Nakamura G R, Byrn R, Wilkes D M, Fox J A, Hobbs M R, Hastings R, Wessling H C, Norcross M A, Fendly B M, Berman P W
Department of Immunology, Genentech, Inc., South San Francisco, California 94080.
J Virol. 1993 Oct;67(10):6179-91. doi: 10.1128/JVI.67.10.6179-6191.1993.
The binding properties of seven CD4-blocking monoclonal antibodies raised against recombinant gp120 of human immunodeficiency virus type 1 strain MN (HIV-1MN) and two CD4-blocking monoclonal antibodies to recombinant envelope glycoproteins gp120 and gp160 of substrain IIIB of HIVLAI were analyzed. With a panel of recombinant gp120s from seven diverse HIV-1 isolates, eight of the nine antibodies were found to be strain specific and one was broadly cross-reactive. Epitope mapping revealed that all nine antibodies bound to epitopes located in the fourth conserved domain (C4) of gp120. Within this region, three distinct epitopes could be identified: two were polymorphic between HIV-1 strains, and one was highly conserved. Studies with synthetic peptides demonstrated that the conserved epitope, recognized by antibody 13H8, was located between residues 431 and 439. Site-directed mutagenesis of gp120 demonstrated that residue 429 and/or 432 was critical for the binding of the seven antibodies to gp120 from HIV-1MN. Similarly, residues 423 and 429 were essential for the binding of monoclonal antibody 5C2 raised against gp120 from HIV-1IIIB. The amino acids located at positions 423 and 429 were found to vary between strains of HIV-1 as well as between molecular clones derived from the MN and LAI isolates of HIV-1. Polymorphism at these positions prevented the binding of virus-neutralizing monoclonal antibodies and raised the possibility that HIV-1 neutralization serotypes may be defined on the basis of C4 domain sequences. Analysis of the binding characteristics of the CD4-blocking antibodies demonstrated that their virus-neutralizing activity was directly proportional to their gp120-binding affinity. These studies account for the strain specificity of antibodies to the C4 domain of gp120 and demonstrate for the first time that antibodies to this region can be as effective as those directed to the principal neutralizing determinant (V3 domain) in neutralizing HIV-1 infectivity.
分析了针对人类免疫缺陷病毒1型MN株（HIV-1MN）重组gp120产生的7种CD4阻断单克隆抗体以及2种针对HIVLAI IIIB亚株重组包膜糖蛋白gp120和gp160的CD4阻断单克隆抗体的结合特性。使用一组来自7种不同HIV-1分离株的重组gp120，发现9种抗体中的8种具有毒株特异性，1种具有广泛交叉反应性。表位作图显示，所有9种抗体均与位于gp120第四保守结构域（C4）的表位结合。在该区域内，可以鉴定出3个不同的表位：2个在HIV-1毒株之间具有多态性，1个高度保守。用合成肽进行的研究表明，抗体13H8识别的保守表位位于431至439位氨基酸之间。gp120的定点诱变表明，429位和/或432位氨基酸对于7种抗体与HIV-1MN的gp120结合至关重要。同样，423位和429位氨基酸对于针对HIV-1IIIB的gp120产生的单克隆抗体5C2的结合至关重要。发现位于423位和429位的氨基酸在HIV-1毒株之间以及源自HIV-1 MN和LAI分离株的分子克隆之间存在差异。这些位置的多态性阻止了病毒中和单克隆抗体的结合，并增加了基于C4结构域序列定义HIV-1中和血清型的可能性。对CD4阻断抗体结合特性的分析表明，它们的病毒中和活性与其gp120结合亲和力直接相关。这些研究解释了针对gp120 C4结构域抗体的毒株特异性，并首次证明该区域的抗体在中和HIV-1感染性方面与针对主要中和决定簇（V3结构域）的抗体一样有效。
