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CD4 immunoadhesin, but not recombinant soluble CD4, blocks syncytium formation by human immunodeficiency virus type
I Sekigawa1, S M Chamow, J E Groopman
1Department of Medicine, New England Deaconess Hospital, Harvrd Medical School, Boston, Massachusetts 02215.
Insights
Recombinant soluble CD4 (rCD4) and its fragments inhibit HIV-1 syncytia formation. However, only CD4-immunoglobulin G blocks HIV-2 syncytia, indicating distinct cell fusion mechanisms between HIV-1 and HIV-2.
Area of Science:
- Virology
- Immunology
Background:
- Recombinant soluble CD4 (rCD4) is known to inhibit HIV-1 and HIV-2 infection in vitro.
- Syncytium formation is a key indicator of viral spread and cell fusion in HIV infection.
Purpose of the Study:
- To investigate the differential effects of rCD4, the V1V2 fragment of CD4, and CD4-immunoglobulin G on syncytium formation mediated by HIV-1 and HIV-2.
- To elucidate differences in cell fusion processes between HIV-1 and HIV-2.
Main Methods:
- In vitro characterization of syncytium formation in lymphoid cells infected with HIV-1 or HIV-2.
- Treatment with rCD4, V1V2 fragment of CD4, and CD4-immunoglobulin G.
Main Results:
- All tested molecules (rCD4, V1V2, CD4-IgG) effectively blocked HIV-1-mediated syncytium formation.
- Only CD4-immunoglobulin G inhibited HIV-2-mediated syncytium formation.
- rCD4 and V1V2 fragment of CD4 enhanced HIV-2-mediated syncytium formation.
Conclusions:
- HIV-1 and HIV-2 exhibit distinct cell fusion mechanisms.
- CD4-based inhibitors show differential efficacy against HIV-1 and HIV-2 syncytium formation.
Abstract:
Recombinant soluble CD4 (rCD4) has been shown to be an effective inhibitor of human immunodeficiency virus type 1 (HIV-1) and HIV-2 infection of lymphoid cells in vitro. In this report, we characterized the effects of rCD4, the V1V2 fragment of CD4, and the immunoadhesin CD4-immunoglobulin G on syncytium formation between lymphoid cells infected by HIV-1 or HIV-2 and uninfected cells. All three molecules blocked HIV-1-mediated syncytium formation, but only CD4-immunoglobulin G blocked HIV-2-mediated syncytium formation. rCD4 and the V1V2 fragment of CD4 enhanced HIV-2-mediated syncytium formation. These results suggest that the process of cell fusion is significantly different between HIV-1- and HIV-2-infected cells.