Data from: Baculovirus infection triggers a positive phototactic response in caterpillars to induce ‘tree-top’ disease

Many parasites manipulate host behaviour to enhance parasite transmission and survival. A fascinating example is baculoviruses, which often induce death in caterpillar hosts at elevated positions (‘tree-top’ disease). To date, little is known about the underlying processes leading to this adaptive host manipulation. Here, we show that the baculovirus Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) triggers a positive phototactic response in S. exigua larvae prior to death and causes the caterpillars to die at elevated positions. This light-dependent climbing behaviour is specific for infected larvae, as movement of uninfected caterpillars during larval development was light-independent. We hypothesize that upon infection, SeMNPV captures a host pathway involved in phototaxis and/or light perception to induce this remarkable behavioural change.诸多寄生虫会通过操控宿主行为以提升自身的传播效率与生存能力。杆状病毒（baculoviruses）便是极具研究价值的典型案例：该类病毒常诱导寄主毛虫在高处死亡，此现象被称为树顶病（tree-top disease）。迄今为止，学界对驱动这一适应性宿主操控行为的底层机制仍知之甚少。本研究证实，甜菜夜蛾多核衣壳核型多角体病毒（Spodoptera exigua multiple nucleopolyhedrovirus，缩写为SeMNPV）会在甜菜夜蛾幼虫死亡前诱导其产生正向趋光性反应，并促使该毛虫在高处死亡。这种依赖光照的攀爬行为仅见于受感染幼虫：未感染的毛虫在幼虫发育阶段的移动行为并不受光照调控。我们据此推测，SeMNPV在侵染宿主后，会劫持宿主体内参与趋光性及/或光感知的信号通路，从而引发这一显著的行为改变。