Nur Liyana K, Fauziah M K, Zainah S, Nor Aziyah R, Salbiah N, Lau I S, Ong Y C, Khadijah N R, Sharifah Aishah W M A, Shatrah O, Thayan R
Virology Unit, Infectious Disease Research Centre, Institute for Medical Research, Kuala Lumpur, Malaysia.
Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
Trop Biomed. 2016 Jun 1;33(2):348-358.
Dengue is a mosquito-borne viral disease caused by four serotypes of dengue virus, affecting the human population for decades in many tropical and subtropical regions of the world. In Malaysia, all four dengue serotypes co-circulates in a dengue season even though any one of the serotypes can predominate. In this study, serum samples were collected from dengue fever and severe dengue fever patients within Klang Valley from 2010-2012 to determine the prevailing dengue serotypes. In addition, sequencing of the envelope/nonstructural 1 (E/NS1) gene junction of the virus isolated was performed to identify the presence of any mutations that are suggestive of increased virulence in the virus. The results showed that Dengue-1 (DEN-1) was the predominant circulating serotype. The E/NS1 gene sequences of the isolates were analysed to trace the evolutionary knowledge of the strains. All sequences of the isolates were compared with DEN-1 prototype Hawaii strain as the reference sequence. The E/NS1 sequences of other dengue strains from neighbouring regions as well as other parts of the world obtained from the GenBank database were also included in the phylogenetic tree analysis. Analyses showed that there was 97% to 100% similarity among the ten isolates at the nucleotide level. Similarly, the amino acid analogue also showed 98% to 100% homology. However, all five non-severe dengue isolates showed variation at position 780, resulting in an amino acid change from valine to alanine as compared to severe dengue isolates. A rooted phylogenetic tree was performed using neighbour-joining method with DEN-2 and DEN-3 as the outgroups. Results showed that all ten isolates were classified as genotype I. In addition, the five isolates from severe dengue patients were found to be clustered together with JN697057 and JN697058, Malaysian DEN-1 strains from the 2005 outbreak.
登革热是一种由四种血清型登革病毒引起的蚊媒病毒性疾病，在世界许多热带和亚热带地区已影响人类数十年。在马来西亚，尽管任何一种血清型都可能占主导，但在登革热季节所有四种登革热血清型都会同时传播。在本研究中，于2010年至2012年从巴生谷地区的登革热和重症登革热患者中采集血清样本，以确定流行的登革热血清型。此外，对分离出的病毒的包膜/非结构1（E/NS1）基因连接处进行测序，以鉴定是否存在任何提示病毒毒力增加的突变。结果显示，登革热1型（DEN-1）是主要的流行血清型。对分离株的E/NS1基因序列进行分析以追踪这些毒株的进化知识。将所有分离株的序列与作为参考序列的DEN-1原型夏威夷毒株进行比较。从GenBank数据库获得的来自邻近地区以及世界其他地区的其他登革热毒株的E/NS1序列也被纳入系统发育树分析。分析表明，十个分离株在核苷酸水平上有97%至100%的相似性。同样，氨基酸类似物也显示出98%至100%的同源性。然而，所有五个非重症登革热分离株在第780位出现变异，与重症登革热分离株相比，导致氨基酸从缬氨酸变为丙氨酸。使用邻接法构建有根系统发育树，以DEN-2和DEN-3作为外群。结果显示，所有十个分离株均被归类为基因型I。此外，发现来自重症登革热患者的五个分离株与2005年疫情中的马来西亚DEN-1毒株JN697057和JN697058聚集在一起。
