狡猾的HIV

世界与我国艾滋病概况艾滋病病毒无疑是人类遇到的最强大的对手之一。到2004年全球累积艾滋病病毒感染者人数为7000多万。其中已经有3000多万人死亡,目前存活的感染者大约为3800万～4200万。由于大多数发达国家重视得比较早,采用宣传教育等干预措施及辅助药物治疗等手段,艾滋病在发达国家的流行势头比较低,而发展中国家则集中了绝大多数艾滋病病毒感染者。美国目前感染者大约为90万,俄罗斯大约为100万,而非洲大约有2000多万,印度约为500多万。     

HIV疫苗研究进展

自从1983年发现人类免疫缺陷病毒(Human immunodeficiency virus,HIV)以来,HIV一直以惊人的速度在全球蔓延,感染HIV的人数也日益增多.到目前为止,因患艾滋病死亡的人数已达到2500万,到2010年这一数字可能会突破8000万,因此研究预防和治疗艾滋病的药物也正日益迫切地摆在人们面前.     

HIV疫苗研究进展

自从1983年发现人类免疫缺陷病毒(Human immunodeficiency virus,HIV)以来,HIV一直以惊人的速度在全球蔓延,感染HIV的人数也日益增多。到目前为止,因患艾滋病死亡的人数已达到2500万,到2010年这一数字可能会突破8000万,因此研究预防和治疗艾滋病的药物也正日益迫切地摆在人们面     

HIV模型动力学分析及抗HIV感染治疗仿真

基于基本病毒感染模型,本文引入了一个包含免疫项的艾滋病病毒(HIV)感染模型.该模型有一个病毒清除平衡点和一个持续带毒平衡点.证明如果病毒感染的基本再生数R1,则病毒清除平衡点是全局渐近稳定的.该结果说明若一个HIV感染者其R1,则即使被感染大量的HIV最终仍然能自愈.基于该模型本文提出了一个抗HIV感染治疗模型.本文定理暗指若抗HIV感染治疗时,患者的R1则迟早患者体内的HIV可以清除.反之数值的仿真模拟表明患者R1时,患者体内的HIV不能被彻底清除.患者的依从性是抗HIV感染成功的重要因素之一.     

HIV超感染防御研究进展

机体在原发感染病毒后,体内能产生某种可能的干扰以阻挡、防止被同种（或同类别）株病毒再次感染现象,HIV感染中也存在这种超感染防御现象。显然,该的研究对于改进HIV疫苗研制策略及其他抗病毒策略十分重要。目前研究认为感染细胞在分子水平上产生的超感染抵抗（superinfection resistance,SIR）和机体免疫反应是感染个体能防御超感染的主要原因。但以上各种假说都没有得到充分验证,HIV超感染防御依然尚未明确。本文将这些研究进行总结,以期找出新的突破口,推进该项研究。     

HIV的生物学特性

爱滋病(AIDS)目前正在全球蔓延,它已遍及五大洲,波及一百多个国家和地区。世界卫生组织估计,到1991年全世界将有50-300万AIDS患者,近1亿人受到HIV的感染,将成为世界十大致命疾病之一。本文就HIV的形态结构、基因组成、复制繁殖等生物学特性作简单的介绍: 一、概述 HIV是60年代分布在中非(扎伊尔、卢旺达、布隆迪、乌干达、坦桑尼亚、肯尼亚等国)绿猴身上的病毒变异而来的。70年代初期由维多利亚湖西部经中非传播,最早传到加勒比地区的海地,随后又传到美国,目前世界上AIDS患者中80%是美国人。1983年5月巴黎巴斯德研究院以蒙塔尼为首的科     

一个HIV感染的动力学模型

考虑到人体免疫缺损病毒(HIV)能感染和杀每T4细胞,病毒颗粒能从感染细胞膜上发芽而出以及感染细胞能与未感染细胞融合等实验事实,建议了一个细胞水平的人体免疫缺损病毒感染的动力学模型。利用这个模型,我们对HIV感染的动力学行为进行了分析。结果表明:在潜伏期,感染细胞的溶度和病毒的溶度都渐渐地趋于一个暂态的平衡值;在表达期,病毒溶度大幅度增加,正常T4细胞溶度渐渐减少,这也许正是AIDS病致病的原因。     

