Anti-V3 Humanized Antibody KD-247 Effectively Suppresses Ex Vivo Generation of Human Immunodeficiency Virus Type 1 and Affords Sterile Protection of Monkeys against a Heterologous Simian/Human Immunodeficiency Virus Infection

The V3 epitope is a known target for HIV-1 neutralizing antibodies (NAbs), and V3-scaffold fusion proteins used as boosting immunogens after gp120 DNA priming were previously shown to induce NAbs in rabbits. Here, we evaluated whether the breadth and potency of the NAb response could be improved when boosted with rationally designed V3-scaffold immunogens. Rabbits were primed with codon-optimized clade C gp120 DNA and boosted with one of five V3-cholera toxin B fusion proteins (V3-CTBs) or with double combinations of these. The inserts in these immunogens were designed to display V3 epitopes shared by the majority of global HIV-1 isolates. Double combinations of V3-CTB immunogens generally induced more broad and potent NAbs than did boosts with single V3-CTB immunogens, with the most potent and broad NAbs elicited with the V3-CTB carrying the consensus V3 of clade C (V3 C -CTB), or with double combinations of V3-CTB immunogens that included V3 C -CTB. Neutralization of tier 1 and 2 pseudoviruses from clades AG, B, and C and of peripheral blood mononuclear cell (PBMC)-grown primary viruses from clades A, AG, and B was achieved, demonstrating that priming with gp120 DNA followed by boosts with V3-scaffold immunogens effectively elicits cross-clade NAbs. Focusing on the V3 region is a first step in designing a vaccine targeting protective epitopes, a strategy with potential advantages over the use of Env, a molecule that evolved to protect the virus by poorly inducing NAbs and by shielding the epitopes that are most critical for infectivity.

Section: Discussionmentioning

confidence: 98%

Cross-Clade HIV-1 Neutralizing Antibodies Induced with V3-Scaffold Protein Immunogens following Priming with gp120 DNA

Zolla‐Pazner

Kong

Jiang

et al. 2011

“…Since CD4i and anti-cryptic V3 Abs are already present in a large number of HIV-1-infected patients, no prevaccination would be necessary for the induction of NAbs. Moreover, the use of bifunctional small molecules, such as an entry inhibitor and a NAb enhancer, should be effective for passive immunization of the anti-HIV NAbs enhanced by the accessibility of epitopes after binding of sCD4, such as 17b (27) and KD-247 (11,12). Elucidation of the molecular details governing the interactions between gp120 and NBD compounds will assist in optimization efforts, as well as in the evaluation of this strategy in more complex biological models for HIV infection.…”

Section: Discussionmentioning

confidence: 99%

Enhanced Exposure of Human Immunodeficiency Virus Type 1 Primary Isolate Neutralization Epitopes through Binding of CD4 Mimetic Compounds

Yoshimura

Harada

Shibata

et al. 2010

Self Cite

100

N-(4-Chlorophenyl)-N-(2,2,6,6-tetramethyl-piperidin-4-yl)-oxalamide (NBD-556) is a low-molecular-weight compound that reportedly blocks the interaction between human immunodeficiency virus type 1 (HIV-1) gp120 and its receptor CD4. We investigated whether the enhancement of binding of anti-gp120 monoclonal antibodies (MAbs) toward envelope (Env) protein with NBD-556 are similar to those of soluble CD4 (sCD4) by comparing the binding profiles of the individual MAbs to Env-expressing cell surfaces. In flow cytometric analyses, the binding profiles of anti-CD4-induced epitope (CD4i) MAbs toward NBD-556-pretreated Envexpressing cell surfaces were similar to the binding profiles toward sCD4-pretreated cell surfaces. To investigate the binding position of NBD-556 on gp120, we induced HIV-1 variants that were resistant to NBD-556 and sCD4 in vitro. At passage 21 in the presence of 50 M NBD-556, two amino acid substitutions (S375N in C3 and A433T in C4) were identified. On the other hand, in the selection with sCD4, seven mutations (E211G, P212L, V255E, N280K, S375N, G380R, and G431E) appeared during the passages. The profiles of the mutations after the selections with NBD-556 and sCD4 were very similar in their three-dimensional positions. Moreover, combinations of NBD-556 with anti-gp120 MAbs showed highly synergistic interactions against HIV-1. We further found that after enhancing the neutralizing activity by adding NBD-556, the contemporaneous virus became highly sensitive to antibodies in the patient's plasma. These findings suggest that small compounds such as NBDs may enhance the neutralizing activities of CD4i and anti-V3 antibodies in vivo.Human immunodeficiency virus type 1 (HIV-1) replicates continuously in the face of a strong antibody (Ab) response, although Abs effectively control many viral infections (3). Neutralizing Abs (NAbs) are directed against the HIV-1 envelope (Env) protein, which is a heterodimer comprising an extensively glycosylated CD4-binding subunit (gp120) and an associated transmembrane protein (gp41). Env proteins are present on the virion surface as "spikes" composed of trimers of three gp120-gp41 complexes (20,21,29). These spikes resist neutralization through epitope occlusion within the oligomer, extensive glycosylation, extension of variable loops from the surface of the complex, and steric and conformational blocking of receptor binding sites (16,18,20).Ab access to conserved regions is further limited because viral entry is a stepwise process involving conformational changes that lead to only transient exposure of conserved domains such as the coreceptor binding site (4, 5). However, some early strains of HIV-1 appear to be highly susceptible to neutralization by Abs (1, 10). For instance, subtype A HIV-1 envelopes from the early stage of infection exhibit a broad range of neutralization sensitivities to both autologous and heterologous plasma (1), suggesting that at least a subset of the envelopes have some preserved and/or exposed neutralization epitopes. It is well known that ...

