A monoclonal antibody to the CDR-3 region of CD4 inhibits soluble CD4 binding to virions of human immunodeficiency virus type 1.
The CDR-3 region of CD4 has been proposed to be involved in the fusion reaction between human immunodeficiency virus type 1 (HIV-1) and CD4+ cells, either at a stage involving virus binding or subsequent to virus binding. Part of the evidence for this has been the observation that monoclonal antibodies (MAbs) to CDR-3 block HIV infection potently without strongly inhibiting the binding of monomeric gp120 to CD4. Here I show that, in a system using oligomeric, virion-bound gp120, a MAb to CDR-3 resembles those to CDR-2 in that it inhibits soluble CD4 binding to virions. Consequently, ternary complexes of MAb-soluble CD4-gp120 cannot be detected with CDR-2 MAbs and are detectable only at a very low level with a CDR-3 MAb, but they clearly form when a control MAb to CD4 domain 4 is used. Although not in direct conflict with previously published data on the role of CDR-3 MAbs in the inhibition of HIV-1 infection, these experiments do not support the hypothesis that the CDR-3 region is specifically involved in virus entry at a postbinding stage.
Aaron Diamond AIDS Research Center, New York University School of Medicine, New York 10016.
J P
JP
Moore
D000163:Acquired Immunodeficiency Syndrome / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000918:Antibody Specificity; D015704:CD4 Antigens / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D012995:Solubility; D013329:Structure-Activity Relationship; D014771:Virion / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D015704:CD4 Antigens