Toward Effective HIV Vaccination: INDUCTION OF BINARY EPITOPE REACTIVE ANTIBODIES WITH BROAD HIV NEUTRALIZING ACTIVITY*

We describe murine monoclonal antibodies (mAbs) raised by immunization with an electrophilic gp120 analog (E-gp120) expressing the rare ability to neutralize genetically heterologous human immunodeficiency virus (HIV) strains. Unlike gp120, E-gp120 formed covalent oligomers. The reactivity of gp120 and E-gp120 with mAbs to reference neutralizing epitopes was markedly different, indicating their divergent structures. Epitope mapping with synthetic peptides and electrophilic peptide analogs indicated binary recognition of two distinct gp120 regions by anti-E-gp120 mAbs, the 421–433 and 288–306 peptide regions. Univalent Fab and single chain Fv fragments expressed the ability to recognize both peptides. X-ray crystallography of an anti-E-gp120 Fab fragment revealed two neighboring cavities, the typical antigen-binding cavity formed by the complementarity determining regions (CDRs) and another cavity dominated by antibody heavy chain variable (V_H) domain framework (FR) residues. Substitution of the FR cavity V_H Lys-19 residue by an Ala residue resulted in attenuated binding of the 421–433 region peptide probe. The CDRs and V_H FR replacement/silent mutation ratios exceeded the ratio for a random mutation process, suggesting adaptive development of both putative binding sites. All mAbs studied were derived from V_H1 family genes, suggesting biased recruitment of the V gene germ line repertoire by E-gp120. The conserved 421–433 region of gp120 is essential for HIV binding to host CD4 receptors. This region is recognized weakly by the FR of antibodies produced without exposure to HIV, but it usually fails to induce adaptive synthesis of neutralizing antibodies. We present models accounting for improved CD4-binding site recognition and broad HIV neutralizing activity of the mAbs, long sought goals in HIV vaccine development.Induction of neutralizing antibodies (Abs)² via adaptive immune processes is the cornerstone of vaccination against microbial antigens. The antigen-binding site is mostly formed by the complementarity determining regions (CDRs) of the light and heavy chain variable domains (V_L and V_H domains). Vaccine-induced adaptive Ab responses entail sequence diversification of Ab V domains expressed within the B cell receptor (BCR) complex, selective noncovalent antigen binding to the high affinity BCR mutants, and proliferation of the mutant B cell clones. No HIV vaccine is available. The surface of HIV is studded with noncovalently associated oligomers of gp120 complexed to gp41. HIV infection and experimental HIV vaccination attempts induce robust Ab responses to the immunodominant epitopes of gp120, which are structurally divergent in various HIV strains responsible for infection in different parts of the world. Abs to such epitopes express strain-specific neutralization (1, 2), i.e. they neutralize the HIV strain from which the immunogen was isolated but not strains genetically heterologous to the immunogen.The gp120 site responsible for binding host CD4 receptors (CD4BS) is structurally more conserved. Precise conformational details of the CD4BS expressed on the HIV surface are not available, but crystallography suggests a large, discontinuous determinant composed of regions distant from each other in the linear protein sequence (3, 4). The 421–433 peptide region is essential for CD4 binding by gp120, suggested by contacts in the crystallized complex and loss of CD4 binding function by site-directed mutagenesis in this region (5, 6). The 421–433 region is a member of a small group of microbial polypeptide sites recognized selectively by Abs produced by the immune system without prior infection by the microbe (preimmune Abs) (7–9). Such sites are designated B cell “superantigens” (SAgs) because of their selective and widespread recognition by the comparatively conserved framework regions (FRs) of Ab V domains (10, 11). Noncovalent SAg binding by preimmune Abs, however, is characterized by low-to-moderate binding strength (12). Most gp120-binding preimmune Abs from humans without infection display poor or no HIV neutralizing activity (13). Patients with the autoimmune disease lupus and no HIV infection produce increased amounts of Abs to the 421–433 CD4BS region (14). A single chain Fv (scFv; V_L and V_H domains linked