Chiron Corporation

About: Chiron Corporation is a based out in . It is known for research contribution in the topics: Antigen & Hepatitis C virus. The organization has 1973 authors who have published 1969 publications receiving 172330 citations.

Biosynthetic binding proteins for immuno-targeting

Abstract: Disclosed is a formulation for targeting an epitope on an antigen expressed in a mammal. The formulation comprises a pharmaceutically acceptable carrier together with a dimeric biosynthetic construct for binding at least one preselected antigen. The biosynthetic construct contains two polypeptide chains, each of which define single-chain Fv (sFv) binding proteins and have C-terminal tails that facilitate the crosslinking of two sFv polypeptides. The resulting dimeric constructs have a conformation permitting binding of a said preselected antigen by the binding site of each said polypeptide chain when administered to said mammal. The formulation has particular utility in in vivo imaging and drug targeting experiments.

Alphavirus structural protein expression cassettes

Abstract: Isolated nucleic acid molecules are disclosed. comprising an alphavirus nonstructural protein gene which, when operably incorporated into a recombinant alphavirus particle, eukaryotic layered vector initiation system, or RNA vector replicon, has a reduced level of vector-specific RNA synthesis, as compared to wild-type, and the same or greater level of proteins encoded by RNA transcribed from the viral junction region promoter, as compared to a wild-type recombinant alphavirus particle. Also disclosed are RNA vector replicons, alphavirus vector constructs, and eukaryotic layered vector initiation systems which contain the above-identified nucleic acid molecules.

Small interfering RNA-mediated inhibition of hepatitis C virus replication in the human hepatoma cell line Huh-7.

Abstract: RNA interference (RNAi) is a process of posttranscriptional gene silencing in plants, insects, and animals (4, 7, 13, 14). In vivo, RNAi is initiated by an endonuclease, DICER, that cleaves long, double-stranded RNA into 21- to 25-bp small interfering RNAs (siRNAs) (2, 3, 6, 15). siRNAs are incorporated into a protein complex, the RNAi silencing complex, that recognizes and cleaves target mRNAs (12). Inhibition of viral infection and modulation of viral replication by siRNA have been demonstrated in human immunodeficiency virus and poliovirus in human cells (5, 8, 10, 11). Hepatitis C virus (HCV) is a positive-stranded RNA virus that has infected some 170 million worldwide. Most HCV-infected individuals develop a chronic infection that can lead to liver disease, including cirrhosis and hepatocellular carcinoma (1). To test whether siRNA inhibits HCV, we made several 21-bp siRNA duplexes that were directed against different regions of the 5′ untranslated region (UTR) of the HCV genome. We transfected these siRNAs into 5-2 cells, a Huh-7 cell line that harbors autonomously replicating subgenomic HCV RNA (9) (Fig. ​(Fig.1A).1A). The subgenomic replicon contains the firefly luciferase gene; therefore, the effect of siRNA on HCV replication was measured through the luciferase assay (9). Compared with those of mock-transfected controls, luciferase activities measured 48 h after transfection of cells with HCV siRNA 5U5 (Fig. ​(Fig.1B)1B) were reduced by up to 85% in a dose-responsive manner (Fig. ​(Fig.2A).2A). This inhibition was not seen in cells that were transfected with the control siRNA SIN, which was targeted to Sindbis virus. Additional control siRNA duplexes, GL2 and GL3, further demonstrated the specificity of the siRNA response. Luciferase activity was reduced by 90% in cells transfected with GL2, which is homologous to the fruit fly luciferase gene. GL3, which contains three nucleotide mismatches to the gene, was unable to inhibit luciferase activity effectively (Fig. ​(Fig.2A).2A). We also tested possible cellular toxicity involved in the siRNA transfections. Measurement of ATP levels within cells showed no viable change in siRNA-transfected cells (Fig. ​(Fig.2B).2B). Finally, we tested the effect of 5U5 on HCV RNA replication in 5-2 cells by a quantitative TaqMan assay. This assay showed that 5U5 could reduce the steady-state level of the HCV RNA in a pattern similar to that obtained with the luciferase assay (data not shown). FIG. 1. Reporter HCV replicon and siRNA duplexes. (A) The components of HCV subgenomic replicons are the HCV 5′ UTR, Neo (neomycin phosphotransferase gene), Luc (firefly luciferase reporter gene), the encephalomyocarditis virus (EMCV) internal ribosome ... FIG. 2. siRNA-mediated inhibition of HCV replication as measured by luciferase activity. (A) Effects of siRNA dose and sequence on luciferase activity. The indicated amounts of siRNA were transfected into 5-2 cells (5 × 104 in a 24-well plate) with 1 ... Our results show that a 21-bp siRNA is capable of mediating specific cleavage of target HCV RNA in human liver cells, implying that the target cell for HCV infection possesses the necessary functional components (RNAi silencing complex) of RNAi. Our observation, however, does not rule out the possibility that HCV interferes with the ability of DICER to generate siRNAs. Since HCV is very effective at persisting in the infected host, it may have evolved a mechanism(s) by which it evades the normal siRNA pathway. However, introduction of a preformed siRNA duplex would bypass the required DICER maturation in HCV-infected cells, making the standard siRNA strategy attractive. This report is a first step in demonstrating that replicating HCV RNA is amenable to siRNA-mediated degradation in human liver cells. Identification of siRNA with higher efficacy, greater stability, and targeting of siRNA is necessary to develop siRNA technology into an effective anti-HCV therapy.

Microparticles for the delivery of DNA vaccines

Abstract: DNA vaccines have demonstrated a lack of adequate potency in humans, which has necessitated the exploration of various adjunct technologies. Inefficient delivery of DNA vaccines, particularly to antigen-presenting cells, may be contributing to this lack of potency. One effective means of facilitating delivery of DNA vaccines to APCs is through the use of microparticles. In this article, we review the background and rationale for microparticles as a vaccine delivery system, data demonstrating their utility and mode of action for DNA delivery, and the prospects for their development.