Human and murine monoclonal antibodies directed against a conserved sequence from gp41 (aa583–599) of human immunodeficiency virus type 1

Summary Human spleen cells from an HIV-seropositive donor were immunized in vitro with the aa583–599 peptide conjugated to an heptalysyl core. This sequence was derived from the putatively HIV-immunosuppressive region of HIV1 gp41. The same conjugated peptide was used to immunize mice. One human and one mouse IgM monoclonal antibody (mAb) directed against the aa583–599 peptide were obtained. The two mAb had distinct patterns of reactivity against a panel of 42 peptides with modified sequences. Neither of the mAb inhibited the immunosuppressive effect of aa583–599 octopus-lysconjugated peptide on anti-CD3 Ab-induced lymphoproliferation. In addition, both mAb did not neutralize cell-free virus transmission or enhance HIV infection. However, HmAb inhibited formation of syncytia between HIV1-infected (but not HIV2-infected cells) and non-infected target cells at concentrations above 20 μg/ml, whereas MmAb did not have any effect. The degree of conservation of the aa583–599 region makes HmAb a candidate for use as a group-specific reagent in future HIV1 passive immunotherapy protocols.