Immunization of Primates with Native, Recombinant HIV-SF2 gp120 Generates Broadly Effective Neutralizing Antibodies Directed to Conformational Epitopes

Steimer, K.S.; Haigwood, Nancy L.

doi:10.1089/aid.1992.8.1391

Cited by 7 publications

(3 citation statements)

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“…Historically, it has been difficult to induce neutralizing antibody responses against diverse primary HIV type 1 (HIV-1) strains by utilizing monomeric HIV Env (i.e., gp120) glycoprotein. Furthermore, it has been shown by several groups that the antibody responses induced by gp120 are directed primarily against the V3 loop and other linear epitopes (22,34,43,44,70,81,82,102,109,110,117) and that limited responses are directed towards the conserved conformational epitopes (9,41,75,88,95,107). Due to the high degree of variability in gp120, these nonconformational anti-gp120-specific antibodies were found to be predominantly subtype specific and, to some extent, isolate specific.…”

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confidence: 99%

Purification and Characterization of Oligomeric Envelope Glycoprotein from a Primary R5 Subtype B Human Immunodeficiency Virus

Srivastava¹,

Stamatatos

Legg³

et al. 2002

J Virol

101

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Human immunodeficiency virus (HIV) continues to be a major public health problem throughout the world, with high levels of mortality and morbidity associated with AIDS. Considerable efforts to develop an effective vaccine for HIV have been directed towards the generation of cellular, humoral, and mucosal immune responses. A major emphasis of our work has been toward the evaluation of oligomeric (o-gp140) forms of the HIV type 1 (HIV-1) envelope protein for their ability to induce neutralizing antibody responses. We have derived stable CHO cell lines expressing o-gp140 envelope protein from the primary non-syncytium-inducing (R5) subtype B strain HIV-1 US4 . We have developed an efficient purification strategy to purify oligomers to near homogeneity. Using a combination of three detectors measuring intrinsic viscosity, light scattering, and refractive index, we calculated the molecular mass of the oligomer to be 474 kDa, consistent with either a trimer or a tetramer. The hydrodynamic radius (R h ) of o-gp140 was determined to be 8.40 nm, compared with 5.07 nm for the monomer. The relatively smaller R h of the oligomer suggests that there are indeed differences between the foldings of o-gp140 and gp120. To assess the structural integrity of the purified trimers, we performed a detailed characterization of the glycosylation profile of o-gp140, its ability to bind soluble CD4, and also its ability to bind to a panel of monoclonal antibodies with known epitope specificities for the CD4 binding site, the CD4 inducible site, the V3 loop, and gp41. Immunogenicity studies with rabbits indicated that the purified o-gp140 protein was highly immunogenic and induced high-titer, high-avidity antibodies directed predominantly against conformational epitopes. These observations confirm the structural integrity of purified o-gp140 and its potential as a vaccine antigen.

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confidence: 99%

Purification and Characterization of Oligomeric Envelope Glycoprotein from a Primary R5 Subtype B Human Immunodeficiency Virus

Srivastava¹,

Stamatatos

Legg³

et al. 2002

J Virol

101

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“…Recently, antibodies obtained from HIV patients have been proven to neutralise a variety of different HIV strains by recognising conserved conformations within the external glycoprotein gp 120 [57], To induce such group-specific neutralising antibodies, but to avoid welldocumented side effects associated with the gp4l trans membrane protein [58][59][60] we established a novel ap proach. which allows stable and covalent anchoring of gpl20 on the surface of recombinant VLP by a heterolo gous transmembrane domain.…”

Section: Coexpression Of Virus-like Pr559"9 Particles and Chimeric Gpmentioning

confidence: 99%

Safety and Immunogenicity of Recombinant Human Immunodeficiency Virus-Like Particles in Rodents and Rhesus Macaques

