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Flow cytometric method to demonstrate whether anti-HIV-1 agents inhibit virion binding to T4+ cells
Abstract:
The first step in the replicative cycle of human immunodeficiency virus type 1 (HIV-1) is binding of the virions to the cellular CD4 receptor. This process may be considered as an important target for chemotherapeutic agents against acquired immune deficiency syndrome (AIDS). A method has now been devised whereby virion binding to the cell membrane was visualized by an indirect immunofluorescence assay using human anti-HIV-1 serum, rabbit anti-human-IG-F(ab')2-fluorescein isothiocyanate, and flow cytometry. Heparin, dextran sulfate, and pentosan polysulfate suppressed HIV-1 binding to MT-4 cells at concentrations that protected the cells against HIV-1 cytopathogenicity. Dextran and dermatan sulfate, two compounds that are inactive against HIV-1, had no inhibitory effect on the binding of HIV-1 to the cells. The potent and selective HIV-1 inhibitor azidothymidine (AZT) did not affect virus binding to the cells, whereas suramin partially blocked HIV-1 binding to the cells at concentrations that fully protected MT-4 cells against destruction of HIV-1. Our immunofluorescence assay thus demonstrated that suramin not only acts as an inhibitor of reverse transcriptase but also interferes with virus-cell binding. Also, Evans blue, an anionic dye structurally related to suramin, partially inhibited HIV-1 attachment to the cells. The present method permits a quantitative determination of the inhibitory effect of anti-HIV-1 agents on virion-cell binding.
Insights
Researchers developed a new assay to visualize human immunodeficiency virus type 1 (HIV-1) binding to cells. This method revealed that suramin and Evans blue inhibit HIV-1 attachment, offering new targets for AIDS therapies.
Area of Science:
- Virology
- Immunology
- Pharmacology
Background:
- The initial stage of human immunodeficiency virus type 1 (HIV-1) replication involves virion attachment to the CD4 receptor on host cells.
- This virus-cell binding is a critical target for developing anti-acquired immune deficiency syndrome (AIDS) therapies.
Purpose of the Study:
- To develop and validate a quantitative method for visualizing and measuring HIV-1 virion binding to cell membranes.
- To evaluate the inhibitory effects of various compounds on HIV-1 binding to MT-4 cells.
Main Methods:
- An indirect immunofluorescence assay was employed to visualize virion binding.
- Flow cytometry was used for quantitative analysis.
- The assay utilized human anti-HIV-1 serum and a fluorescein isothiocyanate-conjugated secondary antibody.
Main Results:
- Heparin, dextran sulfate, and pentosan polysulfate inhibited HIV-1 binding and protected cells from cytopathogenicity.
- Azidothymidine (AZT) did not affect virus binding.
- Suramin and Evans blue demonstrated partial inhibition of HIV-1 binding, with suramin also confirmed as a reverse transcriptase inhibitor.
Conclusions:
- The developed immunofluorescence assay effectively quantifies the inhibition of HIV-1 virion-cell binding by potential therapeutic agents.
- Suramin exhibits a dual mechanism of action, inhibiting both reverse transcriptase and virus-cell attachment.
- This assay provides a valuable tool for identifying novel anti-HIV-1 compounds targeting the initial binding step.