Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
Solena Ag, Foster City, California, United States of America.
PLoS Negl Trop Dis. 2024 Jul 26;18(7):e0012349. doi: 10.1371/journal.pntd.0012349. eCollection 2024 Jul.
In 2018-2019, Thailand experienced a nationwide spread of chikungunya virus (CHIKV), with approximately 15,000 confirmed cases of disease reported. Here, we investigated the evolutionary and molecular history of the East/Central/South African (ECSA) genotype to determine the origins of the 2018-2019 CHIKV outbreak in Thailand. This was done using newly sequenced clinical samples from travellers returning to Sweden from Thailand in late 2018 and early 2019 and previously published genome sequences. Our phylogeographic analysis showed that before the outbreak in Thailand, the Indian Ocean lineage (IOL) found within the ESCA, had evolved and circulated in East Africa, South Asia, and Southeast Asia for about 15 years. In the first half of 2017, an introduction occurred into Thailand from another South Asian country, most likely Bangladesh, which subsequently developed into a large outbreak in Thailand with export to neighbouring countries. Based on comparative phylogenetic analyses of the complete CHIKV genome and protein modelling, we identified several mutations in the E1/E2 spike complex, such as E1 K211E and E2 V264A, which are highly relevant as they may lead to changes in vector competence, transmission efficiency and pathogenicity of the virus. A number of mutations (E2 G205S, Nsp3 D372E, Nsp2 V793A), that emerged shortly before the outbreak of the virus in Thailand in 2018 may have altered antibody binding and recognition due to their position. This study not only improves our understanding of the factors contributing to the epidemic in Southeast Asia, but also has implications for the development of effective response strategies and the potential development of new vaccines.
在 2018-2019 年，泰国经历了基孔肯雅热病毒（CHIKV）的全国性传播，报告了大约 15000 例确诊病例。在这里，我们调查了东/中/南非（ECSA）基因型的进化和分子历史，以确定 2018-2019 年泰国 CHIKV 爆发的起源。这是通过使用 2018 年底和 2019 年初从返回瑞典的旅行者身上新测序的临床样本和以前发表的基因组序列来完成的。我们的系统地理学分析表明，在泰国疫情爆发之前，在 ECSA 内发现的印度洋谱系（IOL）已经在东非、南亚和东南亚进化和传播了大约 15 年。2017 年上半年，该病毒从另一个南亚国家，很可能是孟加拉国，传入泰国，随后在泰国爆发，并出口到邻国。基于对完整 CHIKV 基因组和蛋白建模的比较系统发生分析，我们鉴定了 E1/E2 刺突复合物中的几个突变，如 E1 K211E 和 E2 V264A，这些突变非常重要，因为它们可能导致病毒媒介适应性、传播效率和致病性的变化。一些突变（E2 G205S、Nsp3 D372E、Nsp2 V793A）在 2018 年泰国病毒爆发前不久出现，由于其位置，可能改变了抗体的结合和识别。这项研究不仅提高了我们对东南亚流行因素的认识，而且对制定有效的应对策略和开发新疫苗具有重要意义。
