GENETIC VARIATION AMONG DENGUE VIRUSES

登革热病毒家族包含4种不同的血清型， 可通过病毒中和来区分。 在登革热组中，2型 病毒是最常见的涉及出血热，一个严重的， 致命的登革热。 有相当多的多态性， 2型病毒，如寡核苷酸指纹图谱变异所示 这种变异在地理上有着特定的分布模式 仅限于特定地区。 目前正在努力研究 登革病毒基因变异的分子克隆和核苷酸分析 测序 选择登革2（菌株PR 159）用于序列比较 我们实验室正在克隆和测序登革热4型病毒。 纯化登革2型基因组RNA并转录成RNA-cDNA杂交体， 根据建立的程序在pBR 322载体中直接克隆 登革热4. 琼脂糖凝胶上Pst I消化后的质粒DNA分析 结果表明，大多数重组质粒含有DNA插入片段 长度范围为500- 4，000个碱基对。 具有最大的 选择插入物（2，000个碱基对或更多）用于定位全长 基因组序列 为了这个目的，我们利用了遗传 登革病毒2型和4型之间存在同源性。 放射标记 从登革4型病毒的克隆DNA片段制备的探针， 位置用于登革2插入片段的初始作图和筛选。 到目前为止，超过一半的登革2型基因组序列已被克隆。 克隆，我们的最终目标是获得全长DNA拷贝。 完成 将进行序列分析，以获得更好的 了解登革热流行中病毒多态性的模式， 不同病毒株参与登革出血热。

The dengue virus family contains 4 distinct serotypes that are distinguishable by virus neutralization. Among the dengue group the type 2 virus is most frequently involved in hemorrhagic fever, a severe and often fatal form of dengue disease. There is considerable polymorphism among type 2 viruses as indicated by variation in oligonucleotide fingerprints and this variation has a geographic distribution in that specific patterns are limited to specific localities. Efforts are now underway to study genetic variation of dengue viruses by molecular cloning and nucleotide sequencing. Dengue 2 (strain PR159) was chosen for sequence comparison with dengue 4 that is also being cloned and sequenced in our laboratory. Dengue 2 genomic RNA was purified and transcribed into RNA-cDNA hybrids for direct cloning in the pBR322 vector according to the procedure established for dengue 4. Analysis of plasmid DNA after Pst I digestion on agarose gel showed that a majority of recombinant plasmids contained DNA inserts ranging from 500-4,000 base pairs in length. Recombinants with the largest inserts (2,000 base-pairs or more) were chosen for mapping the full-length genomic sequence. For this purpose we took advantage of the genetic homology that exists between dengue virus type 2 and type 4. Radiolabeled probes prepared from cloned DNA segments of dengue 4 at various map positions were used for initial mapping and screening of dengue 2 inserts. Thus far, more than one-half of the dengue 2 genomic sequences have been cloned and our ultimate goal is to obtain a full-length DNA copy. Complete sequence analysis will be performed in an effort to gain a better understanding of the pattern of virus polymorphism in dengue epidemics and the involvement of different virus strains in dengue hemorrhagic fever.