来自中科院上海巴斯德研究所，清华大学等处的研究人员发表了题为“Potent and broad anti-HIV-1 activity exhibited by a GPI-anchored peptide derived from the CDR H3 of broadly neutralizing antibody PG16”的文章，获得了新型防治HIV-1策略研究新进展。这一研究成果公布在国际知名病毒学杂志《病毒学期刊》（Journal of Virology）上。

文章的通讯作者是上海巴斯德研究所周保罗研究员，其早年毕业于上海第二医科大学，获得美国纽约州立大学博士学位，主要从事HIV和禽流感领域的研究工作。这项研究获得了国家自然科学基金、国家科技部973项目、国家科技重大专项、上海巴斯德健康研究基金会项目以及阿海珐（AREVA）国际合作项目的资助。

PG16 抗体Fab 段结构示意图

PG9和PG16抗体是最近发现的抗HIV-1广谱性中和抗体。PG16晶体结构显示其重链决定簇互补区三（CDR H3）形成了一个独特的，稳定的亚区域，暴露在抗体结构外面。脂伐是细胞膜上特定动态的微区域，是HIV-1出胞和入胞的通道。在此以前周保罗实验室博士研究生温振国等通过GPI瞄定的方式将单链抗体表达到细胞膜上的脂伐区，并且发现GPI瞄定的单链抗体（x5 和48d）能够有效抓住HIV-1 gp120 与受体CD4结合后暴露出的瞬时表位，从而有效阻断多种亚型HIV-1的感染。由此，他们推断将CDR H3（PG9和PG16）瞄定到细胞膜的脂伐区，CDR H3（PG9和PG16）能够结合gp120，从而有效地阻断HIV-1感染。

为了验证该假说，周保罗实验室博士研究生刘立鸿等将人源单克隆抗体：PG16，PG9, b12, E51和AVF 的CDR H3基因与膜瞄定信号基因融合在一起， CDR H3 通过GPI瞄定方式表达在细胞膜上的脂伐区，在转染不同CDR H3基因的TZM-BL细胞系中，GPI-CDR H3 （PG16, PG9 and E51）能够有效阻断多种HIV-1亚型。在CD4+ T细胞系中，GPI-CDR H3 （PG16）能够有效抑制病毒感染。如同IgG PG16突变体，GPI-CDR H3 PG16 突变体中和病毒能力也显著降低。由此，GPI-CDR H3 （PG16, PG9 and E51）因其高效、广谱抗HIV-1作用，有可能被开发成一种新型防治HIV技术。

英文论摘要：

Potent and Broad Anti-HIV-1 Activity Exhibited by a Glycosyl-Phosphatidylinositol-Anchored Peptide Derived from the CDR H3 of Broadly Neutralizing Antibody PG16{triangledown}

PG9 and PG16 are two recently isolated quaternary-specific human monoclonal antibodies that neutralize 70 to 80% of circulating HIV-1 isolates. The crystal structure of PG16 shows that it contains an exceptionally long CDR H3 that forms a unique stable subdomain that towers above the antibody surface to confer fine specificity. To determine whether this unique architecture of CDR H3 itself is sufficient for epitope recognition and neutralization, we cloned CDR H3 subdomains derived from human monoclonal antibodies PG16, PG9, b12, E51, and AVF and genetically linked them to a glycosyl-phosphatidylinositol (GPI) attachment signal. Each fusion gene construct is expressed and targeted to lipid rafts of plasma membranes through a GPI anchor. Moreover, GPI-CDR H3(PG16, PG9, and E51), but not GPI-CDR H3(b12 and AVF), specifically neutralized multiple clades of HIV-1 isolates with a great degree of potency when expressed on the surface of transduced TZM-bl cells. Furthermore, GPI-anchored CDR H3(PG16), but not GPI-anchored CDR H3(AVF), specifically confers resistance to HIV-1 infection when expressed on the surface of transduced human CD4+ T cells. Finally, the CDR H3 mutations (Y100HF, D100IA, and G7) that were previously shown to compromise the neutralization activity of antibody PG16 also abolished the neutralization activity of GPI-CDR H3(PG16). Thus, we conclude that the CDR H3 subdomain of PG16 neutralizes HIV-1 when targeted to the lipid raft of the plasma membrane of HIV-1-susceptible cells and that GPI-CDR H3 can be an alternative approach for determining whether the CDR H3 of certain antibodies alone can exert epitope recognition and neutralization.