Taguchi Fumihiro, Shimazaki Yohko K
National Institute of Neuroscience, NCNP, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan1.
National Veterinary Assay Laboratory, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan2.
J Gen Virol. 2000 Dec;81(Pt 12):2867-2871. doi: 10.1099/0022-1317-81-12-2867.
The monoclonal antibody (MAb) 5B19.2, which has virus-neutralizing and fusion inhibition activities, binds to an epitope (S2A) consisting of nine hydrophobic amino acids in the S2 subunit of the mouse hepatitis virus (MHV) spike (S) protein. This suggests that the S2A epitope may be involved in binding the virus to the MHV receptor and/or in virus-cell fusion. Co-immunoprecipitation analyses demonstrated that while the binding of virus to the receptor was blocked by anti-S1 MAbs, it was not blocked by the S2A antiserum, indicating that S2A was not involved in receptor-binding. The S proteins prepared in this study with mutations in the S2A epitope were either fusogenic or non-fusogenic and their fusogenicity did not correlate with the hydrophobic feature of the S2A epitope. All of these wt and mutated S proteins were similarly transported onto the cell membrane independent of their fusogenicity capability. These results suggest that S2A may mediate the fusion activity of the MHV S protein during virus entry into cells.
单克隆抗体（MAb）5B19.2具有病毒中和及融合抑制活性，它与小鼠肝炎病毒（MHV）刺突（S）蛋白S2亚基中由九个疏水氨基酸组成的表位（S2A）结合。这表明S2A表位可能参与病毒与MHV受体的结合及/或病毒-细胞融合过程。免疫共沉淀分析表明，虽然抗S1单克隆抗体可阻断病毒与受体的结合，但S2A抗血清却不能，这表明S2A不参与受体结合。本研究制备的在S2A表位有突变的S蛋白要么具有融合活性，要么不具有融合活性，且它们的融合活性与S2A表位的疏水特性无关。所有这些野生型和突变型S蛋白均以相似的方式转运至细胞膜上，而与它们的融合活性能力无关。这些结果表明，S2A可能在病毒进入细胞过程中介导MHV S蛋白的融合活性。
