A comparative immunogenicity study in rabbits of disulfide-stabilized, proteolytically cleaved, soluble trimeric human immunodeficiency virus type 1 gp140, trimeric cleavage-defective gp140 and monomeric gp120

Beddows, Simon; Franti, Michael; Dey, Antu; Kirschner, Marc W.; Iyer, Sai Prasad N.; Fisch, Danielle N.; Ketas, Thomas A.; Yuste, Eloísa; Desrosiers, Ronald C.; Klasse, Per Johan; Maddon, Paul J.; Olson, William C.; Moore, John P.

doi:10.1016/j.virol.2006.10.032

Cited by 92 publications

(108 citation statements)

References 52 publications

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“…Furthermore, the gp140 construct utilized in this work contains mutations in both primary and secondary cleavage sites, leading to enhanced trimer stability (12). Whereas other studies have suggested altered quaternary profiles in cleavage-defective clade A gp140 constructs as opposed to cleavage-competent constructs, predominantly in the gp41 region (28), as well as a difference in immunogenicity between cleavagedefective and cleavage-competent clade B constructs (29), the enhanced stability reported for clade C cleavage-defective gp140, as well as the native-like immunochemical binding profile that clade C cleavage-defective gp140 displays (12), allowed for improved homogeneity crucial for data collection and averaging.…”

Section: Discussionmentioning

confidence: 92%

Quaternary structures of HIV Env immunogen exhibit conformational vicissitudes and interface diminution elicited by ligand binding

Moscoso

Sun²,

Poon

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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The human immunodeficiency virus envelope protein is the key element mediating entry into host cells. Conformational rearrangement of Env upon binding to the host CD4 receptor and chemokine coreceptor drives membrane fusion. We elucidated the quaternary arrangement of the soluble Env trimeric immunogen o-gp140ΔV2TV1, in both its native (unliganded) and CD4-induced (liganded) states by cryoelectron microscopy and molecular modeling. The liganded conformation was elicited by binding gp140 to the synthetic CD4-mimicking miniprotein CD4m. Upon CD4m binding, an outward domain shift of the three gp120 subunits diminishes gp120-gp41 interactions, whereas a "flat open" concave trimer apex is observed consequent to gp120 tilting away from threefold axis, likely juxtaposing the fusion peptide with the host membrane. Additional features observed in the liganded conformation include rotations of individual gp120 subunits that may release gp41 for N-and C-helix refolding and also may lead to optimal exposure of the elicited coreceptor binding site. Such quaternary arrangements of gp140 lead to the metastable liganded conformation, with putative locations of exposed epitopes contributing to a description of sequential events occurring prior to membrane fusion. Our observations imply a mechanism whereby a soluble Env trimeric construct, as opposed to trimers extracted from virions, may better expose crucial epitopes such as the CD4 binding site and V3, as well as epitopes in the vicinity of gp41, subsequent to conjugation with CD4m. Structural features gleaned from our studies should aid the design of Env-based immunogens for inducement of potent broadly neutralizing antibodies against exposed conformational epitopes.T he human immunodeficiency virus envelope proteins gp120 and gp41 associate in a trimeric arrangement (1-3) and mediate membrane fusion through conformational rearrangement and fusion peptide insertion into the host membrane. The gp120 tertiary conformational change observed via X-ray crystallography has not been definitively characterized in the context of a quaternary structure. Several observations have been gleaned from tomography studies, though with inconclusive and sometimes contradictory results. Quaternary structural features reported previously include trimer morphology, with some groups reporting a mushroom-like shape and others a more rod-like arrangement, as well as the relative location of the primary epitope, hypervariable loops, and N-and C-termini, which have some variation among the different tomograms. Another point of conflict is the presence of a cavity at the threefold axis, capped by a density. One final feature is the arrangement of gp41, with some groups reporting a thin, stalk-like rod arrangement of gp41 and another group reporting a more splayed out, tripod-like conformation of gp41 proximal to the viral membrane. Taken together, these contrasting features portray a heterogeneous set of registers that seem to hinder a cohesive and thorough model of ligand-induced quaternary arrangement...

