Serum antibodies to HIV-1 in recombinant vaccinia virus recipients boosted with purified recombinant gp160

Serum antibody responses were studied in detail in four vaccinia-naive volunteers in a phase I trial evaluating primary vaccination with a recombinant vaccinia virus expressing the HIV-1 gp160 envelope glycoprotein (HIVAC-1e, Oncogen/Bristol-Myers Squibb), followed by booster immunization with baculovirus-derived rgp160 (VaxSyn, MicroGeneSys). Prior to boosting, low-titer Fc receptor (FcR)-mediated, antibody-dependent enhancing (ADE) activity was detected in two of four volunteers but no IgM, IgG, IgA, neutralizing activity, or complement-mediated ADE activity was detected. Two weeks after boosting, all four volunteers developed HIV-1-specific IgG with titers of 1:160 to 1:640 by immunofluorescence assay. IgG1 was present in sera from each individual, while IgG2 and IgG3 were present in sera from two individuals, and IgG4 was present in serum from one individual. IgM and IgA were undetectable in all sera. Only one volunteer had IgG to the heterologous HIV-1 isolates, RF, MN, and SF2, after boosting. Serum from this volunteer neutralized the vaccine strain, LAV/IIIB, but not the heterologous strains, RF, MN, and SF2. Antibodies from the remaining volunteers had no neutralizing activity. The neutralizing serum had a positive reaction in a peptide-based ELISA utilizing a peptide corresponding to the principal neutralizing domain of the third hypervariable region (i.e., V3 loop) of the envelope glycoprotein. Neutralizing activity was partially removed by adsorption to this peptide, suggesting that it contained a type-specific neutralizing vaccine epitope. A low titer (1:40 to 1:80) of complement-mediated ADE activity to HIV-1 IIIB was present in sera from three vaccinees after boosting. FcR-ADE activity for HIV-1 SF2 and SF-128A were present in sera from two of these three vaccinees. None of the volunteers developed antisyncytial antibodies. These results indicate that inoculation with recombinant vaccinia followed by rgp160 boosting is the most effective strategy to date for inducing serum antibodies to the envelope glycoproteins of HIV-1, but further study is needed to optimize the functionality and cross-reactivity of these responses.     

人免疫缺陷病毒1型(HIV-1)gag基因疫苗的免疫原性

目的 :检测人免疫缺陷病毒 1型 (HIV 1)gag基因疫苗的免疫原性。方法 :分别以ELISA、荧光抗体染色和乳酸脱氢酶释放法 ,检测免疫小鼠血清抗体滴度、脾T细胞亚群的数量和淋巴细胞杀伤效应。结果 :血清抗体滴度、脾T细胞亚群的数量及淋巴细胞杀伤效应 ,重组质粒pVAXGAG免疫组与空载体pVAX1对照组相比较差异显著(分别为P <0 .0 5和P <0 .0 1)。结论 :HIV 1DNA疫苗质粒pVAXGAG在BALB/c小鼠中不仅可诱导特异性体液免疫 ,而且可诱导特异性细胞免疫。     

Conformation of gp120 determines the sensitivity of HIV-1 DH012 to the entry inhibitor IC9564

The HIV-1 envelope glycoprotein gp120 is the key determinant for the anti-HIV-1 entry activity of IC9564. A T198P mutation in the gp120 of the HIV-1 primary isolate, DH012, drastically increases IC9564 sensitivity, which can be reversed by growing the virus in the presence of IC9564. The reversed resistant variants contain a P198S mutation that fully confers the drug-resistant phenotype. Although the amino acid residue at position 198 of gp120 can alter IC9564 sensitivity, results from this study suggest that T198 is not the direct target of the compound. The mutation at position 198 appears to affect the conformation of gp120 and subsequently decreases the accessibility of the drug target. This conformational effect is evidenced by the fact that the T198P mutation significantly increases the neutralizing activity of the conformational antibodies, 1b12 and 48d. On the other hand, the IC9564 escape variant with the P198S mutation is resistant to these conformational antibodies and highly sensitive to the potent neutralizing antiserum, C1206, which recognizes a conformational epitope involving the sequences from V1, V2, and V3 regions in gp120. Thus, results from this study indicate that the conformation of gp120 can be exploited by HIV-1 to escape IC9564.     

