The recombinant immunogen with high-density epitopes of ELDKWA and ELDEWA induced antibodies recognizing both epitopes on HIV-1 gp41

The high mutation rate of HIV-1 (human immunodeficiency virus-1) is a major obstacle to developing an effective vaccine. The mutation of ELDKWA-(aa669-674) to ELDEWA-epitope on HIV-1 gp41 caused the immune escape from neutralization by potent anti-HIV-1 human monoclonal antibody (mAb) 2F5. In this study, we suggested and evaluated a multi-epitope vaccine as a new strategy to develop HIV-1 vaccines. A glutathione S-transferase (GST) fusion protein (GST-K8E8) containing 8 copies of ELDKWA-and mutated ELDEWA-epitopes was constructed and used to immunize mice or rabbits. Analysis of the antisera (rAS3) induced by GST-K8E8 suggested that multi-epitope vaccine immunogen could raise antibodies in mice and rabbits against either the original ELDKWA-epitope or the mutated ELDEWA-epitope that resulted in immune escape. Briefly, ELDKWA-epitope-specific antibodies, directly purified from rAS3 by ELDKWA-epitope-peptide affinity chromatography, recognized either original gp41 protein (ELDKWA, rgp41K) or mutated gp41 (ELDEWA, rgp41E) in immunoblotting assay; in contrast, the existing ELDKWA-epitope antibodies recognized only rgp41K but not rgp41E, which were purified by ELDKWA-epitope-peptide affinity chromatography from rAS3 that were firstly completely pre-absorbed by ELDEWA-epitope-peptide affinity beads. And the same results were also observed when detecting the ELDEWA-epitope-specific antibodies in rAS3 by a means similar to the above. All the data presented here demonstrated that a high density multi-epitope vaccine could be an interesting strategy against HIV-1 mutation.     

马传染性贫血病毒囊膜基因的研究进展

马传染性贫血病毒是反转录病毒科慢病毒属的成员之一 ,不仅与人免疫缺陷病毒具有序列同源性 ,而且与其血清具有交叉反应。马传染性贫血驴白细胞弱毒疫苗是迄今为止唯一研究成功的慢病毒疫苗。在马传贫病毒囊膜基因的研究中有助于弄清其抗原变异、持续感染和疫苗免疫机理 ,为艾滋病疫苗的研究提供借鉴。对囊膜基因的结构、变异及其在机体免疫应答中的作用进行了讨论。     

HIV-1 envelope accessible surface and polarity: clade, blood, and brain

The human immunodeficiency virus type-1 (HIV-1) gp160 (gp120-gp41 complex) trimer envelope (ENV) protein is a potential vaccine candidate for HIV/AIDS. HIV-1 vaccine development has been problematic and charge polarity as well as sequence variation across clades may relate to the difficulties. Further obstacles are caused by sequence variation between blood and brain-derived sequences, since the brain is a separate compartment for HIV-1 infection. We utilize a threedimensional residue measure of solvent exposure, accessible surface area (ASA), which shows that major segments of gp120 and gp41 known structures are solvent exposed across clades. We demonstrate a large percent sequence polarity for solvent exposed residues in gp120 and gp41. The range of sequence polarity varies across clades, blood, and brain from different geographical locations. Regression analysis shows that blood and brain gp120 and gp41 percent sequence polarity range correlate with mean Shannon entropy. These results point to the use of protein modifications to enhance HIV-1 ENV vaccines across multiple clades, blood, and brain. It should be noted that we do not address the issue of protein glycosylation here; however, this is an important issue for vaccine design and development. ABBREVIATIONS: HIV-1 - human immunodeficiency virus type 1, AIDS - acquired immunodeficiency syndrome, ENV - envelope, gp160 - 160,000d glycoprotein, gp120 - 120,000d glycoprotein, gp41 - 41,000d glycoprotein, LANL - Los Alamos National Laboratories, PDB - Protein Data Bank, HVTN - STEP HIV vaccine trial, AA - amino acids, MSA - multiple sequence alignment, ASA - accessible surface area, SNPs- single nucleotide polymorphisms, HAART - Highly Active Antiretroviral Therapy, CCR5 - C-C chemokine receptor type 5, CNS - central nervous system, HIVE - HIV encephalitis, P - polarity, NP - non-polarity, CTL - cytotoxic T lymphocyte, NIAID - National Institute of Allergy and Infectious Diseases.     

