Since in vitro binding assays had demonstrated that CD4bs-M inhibits the interaction of recombinant monomeric gp120 with soluble CD4 (sCD4), we had anticipated that CD4bs-M would be able to inhibit the gp120–CD4 interaction also in the context of HIV-1 infection, thus preventing infection of cells with HIV-1. The gene discussed is CD4; the disease is HIV-1 infection.