含HIV-1 gp120基因的重组腺相关病毒和重组腺病毒疫苗联合免疫的研究

目的 探讨含HIV-1 gp120基因的重组腺相关病毒(rAAV)和重组腺病毒(rAdV)疫苗在BALB／c小鼠中联合免疫的效果。方法 将密码子优化的HIV-1 gp120基因分别插入腺相关病毒(AAV)和腺病毒(AdV)载体质粒，构建含该基因的rAVV和rAdV载体疫苗。将两种疫苗以不同的联合方式免疫BALB／c小鼠，ELISA检测小鼠血清中的gp120特异性抗体，细胞内细胞因子染色法检测小鼠的特异性细胞毒性T淋巴细胞(CTL)应答。结果 两种重组病毒均可表达目的基因gp120；在小鼠体内两种重组病毒联合免疫可诱导特异性的CTL应答和血清1gG抗体反应，但用rAAV初免2次，再用rAdV加强3次所诱发的CTL和血清1gG反应最强。结论 rAAV和rAdV疫苗联合免疫可在小鼠体内诱导特异性的CTL应答和血清1gG抗体反应。     

Ancestral and consensus envelope immunogens for HIV-1 subtype C

Immunogens based on "centralized" (ancestral or consensus) HIV-1 sequences minimize the genetic distance between vaccine strains and contemporary viruses and should thus elicit immune responses that recognize a broader spectrum of viral variants. However, the biologic, antigenic and immunogenic properties of such inferred gene products have to be validated experimentally. Here, we report the construction and characterization of the first full-length ancestral (AncC) and consensus (ConC) env genes of HIV-1 (group M) subtype C. The codon-usage-optimized genes expressed high levels of envelope glycoproteins that were incorporated into HIV-1 virions, mediated infection via the CCR5 co-receptor and retained neutralizing epitopes as recognized by plasma from patients with chronic HIV-1 subtype C infection. Guinea pigs immunized with AncC and ConC env DNA developed high titer binding, but no appreciable homologous or heterologous neutralizing antibodies. When tested by immunoblot analysis, sera from AncC and ConC env immunized guinea pigs recognized a greater number of primary subtype C envelope glycoproteins than sera from guinea pigs immunized with a contemporary subtype C env control. Mice immunized with AncC and ConC env DNA developed gamma interferon T cell responses that recognized overlapping peptides from the cognate ConC and a heterologous subtype C Env control. Thus, both AncC and ConC env genes expressed functional envelope glycoproteins that were immunogenic in laboratory animals and elicited humoral and cellular immune responses of comparable breadth and magnitude. These results establish the utility of centralized HIV-1 subtype C Env immunogens and warrant their continued evaluation as potential components of future AIDS vaccines.     

Antigenicity and immunogenicity of HIV-1 consensus subtype B envelope glycoproteins

"Centralized" (ancestral and consensus) HIV-1 envelope immunogens induce broadly cross-reactive T cell responses in laboratory animals; however, their potential to elicit cross-reactive neutralizing antibodies has not been fully explored. Here, we report the construction of a panel of consensus subtype B (ConB) envelopes and compare their biologic, antigenic, and immunogenic properties to those of two wild-type Env controls from individuals with early and acute HIV-1 infection. Glycoprotein expressed from full-length (gp160), uncleaved (gp160-UNC), truncated (gp145), and N-linked glycosylation site deleted (gp160-201N/S) versions of the ConB env gene were packaged into virions and, except for the fusion defective gp160-UNC, mediated infection via the CCR5 co-receptor. Pseudovirions containing ConB Envs were sensitive to neutralization by patient plasma and monoclonal antibodies, indicating the preservation of neutralizing epitopes found in contemporary subtype B viruses. When used as DNA vaccines in guinea pigs, ConB and wild-type env immunogens induced appreciable binding, but overall only low level neutralizing antibodies. However, all four ConB immunogens were significantly more potent than one wild-type vaccine at eliciting neutralizing antibodies against a panel of tier 1 and tier 2 viruses, and ConB gp145 and gp160 were significantly more potent than both wild-type vaccines at inducing neutralizing antibodies against tier 1 viruses. Thus, consensus subtype B env immunogens appear to be at least as good as, and in some instances better than, wild-type B env immunogens at inducing a neutralizing antibody response, and are amenable to further improvement by specific gene modifications.     

