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To: Logical Extinction
Are most FI's screened? Or are people trying to design them?

Have all the local anesthetics and related ion channel binding molecules been screened?

21 posted on 06/18/2003 10:05:08 AM PDT by tallhappy
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To: tallhappy
Excellent question,

OLD SCHOOL

The interactions between the viral envelope glycoprotein gp120, its cellular receptor CD4, and the specific co-receptor are part of the early events occurring during cell infection by HIV-1. Antagonists of HIV-1 replication at the entry level, via blockade of attachment, gp120/CD4/co-receptor interactions, or gp41 structural changes, represent a potential source for HIV-1 treatment.

Synthetic combinatorial libraries (SCLs) made up of thousands to millions of compounds are a powerful approach for the development of such antagonists.

2 recombinant vaccinia virus-based assays mimicking a T-cell line-tropism (IIIb-X4) and macrophage-tropism (JRFL-R5) have been developed to quantify the inhibition of the fusogenic activity of HIV-1 envelope glycoproteins. The expression of Lac Z from a reporter gene upon fusion was used to measure colorimetrically the fusion of target and effector cells. 2 peptide SCLs were screened in these assays to develop fusion inhibitors: a l-amino acid nonapeptide and a d-amino acid decapeptide SCLs. The inhibitory activities of the identified peptides were assayed in the vaccinia virus-based fusion and replication assays using different laboratory virus strains as well as clinical isolates.

Following the screening of the 2 SCLs in the X4 fusion system, 38 d-amino acid decapeptides and 44 l-amino acid nonapeptides were generated and their inhibitory activities determined. 5 nonapeptides exhibited inhibitory activity with IC90 values lower than 10 µg/mL, while the most active decapeptides have IC90 values around 25 µg/mL when tested in the X4 fusion system. Lower activity was observed in the R5 fusion system. These peptides have similar efficacy in the inhibition of virus replication (IC90 values = 10 to 50 µg/ml in an assay using IIIb/X4 virus and between 50 and 80% inhibition at 25 µg/mL in assays using other X4, R5, and X4R5 virus strains).

Studies toward the understanding the peptides mechanism and target of inhibition have been started.

These studies allowed the rapid identification of novel HIV fusion inhibitors that represent leads for new therapies targeting the entry of HIV-1, and useful tools to further study and enhance the understanding of the fusion process.



NEW WAVE

A novel test has been designed to allow rapid screening of HIV inhibitors The test is based on the measurement of cell-to-cell fusion mediated by the HIV envelope. The HIV fusion test has a high throughput, it is semi-automated and takes 10 to 12 hours maximum including read-out of data and statistical analysis.

It is thus possible to test a large number of samples/inhibitors at the same time. The fusion process can be specifically targeted as the read-out exclusively measures cell-to-cell fusion and does not depend on viral replication or activation of reporter genes.

The test is very versatile in that virtually any envelope sequence from distinct HIV isolates can be used for the donor cell.

Expression of envelope glycoproteins from different viral strains is normalised and there is no bias due to the replication potential of the original HIV-isolate which could result in variations of expression levels of the envelope. Moreover, various cell types including primary cells can be used as target cells.

It is possible to screen for inhibitory molecules targeted against either the HIV envelope glycoproteins gp120 or gp41, against the CD4 receptor or the chemokine receptors. Using cell lines that express only one given co-receptor, molecules can be designed against either CXCR4 or CCR5 or any other receptor molecule. The efficacy of such drugs can subsequently be tested in fusion assays on primary cells such as peripheral blood lymphocytes or macrophages.

This test is also suited for the development of inhibitors of the human T-cell leukemia virus type 1 (HTLV-1).





IN AN ALCHEMY OF LIGHT

Both the changer and the changed
Are found...
25 posted on 06/18/2003 6:00:04 PM PDT by Logical Extinction (Reality is often much more frightening than fiction...)
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