Anti-HIV-1 antibodies 2F5 and 4E10 interact differently with lipids to bind their epitopes.
OBJECTIVE
2F5 and 4E10 are two broadly neutralizing monoclonal antibodies (mAbs) targeting the membrane proximal external region (MPER) of HIV-1 gp41 envelope protein. This region, which contacts the viral membrane, is highly conserved and has been regarded as a promising target for vaccine development. We aimed to clarify the basis of 2F5 and 4E10 molecular interactions with epitope cores in MPER and lipid bilayers.


METHODS
Microscopy-based approaches were used to infer and quantify the effects of both mAbs on membranes, in the presence and absence of the epitope cores. Supported lipid bilayers (SLBs), with and without phase separation, were used as membrane models. Fluorescent-labeled and nonlabeled MPER-derived peptides containing both 2F5 and 4E10 epitopes were used.


METHODS
mAbs 2F5 and 4E10 membrane interactions, in the presence or absence of MPER-derived peptides, were evaluated by combined atomic force and confocal microscopies.


RESULTS
Both mAbs form lipid-segregated aggregates on SLBs and do not induce other significant membrane perturbations. Furthermore, the affinity of MPER toward membranes is differently affected by both mAbs and correlates with the mAbs-epitope core lipid interactions. 2F5 is able to dock the MPER peptide on the membrane, whereas 4E10 extracts the MPER from the lipid bilayer.


CONCLUSIONS
The results reveal the molecular details underneath 2F5/4E10 membrane-epitope binding and a model is proposed to explain the differential mAbs neutralization efficacies, which relates to the exposure of the epitopes in the lipid bilayers and the role of the lipids in mAb-epitope binding.
Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.
Henri G
HG
Franquelim
Salvatore
S
Chiantia
Ana Salomé
AS
Veiga
Nuno C
NC
Santos
Petra
P
Schwille
Miguel A R B
MA
Castanho
D000911:Antibodies, Monoclonal / Q000378:metabolism; D057134:Antibodies, Neutralizing / Q000276:immunology*; D000918:Antibody Specificity; D000080908:Broadly Neutralizing Antibodies; D000939:Epitopes / Q000378:metabolism*; D015483:HIV Antibodies / Q000276:immunology / Q000378:metabolism*; D015700:HIV Envelope Protein gp41 / Q000276:immunology* / Q000378:metabolism; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D008055:Lipids / Q000502:physiology*; D011485:Protein Binding
C558560:2F5 monoclonal antibody; C558559:4E10 monoclonal antibody; D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D000080908:Broadly Neutralizing Antibodies; D000939:Epitopes; D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41; D008055:Lipids