The effects of recombinant-DNA-derived interferons on the growth of myeloid progenitor cells

Interferons (IFNs) have been shown to have significant effects on hematopoietic cell growth. Previous studies defining these effects have utilized mouse and human alpha-, beta-, and gamma-IFN isolated from supernatants of stimulated cells. Despite purification, the possible presence of other lymphokines and soluble factors remains a concern. In this study, the effects of gene-cloned alpha- and gamma-IFN on colony- forming units of granulocyte/macrophage (CFU-GM) progenitors cultured from the peripheral blood of normal volunteers were examined. In addition, blast cell colonies from one patient with acute myelogenous leukemia (AML) were studied. The growth of normal CFU-GM and AML blast cell colonies was inhibited in a dose-dependent manner by gamma- and alpha-IFN. gamma-IFN was ten to 100 times more potent than alpha-IFN in that this species of IFN reduced colony formation by greater than 50% at concentrations of less than 15 antiviral U/mL. The effects of gamma- IFN were neutralized by a monoclonal antibody specific for gamma-IFN. These in vitro studies indicate that human gamma-IFN may be an important modulator of myelopoiesis. Although these data indicate a possible efficacy of gamma-IFN in the treatment of AML, the in vitro results should be considered for their in vivo significance.     

Proof of Concept for the Inhibition of Foot‐and‐Mouth Disease Virus Replication by the Anti‐Viral Drug 2′‐C‐Methylcytidine in Severe Combined Immunodeficient Mice

Recent European contingency plans envisage emergency vaccination as an animal‐friendly control strategy for foot‐and‐mouth disease (FMD). Anti‐viral drugs may be used as an alternative or complementary measure. We here demonstrate that the nucleoside analogue 2′‐C‐methylcytidine (2′CMC) protects severe combined immunodeficient (SCID) mice against lethal FMD virus infection. In brief, SCID mice were inoculated with serotype A FMD virus and treated for five consecutive days with 2′CMC. All 15 treated mice remained healthy until the end of the study at 14 days post‐infection (dpi). At that time, viral RNA was no longer detected in 13 of 15 treated mice. All eight untreated mice suffered from an acute generalized disease and were euthanized for ethical reasons on average at 4 dpi. These results illustrate the potential of small molecules to control FMD.     

FV-100 for the Treatment of Varicella-Virus (VZV) Infections: Quo Vadis?

The bicyclic nucleoside analogue (BCNA) Cf1743 and its orally bioavailable prodrug FV-100 have unique potential as varicella-zoster virus (VZV) inhibitors to treat herpes zoster (shingles) and the therewith associated pain, including post-herpetic neuralgia (PHN). The anti-VZV activity of Cf1743 depends on a specific phosphorylation by the VZV-encoded thymidine kinase (TK). The target of antiviral action is assumed to be the viral DNA polymerase (or DNA synthesis in the virus-infected cells).     

Patterns of resistance and sensitivity to antiviral compounds of drug-resistant strains of human cytomegalovirus selected in vitro

Drug-resistant human Cytomegalovirus (HCMV) strains were selected in human embryonic lung (HEL) fibroblasts under pressure of the (S)-3-hydroxy-2-phosphonylmethoxypropyl (HPMP) derivatives of cytosine (HPMPC) and adenine (HPMPA), the 2-phosphonylmethoxyethyl (PME) derivative of 2,6-diaminopurine (PMEDAP), ganciclovir (GCV), acyclovir (ACV), and foscarnet (PFA). Drug susceptibility profiles of the different drug-resistant (i.e., GCV^r, HPMPC^r, HPMPA^r, PFA^r, ACV^r, and PMEDAP^r) strains were determined in HEL cells. A considerable degree of cross-resistance against GCV, HPMPC, and HPMPA occurred with the GCV^r, HPMPC^r, and HPMPA^r strains. No changes in susceptibility to 9-(2-phosphonylmethoxyethyl)adenine (PMEA), PMEDAP, ACV, or PFA were detected for the HPMPC^r, HPMPA^r, and GCV^r strains when compared to the wild-type virus. On the other hand, a significant degree of cross-resistance was noted with the PMEDAP^r, PFA^r, and ACV^r strains against PMEA, PMEDAP, PFA, and ACV. No differences in susceptibility to HPMPC, HPMPA and GCV were observed for the ACV^r, PFA^r, and PMEDAP^r strains relative to the wild type. The drug susceptibility profiles of the different resistant strains point to a common mechanism of HCMV resistance to PFA and the PME derivatives that is different from the mechanism of HCMV resistance to the HPMP derivatives.     

Comparative activity of various compounds against clinical strains of herpes simplex virus

The following compounds were evaluated for their inhibitory activity against clinical strains of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) in both primary rabbit kidney (PRK) and HeLa cell cultures: (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine (HPMPA), 9-(2-phosphonylmethoxyethyl)adenine (PMEA), (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC), (RS)-9-(3-hydroxy-2-phosphonylmethoxypropyl)-2,6-diaminopurine (HPMPDAP), 5-(5-bromothien-2-yl)-2-deoxyuridine (BTDU), 5-(5-chlorothien-2-yl)-2-deoxyuridine (CTDU), 9-(2-deoxy-2-hydroxymethyl--D-erythro-oxetanosyl)guanine (OXT-G), pentosan polysulfate, heparin, dextran sulfate (MW 10,000), acyclovir, 9-(2-hydroxyethoxymethyl)guanine (ACV), (E)-5-(2-bromovinyl)-2-deoxyuridine (BVDU), 1--D-arabinofuranosyl-(E)-5-(2-bromovinyl)-uracil (BVaraU), vidarabine (9--D-arabinofuranosyladenine) (ara-A) and phosphonoformate (PFA). The most potent inhibitors of HSV-1 were (in order of decreasing activity in PRK cells) BVDU, ACV, BVaraU and OXT-G, their mean 50 % inhibitory concentration (IC₅₀) ranging from 0.02 µg/ml to 0.9 µg/ml. Then followed BTDU and CTDU (IC₅₀ 1–2 µg/ml), the sulfated polysaccharides (IC₅₀ 1.3–5.8 µg/ml), the phosphonylmethoxyalkyl derivatives (IC₅₀ 5.6–25 µg/ml), ara-A (IC₅₀ 11 µg/ml) and PFA (IC₅₀ 38.5 µg/ml). Except for BVDU, BVaraU, BTDU and CTDU, the compounds did not discriminate between HSV-2 and HSV-1. All the compounds studied could be considered specific anti-HSV agents. Their selectivity indexes varied from 3 (PFA) to 6400 (BVDU).     