Induction of anti-HIV neutralizing antibodies by synthetic peptides.

Two synthetic peptides containing amino acid sequences analogous to the envelope glycoprotein of human T-lymphotropic virus (HTLV) type III (HTLV-III) and lymphadenopathy associated virus (LAV) were produced and used to immunize rabbits. The subsequent rabbit antisera neutralized HTLV-III infectivity in vitro. The two synthetic peptides corresponded to regions associated with the gp120 or gp41 subunits respectively, of human immunodeficiency virus (HIV). This data indicates that at least two neutralizing epitopes are present on the envelope glycoprotein of HIV and these epitopes are associated with two distinct virus envelope glycoproteins. Antisera generated against these peptides neutralized infectivity of two different isolates of HTLV-III. The data is discussed in terms of possible strategy for developing an effective vaccine against the etiologic agents of acquired immune deficiency syndrome (AIDS).     

The development of HIV vaccines targeting gp41 membrane-proximal external region (MPER): challenges and prospects

A human immunodeficiency virus type-1 (HIV-1) vaccine which is able to effectively prevent infection would be the most powerful method of extinguishing pandemic of the acquired immunodeficiency syndrome (AIDS). Yet, achieving such vaccine remains great challenges. The membrane-proximal external region (MPER) is a highly conserved region of the envelope glycoprotein (Env) gp41 subunit near the viral envelope surface, and it plays a key role in membrane fusion. It is also the target of some reported broadly neutralizing antibodies (bNAbs). Thus, MPER is deemed to be one of the most attractive vaccine targets. However, no one can induce these bNAbs by immunization with immunogens containing the MPER sequence(s). The few attempts at developing a vaccine have only resulted in the induction of neutralizing antibodies with quite low potency and limited breadth. Thus far, vaccine failure can be attributed to various characteristics of MPER, such as those involving structure and immunology; therefore, we will focus on these and review the recent progress in the field from the following perspectives: (1) MPER structure and its role in membrane fusion, (2) the epitopes and neutralization mechanisms of MPER-specific bNAbs, as well as the limitations in eliciting neutralizing antibodies, and (3) different strategies for MPER vaccine design and current harvests.     

Antibodies with specificity to native gp120 and neutralization activity against primary human immunodeficiency virus type 1 isolates elicited by immunization with oligomeric gp160.

Current human immunodeficiency virus type 1 (HIV-1) envelope vaccine candidates elicit high antibody binding titers with neutralizing activity against T-cell line-adapted but not primary HIV-1 isolates. Serum antibodies from these human vaccine recipients were also found to be preferentially directed to linear epitopes within gp120 that are poorly exposed on native gp120. Systemic immunization of rabbits with an affinity-purified oligomeric gp160 protein formulated with either Alhydrogel or monophosphoryl lipid A-containing adjuvants resulted in the induction of high-titered serum antibodies that preferentially bound epitopes exposed on native forms of gp120 and gp160, recognized a restricted number of linear epitopes, efficiently bound heterologous strains of monomeric gp120 and cell surface-expressed oligomeric gp120/gp41, and neutralized several strains of T-cell line-adapted HIV-1. Additionally, those immune sera with the highest oligomeric gp160 antibody binding titers had neutralizing activity against some primary HIV-1 isolates, using phytohemagglutinin-stimulated peripheral blood mononuclear cell targets. Induction of an antibody response preferentially reactive with natively folded gp120/gp160 was dependent on the tertiary structure of the HIV-1 envelope immunogen as well as its adjuvant formulation, route of administration, and number of immunizations administered. These studies demonstrate the capacity of a soluble HIV-1 envelope glycoprotein vaccine to elicit an antibody response capable of neutralizing primary HIV-1 isolates.     

Inhibition of lymphoproliferation by a synthetic peptide with sequence identity to gp41 of human immunodeficiency virus type 1.