中国株HIV-1外膜蛋白基因疫苗诱导免疫小鼠免疫应答的实验研究

目的 :构建中国流行株HIV 1外膜蛋白 (gp12 0 )基因疫苗并接种小鼠 ,评价其诱导的体液和细胞免疫应答。方法 :将HIV 1gp12 0基因插入到真核表达载体pVAX1中 ,构建重组真核表达质粒pVAX1 GP12 0 ,并经EcoRI和PstI双酶切以及测序鉴定。同时以pVAX1 GP12 0和空载体pVAX1分别免疫BALB/c小鼠 ,采用ELISA检测免疫小鼠的特异性抗体和IFN γ水平 ,用MTT比色法检测免疫小鼠脾淋巴细胞的增殖 ,用乳酸脱氢酶 (LDH)试验检测小鼠特异性细胞毒性T淋巴细胞 (CTL)的应答。结果 :酶切及测序结果表明 ,成功地构建了HIV 1gp12 0基因疫苗。与空载体pVAX1组相比较 ,pVAX1 GP12 0免疫组小鼠血清抗HIV 1gp12 0抗体的滴度和IFN γ的水平均升高 ,两者差异显著 (P <0 .0 1)。pVAX1 GP12 0免疫组小鼠脾淋巴细胞增殖的刺激指数 (SI)及特异性CTL的杀伤活性 ,均高于空载体pVAX1组 (P <0 .0 1)。结论 :构建了针对我国HIV 1流行株的gp12 0基因疫苗。以其免疫BALB/c小鼠可诱导特异性体液和细胞免疫应答 ,为进一步将其用于我国的HIV的治疗奠定了基础。     

Structure-based,targeted deglycosylation of HIV-1 gp120 and effects on neutralization sensitivity and antibody recognition

The human immunodeficiency virus (HIV-1) exterior envelope glycoprotein, gp120, mediates receptor binding and is the major target for neutralizing antibodies. Primary HIV-1 isolates are characteristically more resistant to broadly neutralizing antibodies, although the structural basis for this resistance remains obscure. Most broadly neutralizing antibodies are directed against functionally conserved gp120 regions involved in binding to either the primary virus receptor, CD4, or the viral coreceptor molecules that normally function as chemokine receptors. These antibodies are known as CD4 binding site (CD4BS) and CD4-induced (CD4i) antibodies, respectively. Inspection of the gp120 crystal structure reveals that although the receptor-binding regions lack glycosylation, sugar moieties lie proximal to both receptor-binding sites on gp120 and thus in proximity to both the CD4BS and the CD4i epitopes. In this study, guided by the X-ray crystal structure of gp120, we deleted four N-linked glycosylation sites that flank the receptor-binding regions. We examined the effects of selected changes on the sensitivity of two prototypic HIV-1 primary isolates to neutralization by antibodies. Surprisingly, removal of a single N-linked glycosylation site at the base of the gp120 third variable region (V3 loop) increased the sensitivity of the primary viruses to neutralization by CD4BS antibodies. Envelope glycoprotein oligomers on the cell surface derived from the V3 glycan-deficient virus were better recognized by a CD4BS antibody and a V3 loop antibody than were the wild-type glycoproteins. Absence of all four glycosylation sites rendered a primary isolate sensitive to CD4i antibody-mediated neutralization. Thus, carbohydrates that flank receptor-binding regions on gp120 protect primary HIV-1 isolates from antibody-mediated neutralization.     