et al. 1996

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Data from long-term non-progressing human immunodeficiency virus (HIV)- infected individuals and populations at high risk suggest that an early cytolytic T cell response rather than the humoral immune response might be involved in controlling disease progression. These observations may be used as a guide to the type of response that a vaccine should induce. To clarify the role of different arms of the immune system in conferring protection, the candidate vaccine should allow a regulated, selective induction of different immune responses. Based on a better understanding of the molecular mechanisms regulating the morphogenesis of HIV, we developed an autologous, non-replicating and safe antigen delivery system. This system takes advantage of molecular characteristics of the HIV group-specific antigens (gag) to self-assemble to highly immunogenic virus-like particles (VLP). The immunogenicity of the gag-derived VLP was expanded either by replacing defined domains by selected HIV-1 cytotoxic T lymphocyte (CTL) epitopes (type 1 VLP) or by stable anchoring derivatives of the HIV-1 envelope protein on the surface of the VLP (type 2 VLP). In complete absence of adjuvants, type 1 and type 2 VLP stimulated CD8+ CTL in BALB/c mice, which specifically recognised HIV sequences. In contrast to type 1 VLP, generating an HIV-specific CTL response in the absence of e«v-specific antibodies, type 2 VLP induced both arms of the immune system including reasonable levels of neutralising antibodies. Initial studies performed in rhesus macaques confirmed these results. Thus, depending on the type and formulation of the VLP, the proposed antigen delivery system allows either the induction of a CTL response (1) in the absence and (2) the presence of an envelope-specific antibody response. A comparison of these approaches in appropriate animal models might contribute to further define the correlates of protection.

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“…Abs capable of neutralizing HIV-1 in vitro develop naturally, over several years, in HIV-infected patients (10,31,41,44,57,60,77,78). However, immunization with monomeric forms of the HIV-1 envelope glycoprotein gp120 results in production of Abs which neutralize T-cell line-adapted (TCLA) viruses (4,62,65) but have only marginal activity against primary isolates of HIV-1 (41,42,66,79). Possible explanations for this weak neutralizing activity against primary viral isolates, in contrast to the potent NAbs that can develop during natural infection, include the inaccessibility or absence of relevant epitopes on the immunogen.…”

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Neutralizing Antibodies from the Sera of Human Immunodeficiency Virus Type 1-Infected Individuals Bind to Monomeric gp120 and Oligomeric gp140

Stamatos

Mascola

Kalyanaraman

et al. 1998

J Virol

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Antibodies that neutralize primary isolates of human immunodeficiency virus type 1 (HIV-1) appear during HIV-1 infection but are difficult to elicit by immunization with current vaccine products comprised of monomeric forms of HIV-1 envelope glycoprotein gp120. The limited neutralizing antibody response generated by gp120 vaccine products could be due to the absence or inaccessibility of the relevant epitopes. To determine whether neutralizing antibodies from HIV-1-infected patients bind to epitopes accessible on monomeric gp120 and/or oligomeric gp140 (ogp140), purified total immunoglobulin from the sera of two HIV-1-infected patients as well as pooled HIV immune globulin were selectively depleted of antibodies which bound to immobilized gp120 or ogp140. After passage of each immunoglobulin preparation through the respective columns, antibody titers against gp120 and ogp140 were specifically reduced at least 128-fold. The gp120- and gp140-depleted antibody fraction from each serum displayed reduced neutralization activity against three primary and two T-cell line-adapted (TCLA) HIV-1 isolates. Significant residual neutralizing activity, however, persisted in the depleted sera, indicating additional neutralizing antibody specificities. gp120- and ogp140-specific antibodies eluted from each column neutralized both primary and TCLA viruses. These data demonstrate the presence and accessibility of epitopes on both monomeric gp120 and ogp140 that are specific for antibodies that are capable of neutralizing primary isolates of HIV-1. Thus, the difficulties associated with eliciting neutralizing antibodies by using current monomeric gp120 subunit vaccines may be related less to improper protein structure and more to ineffective immunogen formulation and/or presentation.

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Immunization of Primates with Native, Recombinant HIV-SF2 gp120 Generates Broadly Effective Neutralizing Antibodies Directed to Conformational Epitopes

Cited by 7 publications

References 0 publications

Purification and Characterization of Oligomeric Envelope Glycoprotein from a Primary R5 Subtype B Human Immunodeficiency Virus

Purification and Characterization of Oligomeric Envelope Glycoprotein from a Primary R5 Subtype B Human Immunodeficiency Virus

Safety and Immunogenicity of Recombinant Human Immunodeficiency Virus-Like Particles in Rodents and Rhesus Macaques

Neutralizing Antibodies from the Sera of Human Immunodeficiency Virus Type 1-Infected Individuals Bind to Monomeric gp120 and Oligomeric gp140

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