GENETIC DETERMINANTS OF DENGUE VIRUS MOUSE NEUROVIRULENCE

登革热病毒小鼠神经毒力的遗传决定因素

• 批准号: 3746660
• 负责人: C J LAI
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3746660
• 关键词: attenuated microorganism; dengue virus; gene mutation; glycoproteins; glycosylation; laboratory mouse; microorganism culture; microorganism immunology; protein sequence; structural genes; virulence; virus envelope; virus genetics; virus protein

Shortly after the first strains of dengue virus were isolated in the laboratory, serial intracerebral passage of dengue type 1 or type 2 virus (DEN1 or DEN2) in mice was employed to attenuate these viruses for use as live attenuated vaccines in humans. Studies by Sabin revealed that at a low passage level these viruses had lost most of their virulence. In addition, a highly neurovirulent mutant of the non-pathogenic parental DEN4 strain H241 was selected by serial intracerebral passage in mice. The genetic basis for neurovirulence of the DEN4 mouse-adapted mutant was studied by comparing intratypic chimeric viruses that contained the three structural protein genes of the parental virus or its neurovirulent mutant on the background sequence of non-neurovirulent DEN4 strain 814669. The chimera that contained the three structural protein genes of mouse neurovirulent DEN4 H241 was highly neurovirulent in mice, whereas the chimera that contained the corresponding genes of its non- mouse adapted parent was not neurovirulent. Thus, some or all of the genetic loci for neurovirulence of the DEN4 mutant map within the structural protein genes. The parent and its mouse neurovirulent mutant were found to differ by only five amino acid differences in their structural proteins. Three of the mutations were located in the envelope (E) glycoprotein. Two of these amino acid changes were identified as important determinants of DEN4 mouse neurovirulence: (i) the single substitution of Ile for Thr434 which ablated one of the two conserved glycosylation sites in DEN4 E yielded a virus that was almost as neurovirulent as the mouse-adapted mutant; and (ii) the Leu for Phe680 substitution also yielded a neurovirulent virus but it was less neurovirulent than the glycosylation mutant. The parental DEN1 Hawaii strain and its mouse neurovirulent mutant were also studied in an attempt to map the DEN1 genetic loci responsible for mouse neurovirulence. Thirteen amino acid differences in the C-PreM-E structural protein region were identified. Among the 13 changes 7 are located in E, 3 in PreM and 3 in C.

在第一批登革热病毒株被分离后不久 登革热1型或2型病毒脑内连续传代实验室 在小鼠体内使用(DEN1或DEN2)来减弱这些病毒以供使用 作为人体内的减毒活疫苗。萨宾的研究表明， 在低传代水平，这些病毒已经失去了大部分的毒力。 此外，非致病亲本的高神经毒力突变体 用小鼠脑内连续传代的方法筛选出DEN4菌株H2 41。 DEN4小鼠适应突变体的神经毒力的遗传基础是 通过比较包含这三种病毒的类型内嵌合病毒进行了研究 亲本病毒或其神经毒力的结构蛋白基因 非神经毒力株DEN4的背景序列突变 814669。含有三种结构蛋白基因的嵌合体 小鼠神经毒力的DEN4 H241对小鼠有很强的神经毒力， 而含有相应基因的嵌合体非- 小鼠适应亲本不具有神经毒性。因此，部分或全部 日本血吸虫DEN4突变图谱神经毒力的遗传位点 结构蛋白基因。亲本及其小鼠神经毒力突变体 只有五个氨基酸的差异 结构蛋白。其中三个突变位于包膜中 (E)糖蛋白。这些氨基酸变化中有两个被确认为 DEN4小鼠神经毒力的重要决定因素：(I)单一 Ile替代Thr434，消融了两个保守的 DEN4E上的糖基化位点产生了一种几乎与 作为小鼠适应突变体的神经毒性；和(Ii)Phe680的Leu 代换也产生了一种神经毒力病毒，但它的 比糖基化突变体更具神经毒性。夏威夷的父母DEN1 菌株及其小鼠神经毒力突变体也在尝试中进行了研究 绘制导致小鼠神经毒力的DEN1基因座图。 C-Prem-E结构蛋白区域的13个氨基酸差异 都被确认了。在13个变化中，7个位于E，3个位于Prem和 3英寸C