School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, LE12 5RD, United Kingdom.
Vet Parasitol. 2009 Aug 26;163(4):307-14. doi: 10.1016/j.vetpar.2009.03.019. Epub 2009 Mar 21.
The question of how Sarcocystis neurona is able to overcome species barrier and adapt to new hosts is central to the understanding of both the evolutionary origin of S. neurona and the prediction of its field host range. Therefore, it is worth reviewing current knowledge on S. neurona host specificity. The available host range data for S. neurona are discussed in relation to a subject of evolutionary importance-specialist or generalist and its implications to understand the strategies of host adaptation. Current evidences demonstrate that a wide range of hosts exists for S. neurona. This parasite tends to be highly specific for its definitive host but much less so for its intermediate host (I.H.). The unique specificity of S. neurona for its definitive host may be mediated by a probable long coevolutionary relationship of the parasite and carnivores in a restricted ecological niche 'New World'. This might be taken as evidence that carnivores are the 'original' host group for S. neurona. Rather, the capacity of S. neurona to exploit an unusually large number of I.H. species probably indicates that S. neurona maintains non-specificity to its I.H. as an adaptive response to insure the survival of the parasite in areas in which the 'preferred' host is not available. This review concludes with the view that adaptation of S. neurona to a new host is a complex interplay that involves a large number of determinants.
神经内孢子虫属如何能够克服物种障碍并适应新宿主，这是理解神经内孢子虫属的进化起源和预测其野外宿主范围的核心问题。因此，值得回顾一下关于神经内孢子虫属宿主特异性的现有知识。本文讨论了神经内孢子虫属的现有宿主范围数据，涉及到一个具有进化重要性的主题——专性宿主或兼性宿主，以及它对理解宿主适应策略的影响。目前的证据表明，神经内孢子虫属存在广泛的宿主。这种寄生虫对其终末宿主具有高度特异性，但对中间宿主（I.H.）则不那么特异性。神经内孢子虫属对其终末宿主的独特特异性可能是由寄生虫和肉食动物在有限的生态位“新世界”中可能存在的长期共同进化关系介导的。这可以被视为肉食动物是神经内孢子虫属的“原始”宿主群的证据。相反，神经内孢子虫属能够利用异常多的中间宿主物种，这可能表明神经内孢子虫属对其中间宿主保持非特异性，作为一种适应性反应，以确保寄生虫在“首选”宿主不可用的地区生存。本文的结论是，神经内孢子虫属适应新宿主是一个复杂的相互作用过程，涉及到大量的决定因素。
