[Antiviral activity in vitro and pharmacokinetics of HCV entry inhibitor AVR560].

Several novel compounds were found to be potent inhibitors of the HCV (JFH-1 isolate) infection in vitro. Human serum did not significantly reduce antiviral activity of the lead compound, AVR560 (< 4-fold). The immunohistochemistry studies with the Huh7 cell line, infectable with the HCV (JFH-1 strain), demonstrated that AVR560 inhibited the early steps of viral infection and blocked the spread of the HCV infection in tissue culture. The cytotoxicity in Huh7 and Vero-76 cell lines was mild. AVR560 proved to be a specific HCV inhibitor and exhibited no activity against other flaviviruses such as yellow fever (strain 17D), West Nile (strain NY99), and dengue (New Guinea type 2) in in vitro infection experiments. AVR560 also did not inhibit any of the tested human CYP450 isozymes (3A4, 1A2, 2C19 and 2D6). In the pharmacokinetic studies in mice, rats and dogs, favorable pharmacokinetic profiles and good oral bioavailability were observed for AV560. Further pre-clinical studies with this novel HCV inhibitor are in progress.

[Preclinical study of AV0012 early stage inhibitor of hepatitis C virus infection: I. In vitro ADME and pharmacokinetics].

In vitro immunohistochemical investigations on the human hepatoma cell line (Huh7) infected with hepatitis C virus (HCV) strain JFH-1 showed that AV0012 compound blocks the early stages of viral infection. AV0012 also blocked viral infection spread in tissue culture through the secreted virus and through tight cell-to-cell contact. AV0012 is a specific inhibitor of HCV but not of related pestivirus, flaviviruses and other RNA-containing viruses such as bovine diarrhea (BVDV), Venezuelan equine encephalitis (strain TC-83), dengue type 2 (New Guinea), yellow fever (strain 17D), west Nile fever, parainfluenza (type 3) virus, RSV (strain A2), and Rhinovirus (type 2 strain HGP). It is established that human serum does not significantly affect the antiviral activity of AV0012 in vitro. The drug combination studies with AV0012 and interferon alpha 2a in vitro showed that the two inhibitors act additively, which makes possible the use of this combination in clinical tests. AV0012 is highly soluble and stable in aqueous solutions and murine blood plasma, has limited metabolic stability, low binding to human plasma proteins, high permeability through biological membranes, and only interacts with isoenzymes 2D6 and 3A4 of human cytochrome P450. In animal pharmacokinetic studies, AV0012 was rapidly absorbed into the blood stream upon oral administration, showed sufficiently long half-elimination times, and had high oral bioavailability that reached 92% in monkeys. Further preclinical development of AV0012 is in progress.

[Preclinical study of safety of the new pharmacological substance AV0012 to treat hepatitis C].

Pharmacological safety of a new type of HCV inhibitor, AV0012, was studied including acute, subchronic and chronic toxicity in mice, rats and monkeys. Genotoxicity was assessed using the Ames test and the chromosomal aberrations assay in the bone marrow cells of mice. It is established that AV0012 has low toxicity in SHK line mice, Wistar line rats, and monkey of Rhesus macaques species. Results obtained in the study of genetic toxicity showed that AV0012 exhibits no mutagenic activity. Data on general toxicity and mutagenicity discussed in this paper, together with data on 1 the pharmacological activity, pharmacokinetics, and metabolism published previously, allow us to consider AV0012 as a candidate drug for clinical research phase I.

[Genetic transformation of somatic cells. XIV. Expression of gene coding for the human hepatitis B virus surface antigen in mammalian cells]. / Geneticheskaia transformatsiia somaticheskikh kletok. XIV. Ekspressiia gena, kodiruiushchego poverkhnostnyi antigen virusa gepatita B cheloveka, v kletkakh mlekopitaiushchikh.

A set of recombinant plasmids with a gene encoding surface antigen of hepatitis B virus (HBsAg) is constructed. The plasmids were transfected by DEAE-dextran method into different lines of cultured cells and transient expression of the HBsAg gene was studied. The results indicate that: transcriptional enhancer of hepatitis B virus situated downstream from HBsAg gene is active in green monkey kidney cells (CVI), promoter of 5 LTR of bovine leukemia virus is trans-activated in the goat or calf cells infected with BLV. The results are discussed in the light of hypothesis on the role of transcriptional enhancers in determination of tissue-specificity of hepatitis B virus.

[Primary structure of the 3'-terminal region of the cloned DNA of the bovine leukemia virus]. / Pervichnaia struktura 3'-kontsevoi oblasti klonirovaniia kDNK virusa bych'ego leikoza.

The nucleotide sequence of the 3'-terminal region of the cloned bovine leukaemia virus cDNA (1474 bp) was elucidated using both Sanger and Maxam-Gilbert techniques. This DNA region contains U3 and R parts of the BLV LTR and an upstream sequence with four open reading frames (ORF) of unknown function. The comparison of the nucleotide substitutions in these ORF with the two variants of proviral BLV DNA suggests that the only pX1 ORF possesses a coding function. The role of the pX1 protein is discussed.

[The comparative mapping of virion and cloned DNA of the hepatitis B virus]. / Sravnitel'noe kartirovanie virionnoi i klonirovannoi DNK virusa gepatita B.

The entire hepatitis B virus (HBV) genome and its fragments have been cloned into the BamHI site of the plasmid pBR322 vector. The identity of physical maps of cloned and authentic virion DNAs was demonstrated by restriction enzyme analysis. The location of restriction sites is suggestive of a certain similarity between the studied HBV DNA and HBV DNA, subtype ayw (Galibert et al., 1979). From the restriction enzyme analysis of virion DNA repaired and 32P-labeled by the endogenous DNA-polymerase reaction, the new information concerning the location and maximal length (approximately 1500 nucleotides) of the single-stranded region of HBV DNA has been established.

[Subjection of tetracycline resistance genes to cat promotor gene in plasmid pBR325]. / Podstanovka genov, opredeliaiushchikh ustoichivost' k tetratsiklinu, pod promotor gena cat v plazmide pBR325.

A series of plasmids with tetracycline resistance genes (Tcr-operon) subjected to transcription from chloramphenicol acetyl transferase promoter (Cmr-promoter) have been constructed on the basis of plasmid pBR325, AprCmrTcr. For this purpose, a 0.8 Md fragment in pBR325 DNA bordered by unique EcoRI and HindIII restriction sites was cut out and structural genes of Tcr-operon were fused to the cat gene nucleotides corresponding to Cmr-promoter and first 72 amino acids of cat (alton, Vapnek, 1979; Marcoli et al., 1980). These plasmids with molecular weight amounting to 3 Md confer AprTcr phenotype to host cells. Tetracycline resistance can be eliminated completely by the deletion of a) Cmr-promoter; b) part of the first Tcr-operon gene.