in a hormonal-like modulation of growth of tumors. Large dose MuIFN treatment (10(5) units per mouse daily, for 14 days) inhibited the MSV-induced tumors. On the other hand, small-dose MuIFN treatment (100 units per mouse daily, for 14 days or 10(4) units per mouse, every second day in 3-4 doses) enhanced the tumor growth. The simultaneous administration of large doses of MuIFN and PDGF significantly diminished the antitumor effect of IFN. The results suggest that the negative and positive interaction between IFN and PDGF takes place in vivo.

Platelet-derived growth factor (PDGF) enhances the growth of Moloney sarcoma virus-induced tumors in mice.

The intramuscular (i.m.) administration of bovine or human platelet derived growth factor (PDGF) had a marked potentiating effect on the growth of Moloney sarcoma virus (MSV)-induced tumors in Balb/c mice. PDGF had the tumor-promoting-activity when administered i.m. on the side of inoculation of MSV two days after the virus, and subsequently every second day for 2-3 weeks. The extent of MSV-induced tumor promoting activity of PDGF was age and sex-related. In view of the recently described antagonism in action between growth factors and interferons it is suggested that both families of hormones play an important role in controlling the neoplastic proliferation.

Dextran T fractions substituted with cibacron blue F3G-A as carriers for mouse interferon.

Commercial dextran T fractions covering the molecular weight (Mt) range 10,000-2,000,000 were substituted with a covalently linked chromophore: Cibacron blue F3G-A. Mouse interferon (IF) was found to bind firmly to the blue dextran (BD) fractions. Fractions of high Mt (BD 2000 and BD 500) associated with IF are precipitated from the solution by polyethylene glycol (PEG). Fractions of lower Mt (BD 70, BD 40 and BD 10) associated with IF are only partially, if at all, precipitated by PEG. However, when BD-IF complexes of various Mt were analyzed by chromatography on Sephadex G-150, IF activity migrates together with BD and not at the distance characteristic of native IF. These data suggested that IF is bound to various BD fractions. BD-IF complexes of various Mt have almost the same antiviral and anticellular activities as native IF. BD-IF complexes are neutralized to a greater extent by antibody than native IF. Clearance of BD 70-IF complex from the mouse peritoneal cavity is slightly slower than native IF. However, the i.v. clearance of both forms of IF is almost the same.

Effect of anti-mouse type-1 interferon globulin on the evolution of Moloney sarcoma virus induced disease in mice.

The prolonged administration of potent sheep anti-mouse type-1 interferon globulin (anti-IF IgG) had a marked potentiating effect on Moloney sarcoma virus (MSV) infection in mice. The extent of resistance to the MSV-induced disease was age-related. In 4-week-old BALB/c mice, anti-IF IgG consistently induced 70-80% mortality due to the progression of early or late tumours and erythroleukaemia, whereas mortality of control mice was significantly lower. The same effect was obtained in 1-year-old BALB/c mice. However, in 4-week-old C57BL/6 or 6-week old BALB/c mice, anti-IF IgG enhanced only the growth of early tumours but had no effect on their regression. Antigenic stimulation with normal sheep globulin suppressed the growth of early tumours in suckling BALB/c or C57BL/6 mice and enhanced the evolution of late MSV-induced disease in older mice.

Antigenic similarity of morphologic type CIII1 bacteriophages.

The aim of the study was to demonstrate antigenic differentiation among bacteriophages belonging to the same morphologic type--CIII1 according to Krzywy and Slopek or A2 according to Ackermann. Twenty-six bacteriophages which multiplied on various strains of bacteria of the genera Escherichia, Shigella and Klebsiella, were studied. Serologic tests were done by the quantitative complement fixation test. Immune sera against 5 phi E. coli. D8 Sh. flexneri, G35 Sh. sonnei and Kl7 Klebsiella bacteriophages were obtained from rabbits. It was shown that bacteriophages of CIII1 morphologic type, with morphologically identical virion had different antigenic specificity. On the basis of results obtained the phages could be divided into eight serologic groups. The bacteriophages for which antisera were obtained belonged to four different serologic groups. All bacteriophages had some common antigens with 5 phi E. coli phage. The similarity points to a phylogenetic relationship among phages of CIII1 morphologic type.

Biological properties of mouse interferon bound to a high molecular weight carrier: Blue Dextran 2000.

Mouse C-243 cell interferon (IF) binds to Blue Dextran 2000 (BD). The BD-IF complex could be precipitated by polyethylene glycol. When 0.05 to 0.2 per cent solutions of BD were used for binding IF, the recovery of IF activity in the sediment was complete. The BD-IF complex was shown to have high antiviral activity, it was stable for months at 4 degrees C but it was inactivated by heating at 37 degrees, 56 degrees and 65 degrees C as native IF. The rate of clearance of IF bound to BD from the mouse peritoneal cavity was found to be significantly slower than that of native IF. The BD-IF complex was highly immunogenic for rabbits and sheep. Furthermore, the BD-IF complex was neutralized to a greater extent by specific antibodies than native IF.

Effects of anti-interferon serum on growth and regression of Moloney sarcoma virus induced tumours in mice.

Administration of sheep anti-mouse interferon serum or globulin to weanling BALB/c mice infected with Moloney sarcoma virus (MSV) accelerated the growth of tumours at the site of virus inoculation, increased the number and size of tumours, and inhibited their regression. The outcome of the MSV-induced disease after injection of anti-interferon globulin depended on the age of mice. The antigenic stimulation by normal sheep serum or globulin also enhanced the growth and mortality due to MSV but to a significantly lesser extent than anti-interferon globulin.

Actinomycetes of the genus Streptomyces in soil from Syria.

Species identification and antagonistic properties of 55 actinomycete strains isolated from Syrian soil were studied. The actinomycete strains belonged to 22 species, of which most abundantly represented were Streptomyces antimycoticus, S. rubiginosohelvolus, S. macrosporeus and S. coerulescens. Actinomycetes belonging to 16 species exhibited antagonism in relation to Gram-positive and Gram-negative bacteria, fungi and neoplastic cells.