“…The shortest reactive peptide recognized by KD-247 was determined to be IGPGR, which is shared by 49% of HIV-1 isolates in clade B (35). In addition, complete protection from challenge infection by a pathogenic strain of simian-human immunodeficiency virus 89.6 was observed when a high concentration of the antibody was used in an animal model (10). A molecularly cloned CCR5-tropic HIV-1 strain, JR-FL, which is relatively resistant to neutralization (15,50), was exposed to KD-247 to obtain a neutralization escape mutant (67).…”

mentioning

confidence: 99%

Impact of V2 Mutations on Escape from a Potent Neutralizing Anti-V3 Monoclonal Antibody during In Vitro Selection of a Primary Human Immunodeficiency Virus Type 1 Isolate

Shibata

Yoshimura

Honda

et al. 2007

Self Cite

KD-247, a humanized monoclonal antibody to an epitope of gp120-V3 tip, has potent cross-neutralizing activity against subtype B primary human immunodeficiency virus type 1 (HIV-1) isolates. To assess how KD-247 escape mutants can be generated, we induced escape variants by exposing bulked primary R5 virus, MOKW, to increasing concentrations of KD-247 in vitro. In the presence of relatively low concentrations of KD-247, viruses with two amino acid mutations (R166K/D167N) in V2 expanded, and under high KD-247 pressure, a V3 tip substitution (P313L) emerged in addition to the V2 mutations. However, a virus with a V2 175P mutation dominated during passaging in the absence of KD-247. Using domain swapping analysis, we demonstrated that the V2 mutations and the P313L mutation in V3 contribute to partial and complete resistance phenotypes against KD-247, respectively. To identify the V2 mutation responsible for the resistance to KD-247, we constructed pseudoviruses with single or double amino acid mutations in V2 and measured their sensitivity to neutralization. Interestingly, the neutralization phenotypes were switched, so that amino acid residue 175 (Pro or Leu) located in the center of V2 was exchanged, indicating that the amino acid at position 175 has a crucial role, dramatically changing the Env oligomeric state on the membrane surface and affecting the neutralization phenotype against not only anti-V3 antibody but also recombinant soluble CD4. These data suggested that HIV-1 can escape from anti-V3 antibody attack by changing the conformation of the functional envelope oligomer by acquiring mutations in the V2 region in environments with relatively low antibody concentrations.The envelope protein (Env) of human immunodeficiency virus type 1 (HIV-1) presents on the virus surface as "spikes" composed of trimers comprising three gp120-gp41 complexes (6,32,33). Among the regions that induce the neutralization antibody (NAb) response, the third variable domain (V3 loop) of gp120 is considered one of the major targets of the host immune response (23, 69). It has been estimated that as much as half of the antibody response against HIV-1 Env in patient serum is directed against the V3 region (43). A recent crystallographic study revealed that the V3 loop contains features that are essential for coreceptor binding and that the extended nature and antibody accessibility of V3 are associated with its immunodominance (20).HIV-1 primary isolates are relatively resistant to neutralization by NAbs and recombinant soluble CD4 (rsCD4) compared with variants selected for growth in permanent cell lines (42,52,55). Studies addressing differences between neutralization-sensitive and -resistant variants have revealed the involvement of several mechanisms that underlie the neutralization resistance of primary isolates, including the occlusion of epitopes within the oligomer, extensive glycosylation, and extension of variable loops from the surface of the complex, as well as steric and conformational blocking of receptor binding sites ...