Effect of partial and complete variable loop deletions of the human immunodeficiency virus type 1 envelope glycoprotein on the breadth of gp160-specific immune responses

Induction of cross-reactive cellular and humoral responses to the HIV-1 envelope (env) glycoprotein was examined after DNA immunization of BALB/c mice with gp140(89.6)-derived constructs exhibiting partial or complete deletions of the V1, V2, and V3 domains. It was demonstrated that specific modification of the V3 loop (mV3) in combination with the V2-modified (mV2) or V1/V2-deleted (DeltaV1/V2) region elicited increased levels of cross-reactive CD8(+) T cell responses. Mice immunized with the mV2/mV3 or DeltaV1/V2/mV3 gp140(89.6) plasmid DNA were greater than 50-fold more resistant to challenge with recombinant vaccinia virus (rVV) expressing heterologous env gene products than animals immunized with the wild-type (WT) counterpart. Sera from mV2/mV3- and DeltaV1/V2/mV3-immunized mice exhibited the highest cross-neutralizing activity and displayed intermediate antibody avidity values which were further enhanced by challenge with rVV expressing the homologous gp160 glycoprotein. In contrast, complete deletion of the variable regions had little or no effect on the cross-reactive antibody responses. The results of these experiments indicate that the breadth of antibody responses to the HIV-1 env glycoprotein may not be increased by removal of the variable domains. Instead, partial deletions within these regions may redirect specific responses toward conserved epitopes and facilitate approaches for boosting cross-reactive cellular and antibody responses to the env glycoprotein.     

小鼠对HIV-2 gp105核酸疫苗免疫应答的研究

目的: 探讨HIV- 2gp105基因核酸疫苗在小鼠体内的免疫应答, 为开发HIV- 2核酸疫苗提供实验依据。方法:将HIV- 2外膜蛋白 (gp105 )基因插入真核表达质粒载体pVAX1中, 构建pVAX1 gp105重组表达质粒。将其肌注免疫BALB/c小鼠, 用ELISA法检测小鼠血清抗HIV -2抗体, 用流式细胞仪测定CD4 、CD8 T细胞亚群数, 以乳酸脱氢霉释放法检测脾特异性CTL的杀伤活性。结果: 重组质粒pVAX1 -gp105免疫组小鼠的血清抗体滴度、脾T细胞亚群的数量及特异性CTL的杀伤活性, 均明显高于对照组, 分别为P<0. 01, P<0. 05和P<0. 01。结论: HIV -2gp105核酸疫苗能诱导小鼠产生特异性细胞和体液免疫。     

含密码子优化型HIV-1 gp120基因重组腺病毒的构建及其免疫效果研究

目的 构建能表达野生型和密码子优化型人免疫缺陷病毒Ⅰ型(HIV-1)B亚型中国流行株gp120基因的非复制型腺病毒。方法 按哺乳动物细胞偏好的密码子对HIV-1B亚型中国流行株Ch gp42的gp120基因进行优化，合成优化基因。将野生型和密码子优化的gp120基因插入穿梭质粒，再与腺病毒骨架质粒pAdEasy-1共转化E．coli BJ5183，获得重组子，转染293细胞后获得重组病毒。分别以两种重组腺病毒疫苗免疫小鼠，ELISA检测小鼠血清中的特异性抗体，乳酸脱氢酶法检测小鼠细胞毒性T淋巴细胞(CTL)反应。结果 获得两株重组腺病毒rAd-wt．gp120和rAd．mod．gp120，能正确表达Gp120。rAd-mod．gp120比rAd-wt．gp120蛋白表达水平明显提高。重组腺病毒免疫小鼠后能产生HIV-1特异性的抗体及CTL反应，rAd-mod．gp120组明显优于rAd-wt．gp120组。结论 成功构建了表达野生型和密码子优化的HIV-1 gp120基因的重组腺病毒，能诱导HIV-1特异性体液和细胞免疫反应。     

