CHARACTERIZATION OF BACULOVIRUS EARLY GENE EXPRESSION

杆状病毒是一个大的DNA病毒家族，其致病性为 昆虫 目前，它们被用作重要的生物 控制害虫，并正在设计改进 毒性和更广泛的宿主范围。 这些药物的安全性评价 对于非目标生物体，包括人类， 需要对它们的分子生物学有更多的了解 以及控制其复制的机制。 从 从病毒学的角度来看，杆状病毒是令人感兴趣的，因为 它们庞大的超螺旋基因组， 循环导致两种传染性形式的不寻常的生产 病毒基因组与宿主融合的能力 衍生转座因子 我们建议研究 参与最早的表达的分子机制 使用杆状病毒模式，苜蓿银纹夜蛾， 核型多角体病毒（AcNPV）。 我们的目标包括 定义了介导直接- 早期（IE）转录，采用瞬时表达， 嵌合基因及其转移后的表达 回到病毒基因组中 我们将描述的产品 两个相邻的IE基因，并检查它们的潜在调控， 重叠的反义RNA 该提案的主要部分 还研究了一种新的 插入IE区域内的经鉴定的转座因子（TED AcNPV的基因组。 TED是一种反转录转座子， 整合引导邻近病毒的大量转录 基因. 反转录转座子与反转录前病毒非常相似， 代表真核生物中一类重要的插入诱变剂。 其致突变的确切机制尚不清楚。 我们将 详细分析TED整合对表达的影响 AcNPV基因。 此外，我们将利用克隆 分离病毒基因组中的TED，以检查其结构 组织和转录表达的调节 主动反转录转座子 这些研究预计将产生 进一步深入了解遗传改变的机制， 通过这些移动的元素以及复杂的信息 控制真核基因表达的机制。

The baculoviruses are a family of large DNA viruses pathogenic to insects. They are currently employed as important biological controls of insect pests and are being engineered for improved toxicity and wider host ranges. Evaluations on the safety of these viruses in regard to non-target organisms, including humans, have demanded an increased understanding of their molecular biology and the mechanisms which govern their replication. From a virological perspective, the baculoviruses are of interest because of their large, superhelical genome, their complex replicative cycle resulting in an unusual production of two infectious forms of progeny, and the ability of the viral genome to incorporate host- derived transposable elements. We propose to examine the molecular mechanisms involved in the expression of the earliest of viral genes using the model baculovirus, Autographa californica nuclear polyhedrosis virus (AcNPV). Our objectives include defining the cis-acting DNA sequences which mediate immediate- early (IE) transcription employing both transient expression of chimeric genes and expression of such genes after their transfer back into the viral genome. We will characterize the products of two adjacent IE genes and examine their potential regulation by overlapping, anti-sense RNAs. A major portion of this proposal also examines the nature and mutagenic effects of a newly identified transposable element (TED) inserted within an IE region of the AcNPV genome. TED is a retrotransposon which upon integration directs abundant transcription of neighboring viral genes. Retrotransposons closely resemble the retroproviruses and represent an important class of insertion mutagens in eukaryotes. The exact mechanisms of their mutagenesis are unknown. We will analyze in detail the effects of TED integration on the expression of AcNPV genes. In addition, we will take advantage of the clonal isolate of TED within the viral genome to examine the structural organization and regulation of expression of a transcriptionally active retrotransposon. These studies are expected to yield further insight into the mechanisms of genetic alterations caused by these mobile elements as well as information on the complex mechanisms which control eukaryotic gene expression.