BACKGROUND Dengue hemorrhagic fever is an acute viral infection transmitted by mosquitoes. In the 2017, a dengue epidemic occurred in Hanoi in a short time interval and many cases were serious with associated mortality. This was the largest and unusual dengue fever outbreak in the North of Vietnam over the past 20 years. The objective of the present study was to understand the genetic characteristics of the DENV-1 strain in the 2017 epidemic and its relationship with previous viruses in Vietnam and the rest of the world. METHODS Complete genomes of 72 DENV-1 from patients in the 2017 epidemic were sequenced using NGS. The full genome sequences were then analyzed to find out the genetic variants in the groups of 72 strains, followed by their comparison with other strains that caused disease in Vietnam previously and several other regions of the world, revealing a genetic relationship between them. RESULTS The complete genome sequence of 72 DENV-1 strains comprised 10,697 nucleotides with an open reading frame coding for 3392 amino acids. The genomic analysis revealed different amino acid substitutions in all genes, especially varying at position S75 (Capsid), M125 (PrM), D54 (E), T147, V180 (NS1), G45, Y126, I154 (NS2A), A94 (NS2B), M298 (NS3), K47, V68 (NS4A), I29 (NS4B), and R166, E536, G614, T821 (NS5). The genetic analysis suggested that the viruses were most closely related to the causative virus of the dengue outbreak in Vietnam and Cambodia from 2006 to 2008. These results indicated that DENV-1 from the dengue epidemic 2017 in Northern Vietnam originated from the virus that caused the dengue outbreak during the 2007 to 2008 period in Vietnam. CONCLUSION The present study is the first of its kind to describe complete genome sequence as well as genetic variants and phylogenetic analysis of DENV-1 associated with the unusual dengue epidemic of 2017 in northern Vietnam. These results provide detailed evidence to elucidate the origin, circulation, and genetic evolution of DENV in Vietnam.

中文翻译：

---

越南2017年异常登革热流行的几种登革热病毒1型毒株的全基因组测序和遗传变异。

背景技术登革出血热是由蚊子传播的急性病毒感染。2017年，河内在较短的时间间隔内发生了登革热流行病，许多病例都伴有严重的死亡率。这是过去20年来越南北部最大，最罕见的登革热疫情。本研究的目的是了解DENV-1株在2017年流行中的遗传特征及其与越南和世界其他地区以前的病毒的关系。方法使用NGS对2017年流行病患者的72个DENV-1完整基因组进行测序。然后分析完整的基因组序列，以找出72个菌株组中的遗传变异，然后将它们与先前在越南以及世界其他几个地区引起疾病的其他菌株进行比较，揭示它们之间的遗传关系。结果72株DENV-1菌株的完整基因组序列包含10697个核苷酸，其开放阅读框编码3392个氨基酸。基因组分析揭示了所有基因中不同的氨基酸取代，特别是在S75（衣壳），M125（PrM），D54（E），T147，V180（NS1），G45，Y126，I154（NS2A），A94（NS2B） ），M298（NS3），K47，V68（NS4A），I29（NS4B）和R166，E536，G614，T821（NS5）。遗传分析表明，该病毒与2006年至2008年越南和柬埔寨的登革热暴发致病病毒关系最密切。这些结果表明，越南北部2017年登革热流行的DENV-1源自于2007年至2008年期间在越南引起登革热暴发的病毒。结论本研究是首次描述完整的基因组序列以及与越南北部2017年罕见登革热相关的DENV-1的遗传变异和系统发育分析。这些结果提供了详细的证据，以阐明越南DENV的起源，传播和遗传进化。