by a flexible peptide) from the lupus Ab repertoire that binds the 421–433 region reversibly neutralizes genetically diverse strains of HIV (15). Following completion of the noncovalent binding step, certain Abs can hydrolyze polypeptides via nucleophilic attack on carbonyl groups (16–21). The proteolytic reaction imparts improved antigen inactivation potency to Abs (22). We reported the neutralization of HIV by secretory IgA from humans without infection, an Ab class distinguished by the ability to catalyze the hydrolysis of gp120 selectively because of initial noncovalent recognition of the 421–433 CD4BS region (13).The conserved character of the CD4BS in genetically diverse HIV strains renders it suitable as a vaccine target. The CD4BS, however, is poorly immunogenic. Traditional immunization methods do not stimulate the adaptive synthesis of neutralizing Abs to the 421–433 region or other CD4BS epitopes. Neutralizing Abs that bind the CD4BS are found in the blood of a subset of patients after years of HIV infection, but the target epitope is not identified, and Ab response is weak (23, 24). Certain monoclonal Abs (mAbs) that bind the CD4BS expressed by purified monomer gp120 do not neutralize HIV appreciably or display limited ability to neutralize genetically diverse HIV strains (25, 26). The CD4BS is a flexible structure expressed in differing conformational states by monomer gp120 and the native gp120 oligomers of the virus (27–30). Moreover, the process of binding CD4 may induce movements within the CD4BS (31). Reproducing the native CD4BS conformation in experimental vaccine candidates has been difficult. A CD4BS mimetic of the epitope recognized by a well known anti-CD4BS neutralizing mAb (clone b12) did not induce the synthesis of neutralizing Abs (32). Polyclonal Abs raised by immunization with synthetic peptides spanning the 421–433 CD4BS region neutralized laboratory-adapted, coreceptor CXCR4-dependent HIV strains inconsistently (33–35). Neutralization of coreceptor CCR5-dependent strains responsible for initiating most HIV infections was not studied. Importantly, small synthetic peptides are often more flexible than the corresponding native protein segments. Inducing a traditional adaptive immune response in which the Ab CDRs develop binding specificity for the peptide immunogen therefore does not ensure recognition of the native 421–433 CD4BS region (35, 36). From mutagenesis and sequence identity studies, the gp120-binding site of preimmune Abs, in contrast, is composed mainly of the V_H domain FR1 and FR3 (10, 11, 37). As certain preimmune Abs express HIV neutralizing activity attributable to recognition of the 421–433 region (13), the FR-dominated site must recognize the native state of this CD4BS epitope expressed on the viral surface.There is, however, substantial difficulty in amplifying and improving the subset of preimmune Abs with HIV neutralizing activity for vaccination against the virus; SAg binding to Ab FRs fails to stimulate adaptive B cell differentiation and synthesis of specific IgG class Abs (38, 39). Indeed, the binding at the FRs may even lead to premature death of the B cells (12, 40). The SAg character of the 421–433 CD4BS epitope is therefore predicted to render it hypoimmunogenic with respect to the adaptive synthesis of neutralizing Abs following infection or traditional vaccination procedures.We reported previously the induction of nucleophilic Abs by covalent immunization with full-length gp120 and a gp120 V3 peptide containing strongly electrophilic phosphonate groups (41–43). The electrophile reacts covalently with BCRs (44), resulting in adaptively strengthened nucleophilic reactivity coordinated with specific noncovalent recognition of gp120. The Abs obtained by covalent immunization formed very stable immune complexes with HIV resulting from pairing of Ab nucleophiles with the naturally occurring electrophilic groups of gp120 (e.g. the backbone and side chain carbonyls, see Refs. 42, 43). A minority of the Abs proceeded to catalyze the hydrolysis of gp120, aided by water attack on the covalent acyl-Ab complex (41). Here we report the neutralization of HIV strains heterologous to the full-length electrophilic gp120 immunogen (E-gp120) by mAbs with binary CD4BS and V3 loop recognition capability. We also present models that explain synthesis of the mAbs in response to immunization with E-gp120.     