Peptides were synthesized that contained sequences from two regions (env amino acids [aa] 581 to 597 and 655 to 671) of the transmembrane protein gp41 and one region of the external envelope glycoprotein gp120 (aa 457 to 464) of human immunodeficiency virus type 1. Selection of these sequences was based on their homology to the highly conserved and immunosuppressive sequence contained within the transmembrane proteins p15E and gp21 of animal and human retroviruses, respectively. Peptide aa581-597 was found to specifically inhibit human and murine lymphoproliferation, whereas peptides aa655-671 and aa457-464 had no activity. These results suggest a mechanism by which human immunodeficiency virus type 1 gp41 exerts a direct immunosuppressive effect in vivo, analogous to that postulated for p15E and gp21, which could contribute to the immune dysfunction observed in patients suffering from acquired immunodeficiency syndrome. It is of particular interest that the sequence aa 584 to 609, shown to contain B- and T-helper-cell epitopes, overlaps with the sequence aa 581 to 597 that is shown here to inhibit lymphoproliferation. The potential implications of this overlap of immunologic activities are discussed.     

Covalently linked human immunodeficiency virus type 1 gp120/gp41 is stably anchored in rhabdovirus particles and exposes critical neutralizing epitopes

Rabies virus (RV) vaccine strain-based vectors show significant promise as potential live-attenuated vaccines against human immunodeficiency virus type 1 (HIV-1). Here we describe a new RV construct that will also likely have applications as a live-attenuated or killed-particle immunogen. We have created a RV containing a chimeric HIV-1 Env protein, which contains introduced cysteine residues that give rise to an intermolecular disulfide bridge between gp120 and the ectodomain of gp41. This covalently linked gp140 (gp140 SOS) is fused in frame to the cytoplasmic domain of RV G glycoprotein and is efficiently incorporated into the RV virion. On the HIV-1 virion, the gp120 and gp41 moieties are noncovalently associated, which leads to extensive shedding of gp120 from virions and virus-infected cells. The ability to use HIV-1 particles as purified, inactivated immunogens has been confounded by the loss of gp120 during preparation. Additionally, monomeric gp120 and uncleaved gp160 molecules have been shown to be poor antigenic representations of virion-associated gp160. Because the gp120 and gp41 portions are covalently attached in the gp140 SOS molecule, the protein is maintained on the surface of the RV virion throughout purification. Surface immunostaining and fluorescence-activated cell sorting analysis with anti-envelope antibodies show that the gp140 SOS protein is stably expressed on the surface of infected cells and maintains CD4 binding capabilities. Furthermore, Western blot and immunoprecipitation experiments with infected-cell lysates and purified virions show that a panel of neutralizing anti-envelope antibodies efficiently recognize the gp140 SOS protein. The antigenic properties of this recombinant RV particle containing covalently attached Env, as well as the ability to present Env in a membrane-bound form, suggest that this approach could be a useful component of a HIV-1 vaccine strategy.     

Prediction and validation of HIV-1 gp41 ecto-transmembrane domain post-fusion trimeric structure using molecular modeling

Abstract

The glycoproteins on the surface of human immunodeficiency virus (HIV) undergoes cascade of conformational transitions to evade the human immune system. The virus replicates inside the host and infects the T-cells instigating acquired immunodeficiency syndrome (AIDS). The glycoprotein 41 (gp41) of HIV helps to mediate the fusion of virus and host membranes. The detailed mechanism of host cell invasion by virus remains obscure due to the unavailability of experimental structure of complete gp41. In the current study, the post-fusion (PoF) trimeric structure of ecto-domain including transmembrane domain of gp41 was modeled using multiple homologous templates of Simian immunodeficiency virus (SIV) and HIV-1. In order to validate the gp41 model, interactions of three peptide inhibitors: T20, C37 and C34; were studied using all-atom molecular dynamics (MD) simulations, binding free-energy calculation and per-residue energy decomposition analysis. The binding free energy calculated using MM-PBSA (Molecular Mechanics Poisson-Boltzmann surface area) method predicts maximum affinity for C34 and minimum by T20 for gp41, which is in good agreement with the available computational and experimental studies. The van der Waals interaction is a dominant contributor for the peptide-gp41 complexes. The per-residue decomposition of energy confirmed the role of Trp117, Trp120 and Ile124, present in C34 and C37, for the strong hydrophobic interactions with the deep pocket localized around the N-terminal of gp41, which is lacking in T20. The HIV-1 gp41 structure developed in this work can be used in future study to gain insight into the mechanism of virus invasion and probing potent inhibitor to eliminate AIDS.

