An anti-phosphoinositide-specific monoclonal antibody that neutralizes HIV-1 infection of human monocyte-derived macrophages

HIV-1 entry into cells requires the interaction of both HIV-1 envelope proteins and membrane lipids. We investigated the mechanism of neutralization of HIV-1 infection of primary monocyte-derived macrophages (MDM) by a murine monoclonal antibody (mAb) WR321. WR321 specifically binds phosphatidylinositol-4-phosphate and phosphatidylinositol-4,5-bisphosphate. These phosphoinositides are present not only on the inner surface of the plasma membranes of cells but also on the surface of virions. HIV-1 acquires these lipids during the budding process. Pre-incubation of WR321 with the virus but not with MDM neutralized HIV-1 infection of MDM. Our results demonstrate that WR321 was internalized only when it was bound to HIV-1. WR321 did not prevent the entry of HIV-1 into MDM. However, once WR321 was internalized along with HIV-1 the mAb acted intracellulary to prevent the release of virions from MDM and also triggered the release of β-chemokines.