细粒棘球绦虫EG95序列的遗传多样性及系统发育分析：对EG95疫苗应用的启示

Genetic diversity and phylogenetic analysis of EG95 sequences of Echinococcus granulosus: Implications for EG95 vaccine application.

作者信息

Pan Wei, Chen De-Sheng, Lu Yun-Juan, Xu Hui-Wen, Hao Wen-Ting, Zhang Ya-Wen, Qin Su-Ping, Zheng Kui-Yang, Tang Ren-Xian

机构信息

Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, Laboratory of Infection and Immunity, Xuzhou Medical University, Xuzhou, Jiangsu Province, 221004, PR China; Department of Clinical Medicine, Xuzhou Medical University, Xuzhou, Jiangsu Province, 221004, PR China.

出版信息

Asian Pac J Trop Med. 2017 May;10(5):524-527. doi: 10.1016/j.apjtm.2017.05.011. Epub 2017 May 18.

DOI:10.1016/j.apjtm.2017.05.011

PMID:28647192

Abstract

OBJECTIVE

To analyse the genetic variability of EG95 sequences and provide guidance for EG95 vaccine application against Echinococcus granulosus (E. granulosus).

METHODS

We analysed EG95 polymorphism by collecting total 97 different E. granulosus isolates from 12 different host species that originated from 10 different countries. Multiple sequence alignments and the homology were performed by Lasergene 1 (DNASTAR Inc., Madison, WI), and the phylogenetic analysis was performed by using MEGA5.1 (CEMI, Tempe, AZ, USA). In addition, linear and conformational epitopes were analysed, including secondary structure, NXT/S glycosylation, fibronectin type III (FnIII) domain and glycosylphosphatidylinositol anchor signal (GPI-anchor). The secondary structure was predicted by PSIPRED method.

RESULTS

Our results indicated that most isolates overall shared 72.6-100% identity in EG95 gene sequence with the published standard EG95 sequence, X90928. However, EG95 gene indeed has polymorphism in different isolates. Phylogenetic analysis showed that different isolates could be divided into three subgroups. Subgroup 1 contained 87 isolates while Subgroup 2 and Subgroup 3 consisted of 3 and 7 isolates, respectively. Four sequences cloned from oncosphere shared a high identity with the parental sequence of the current vaccine, X90928, and they belonged to Subgroup 1. However, in comparison to X90928, several amino acid mutations occurred in most isolates besides oncosphere, which potentially altered the immunodominant linear epitopes, glycosylation sites and secondary structures in EG95 genes. All these variations might change their previous antigenicity and thereby affecting the efficacy of current EG95 vaccine.

CONCLUSIONS

This study reveals the genetic variability of EG95 sequences in different E. granulosus isolates, and proposed that more vaccination trials would be needed to test the effectiveness of current EG95 vaccine against distinct isolates in different countries.

摘要

目的

分析EG95序列的遗传变异性，为细粒棘球绦虫EG95疫苗的应用提供指导。

方法

我们通过收集来自10个不同国家的12种不同宿主物种的总共97株不同的细粒棘球绦虫分离株，分析EG95多态性。使用Lasergene 1（DNASTAR公司，威斯康星州麦迪逊）进行多序列比对和同源性分析，并使用MEGA5.1（美国亚利桑那州坦佩的CEMI）进行系统发育分析。此外，分析了线性和构象表位，包括二级结构、NXT/S糖基化、纤连蛋白III型（FnIII）结构域和糖基磷脂酰肌醇锚定信号（GPI锚定）。通过PSIPRED方法预测二级结构。

结果

我们的结果表明，大多数分离株的EG95基因序列与已发表的标准EG95序列X90928总体上具有72.6%-100%的同一性。然而，EG95基因在不同分离株中确实存在多态性。系统发育分析表明，不同分离株可分为三个亚组。亚组1包含87株分离株，而亚组2和亚组3分别由3株和7株分离株组成。从六钩蚴克隆的4个序列与当前疫苗的亲本序列X90928具有高度同一性，它们属于亚组1。然而，与X90928相比，除六钩蚴外，大多数分离株中发生了几个氨基酸突变，这可能改变了EG95基因中的免疫显性线性表位、糖基化位点和二级结构。所有这些变异可能会改变其先前的抗原性，从而影响当前EG95疫苗的效力。