Communicated by Ramaswamy H. Sarma     

Common immunologic determinant between human immunodeficiency virus type 1 gp41 and astrocytes.

Monoclonal antibodies against a synthetic 12-amino-acid peptide that comprises the immunodominant domain of human immunodeficiency virus type 1 gp41 (amino acids 598 through 609) reacted with astrocytes found in human and rodent central nervous system tissue. The monoclonal antibodies bound to a 43-kDa protein found in central nervous system tissue preparations. These results indicate that human immunodeficiency virus type 1 gp41 contains a common epitope with astrocytes and that an immune response to human immunodeficiency virus type 1 gp41 could generate antibodies that are cross-reactive to astrocytes. Furthermore, anti-astrocyte antibodies, which were directed at a common epitope with the gp41 sequence, were found to be present in cerebrospinal fluid from some AIDS patients with central nervous system complications. Astrocytes regulate the environment for appropriate neuronal function, and astrocyte hyperactivity (astrocytosis) is known to be the common and early pathologic event in brains from patients with central nervous system AIDS. We suggest that antibody-induced effect(s) on astrocytes could lead to the physiologic neuronal dysfunctions observed in AIDS patients.     

Glucocorticoids exacerbate the deleterious effects of gp120 in hippocampal and cortical explants

Glucocorticoids (GCs), the adrenal steroids secreted during stress, can compromise the ability of hippocampal neurons to survive numerous necrotic insults. We have previously observed that GCs worsen the deleterious effects of gp120, the glycoprotein of the acquired immune deficiency syndrome virus, which can indirectly damage neurons and which is thought to play a role in the neuropathological features of human immunodeficiency virus infection. Specifically, GCs augment gp120-induced calcium mobilization, ATP depletion, decline in mitochondrial potential, and neurotoxicity in fetal monolayer cultures from a number of brain regions. In the present report, we demonstrate a similar gp120/GC synergy in adult hippocampal and cortical explants. We generated explants from rats that were either adrenalectomized, adrenally intact, or intact and treated with corticosterone to produce levels seen in response to major stressors. Metabolic rates in explants were then indirectly assessed with silicon microphysiometry, and cytosolic calcium concentrations were assessed with fura-2 fluorescent microscopy. We observed that basal levels of GCs tonically augment the disruptive effects of gp120 on metabolism in the CA1 cell field of the hippocampus and in the cortex. Moreover, raising GC concentrations into the stress range exacerbated the ability of gp120 to mobilize cytosolic calcium in a number of hippocampal cell fields. Finally, we observed that the synthetic GC prednisone had similarly exacerbating effects on gp120. Thus, GCs can worsen the deleterious effects of gp120 in a system that is more physiologically relevant than the fetal monolayer culture and in a region-specific manner.     

Perspectives on the development of anti-HIV vaccines.

Progress towards the development of a vaccine against acquired immune deficiency syndrome is proceeding along several fronts. First and foremost, it rests on the basic research being done with the virus, particularly its mechanisms of replication, pathogenesis and evolution. More directly, progress comes from studies of animal models with the simian and human immunodeficiency viruses where vaccine candidates have proven effective in blocking infection. Principally because the animal models cannot answer all of the critical questions that apply to a vaccine for man, parallel studies in human volunteers have been initiated.     

Identification of putative, stable binding regions through flexibility analysis of HIV-1 gp120

