Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan, ROC.
Arboviral Diseases Branch, Centers for Disease Control and Prevention, Fort Collins, CO, USA.
J Gen Virol. 2012 Jun;93(Pt 6):1185-1192. doi: 10.1099/vir.0.040238-0. Epub 2012 Feb 15.
Group and serocomplex cross-reactive epitopes have been identified in the envelope (E) protein of several flaviviruses and have proven critical in vaccine and diagnostic antigen development. Here, we performed site-directed mutagenesis across the E gene of a recombinant expression plasmid that encodes the Japanese encephalitis virus (JEV) premembrane (prM) and E proteins and produces JEV virus-like particles (VLPs). Mutations were introduced at I135 and E138 in domain I; W101, G104, G106 and L107 in domain II; and T305, E306, K312, A315, S329, S331, G332 and D389 in domain III. None of the mutant JEV VLPs demonstrated reduced activity to the five JEV type-specific mAbs tested. Substitutions at W101, especially W101G, reduced reactivity dramatically with all of the flavivirus group cross-reactive mAbs. The group and JEV serocomplex cross-reactive mAbs examined recognized five and six different overlapping epitopes, respectively. Among five group cross-reactive epitopes, amino acids located in domains I, II and III were involved in one, five and three epitopes, respectively. Recognition by six JEV serocomplex cross-reactive mAbs was reduced by amino acid substitutions in domains II and III. These results suggest that amino acid residues located in the fusion loop of E domain II are the most critical for recognition by group cross-reactive mAbs, followed by residues of domains III and I. The amino acid residues of both domains II and III of the E protein were shown to be important in the binding of JEV serocomplex cross-reactive mAbs.
已在几种黄病毒的包膜（E）蛋白中鉴定出了类群和血清型交叉反应表位，这些表位在疫苗和诊断抗原的开发中已被证明是至关重要的。在此，我们对编码日本脑炎病毒（JEV）前膜（prM）和 E 蛋白并产生 JEV 病毒样颗粒（VLPs）的重组表达质粒的 E 基因进行了定点诱变。突变引入了结构域 I 中的 I135 和 E138；结构域 II 中的 W101、G104、G106 和 L107；以及结构域 III 中的 T305、E306、K312、A315、S329、S331、G332 和 D389。突变的 JEV VLP 没有一种对 5 种 JEV 型特异性 mAb 的活性降低。W101，特别是 W101G 的取代，与所有黄病毒类群交叉反应 mAb 的反应性明显降低。检查的类群和 JEV 血清型交叉反应 mAb 分别识别五个和六个不同重叠的表位。在五个类群交叉反应表位中，位于结构域 I、II 和 III 的氨基酸分别参与一个、五个和三个表位。六个 JEV 血清型交叉反应 mAb 的识别因结构域 II 和 III 的氨基酸取代而降低。这些结果表明，E 结构域 II 融合环中位于氨基酸残基是与类群交叉反应 mAb 识别最关键的，其次是 III 结构域和 I 结构域的残基。E 蛋白的 II 结构域和 III 结构域的氨基酸残基在 JEV 血清型交叉反应 mAb 的结合中均很重要。
