Effects of partially dismantling the CD4 binding site glycan fence of HIV-1 Envelope glycoprotein trimers on neutralizing antibody induction

ABSTRACTThe HIV-1 envelope glycoprotein (Env) is a trimer of gp120/gp41 heterodimers that mediates viral entry. Env binds cellular CD4, an association which stabilizes a conformation favorable to its subsequent association with a coreceptor, typically CCR5 or CXCR4. The CD4- and coreceptor-binding sites serve as epitopes for two classes of HIV-1-neutralizing antibodies: CD4-binding site (CD4bs) and CD4-induced (CD4i) antibodies, respectively. Here we observed that, at a fixed total concentration, mixtures of the CD4i antibodies (E51 or 412d) and the CD4bs antibody VRC01 neutralized the HIV-1 isolates 89.6, ADA, SG3, and SA32 more efficiently than either antibody alone. We found that E51, and to a lesser extent 412d and 17b, promoted association of four CD4bs antibodies to the Env trimer but not to monomeric gp120. We further demonstrated that the binding of the sulfotyrosine-binding pocket by CCR5mim2-Ig was sufficient for promoting CD4bs antibody binding to Env. Interestingly, the relationship is not reciprocal: CD4bs antibodies were not as efficient as CD4-Ig at promoting E51 or 412d binding to Env trimer. Consistent with these observations, CD4-Ig, but none of the CD4bs antibodies tested, substantially increased HIV-1 infection of a CD4-negative, CCR5-positive cell line. We conclude that the ability of CD4i antibodies to promote VRC01 association with Env trimers accounts for the increase potency of VRC01 and CD4i antibody mixtures. Our data further suggest that potent CD4bs antibodies avoid inducing Env conformations that bind CD4i antibodies or CCR5.IMPORTANCEPotent HIV-1-neutralizing antibodies can prevent viral transmission and suppress an ongoing infection. Here we show that CD4-induced (CD4i) antibodies, which recognize the conserved coreceptor-binding site of the HIV-1 envelope glycoprotein (Env), can increase the association of Env with potent broadly neutralizing antibodies that recognize the CD4-binding site (CD4bs antibodies). We further show that, unlike soluble forms of CD4, CD4bs antibodies poorly induce envelope glycoprotein conformations that efficiently bind CCR5. This study provides insight into the properties of potent CD4bs antibodies and suggests that, under some conditions, CD4i antibodies can improve their potency. These observations may be helpful to the development of vaccines designed to elicit specific antibody classes.

Download Full-text

The envelope glycoprotein of HIV-1 may have incorporated the CD4 binding site from HLA-DQβ1

Life Sciences ◽

10.1016/0024-3205(89)90536-5 ◽

1989 ◽

Vol 45 (20) ◽

pp. iii-ix ◽

Cited By ~ 7

Author(s):

R.I. Brinkworth

Keyword(s):

Binding Site ◽

Envelope Glycoprotein ◽

Cd4 Binding Site ◽

Hiv 1

Download Full-text

Circular dichroism study on the secondary structural change induced by complex formation of a peptide derived from a CD4 binding site of HIV-1 envelope glycoprotein gp120 and a peptide from the N-terminal domain of CD4

Letters in Peptide Science ◽

10.1007/bf00127663 ◽

1996 ◽

Vol 3 (5) ◽

pp. 293-300

Author(s):

Ding-Kwo Chang ◽

Shu-Fang Cheng

Keyword(s):

Structural Change ◽

Complex Formation ◽

Binding Site ◽

Envelope Glycoprotein ◽

Terminal Domain ◽

Envelope Glycoprotein Gp120 ◽

Cd4 Binding Site ◽

Glycoprotein Gp120 ◽

Secondary Structural Change ◽

Hiv 1

Download Full-text

HIV-1 Fitness Cost Associated with Escape from the VRC01 Class of CD4 Binding Site Neutralizing Antibodies

Journal of Virology ◽

10.1128/jvi.03608-14 ◽

2015 ◽

Vol 89 (8) ◽

pp. 4201-4213 ◽

Cited By ~ 90

Author(s):

Rebecca M. Lynch ◽

Patrick Wong ◽

Lillian Tran ◽

Sijy O'Dell ◽

Martha C. Nason ◽

...

