Related Wasp and Polydnavirus Genes: Role in Parasitism

一些昆虫寄生虫将分泌物与卵一起注入宿主，从而避免免疫防御，导致宿主发育停滞。对于松突弯孢菌，这两种现象都可能是由多聚核糖核酸病毒(PDV)诱导的。PDV是唯一一种具有异质性、节段性基因组的动物DNA病毒。已鉴定出几个在寄生过程中表达的病毒基因家族，并且病毒基因的表达具有组织和/或宿主特异性。通过进化，寄生虫获得了组装、放大并以病毒形式将这些遗传信息转移到另一种真核宿主上的能力，这对寄生虫的生存至关重要。我们已经展示了一个与毒液相关的(VR)黄蜂家族和PDV基因编码的结构基序，这些结构基序属于“死亡”蛋白家族。这表明，这些独特的基因可能编码参与调控、剪接或翻译的产物。我们最近的研究还表明，CsPDV基因包含编码半胱氨酸基序的序列，该基序是多肽毒素的特征。这个基序的存在不太可能是偶然的，相反，它可能反映了作为细胞表面受体配体的功能，这也可能与寄生虫生存相关的功能相关。这项研究的意义在于强调了寄生虫诱导昆虫防御系统回避的分子基础，在NSF的支持下进行的研究将致力于鉴定这些表达产物并确定它们的功能意义。

Some insect parasites inject secretions into the host along with their egg which results in avoiding immune defenses and causes host developmental arrest. For Campoletis sonorensis, both phenomena may be induced by a polydnavirus (PDV). PDV is the only animal DNA virus with a heterogeneous, segmented genome. Several viral gene families have been identified that are expressed during parasitism, and viral gene expression is tissue and/or host specific. Through evolution the parasite has acquired to assemble, amplify and transfer this genetic information in a viral form to another eucaryotic host which is essential for parasite survival. We have shown one family of the venom related (VR) wasp and PDV genes encode structural motifs that belong to "DEAD" protein family. This suggests that these unique genes may encode products involved in regulating, splicing or translation. Our recent studies show also that CsPDV genes contain sequences that encode a cysteine motif characteristic of peptide toxins. The presence of this motif is unlikely to be fortuitous, rather it may reflect a function as a ligand of cell surface receptors which may also be correlated with functions related to parasite survival. The significance of this study emphasizes the molecular basis of parasite induced avoidance of insect defense systems and the research conducted with NSF support will be directed to identifying these expression products and determining their functional significance.