Schmidt O, Schuchmann-Feddersen I
Subcell Biochem. 1989;15:91-119. doi: 10.1007/978-1-4899-1675-4_4.
Insect endoparasitoids are capable of suppressing the immune reaction of their habitual hosts in a specific way. Salt (1968) characterized some of the implications: This seeming contradiction--that defence reactions against all kinds of foreign bodies are available to insects and that endophagous parasitoids are nevertheless able to develop in insect hosts--is resolved by recourse to one of the principles of host specificity. Although insects as a group react to every foreign body in the sense that any organism or substance evokes a reaction in most insects, each species of insect fails to make a reaction (or makes an ineffective reaction) to a small group of organisms, its habitual parasites. It is the common paradox of parasitology that defence reactions are least effective against the most noxious parasites, involving the tautology that the most noxious parasites are those against which defence reactions are least effective. Recently, VLP of hymenopteran wasps have been shown to play a crucial part in suppressing the cellular encapsulation reaction (Stoltz and Vinson, 1979a). In some parasitoid wasps, polydnavirus particles are involved in the phenotypic transformation of hemocytes, reducing the capability of the host to mount an immune reaction towards the parasitoid egg (Stoltz and Guzo, 1986; Davies et al., 1987). However, at least in Venturia, the eggs are effectively protected by VLP that lack significant amounts of nucleic acids, precluding any virus expression in the host. The question was raised whether VLP could have acquired properties of the host immune system, which allows specific suppression of the immune response. The finding of structural similarities between VLP proteins and a host component indicated that a host function is expressed in VLP (Feddersen et al., 1986) and this observation has subsequently permitted the identification and characterization of a protein in caterpillars, which appears to inhibit cellular defense reactions (Berg et al., 1987). On the basis of these results we continue to approach this parasitoid-host interaction, assuming that VLP have evolved in the host organism and eventually acquired the coding sequences of a host protein with properties of an inhibitor of encapsulation. Although there are several ways to explain the emergence of VLP in endophagous parasitoid wasps, a simple proposal would be that such hypothetical viruses, which were able to suppress immune reaction in lepidopteran hosts, were incorporated into a parasitoid wasp to become part of the life cycle of the parasitoid.(ABSTRACT TRUNCATED AT 400 WORDS)
昆虫体内寄生蜂能够以特定方式抑制其宿主体内的免疫反应。索尔特（1968年）描述了其中一些影响：这个看似矛盾的现象——昆虫对各种异物都有防御反应，然而内寄生蜂却能在昆虫宿主体内发育——可以通过诉诸宿主特异性的一个原理来解决。虽然昆虫群体对任何异物都会做出反应，即任何生物体或物质都会在大多数昆虫中引发反应，但每种昆虫对一小部分生物体，即其常见寄生虫，却不会做出反应（或做出无效反应）。这是寄生虫学中常见的悖论，即防御反应对最有害的寄生虫效果最差，这就形成了一种赘述：最有害的寄生虫就是那些防御反应效果最差的寄生虫。最近，膜翅目黄蜂的病毒样颗粒已被证明在抑制细胞包囊化反应中起关键作用（斯托尔茨和文森，1979年a）。在一些寄生蜂中，多分DNA病毒颗粒参与血细胞的表型转化，降低宿主对寄生蜂卵产生免疫反应的能力（斯托尔茨和古佐，1986年；戴维斯等人，1987年）。然而，至少在云尺蛾属中，卵受到缺乏大量核酸的病毒样颗粒的有效保护，从而排除了宿主中任何病毒表达的可能性。有人提出疑问，病毒样颗粒是否获得了宿主免疫系统的特性，从而能够特异性抑制免疫反应。病毒样颗粒蛋白与宿主成分之间结构相似性的发现表明，宿主功能在病毒样颗粒中得以表达（费德森等人，1986年），随后这一观察结果使得人们能够鉴定和表征毛虫体内一种似乎能抑制细胞防御反应的蛋白质（伯格等人，1987年）。基于这些结果，我们继续研究这种寄生蜂与宿主的相互作用，并假设病毒样颗粒在宿主体内进化，最终获得了具有包囊化抑制特性的宿主蛋白的编码序列。虽然有几种方式可以解释内寄生蜂中病毒样颗粒的出现，但一个简单的推测是，这种能够抑制鳞翅目宿主免疫反应的假设病毒被整合到寄生蜂中，成为寄生蜂生命周期的一部分。（摘要截选至400字）
