Cellular factors influence the binding of HIV type 1 to cells

The goal of this study was to determine the importance of cellular factors for binding of HIV to cells. HIV primary isolates (PIs) produced in peripheral blood mononuclear cells (PBMCs) bound at relatively high levels to PBMCs but at low levels to cell lines, whereas T cell line-adapted (TCLA) virus produced in the H9 T cell line bound at high levels to both cell lines and PBMCs. Expression of CD4 in CD4-negative cells or blocking CD4 with antibody on CD4-positive cells did not affect virus binding. Blocking of gp120/gp41 with antibodies or a lack of expression of gp120/gp41 in virus particles also did not affect virus binding. However, the cell type from which virus was produced did affect virus binding. Thus, the binding pattern of TCLA virus shifted to that of a PI virus when produced in PBMCs. A PI binding pattern also occurred when a cloned TCLA virus (NL4-3) was produced in PBMCs, indicating that the virus-producing cell type has more of an effect on virus binding than the virus strain. These experiments show that both the virus-producing cell and the target cell have a major influence on HIV binding and suggest that host cell factors incorporated into virions are important for virus binding.