Chemical Library Screens Targeting an HIV-1 Accessory factor/Host Cell Kinase Complex Identify Novel Antiretroviral Compounds

Nef is an HIV-1 accessory protein essential for AIDS progression and an attractive target for drug discovery. Lack of a catalytic function makes Nef difficult to assay in chemical library screens. We developed a high-throughput screening assay for Inhibitors of Nef function by coupling it to one of its host cell binding partners; the Src-family kinase Hck. Hck activation is dependent upon Nef in this assay, providing a direct readout of Nef activity in vitro. Using this screen; a unique diphenylfuropyrimidine was identified as a strong inhibitor of Nef-dependent Hck activation. This compound also exhibited remarkable antiretroviral effects, blocking Nef-dependent HIV replication in cell culture. Structurally related analogs were synthesized and shown to exhibit similar Nef-dependent antiviral activity, identifying the diphenylfuropyrimidine substructure as a new lead for antiretroviral drug development. This study demonstrates that coupling noncatalytic HIV accessory factors with host cell target proteins addressable by high-throughput assays may afford new avenues for the discovery of anti-HIV agents.