Antiviral drugs: current state of the art.

The chemotherapy of virus infections has definitely come of age. There are now 15 antiviral agents that have been formally licensed for the treatment of human immunodeficiency virus infections (zidovudine, didanosine, zalcitabine, stavudine, lamivudine, abacavir, nevirapine, delavirdine, efavirenz, saquinavir, ritonavir, indinavir, nelfinavir, amprenavir, lopinavir) and several others, such as tenofovir disoproxil, emtricitabine, capravirine, emivirine, T-20 (pentafuside) and AMD3100 (bicyclam) are under clinical development. Lamivudine has been approved, and several other compounds (such as adefovir dipivoxil, emtricitabine and entecavir) are under clinical development, for the treatment of hepatitis B virus infections. Among the anti-herpesvirus agents, aciclovir, valaciclovir, penciclovir, famciclovir, idoxuridine, trifluridine and brivudin are used in the treatment of herpes simplex virus and varicella-zoster virus infections, and ganciclovir, foscarnet, cidofovir, fomivirsen and maribavir (the latter in the developmental stage) are used in the treatment of cytomegalovirus infections. Following amantadine and rimantadine, the neuraminidase inhibitors, zanamivir and oseltamivir, have now become available for the therapy and prophylaxis of influenza virus infections, and so is ribavirin for the treatment of respiratory syncytial virus infections and the combination of ribavirin with interferon-alpha for the treatment of hepatitis C virus infections.     

Pentosan polysulfate, a sulfated oligosaccharide, is a potent and selective anti-HIV agent in vitro

Several sulfated oligo- or polysaccharides such as pentosan polysulfate, fucoidan, dextran sulfate, heparin and iota-, kappa- and lambda-carrageenans proved to be potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) in vitro. The most potent anti-HIV-1 activity was recorded for the oligosaccharide pentosan polysulfate, its 50% antiviral effective dose (ED50) being 0.19 microgram/ml in MT-4 cells. It inhibited HIV-1 antigen expression in HUT-78 cells at an ED50 of 0.02 microgram/ml, and complete inhibition of HIV-1 antigen expression was obtained at a concentration of 4.0 micrograms/ml. No toxicity for MT-4 cells was observed with pentosan polysulfate at a concentration of 2500 micrograms/ml. The anticoagulant activity of pentosan polysulfate was more than ten-fold lower than that of heparin (14.4 and 177 U/mg, respectively). In fact, pentosan polysulfate achieved its anti-HIV-1 activity at a concentration that is 370-fold below its anticoagulant threshold (1 U). Pentosan polysulfate inhibits virus adsorption to the cells, as was demonstrated by monitoring the association of radiolabeled HIV-1 virions with MT-4 cells.     

Rapid and automated tetrazolium-based colorimetric assay for the detection of anti-HIV compounds

A rapid, sensitive and automated assay procedure was developed for the in vitro evaluation of anti-HIV agents. An HTLV-I transformed T4-cell line, MT-4, which was previously shown by Koyanagi et al. (1985) to be highly susceptible to, and permissive for, HIV infection, served as the target cell line. Inhibition of the HIV-induced cytopathic effect was used as the end point. The viability of both HIV-and mock-infected cells was assessed spectrophotometrically via the in situ reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The procedure was optimized as to make optimal use of multichannel pipettes, microprocessor-controlled dispensing and optical density reading. The absorbance ratio of the mock-infected control to the HIV-infected samples was about 20. This allowed an accurate determination of the 50% effective doses, as demonstrated for 3'-azido-2',3'-dideoxythymidine (AZT), 2',3'-dideoxycytidine (ddCyd), dextran sulfate and heparin. The technique significantly reduced labor time as compared to the trypan blue exclusion method, and permits the evaluation of large numbers of compounds for their anti-HIV activity.     

Wolbachia induces strong cytoplasmic incompatibility in the predatory bug Macrolophus pygmaeus

Macrolophus pygmaeus is a heteropteran predator that is widely used in European glasshouses for the biological control of whiteflies, aphids, thrips and spider mites. We have demonstrated that the insect is infected with the endosymbiotic bacterium Wolbachia pipientis . Several gene fragments of the endosymbiont were sequenced and subsequently used for phylogenetic analysis, revealing that it belongs to the Wolbachia supergroup B. The endosymbiont was visualized within the ovarioles using immunolocalization. Tetracycline treatments were used to cure M. pygmaeus from its infection. Although a completely cured line could not be obtained by this approach, the application of a constant antibiotic pressure over 13 generations resulted in a line with a significantly reduced Wolbachia concentration. Crosses performed with this tetracycline-treated line revealed that the endosymbiont causes severe cytoplasmic incompatibility. This is the first report of a reproductive effect induced by Wolbachia in an economically important heteropteran predator that may have vital implications for its commercial production and use in biological control.