Recombinant HIV envelope proteins fail to engage germline versions of anti-CD4bs bNAbs.

TitleRecombinant HIV envelope proteins fail to engage germline versions of anti-CD4bs bNAbs.
Publication TypeJournal Article
Year of Publication2013
AuthorsHoot S, McGuire AT, Cohen KW, Strong RK, Hangartner L, Klein F, Diskin R, Scheid JF, Sather ND, Burton DR, Stamatatos L
JournalPLoS Pathog
Volume9
Issue1
Paginatione1003106
Date Published01/09/2013
ISSN1553-7374
Abstract

Vaccine candidates for HIV-1 so far have not been able to elicit broadly neutralizing antibodies (bNAbs) although they express the epitopes recognized by bNAbs to the HIV envelope glycoprotein (Env). To understand whether and how Env immunogens interact with the predicted germline versions of known bNAbs, we screened a large panel (N:56) of recombinant Envs (from clades A, B and C) for binding to the germline predecessors of the broadly neutralizing anti-CD4 binding site antibodies b12, NIH45-46 and 3BNC60. Although the mature antibodies reacted with diverse Envs, the corresponding germline antibodies did not display Env-reactivity. Experiments conducted with engineered chimeric antibodies combining the mature and germline heavy and light chains, respectively and vice-versa, revealed that both antibody chains are important for the known cross-reactivity of these antibodies. Our results also indicate that in order for b12 to display its broad cross-reactivity, multiple somatic mutations within its VH region are required. A consequence of the failure of the germline b12 to bind recombinant soluble Env is that Env-induced B-cell activation through the germline b12 BCR does not take place. Our study provides a new explanation for the difficulties in eliciting bNAbs with recombinant soluble Env immunogens. Our study also highlights the need for intense efforts to identify rare naturally occurring or engineered Envs that may engage the germline BCR versions of bNAbs.

DOI10.1371/journal.ppat.1003106
Alternate JournalPLoS Pathog.
PubMed ID23300456
PubMed Central IDPMC3536657
Grant ListP01AI081625 / AI / NIAID NIH HHS / United States
P30 AI027757 / AI / NIAID NIH HHS / United States
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