Gopko Mikhail, Chowdhury M Motiur R, Taskinen Jouni
A.N. Severtsov Institute of Ecology and Evolution Russian Academy of Sciences Moscow Russia.
Department of Biological and Environmental Science University of Jyväskylä Jyvaskyla Finland.
Ecol Evol. 2018 Sep 29;8(20):9986-9997. doi: 10.1002/ece3.4406. eCollection 2018 Oct.
Preinfection by one parasitic species may facilitate or by contrast hamper the subsequent penetration and/or establishment of other parasites in a host. The biology of interacting species, timing of preinfection, and dosage of subsequent parasite exposure are likely important variables in this multiparasite dynamic infection process. The increased vulnerability to subsequent infection can be an important and often overlooked factor influencing parasite virulence. We investigated how the preinfection by freshwater pearl mussel glochidia could influence the success of subsequent infection by the common trematode in brown trout and whether preinfection by the trematode made fish more susceptible to glochidia infection. The first experiment was repeated twice with different (low and high) exposure doses to initiate the subsequent trematode infection, while in the second experiment we varied the timing of the preinfection with trematodes. The preinfection with glochidia made fish more vulnerable to subsequent infection with trematodes. Since the trematodes penetrate through the gills, we suggest that increased host vulnerability was most likely the result of increased respiration caused by the freshwater pearl mussel glochidia encysted on gills. In turn, brown trout preinfected with trematodes were more vulnerable to the subsequent glochidial infection, but only if they were preinfected shortly before the subsequent infection (20 hr). Fish preinfected with trematodes earlier (2 weeks before the subsequent infection) did not differ in their vulnerability to glochidia. These effects were observed at moderate intensities of infections similar to those that occur in nature. Our study demonstrates how the timing and sequence of exposure to parasitic species can influence infection success in a host-multiparasite system. It indicates that the negative influence of glochidia on host fitness is likely to be underestimated and that this should be taken into consideration when organizing freshwater pearl mussel restoration procedures.
一种寄生虫物种的感染前状态可能会促进或相反地阻碍其他寄生虫随后在宿主体内的侵入和/或定殖。相互作用物种的生物学特性、感染前的时间以及随后寄生虫暴露的剂量可能是这个多寄生虫动态感染过程中的重要变量。对随后感染的易感性增加可能是影响寄生虫毒力的一个重要且常常被忽视的因素。我们研究了淡水珍珠蚌钩介幼虫的感染前状态如何影响褐鳟随后被常见吸虫感染的成功率，以及吸虫的感染前状态是否会使鱼类更容易受到钩介幼虫的感染。第一个实验用不同（低和高）暴露剂量重复了两次，以引发随后的吸虫感染，而在第二个实验中，我们改变了吸虫感染前的时间。钩介幼虫的感染前状态使鱼类更容易受到随后吸虫的感染。由于吸虫通过鳃侵入，我们认为宿主易感性增加很可能是鳃上寄生的淡水珍珠蚌钩介幼虫导致呼吸增加的结果。反过来，预先感染吸虫的褐鳟更容易受到随后钩介幼虫的感染，但前提是它们在随后感染前不久（20小时）被预先感染。更早（在随后感染前2周）被预先感染吸虫的鱼类对钩介幼虫的易感性没有差异。这些影响是在与自然发生情况相似的中等感染强度下观察到的。我们的研究证明了接触寄生虫物种的时间和顺序如何影响宿主 - 多寄生虫系统中的感染成功率。它表明钩介幼虫对宿主健康的负面影响可能被低估了，在组织淡水珍珠蚌恢复程序时应考虑到这一点。