The acquired-immunodeficiency syndrome has evolved into a major worldwide epidemic. Significant effort has been made in the development of antiviral therapies. A new strategy for vaccine and drug design that complements the existing cocktail therapy is to target entry of the human immunodeficiency virus (HIV). Such an approach provides the advantage of interfering with multiple intermediates in this multi-step process. The extraordinary conformational flexibility, glycosylation, and strain variations of viral glycoprotein gp120 cause general viral evasion of humoral immune response and thus complicate the development of an effective vaccine. Especially difficult to define are the conformation of gp120 before CD4 engagement as well as the relative orientations of the V1/V2 and V3 loops with respect to the inner and outer domains. In this study, we used Floppy Inclusion and Rigid Substructure Topography (FIRST), a program based on graph theory, to analyze the flexibility and rigidity of all known HIV-1 gp120 structures. A flexibility index is used to describe and compare the spatial distribution of protein flexibility and rigidity of these structures in isolation and in complex with CD4, CD4-mimics, and neutralizing antibodies. Using this flexibility analysis, we identified a universal rigid region (the alpha2 helix) as well as the consensus largest rigid cluster involving a beta-sheet located on the coreceptor binding face. Both of these regions may serve as stable targets for vaccine design and drug discovery. Detailed comparisons of the changes in flexibility based on strain variations, stabilizing mutations, binding features of CD4 mimics, and impact of b12 binding are reported.     

A Fusion Intermediate gp41 Immunogen Elicits Neutralizing Antibodies to HIV-1

The membrane-proximal external region (MPER) of the human immunodeficiency virus, type 1 (HIV-1) envelope glycoprotein subunit gp41 is targeted by potent broadly neutralizing antibodies 2F5, 4E10, and 10E8. These antibodies recognize linear epitopes and have been suggested to target the fusion intermediate conformation of gp41 that bridges viral and cellular membranes. Anti-MPER antibodies exert different degrees of membrane interaction, which is considered to be the limiting factor for the generation of such antibodies by immunization. Here we characterize a fusion intermediate conformation of gp41 (gp41_int-Cys) and show that it folds into an elongated ∼12-nm-long extended structure based on small angle x-ray scattering data. Gp41_int-Cys was covalently linked to liposomes via its C-terminal cysteine and used as immunogen. The gp41_int-Cys proteoliposomes were administered alone or in prime-boost regimen with trimeric envelope gp140_CA018 in guinea pigs and elicited high anti-gp41 IgG titers. The sera interacted with a peptide spanning the MPER region, demonstrated competition with broadly neutralizing antibodies 2F5 and 4E10, and exerted modest lipid binding, indicating the presence of MPER-specific antibodies. Although the neutralization potency generated solely by gp140_CA018 was higher than that induced by gp41_int-Cys, the majority of animals immunized with gp41_int-Cys proteoliposomes induced modest breadth and potency in neutralizing tier 1 pseudoviruses and replication-competent simian/human immunodeficiency viruses in the TZM-bl assay as well as responses against tier 2 HIV-1 in the A3R5 neutralization assay. Our data thus demonstrate that liposomal gp41 MPER formulation can induce neutralization activity, and the strategy serves to improve breadth and potency of such antibodies by improved vaccination protocols.     

HIV-1 gp120 mannoses induce immunosuppressive responses from dendritic cells

The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp120 is a vaccine immunogen that can signal via several cell surface receptors. To investigate whether receptor biology could influence immune responses to gp120, we studied its interaction with human, monocyte-derived dendritic cells (MDDCs) in vitro. Gp120 from the HIV-1 strain JR-FL induced IL-10 expression in MDDCs from 62% of donors, via a mannose C-type lectin receptor(s) (MCLR). Gp120 from the strain LAI was also an IL-10 inducer, but gp120 from the strain KNH1144 was not. The mannose-binding protein cyanovirin-N, the 2G12 mAb to a mannose-dependent gp120 epitope, and MCLR-specific mAbs inhibited IL-10 expression, as did enzymatic removal of gp120 mannose moieties, whereas inhibitors of signaling via CD4, CCR5, or CXCR4 were ineffective. Gp120-stimulated IL-10 production correlated with DC-SIGN expression on the cells, and involved the ERK signaling pathway. Gp120-treated MDDCs also responded poorly to maturation stimuli by up-regulating activation markers inefficiently and stimulating allogeneic T cell proliferation only weakly. These adverse reactions to gp120 were MCLR-dependent but independent of IL-10 production. Since such mechanisms might suppress immune responses to Env-containing vaccines, demannosylation may be a way to improve the immunogenicity of gp120 or gp140 proteins.     

