An approach for development of new drugs for AIDS which inhibit the novel receptor for AIDS virus

人类免疫缺陷病毒(HIV)的感染是由于HIV包膜糖蛋白gp120与存在于T4^+淋巴细胞表面的CD4分子相互作用而介导的病毒-细胞融合。然而，CD4分子可能不是HIV受体的唯一成分，因为表达人类CD4分子的小鼠细胞不会感染HIV。我们最近在人T4^+淋巴细胞中发现了一种新的膜结合丝氨酸蛋白酶，命名为类胰蛋白酶TL2，它与HIV gp120的V3结构域特异结合。据报道，V3结构域是HIV的主要中和决定因素，也是HIV感染的细胞嗜性的决定因素。Scatchard分析显示，类胰蛋白酶TL2上只有一类gp120结合位点，其表观解离常数为3.8×10~(-8)&gt；M。为了寻找能有效抑制gp120与类胰蛋白酶TL2结合的化合物(S)，我们分析了活性部位为gpcR序列的几种kunitz型蛋白酶抑制剂和中心序列为gpcr的合成V3结构域肽，它们对应于不同毒株gp120的主要中和表位和抗类胰蛋白酶TL2抗体。结果表明，类胰蛋白酶抑制剂Trypstatin和抗类胰蛋白酶TL2抗体能有效抑制gp120与类胰蛋白酶TL2的结合。它们还能抑制HIV诱导的合胞体形成。虽然V3结构域是一个高变区，但类胰蛋白酶TL2可能是各种HIV毒株V3结构域T淋巴细胞膜上的共同结合受体。提示类胰抑素和抗类胰蛋白酶TL2抗体可用于艾滋病的治疗。胰岛抑素基因的克隆及其在大肠杆菌中的表达研究正在进行中。需要进一步的研究来证实这些化合物在体内和体外对HIV感染的影响

Infection by human immunodeficiency virus (HIV) is due to virus-cell fusion mediated by interaction of the envelope glycoprotein gp120 of HIV with the CD4 molecule present on the surface of T4^+ lymphocytes. However, the CD4 molecule may not be the only component of HIV receptor because mouse cells expressing the human CD4 molecule are not infected by HIV. We recently found a novel membrane-bound serine protease, named tryptase TL2, other than CD4 receptor in human T4^+ lymphocytes which specifically binds V3 domain of HIV gp120. The V3 domain has been reported to be the principal neutralizing determinant of HIV and also to be a determinant for cellular tropism of HIV infection. Scatchard analysis revealed a single class of gp120 binding site on tryptase TL2 with an apparent dissociation constant of 3.8 x 10^<-8> M for tryptase TL2.In order to find the compound(s) which effectively inhibit the binding of gp120 to tryptase TL2, we have analyzed the effect of various Kunitztype protease inhibitors with the sequence GPCR in their active site and synthetic V3 domain peptides with the sequence GPCR in their center, which correspond to the principal neutralizing epitopes of gp120 of various HIV strains and of antibody against tryptase TL2. The results show that trypstatin, Kunitz type protease inhibitor, and antibody against tryptase TL2 effectively inhibited the binding of gp120 to tryptase TL2. They also inhibited syncytia formation induced by HIV. Although V3 domain is a hypervariable region, tryptase TL2 may be a common binding receptor in the membrane of T lymphocytes for various V3 domain of HIV strains. These results suggest that trypstatin and the antibody against tryptase TL2 may be useful for therapeutic treatment for AIDS. The studies on DNA cloning of trypstatin and its expression in E. Coli are now in progress. Further studies are need to confirm the effect of these compounds on HIV infection in vivo and in vitro