Modification of native baculoviruses; efficacy, characterization and ecological risk assessment

加拿大的主要森林资源提供了巨大的吸收二氧化碳排放量的能力，这是京都协定的一个重要组成部分，但前提是必须适当保护这一资源，使其免受云杉芽虫和帐篷毛虫等主要森林害虫的侵害。保护我们的森林还将直接使林业受益，2001年，林业的国内生产总值为280亿美元，贸易差额为340亿美元，销售额为740亿美元。然而，保护必须是可持续的和环境友好的，重点是具体的害虫物种。CfMNPV是云杉芽虫Choristoneura fumiferana特有的一种天然生物制剂，历史上它是加拿大北方森林的主要食叶害虫，每年造成100万至5000万公顷的损失。为了使这种天然病毒更有效地控制这种害虫，我们打算将仅从病毒-毛虫生态系统中借来的小片段遗传信息整合到CfMNPV基因组中。例如，我们打算重新编程病毒，使其产生能够破坏云杉芽虫的蛋白质，如病毒组织蛋白酶和几丁质酶，时间更早，水平更高。云杉芽虫调节蛋白的基因也将被纳入，这样病毒产生的蛋白质将破坏昆虫的正常发育，并导致行为变化，如停止进食。 这两种战略都应该是无害环境的，因为它们只利用自然生态系统固有的遗传物质。将在不同的环境条件下表征修饰的变体的活性和功效（例如剂量、杀灭时间、摄食损害的减少），以鉴定提供改善的保护的那些。 这些数据，以及关于宿主范围、传播、持久性和与天然病毒的竞争性的其他研究，将用于评估经修饰的病毒的潜在生态影响。我们的方法不会改变现有的森林“基因库”，但预计将提供更好的控制剂对这种重要的害虫。我们的研究可以扩大到森林帐篷毛虫（1至2400万公顷的损害）。此外，我们还将评估一种用于防治农业害虫的类似方法。

Canada's major forest resource provides an enormous capacity to sequester carbon dioxide emissions, an important component of the Kyoto agreement but only if that resource is properly protected from the major forest insect pests such as the spruce budworm and tent caterpillar. Protection of our forests would also directly benefit the forest industry, responsible, in 2001, for a $28 billion GDP, a $34 billion trade balance and sales of $74 billion. However, protection must be sustainable and environmentally benign, focusing on the specific pest species. CfMNPV is a natural biological agent specific to the spruce budworm, Choristoneura fumiferana, historically the major defoliator in Canada's boreal forest and responsible for damage to 1 to 50 million hectares per year. To make this native virus more effective at controlling this pest, we intend to incorporate small pieces of genetic information, borrowed only from within the virus-caterpillar ecosystem, into the CfMNPV genome. For example, we intend to reprogram the virus to produce proteins that will damage spruce budworm, like viral cathepsin and chitinase, at times earlier, and at higher levels than in the native virus. Genes for spruce budworm regulatory proteins will also be incorporated so that their production by the virus will disrupt the insect's normal development and lead to behavioural changes such as cessation of feeding.  Both strategies should be environmentally benign since they utilize only genetic material indigenous to the natural ecosystem. The activity and efficacy of the modified variants will be characterized under different environmental conditions (e.g. dosage, kill times, reduction in feeding damage) to identify those providing improved protection.  These data, together with additional studies on host range, transmission, persistence and  competitiveness with the native virus, will be used to assess the potential ecological impact of the modified viruses. Our approach does not alter the existing forest "gene pool", but is expected to provide better control agents against this significant pest. Our research could be expanded to the forest tent caterpillar (1 to 24 million ha damage). Moreover we will also evaluate a similar approach for use against agricultural pest insects.