Real and Apparent Complexity in Polydnavirus Genomes

本研究将阐明多dna病毒（PDV）基因组结构在产生病毒基因变异中的作用。PDV基因组结构似乎促进了病毒基因家族的变异性，促进了基因表达水平的改变，并允许获得新基因。支持这一假设的证据包括：1)PDV基因组中功能显著变异的鉴定，2)PDV基因组和片段结构的保守性，以及3)片段类型之间的功能特化。初步数据表明，通过改变鱼病毒的拷贝数来调节基因表达只是更大的PDV组织模式的一部分。这些数据支持了更普遍的假设，即PDV基因组片段不仅影响基因表达水平，而且促进了基因变异的产生和从宿主基因组中获得新基因。这一假设在三个研究目标下得到验证：1)确定索诺Campoletis sonorenis技术病毒（CsIV）的遗传变异是否影响病毒功能和寄生虫宿主范围；2)确定CsIV的结构组织是否具有其他技术病毒的代表性；3)确定整合能力片段是否支持基因进入病毒基因组。多dna病毒必须抑制宿主免疫并改变其他宿主生理系统，以支持寄生虫的发育，从而使病毒垂直传播。寄生生物对抗不断进化的宿主抗性机制的能力可能需要不断产生功能变异，从而能够继续利用宿主或入侵新的宿主物种。在黄蜂寄生虫中，寄主和寄生虫的生命周期是同步的，pdv可能提供了一个高度可变的基因组，被寄生虫选择，从而允许持续产生免疫抑制基因变异，从而赋予可持续的进化优势。在更广泛的背景下，这项工作将阐明圈养基因组对真核生物高度可变性状进化的一些关键贡献。转座因子、逆转录病毒和非编码序列构成了人类和其他生物体中90%以上的DNA，但这类DNA通常被称为垃圾DNA，因为其功能作用尚不清楚。这项研究还可能阐明病毒和非编码序列在多dna病毒生物学相关性状进化中的作用，从而有助于更好地理解其他生物体中这些明显非必需的序列。

This research will elucidate the role of polydnavirus (PDV) genome structure in generating viral gene variants. PDV genome structure appears to promote variability within viral gene families, facilitate alteration of the level to which genes are expressed and allow for acquisition of novel genes. Evidence in support of this hypothesis the: 1) identification of functionally significant variants in PDV genomes, 2) conservation of PDV genome and segment structure and 3) functional specialization among segment types. The preliminary data suggest that regulation of gene expression by changing copy number in ichnoviruses is but one part of a larger PDV organizational paradigm. These data support the more general hypothesize that PDV genome segmentation not only influences gene expression levels but also facilitates production of gene variants and acquisition of novel genes from the host genome. This hypothesis is tested under three research objectives intended to: 1) determine if Campoletis sonorensis ichnovirus (CsIV) genetic variation impacts virus function and parasite host range, 2) To determine if the structural organization of CsIV is representative of other ichnoviruses, 3) To determine if integration-competent segments support gene entry into viral genomes. Polydnaviruses must suppress host immunity and alter other host physiological systems in support of parasite development for the virus to be vertically transmitted. A parisite's ability to counter evolving host resistance mechanisms may require continual production of functional variants that enable continued host exploitation or invasion of new host species. In wasp parasites, where host and parasite life cycles are synchronized, PDVs may provide a highly mutable genome co-opted by the parasite to allow continual production of immunosuppressive gene variants that confer a sustainable evolutionary advantage. In a broader context, this work will elucidate some of the critical contributions of captive genomes to the evolution of highly variable traits in eukaryotic organisms. Transposable elements, retroviral and non-coding sequence comprise over 90% of the DNA in humans and other organisms but this type of DNA is often described as junk DNA because its functional role is not clearly understood. This research may also elucidate the role of viral and non-coding sequences in the evolution of biologically relevant traits in polydnaviruses and thereby contribute to a better understanding of these apparently non-essential sequences in other organisms.