Arbovirus evolution in vivo is constrained by host alternation
Arbovirus evolution in vivo is constrained by host alternation
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DOI：
10.1073/pnas.0712130105
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发表时间：
2008-05-13
影响因子：
11.1
通讯作者：
Weaver, Scott C.
中科院分区：
文献类型：
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作者：
Coffey, Lark L.;Vasilakis, Nikos;Weaver, Scott C.
RNA病毒的内在可塑性可以促进宿主范围的变化，从而导致流行病。然而，促进跨物种转移的进化过程还不清楚，特别是节肢动物传播的病毒(虫媒病毒)。从理论上讲，虫媒病毒的跨物种传播可能受到它们对不同宿主的交替感染的限制，其中在一个宿主上的最佳复制涉及到另一个宿主的适合性权衡。因此，通过在单一宿主中的专门化将虫媒病毒从交替复制中解放出来，应该会加速适应。这一假设已经通过使用细胞培养模型系统进行了检验，但结果并不确定。因此，我们使用体内系统对委内瑞拉马脑炎病毒(VEEV)进行了测试，VEEV是一种新出现的美洲甲型病毒。在蚊子中连续传代的Veev表现出更高的蚊子传染性，脊椎动物特有的菌株产生更高的病毒群。相反，交替传代的VEEV在两个宿主中都没有可检测到的健康增长。这些结果表明虫媒病毒的适应和进化受到预定宿主交替的限制，并预测通过宿主范围变化而出现的虫媒病毒可能比单一宿主动物RNA病毒更少出现。
The intrinsic plasticity of RNA viruses can facilitate host range changes that lead to epidemics. However, evolutionary processes promoting cross-species transfers are poorly defined, especially for arthropod-borne viruses (arboviruses). In theory, cross species transfers by arboviruses may be constrained by their alternating infection of disparate hosts, where optimal replication in one host involves a fitness tradeoff for the other. Accordingly, freeing arboviruses from alternate replication via specialization in a single host should accelerate adaptation. This hypothesis has been tested by using cell culture model systems with inconclusive results. Therefore, we tested it using an in vivo system with Venezuelan equine encephalitis virus (VEEV), an emerging alphavirus of the Americas. VEEV serially passaged in mosquitoes exhibited increased mosquito infectivity and vertebrate-specialized strains produced higher viremias. Conversely, alternately passaged VEEV experienced no detectable fitness gains in either host. These results suggest that arbovirus adaptation and evolution is limited by obligate host alternation and predict that arboviral emergence via host range changes may be less frequent than that of single host animal RNA viruses.