A yeast assay for high throughput screening of natural anti-viral agents.

Over the last decade the yeast Saccharomyces cerevisiae has become a popular organism for studying heterologous gene expression and in vivo protein-protein interactions. Many variations of these basic systems have originated over the years. Besides these vast and varied applications of the yeast expression system, S. cerevisiae has also been used extensively in fundamental research as a model simple eukaryote. We have used the S. cerevisiae system to design a high throughput screen for anti-viral agents from natural sources. The design of the assay rests on the ability of the L-A helper virus and the M(1) satellite virus to detect small variations in -1 ribosomal frameshifting. A minor change in frameshifting efficiencies can be detected and clearly shown phenotypically in terms of zones of clearing on an agar plate. Using such a process, we have initiated a high throughput screening process for natural anti-viral agents.

The effect of hexadimethrine bromide (polybrene) on the infection of the primate retroviruses SSV 1/SSAV 1 and BaEV.

Polybrene was shown to enhance the adsorption of simian sarcoma virus-simian sarcoma associated virus complex (SSV-1/SSAV-1) and baboon endogenous virus (BaEV) onto cells in culture. A 16- to 18-fold increased adsorption of both viruses occurred at 8 micrograms/ml polybrene within one hour after infection. The polybrene mediated adsorption was found to be inhibited by the addition of tri-sodium citrate to the culture medium, suggesting the involvement of electrostatic forces. This contention was further supported by the demonstration of temperature independence of the polybrene mediated interaction.

[Experimental results with systematically synthetized substances for antiviral chemotherapy / 4th communication: The role of physical binding in the synthesis of antiviral chemotherapeutics and its influence on potential mutagenic effects (author's transl)]. / Experimentelle Ergebnisse mit gezielt synthetisierten Substanzen zur antiviralen Chemotherapie. 4. Der Wert hysikalischer Bindungen bei der Synthese antiviraler Chemotherapeutika und deren Einfluss auf potentielle mutagene Effekte

13 antiviral substances containing specific hydrogen bridge linkage systems out of the classes of 2-substituted 4-phenylthiazoles, 4-phenylimidazoles and indandiones-(1,3) were tested for their mutagenic potency in the host-mediated assay, in bone marrow of rats, in spermatogonia of mice and in the micronucleus test of rats. Only one substance, N1-methyl-N2-[4-phenylthiazolyl-(2)]-urea, was found to be mutagenic. This fact substantiates the hypothesis that the antiviral effectiveness of the substances is not caused by a chemical change in the coding system but by forming "physical" linkages like hydrogen bridge complexes with coding structures. Altogether 159 compounds of very different structures were investigated for their antiviral chemotherapeutic potency in 893 tests in cell cultures and 461 animal tests. It can be stated that compounds with a low molecular weight containing the "effective structures" (see article) show a larger yield of antiviral compounds than do substances without these structures (about 50% positive results in cell cultures and 25% in animals 15% and 0%, respectively).

[Study of the possibilities of inactivating adeno-associated virus type 4]. / Izuchenie vozmozhnostei inaktivatsii adenoassotsiirovannogo virusa tipa 4

Adeno-associated type 4 virus (AAV-4) is inactivated by formalin dilutions 1 : 400, 1 : 1000 and 1 : 2000 for 24 hours at 37 degrees C. Under these conditions hemogglutinins (HA) and complement-fixing antigen (CFA) are retained. The residual formalin must be neutralized with sodium bisulphite. AAV-4 can also be inactivated by 3% hydrogen peroxide and HA and CFA are retained too. Hydrogen peroxide may be neutralized with catalase. No inactivation of AAV-4 could be achieved with lowere concentrations of hydrogen peroxide, even in the presence of copper sulphate.