Linsley P S, Ledbetter J A, Kinney-Thomas E, Hu S L
Oncogen, Seattle, Washington 98121.
J Virol. 1988 Oct;62(10):3695-702. doi: 10.1128/JVI.62.10.3695-3702.1988.
Monoclonal antibodies (MAbs) to defined peptide epitopes on gp120 from human immunodeficiency virus type 1 were used to investigate the involvement of their epitopes in gp120 binding to the CD4 receptor. Recombinant vaccinia viruses were constructed that expressed either full-length gp120 (v-ED6), or a truncated gp120 lacking 44 amino acids at the carboxyl terminus (v-ED4). Binding of these glycoproteins to the CD4 receptor was detected directly with metabolically labeled gp120 or indirectly with the gp120 MAbs. Truncated gp120 from v-ED4 bound to CD4-positive cells less than 1/12 as well as gp120 from v-ED6, indicating that the C-terminal region of gp120, which is conserved in numerous isolates of human immunodeficiency virus type 1, is critical for CD4 binding. However, MAb 110-1, which recognizes a peptide contained in the region deleted from v-ED4 (amino acids 489 through 511), did not inhibit binding of gp120 to CD4. MAb 110-1 also reacted with gp120 bound to the CD4 receptor, indicating that the epitope for this antibody does not directly interact with CD4. A second MAb, 110-4, which recognizes a peptide epitope located between amino acids 303 and 323 and has potent viral neutralizing activity, also bound to gp120 on the CD4 receptor. Furthermore, pretreatment of gp120 with MAb 110-4 at concentrations approximately 1,000-fold higher than those required for complete virus neutralization inhibited subsequent CD4 binding by only about 65%. Taken together, these data suggest that neutralization mediated by antibody 110-4 does not result from binding of this MAb to the CD4-binding site of gp120.
利用针对1型人类免疫缺陷病毒gp120上特定肽表位的单克隆抗体（MAb），研究其表位在gp120与CD4受体结合过程中的作用。构建了表达全长gp120（v-ED6）或在羧基末端缺失44个氨基酸的截短型gp120（v-ED4）的重组痘苗病毒。这些糖蛋白与CD4受体的结合可通过代谢标记的gp120直接检测，或通过gp120单克隆抗体间接检测。来自v-ED4的截短型gp120与CD4阳性细胞的结合能力不到来自v-ED6的gp120的1/12，这表明gp120的C末端区域在众多1型人类免疫缺陷病毒分离株中是保守的，对CD4结合至关重要。然而，识别v-ED4缺失区域（氨基酸489至511）中包含的肽的单克隆抗体110-1并不抑制gp120与CD4的结合。单克隆抗体110-1也与结合到CD4受体上的gp120发生反应，表明该抗体的表位不直接与CD4相互作用。第二种单克隆抗体110-4识别位于氨基酸303和323之间的肽表位并具有强大的病毒中和活性，它也与CD4受体上的gp120结合。此外，用浓度比完全中和病毒所需浓度高约1000倍的单克隆抗体110-4预处理gp120，随后的CD4结合仅被抑制约65%。综上所述，这些数据表明，单克隆抗体110-4介导的中和作用并非源于该单克隆抗体与gp120的CD4结合位点的结合。