HIV蛋白质优势B细胞抗原表位的筛选、重组表达与抗原性鉴定

设计了一种新的病原体蛋白质B细胞抗原表位的筛选和重 组表达方法。不须使用抗原,而通过交替用病人血清IgG抗体“淘洗”(biopanning)随机肽库和用正常人血清IgG反向吸附,来获得特异抗原表位资料。用HIV病人血清的IgG抗体淘洗噬菌体递呈随机十二肽库,再以正常人IgG抗体吸附,筛选到了能和HIV病人血清发生特异反应的噬菌体克隆,经ELISA、DNA测序等,成功地筛选出了位于HIV gp41外膜蛋白、高亲和力、构型特异的优势B细胞抗原表位(602GCSGKLICTTNV613)。用大肠杆菌硫氧还蛋白作为骨架,在其活性部位以“内融合”形式重组表达了该抗原表位,纯化的重组蛋白具有良好的抗原性,能与HIV(+)IgG抗体及艾滋病人血清呈特异反应,表明本技术路线可以有 效地进行HIV蛋白质的B细胞抗原表位筛选和重组表达。此方法也可移植于其它病原微生物抗原或自身抗原的表位研究,继而为基于抗原表位水平的特异诊断试剂的研制、疫苗的设计提供依据。     

ETHICS OF MANDATORY PREMARITAL HIV TESTING IN AFRICA: THE CASE OF GOMA, DEMOCRATIC REPUBLIC OF CONGO

Despite decades of prevention efforts, millions of persons worldwide continue to become infected by the human immunodeficiency virus (HIV) every year. This urgent problem of global epidemic control has recently lead to significant changes in HIV testing policies. Provider-initiated approaches to HIV testing have been embraced by the Centers for Disease Control and Prevention and the World Health Organization, such as those that routinely inform persons that they will be tested for HIV unless they explicitly refuse ('opt out'). While these policies appear to increase uptake of testing, they raise a number of ethical concerns that have been debated in journals and at international AIDS conferences. However, one special form of 'provider-initiated' testing is being practiced and promoted in various parts of the world, and has advocates within international health agencies, but has received little attention in the bioethical literature: mandatory premarital HIV testing. This article analyses some of the key ethical issues related to mandatory premarital HIV testing in resource-poor settings with generalized HIV epidemics. We will first briefly mention some mandatory HIV premarital testing proposals, policies and practices worldwide, and offer a number of conceptual and factual distinctions to help distinguish different types of mandatory testing policies. Using premarital testing in Goma (Democratic Republic of Congo) as a point of departure, we will use influential public health ethics principles to evaluate different forms of mandatory testing. We conclude by making concrete recommendations concerning the place of mandatory premarital testing in the struggle against HIV/AIDS.     

艾滋病血清学诊断新方法——免疫斑点法的建立

运用基因重组技术在大肠杆菌生产出有诊断意义的人免疫缺损病毒(HIV)蛋白,将其初步提纯,再用快速蛋白液相层析技术进一步纯化,即可直接点样至硝酸纤维膜,用来检测HIV抗体。实验显示,这种免疫斑点法(Immunodot assay,IDA)的敏感性与间接免疫荧光法(IIF)相同,而特异性比它高,与蛋白印迹法(WB)相近。由于IDA试剂成本比IIF低,可用于HIV抗体检测的初筛。与IIF相比,IDA法具有假阳性率低、试剂稳定性高、操作简便和不需要昂贵的荧光显微镜等优点。因而是一种适合在基层应用的方法。     

A NEW PROCEDURE FOR THE PHOSPHORYLATION OF NUCLEOSIDES: APPLICATION TO THE DISCOVERY OF INHIBITORS OF HIV INTEGRASE

A new phosphorylating agent for nucleosides, 2-O-(4,4′-dimethoxytrityl) ethylsulfonylethan-2′-yl-phosphate (1), has been developed by us. In the many examples studied by us, phosphorylation yields were found to be very high (about 90%). The procedure appears to be remarkably general and can be utilized for the phosphorylation of many biomolecules. Successful application of this phosphorylation method has contributed to the discovery of inhibitors of HIV integrase in our laboratory.     

MODIFIED DINUCLEOSIDE TETRAPHOSPHONATES,NEW POTENTIAL INHIBITORS OF HIV REVERSE TRANSCRIPTASE

New γ-substituted analogues of dNTP were synthesized and their enzymatic stability and antiviral properties were evaluated.     

我国一例典型艾滋病家庭的确认及其病毒env基因片段的序列分析

报道一例我国典型的ＨＩＶ感染家庭,其中对新生儿通过垂直传播感染的早期诊断为我国首例报道。父亲通过静脉吸毒感染ＨＩＶ,经性途径传播给妻子,并通过母婴途径传播至婴儿,导致婴儿发病。通过血清学、ＰＣＲ检测和病毒培养确认为整个家庭的感染。序列分析结果强烈支持杂来自同一毒株,流行背景主实了上述感染的传播途径。