Mahidol-Osaka Center for Infectious Diseases, Ratchathewi, Bangkok 10400, Thailand.
Biochem Biophys Res Commun. 2011 Sep 16;413(1):136-42. doi: 10.1016/j.bbrc.2011.08.069. Epub 2011 Aug 22.
Generally, RNA viruses exhibit significant genetic diversity that sometimes effect viral fitness in infected hosts and probably also pathogenesis. Dengue viruses (DENVs) consist of four antigenically distinct serotypes. All the serotypes of DENV can cause mild to severe dengue illnesses. In this study, we examined the sequence variation of DENV in plasma obtained from four patients living in Bangkok who had been secondarily infected with serotype 2 (DENV-2) in 2010. The plasma-derived RNA was directly subjected to reverse transcriptase (RT)-polymerase chain reaction (PCR) at a region including most of domain III of the envelope (E) protein gene, and the PCR products obtained were subjected to clonal sequencing. Using 19-20 clones sequenced from each patient (78 total) plus 601 corresponding sequences from a public database, phylogenetic analysis revealed that the nucleic acid sequences fell into two clusters with clearly different origins. Interestingly, all patients gave sequences indicating that they carried viral populations containing 2, 3 or 5 genetic variants that consisted of one major variant plus one or more minor variants. Three patients showed a major variant from one cluster plus one or more minor components from the other while one showed major and minor variants from a single cluster. Thus, it can be concluded that DENV belonging to two different genetic lineages were co-circulated in Bangkok in 2010. For these two genotype clusters there was also a clear difference in H or Y at the deduced amino acid position 346 (i.e. H346Y) that was consistent for our sequences and 601 sequences from the public database. Thus, one among the mixed viral genotypes introduced into human individuals seems to be variably selected as the predominant component of the carried viral population, and it is possible that the dynamics of this process could influence virus evolution and disease severity.
一般来说，RNA 病毒表现出显著的遗传多样性，这种多样性有时会影响感染宿主中的病毒适应性，可能还会影响发病机制。登革病毒（DENV）由四个血清型组成，具有明显的抗原差异。所有血清型的 DENV 都可能导致轻度至重度登革热疾病。在这项研究中，我们研究了在 2010 年二次感染血清型 2（DENV-2）的居住在曼谷的四名患者的血浆中 DENV 的序列变异情况。将来自每位患者的 19-20 个克隆（78 个克隆）的直接从血浆中获得的 RNA 进行逆转录酶（RT）-聚合酶链反应（PCR），在包膜（E）蛋白基因的大部分区域 III 进行扩增，然后对获得的 PCR 产物进行克隆测序。使用从每位患者（共 78 个克隆）和公共数据库中的 601 个相应序列中获得的 19-20 个克隆进行序列分析，结果显示，核酸序列分为两个具有明显不同起源的聚类。有趣的是，所有患者的序列都表明他们携带的病毒群体中含有 2、3 或 5 种遗传变异，这些变异由一个主要变异株和一个或多个次要变异株组成。3 名患者显示来自一个聚类的主要变异株和来自另一个聚类的一个或多个次要成分，而 1 名患者显示来自单个聚类的主要和次要变异株。因此，可以得出结论，2010 年曼谷有两种不同遗传谱系的 DENV 共同循环。对于这两个基因型聚类，在推导的氨基酸位置 346 处（即 H346Y）也存在 H 或 Y 的明显差异，这与我们的序列和公共数据库中的 601 个序列一致。因此，引入人类个体的混合病毒基因型之一似乎会作为携带病毒群体的主要成分发生不同程度的选择，而且这种选择过程的动态变化可能会影响病毒进化和疾病严重程度。
