Fusion proteins of HIV-1 envelope glycoprotein gp120 with CD4-induced antibodies showed enhanced binding to CD4 and CD4 binding site antibodies.
Development of successful AIDS vaccine immunogens continues to be a major challenge. One of the mechanisms by which HIV-1 evades antibody-mediated neutralizing responses is the remarkable conformational flexibility of its envelope glycoprotein (Env) gp120. Some recombinant gp120s do not preserve their conformations on gp140s and functional viral spikes, and exhibit decreased recognition by CD4 and neutralizing antibodies. CD4 binding induces conformational changes in gp120 leading to exposure of the coreceptor-binding site (CoRbs). In this study, we test our hypothesis that CD4-induced (CD4i) antibodies, which target the CoRbs, could also induce conformational changes in gp120 leading to better exposed conserved neutralizing antibody epitopes including the CD4-binding site (CD4bs). We found that a mixture of CD4i antibodies with gp120 only weakly enhanced CD4 binding. However, such interactions in single-chain fusion proteins resulted in gp120 conformations which bound to CD4 and CD4bs antibodies better than the original or mutagenically stabilized gp120s. Moreover, the two molecules in the fusion proteins synergized with each other in neutralizing HIV-1. Therefore, fusion proteins of gp120 with CD4i antibodies could have potential as components of HIV-1 vaccines and inhibitors of HIV-1 entry, and could be used as reagents to explore the conformational flexibility of gp120 and mechanisms of entry and immune evasion.
Protein Interactions Group, Frederick National Laboratory for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA. chenw3@mail.nih.go
Weizao
W
Chen
Yang
Y
Feng
Yanping
Y
Wang
Zhongyu
Z
Zhu
Dimiter S
DS
Dimitrov
D016915:AIDS Vaccines / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D057134:Antibodies, Neutralizing / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D001665:Binding Sites / Q000276:immunology; D015704:CD4 Antigens / Q000276:immunology*; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D057809:HEK293 Cells; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D053586:Virus Internalization
D016915:AIDS Vaccines; D057134:Antibodies, Neutralizing; D015704:CD4 Antigens; D000939:Epitopes; D015699:HIV Envelope Protein gp120; D011993:Recombinant Fusion Proteins