Design,synthesis and activity evaluation of novel peptide fusion inhibitors targeting HIV-1 gp41

Human immunodeficiency virus type 1 (HIV-1), the pathogen of acquired immunodeficiency syndrome (AIDS), causes about 2 million people to death every year. Fusion inhibitors targeted the envelope protein (gp41) represent a novel and alternative approach for anti-AIDS therapy, which terminates the HIV-1 life cycle at an early stage. Using CP621-652 as a template, a series of peptides were designed, synthesized and evaluated in vitro assays. An interesting phenomenon was found that the substitution of hydrophobic residues at solvent accessible sites could increase the anti-HIV activity when the C-terminal sequence was extended with an enough numbers of amino acids. After the active peptides was synthesized and evaluated, peptide 8 showed the best anti-HIV-1 IIIB whole cell activity (MAGI IC₅₀ = 53.02 nM). Further study indicated that peptide 8 bound with the gp41 NHR helix, and then blocked the conformation of 6-helix, thus inhibited virus–cell membrane fusion. The results would be helpful for the design of peptide fusion inhibitors against HIV-1 infection.     

Membrane topology of gp41 and amyloid precursor protein: Interfering transmembrane interactions as potential targets for HIV and Alzheimer treatment

The amyloid precursor protein (APP), that plays a critical role in the development of senile plaques in Alzheimer disease (AD), and the gp41 envelope protein of the human immunodeficiency virus (HIV), the causative agent of the acquired immunodeficiency syndrome (AIDS), are single-spanning type-1 transmembrane (TM) glycoproteins with the ability to form homo-oligomers. In this review we describe similarities, both in structural terms and sequence determinants of their TM and juxtamembrane regions. The TM domains are essential not only for anchoring the proteins in membranes but also have functional roles. Both TM segments contain GxxxG motifs that drive TM associations within the lipid bilayer. They also each possess similar sequence motifs, positioned at the membrane interface preceding their TM domains. These domains are known as cholesterol recognition/interaction amino acid consensus (CRAC) motif in gp41 and CRAC-like motif in APP. Moreover, in the cytoplasmic domain of both proteins other α-helical membranotropic regions with functional implications have been identified. Recent drug developments targeting both diseases are reviewed and the potential use of TM interaction modulators as therapeutic targets is discussed.     

Mutations in envelope gp120 can impact proteolytic processing of the gp160 precursor and thereby affect neutralization sensitivity of human immunodeficiency virus type 1 pseudoviruses

The design of an efficient human immunodeficiency virus (HIV) immunogen able to generate broad neutralizing antibodies (NAbs) remains an elusive goal. As more data emerge, it is becoming apparent that one important aspect of such an immunogen will be the proper representation of the envelope protein (Env) as it exists on native virions. Important questions that are yet to be fully addressed include what factors dictate Env processing, how different Env forms are represented on the virion, and ultimately how these issues influence the development and efficacy of NAbs. Recent data have begun to illuminate the extent to which changes in gp41 can impact the overall structure and neutralizing sensitivity of Env. Here, we present evidence to suggest that minor mutations in gp120 can significantly impact Env processing. We analyzed the gp120 sequences of 20 env variants that evolved in multiple macaques over 8 months of infection with simian/human immunodeficiency virus 89.6P. Variant gp120 sequences were subcloned into gp160 expression plasmids with identical cleavage motifs and gp41 sequences. Cells cotransfected with these plasmids and Δenv genomes were able to produce competent virus. The resulting pseudoviruses incorporated high levels of Env onto virions that exhibited a range of degrees of virion-associated Env cleavage (15 to 40%). Higher levels of cleavage correlated with increased infectivity and increased resistance to macaque plasma, HIV immunoglobulin, soluble CD4, and human monoclonal antibodies 4E10, 2F5, and b12. Based on these data, we discuss a model whereby changes in gp120 of 89.6P impact Env processing and thereby mediate escape from a range of neutralizing agents.     

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

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.     

人类免疫缺陷病毒1型gp41结构与功能的研究进展

人类免疫缺陷病毒1型(HIV-1)通过其包膜糖蛋白(Env)介导侵入靶细胞.Env由受体特异性结合单位gp120和膜融合单位gp41组成.HIV-1的gp41分为3个功能区:膜外区、跨膜区和膜内区.膜外区是病毒感染时膜融合的主要结构基础;跨膜区通过疏水残基使Env锚定在脂质膜上;膜内区则表现多重功能,参与病毒的感染、复...