This method provides a method for reducing HIV-1 viral load in an HIV-1-infected human subject which comprises administering to the subject at a predefined interval effective HIV-1 viral load-reducing doses of (a) a humanized antibody designated PRO 140, or of (b) an anti-CCR5 receptor monoclonal antibody. This invention also provides a method for inhibiting in a human subject the onset or progression of an HIV-1-associated disorder, the inhibition of which is effected by inhibiting fusion of HIV-1 to CCR5+CD4+ target cells in the subject. This invention also provides a method for treating a subject infected with HIV-1 comprising administering to the subject (a) a monoclonal antibody which (i) binds to a CCR5 receptor on the surface of the subject's CD4+ cells and (ii) inhibits fusion of HIV-1 to the subject's CCR5+CD4+ cells, and (b) a non-antibody CCR5 receptor antagonist, in amounts effective to treat the subject.