HIV-1糖蛋白gp120激发人小胶质细胞钙内流效应和ERK磷酸化

目的： 探讨HIV-1糖蛋白gp120对人小胶质细胞钙离子内流和ERK磷酸化的作用及其机制。方法: 用钙离子探针Fluo-4标记粘附在盖玻片上的人小胶质细胞，运用共聚焦显微镜以荧光强度为指标实时观察各种条件下的细胞内钙离子水平的变化；用gp120处理并用anti-gp120-FITC进行染色，运用共聚焦显微镜术和流式细胞术分析人小胶质细胞与gp120结合情况；用抗磷酸化ERK 抗体免疫荧光方法进行染色，运用共聚焦显微镜术和流式细胞术进行ERK磷酸化水平分析。结果: 共聚焦显微镜检测结果显示HIV-1 糖蛋白gp120能够激发人小胶质细胞钙离子内流效应；共聚焦显微镜和流式细胞仪分析结果显示gp120可以与人小胶质细胞结合；共聚焦显微镜和流式细胞仪分析结果显示gp120刺激可增加人小胶质细胞ERK磷酸化。结论: HIV-1 糖蛋白gp120能在人小胶质细胞激发钙离子内流并且增加胞内ERK的磷酸化，从而导致了小胶质细胞的活化，这一效应提示，在HIV-1相关性脑炎中，gp120可能参与了某些发病机制。     

Assembly, structure, and antigenic properties of virus-like particles rich in HIV-1 envelope gp120

In order to improve the immunogenicity of HIV-1 envelope glycoproteins, we have fused gp120 to a carrier protein, hepatitis B surface antigen (HBsAg), which is capable of spontaneous assembly into virus-like particles. The HBsAg-gp120 hybrid proteins assembled efficiently into 20-30 nm particles. The particles resemble native HBsAg particles in size and density, consistent with a lipid composition of about 25% and a gp120 content of about 100 per particle. Particulate gp120 folds in its native conformation and is biologically active, as shown by high affinity binding of CD4. The particles express conformational determinants targeted by a panel of broadly cross-reactive neutralizing antibodies, and they show tight packing of gp120. Because the particles are lipoprotein micelles, an array of gp120 on their surface closely mimics gp120 on the surface of HIV-1 virions. These gp120-rich particles can enhance the quality, as well as quantity, of antibodies elicited by a gp120 vaccine.     

HIV-1 B''亚型gag-env融合基因的DNA疫苗构建和免疫原性分析

目的 构建HIV-1 B′亚型中国流行株gag和env融合基因的DNA疫苗，对其免疫原性进行研究。方法 根据已报道的HIV-1 B′亚型RIA2分离株gag和env基因的氨基酸序列按哺乳动物密码子使用频率进行优化并人工合成基因，插入真核表达载体pDRVISV1．0中，构建表达RL42 gag-env，融合蛋白的DNA疫苗，pSVRL／GE。用Western blot和抗gag p55抗体细胞内染色的方法体外检测pSVRUGE的表达效率。DNA疫苗pSVRL/GE免疫BALB／c小鼠后，用ELISPOT检测小鼠的细胞免疫反应。结果 限制性内切酶鉴定表明融合基因已成功插入pDRVISV1．0载体中，Western blot证实融合基因可有效表达融合蛋白；细胞内染色结果表明，pSVRL/GE转染的293T细胞中49．8％表达gag p55，荧光强度均值为924；而空载体pDRVISV1．0转染的293T细胞中非特异背景染色只有0．5％。经免疫的小鼠脾细胞体外用H-2^d限制性表位肽AMQMIKET刺激后，ELISPOT检测显示，pSVRUGE免疫小鼠每10^6脾细胞形成226个斑点（SD=140），而空载对照组每1驴脾细胞形成29个斑点（SD=16）（P〈0．05）。结论 所构建的DNA疫苗pSVRL/GE可高效表达相应抗原蛋白，并可有效激活机体的细胞免疫反应。     

Point mutations in the C-terminus of HIV-1 gp160 reduce apoptosis and calmodulin binding without affecting viral replication

