Rodpothong Patsarin, Auewarakul Prasert
Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Virus Genes. 2012 Jun;44(3):408-14. doi: 10.1007/s11262-011-0709-2. Epub 2012 Jan 6.
The existence of four dengue serotypes is associated with a phenomenon called "Antibody-Dependent Enhancement" that has been suggested to cause a severe form of dengue hemorrhagic fever and shock syndrome. To study the evolutionary event that drove the serotype separation, we employed the maximum likelihood approach by focusing on the Premembrane (prM) and Envelop (E) genes. We showed that the separation of dengue serotypes had been dominantly under purifying selection. In spite of the strong selective constraint, one codon of prM gene and twelve codons of E gene were detected to be under positive selection. This indicates that the E protein might have been under a stronger positive pressure than the PrM protein. The codons under positive selection were identified along the interserotypic branches, suggesting that changes at these sites were probably associated with the emergence of the four serotypes and/or adaptation to the new transmission environments.
四种登革热血清型的存在与一种名为“抗体依赖增强作用”的现象相关，该现象被认为会引发严重形式的登革出血热和休克综合征。为了研究驱动血清型分离的进化事件，我们采用最大似然法，重点关注前膜（prM）基因和包膜（E）基因。我们发现登革热血清型的分离主要处于纯化选择之下。尽管存在强烈的选择限制，但仍检测到prM基因的一个密码子和E基因的十二个密码子处于正选择之下。这表明E蛋白可能比PrM蛋白承受更强的正选择压力。正选择下的密码子沿着血清型间的分支被识别出来，这表明这些位点的变化可能与四种血清型的出现和/或对新传播环境的适应有关。