Keyword(s):

Viral Replication ◽

Binding Site ◽

Viral Entry ◽

Envelope Glycoprotein ◽

Neutralizing Antibodies ◽

Viral Escape ◽

Replicative Fitness ◽

Cd4 Binding Site ◽

Compensatory Mutations ◽

Hiv 1

ABSTRACTBroadly neutralizing antibodies (bNAbs) have been isolated from selected HIV-1-infected individuals and shown to bind to conserved sites on the envelope glycoprotein (Env). However, circulating plasma virus in these donors is usually resistant to autologous isolated bNAbs, indicating that during chronic infection, HIV-1 can escape from even broadly cross-reactive antibodies. Here, we evaluate if such viral escape is associated with an impairment of viral replication. Antibodies of the VRC01 class target the functionally conserved CD4 binding site and share a structural mode of gp120 recognition that includes mimicry of the CD4 receptor. We examined naturally occurring VRC01-sensitive and -resistant viral strains, as well as their mutated sensitive or resistant variants, and tested point mutations in the backbone of the VRC01-sensitive isolate YU2. In several cases, VRC01 resistance was associated with a reduced efficiency of CD4-mediated viral entry and diminished viral replication. Several mutations, alone or in combination, in the loop D or β23-V5 region of Env conferred a high level of resistance to VRC01 class antibodies, suggesting a preferred escape pathway. We further mapped the VRC01-induced escape pathwayin vivousing Envs from donor 45, from whom antibody VRC01 was isolated. Initial escape mutations, including the addition of a key glycan, occurred in loop D and were associated with impaired viral replication; however, compensatory mutations restored full replicative fitness. These data demonstrate that escape from VRC01 class antibodies can diminish viral replicative fitness, but compensatory changes may explain the limited impact of neutralizing antibodies during the course of natural HIV-1 infection.IMPORTANCESome antibodies that arise during natural HIV-1 infection bind to conserved regions on the virus envelope glycoprotein and potently neutralize the majority of diverse HIV-1 strains. The VRC01 class of antibodies blocks the conserved CD4 receptor binding site interaction that is necessary for viral entry, raising the possibility that viral escape from antibody neutralization might exert detrimental effects on viral function. Here, we show that escape from VRC01 class antibodies can be associated with impaired viral entry and replication; however, during the course of natural infection, compensatory mutations restore the ability of the virus to replicate normally.

Download Full-text

Influence of Novel CD4 Binding-Defective HIV-1 Envelope Glycoprotein Immunogens on Neutralizing Antibody and T-Cell Responses in Nonhuman Primates

Journal of Virology ◽

10.1128/jvi.01896-09 ◽

2009 ◽

Vol 84 (4) ◽

pp. 1683-1695 ◽

Cited By ~ 39

Author(s):

Iyadh Douagi ◽

Mattias N. E. Forsell ◽

Christopher Sundling ◽

Sijy O'Dell ◽

Yu Feng ◽

...

Keyword(s):

Binding Site ◽

Conformational Changes ◽

Envelope Glycoprotein ◽

Specific Binding ◽

Rhesus Macaques ◽

Neutralizing Antibody ◽

Antibody Activity ◽

The Impact ◽

Hiv 1

ABSTRACT The high-affinity in vivo interaction between soluble HIV-1 envelope glycoprotein (Env) immunogens and primate CD4 results in conformational changes that alter the immunogenicity of the gp120 subunit. Because the conserved binding site on gp120 that directly interacts with CD4 is a major vaccine target, we sought to better understand the impact of in vivo Env-CD4 interactions during vaccination. Rhesus macaques were immunized with soluble wild-type (WT) Env trimers, and two trimer immunogens rendered CD4 binding defective through distinct mechanisms. In one variant, we introduced a mutation that directly disrupts CD4 binding (368D/R). In the second variant, we introduced three mutations (423I/M, 425N/K, and 431G/E) that disrupt CD4 binding indirectly by altering a gp120 subdomain known as the bridging sheet, which is required for locking Env into a stable interaction with CD4. Following immunization, Env-specific binding antibody titers and frequencies of Env-specific memory B cells were comparable between the groups. However, the quality of neutralizing antibody responses induced by the variants was distinctly different. Antibodies against the coreceptor binding site were elicited by WT trimers but not the CD4 binding-defective trimers, while antibodies against the CD4 binding site were elicited by the WT and the 423I/M, 425N/K, and 431G/E trimers but not the 368D/R trimers. Furthermore, the CD4 binding-defective trimer variants stimulated less potent neutralizing antibody activity against neutralization-sensitive viruses than WT trimers. Overall, our studies do not reveal any potential negative effects imparted by the in vivo interaction between WT Env and primate CD4 on the generation of functional T cells and antibodies in response to soluble Env vaccination.

Download Full-text