Genome-Scale Phylogenetic Analyses of Chikungunya Virus Reveal Independent Emergences of Recent Epidemics and Various Evolutionary Rates
Genome-Scale Phylogenetic Analyses of Chikungunya Virus Reveal Independent Emergences of Recent Epidemics and Various Evolutionary Rates
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DOI：
10.1128/jvi.01603-09
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发表时间：
2010-07-01
影响因子：
5.4
通讯作者：
Weaver, Scott C.
中科院分区：
文献类型：
--
作者：
Volk, Sara M.;Chen, Rubing;Weaver, Scott C.
基孔肯雅病毒 (CHIKV) 是一种由蚊子传播的甲病毒，传统上在非洲和亚洲传播，导致人类发烧并伴有严重的慢性关节疼痛。在非洲，CHIKV 流行病的出现涉及从涉及树栖蚊媒和非人类灵长类动物的地方性森林循环转变为家庭周围蚊子在人类之间传播的城市循环。然而，在亚洲，CHIKV 似乎仅在地方性城市循环中传播。近期，CHIKV进入印度洋和印度次大陆，造成重大流行。为了研究 CHIKV 的进化模式和这些爆发的起源，以及检查地方性传播和流行性传播之间的进化速率是否存在差异，我们对 40 个 CHIKV 毒株的基因组进行了测序，并进行了系统发育分析，这是迄今为止同类研究中最全面的。我们推断，现存的 CHIKV 毒株是从过去 500 年内存在的祖先进化而来的，并且以前被认为在非洲地理上分离的两个主要地方性动物谱系之间存在一些地理重叠。我们估计CHIKV是在70到90年前从非洲传入亚洲的。最近的印度洋和印度次大陆疫情似乎是独立于东非大陆出现的。这一发现强调了在出口发生之前进行监测以快速发现和控制非洲疫情的重要性。城市期间的核苷酸替代率似乎明显高于地方性动物传播期间。这些结果表明这两个传输周期中传输模式和/或动态的根本差异。
Chikungunya virus (CHIKV), a mosquito-borne alphavirus, has traditionally circulated in Africa and Asia, causing human febrile illness accompanied by severe, chronic joint pain. In Africa, epidemic emergence of CHIKV involves the transition from an enzootic, sylvatic cycle involving arboreal mosquito vectors and nonhuman primates, into an urban cycle where peridomestic mosquitoes transmit among humans. In Asia, however, CHIKV appears to circulate only in the endemic, urban cycle. Recently, CHIKV emerged into the Indian Ocean and the Indian subcontinent to cause major epidemics. To examine patterns of CHIKV evolution and the origins of these outbreaks, as well as to examine whether evolutionary rates that vary between enzootic and epidemic transmission, we sequenced the genomes of 40 CHIKV strains and performed a phylogenetic analysis representing the most comprehensive study of its kind to date. We inferred that extant CHIKV strains evolved from an ancestor that existed within the last 500 years and that some geographic overlap exists between two main enzootic lineages previously thought to be geographically separated within Africa. We estimated that CHIKV was introduced from Africa into Asia 70 to 90 years ago. The recent Indian Ocean and Indian subcontinent epidemics appear to have emerged independently from the mainland of East Africa. This finding underscores the importance of surveillance to rapidly detect and control African outbreaks before exportation can occur. Significantly higher rates of nucleotide substitution appear to occur during urban than during enzootic transmission. These results suggest fundamental differences in transmission modes and/or dynamics in these two transmission cycles.