One hallmark of AIDS progression is a decline in CD4+ T lymphocytes, though the mechanism is poorly defined. There is ample evidence that increased apoptosis is responsible for some, if not all, of the decline. Prior studies have shown that binding of cellular calmodulin to the envelope glycoprotein (Env) of HIV-1 increases sensitivity to fas-mediated apoptosis and that calmodulin antagonists can block this effect. We show that individual mutation of five residues in the C-terminal calmodulin-binding domain of Env is sufficient to significantly reduce fas-mediated apoptosis in transfected cells. The A835W mutation in the cytoplasmic domain of gp41 eliminated co-immunoprecipitation of Env with calmodulin in studies with stably transfected cells. Four point mutations (A835W, A838W, A838I, and I842R) and the corresponding region of HIV-1 HXB2 were cloned into the HIV-1 proviral vector pNL4-3 with no significant effect on viral production or envelope expression, although co-immunoprecipitation of calmodulin and Env was decreased in three of these mutant viruses. Only wild-type envelope-containing virus induced significantly elevated levels of spontaneous apoptosis by day 5 post-infection. Fas-mediated apoptosis levels positively correlated with the degree of calmodulin co-immunoprecipitation, with the lowest apoptosis levels occurring in cells infected with the A835W envelope mutation. While spontaneous apoptosis appears to be at least partially calmodulin-independent, the effects of HIV-1 Env on fas-mediated apoptosis are directly related to calmodulin binding.     

Autoproliferation in HIV-1-infected patients undergoing active HIV-1-specific immunotherapy.

We have observed a treatment-associated autoproliferative response in cultured peripheral blood mononuclear cells (PBMC) of asymptomatic HIV-1-infected subjects receiving a gp120-depleted, inactivated HIV-1 antigen in incomplete Freund's adjuvant (IFA; HIV-1 Immunogen). The frequency and magnitude of the autoproliferative response appeared to be dose-related (P < 0.05), and was not observed in subjects receiving IFA alone. Immunophenotyping of the proliferating cells demonstrated the presence of both CD4+ and CD8+ lymphocytes, with the CD4+ blasts almost exclusively expressing the CD45RO+ phenotype. A comparison of this response with the HIV-1-specific antigen stimulation responses in this cohort revealed a significant correlation between increases in HIV-1-specific cell-mediated immunity and autoproliferation (r2 = 0.61, P < 0.001). These findings suggest that immunization with the HIV-1 Immunogen induces an autoproliferative response that may reflect changes in HIV-1-specific cell-mediated immunity in infected individuals.     

RECOMBINATION PROPERTY OF THE HIV-1 gp120 GENE

Using a chimeric primer consisting of the nucleotide sequence derived from the HIV-1 envelope gene coding for the second conserved region of gp120, and the highly conserved sequence derived from the human immunoglobulin gene coding for the V_HIII domain, it has been identified in sera of AIDS patients HIV-1 field isolates carrying the complete and active Chi recombination hot spot (GCTGGTGG). The recombination between the HIV-1 gene coding for the central portion of gp120 and the bacterial gene coding for the clp protease was also demonstrated in vivo. These results point out serious concern that vectored AIDS vaccine candidates carrying the HIV-1 env gene on viral and bacterial vectors could become the source of potentially new infectious diseases rather than an effective instrument for AIDS prevention.     

HIV-1 gp41重组抗原的表达及其免疫反应性检测

为了在大肠杆菌中表达具有良好免疫反应性的HIV-1gp41重组抗原,本实验运用基因工程技术,经PCR扩增gp41的主要抗原表位序列,BamHⅠ、XhoⅠ双酶切后与E3质粒连接,转化克隆宿主菌DH5α,再提取重组质粒进一步转化表达宿主菌BL21(DE3),经IPTG诱导表达重组蛋白,纯化后标记HRP,通过双抗原夹心酶联免疫方法检测其免疫反应性和特异性。结果表明,获得的HIV-1gp41重组抗原能够与相应抗体特异性结合,与多种无关抗体间无交叉反应,对825份HIV阴性标本检测无错检。检测结果说明该重组抗原具有良好的免疫反应性,在HIV-1抗体诊断试剂中具有潜在的应用价值,为进一步研究gp41抗原奠定了基础。