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Section: Discussionmentioning

confidence: 92%

Quaternary structures of HIV Env immunogen exhibit conformational vicissitudes and interface diminution elicited by ligand binding

Moscoso

Sun²,

Poon

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Most studies that have compared the two forms using the same Env genotype have shown that gp140 trimers are superior to gp120 monomers at inducing neutralizing antibodies (19)(20)(21). However, the improvement in immunogenicity is not yet good enough to conclude that any forms of gp140 trimers, in their current iteration, are good enough to use in practical HIV-1 vaccines.…”

Section: Discussionmentioning

confidence: 99%

Trimeric HIV-1 glycoprotein gp140 immunogens and native HIV-1 envelope glycoproteins display the same closed and open quaternary molecular architectures

Harris

Borgnia

Shi

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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144

180

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The initial step in HIV-1 infection occurs with the binding of cell surface CD4 to trimeric HIV-1 envelope glycoproteins (Env), a heterodimer of a transmembrane glycoprotein (gp41) and a surface glycoprotein (gp120). The design of soluble versions of trimeric Env that display structural and functional properties similar to those observed on intact viruses is highly desirable from the viewpoint of designing immunogens that could be effective as vaccines against HIV/AIDS. Using cryoelectron tomography combined with subvolume averaging, we have analyzed the structure of SOSIP gp140 trimers, which are cleaved, solubilized versions of the ectodomain of trimeric HIV-1 Env. We show that unliganded gp140 trimers adopt a quaternary arrangement similar to that displayed by native unliganded trimers on the surface of intact HIV-1 virions. When complexed with soluble CD4, Fab 17b, which binds to gp120 at its chemokine coreceptor binding site, or both soluble CD4 and 17b Fab, gp140 trimers display an open conformation in which there is an outward rotation and displacement of each gp120 protomer. We demonstrate that the molecular arrangements of gp120 trimers in the closed and open conformations of the soluble trimer are the same as those observed for the closed and open states, respectively, of trimeric gp120 on intact HIV-1 BaL virions, establishing that soluble gp140 trimers can be designed to mimic the quaternary structural transitions displayed by native trimeric Env. viral entry | cryoelectron microscopy | HIV spike | HIV vaccine | AIDS vaccine

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“…It is possible that immunizing with an immunogen with better CD4-binding properties would result in more potent VHH. Previous studies have shown that purified trimeric envelope proteins are somewhat better at eliciting cross-subtype-neutralizing antibodies than monomeric recombinant gp120 (6,7,22,32,38,90). We are currently screening llamas immunized with recombinant trimeric gp140.…”

Section: Discussionmentioning

confidence: 99%

Llama Antibody Fragments with Cross-Subtype Human Immunodeficiency Virus Type 1 (HIV-1)-Neutralizing Properties and High Affinity for HIV-1 gp120

Forsman

Beirnaert

Aasa-Chapman

et al. 2008

J Virol

111

138

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Members of the Camelidae family produce immunoglobulins devoid of light chains. We have characterized variable domains of these heavy chain antibodies, the VHH, from llamas immunized with human immunodeficiency virus type 1 (HIV-1) envelope protein gp120 in order to identify VHH that can inhibit HIV-1 infection. To increase the chances of isolating neutralizing VHH, we employed a functional selection approach, involving panning of phage libraries expressing the VHH repertoire on recombinant gp120, followed by a competitive elution with soluble CD4. By immunizing with gp120 derived from an HIV-1 subtype B /C primary isolate, followed by panning on gp120 from HIV-1 isolates of subtypes A, B, and C, we could select for VHH with cross-subtype neutralizing activity. Three VHH able to neutralize HIV-1 primary isolates of subtypes B and C were characterized. These bound to recombinant gp120 with affinities close to the suggested affinity ceiling for in vivo-maturated antibodies and competed with soluble CD4 for this binding, indicating that their mechanism of neutralization involves interacting with the functional envelope spike prior to binding to CD4. The most potent VHH in terms of low 50% inhibitory concentration (IC 50 ) and IC 90 values and cross-subtype reactivity was A12. These results indicate that camelid VHH can be potent HIV-1 entry inhibitors. Since VHH are stable and can be produced at a relatively low cost, they may be considered for applications such as HIV-1 microbicide development. Antienvelope VHH might also prove useful in defining neutralizing and nonneutralizing epitopes on HIV-1 envelope proteins, with implications for HIV-1 vaccine design.

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A comparative immunogenicity study in rabbits of disulfide-stabilized, proteolytically cleaved, soluble trimeric human immunodeficiency virus type 1 gp140, trimeric cleavage-defective gp140 and monomeric gp120

Cited by 92 publications

References 52 publications

Quaternary structures of HIV Env immunogen exhibit conformational vicissitudes and interface diminution elicited by ligand binding

Quaternary structures of HIV Env immunogen exhibit conformational vicissitudes and interface diminution elicited by ligand binding

Trimeric HIV-1 glycoprotein gp140 immunogens and native HIV-1 envelope glycoproteins display the same closed and open quaternary molecular architectures

Llama Antibody Fragments with Cross-Subtype Human Immunodeficiency Virus Type 1 (HIV-1)-Neutralizing Properties and High Affinity for HIV-1 gp120

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