Immunoevasive protein (IEP)-containing surface layer covering polydnavirus particles is essential for viral infection.
Immunoevasive protein (IEP)-containing surface layer covering polydnavirus particles is essential for viral infection.
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DOI：
10.1016/j.jip.2013.10.013
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发表时间：
2014
影响因子：
3.4
通讯作者：
Shunsuke Furihata;Kohjiro Tanaka;Masasuke Ryuda;M. Ochiai;H. Matsumoto;Gyorge Csikos;Y. Hayakawa
中科院分区：
文献类型：
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作者：
Shunsuke Furihata;Kohjiro Tanaka;Masasuke Ryuda;M. Ochiai;H. Matsumoto;Gyorge Csikos;Y. Hayakawa
多脱氧核糖核酸病毒（PDV）是与寄生蜂相关的独特的共生病毒：PDV颗粒沿着蜂卵注入鳞翅目宿主，并表达干扰宿主生理学方面的基因，如免疫防御和发育。最近的比较基因组研究PDV显着提高了我们的理解，他们的起源以及基因组组织。然而，功能性PDV颗粒的结构特征仍然不明确。为了弄清CotesiakariyaiPDV（CkPDV）颗粒的结构，我们将重点放在免疫逃避蛋白（IEP）上，该蛋白是黄蜂从宿主昆虫血细胞的包封反应中免疫逃避的介体，因为它已被证明存在于病毒颗粒的表面上。我们发现IEP倾向于聚合并构成一个之前未识别的薄表面层，覆盖CkPDV颗粒。该最外表面层看起来易碎，并且通过机械应激（例如摇动）容易地从CkPVD颗粒去除，这阻止了CkPDV在宿主靶组织（例如脂肪体或血细胞）中表达编码的基因。此外，我们检测到IEP同源基因在黄蜂的毒液库中的表达，这意味着IEP在黄蜂或寄生宿主中具有另一种未知的生物学功能。综上所述，本研究结果表明，femaleC. kariyaiwasp产生部分由IEP组成的脆弱薄层以覆盖CkPDV颗粒的外表面;否则，它们不能在黄蜂的宿主中作为感染剂发挥作用。IEP家族蛋白在毒液库和输卵管中都表达的事实表明，这两种组织在黄蜂寄生策略的发展中存在密切的关系。
Polydnaviruses (PDVs) are unique symbiotic viruses associated with parasitoid wasps: PDV particles are injected into lepidopteran hosts along with the wasp eggs and express genes that interfere with aspects of host physiology such as immune defenses and development. Recent comparative genomic studies of PDVs have significantly improved our understanding of their origin as well as the genome organization. However, the structural features of functional PDV particles remain ambiguous. To clear up the structure of CotesiakariyaiPDV (CkPDV) particles, we focused on immunoevasive protein (IEP), which is a mediator of immunoevasion by the wasp from the encapsulation reaction of the host insect’s hemocytes, because it has been demonstrated to be present on the surface of the virus particle. We discovered that IEP tends to polymerize and constitutes a previously unidentified thin surface layer covering CkPDV particles. This outermost surface layer looked fragile and was easily removed from CkPVD particles by mechanical stressors such as shaking, which prevented CkPDV from expressing the encoded genes in the host target tissues such as fat body or hemocytes. Furthermore, we detected IEP homologue gene expression in the wasp’s venom reservoirs, implying IEP has another unknown biological function in the wasp or parasitized hosts. Taken together, the present results demonstrated that femaleC. kariyaiwasps produce the fragile thin layer partly composed of IEP to cover the outer surfaces of CkPDV particles; otherwise, they cannot function as infectious agents in the wasp’s host. The fact that IEP family proteins are expressed in both venom reservoirs and oviducts suggests an intimate relationship between both tissues in the development of the parasitism strategy of the wasp.