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封存二氧化碳排放的能力，这是京都协议的一个重要组成部分，但前提是该资源得到适当保护，不受云杉芽孢子虫和帐篷毛虫等主要森林害虫的侵害。保护我们的森林也将使森林业直接受益，2001年，森林业创造了280亿美元的国内生产总值、340亿美元的贸易差额和740亿美元的销售额。然而，保护必须是可持续的和对环境无害的，重点是特定的害虫物种。CfMNPV是一种针对云杉芽孢子虫的天然生物制剂，Choristoneura fumiferana历来是加拿大北方森林的主要毁叶者，每年造成100至5000万公顷的损失。为了使这种本地病毒更有效地控制这种害虫，我们打算将仅从病毒-毛虫生态系统中借用的小片段遗传信息整合到CfMNPV基因组中。例如，我们打算对病毒进行重新编程，以产生会损害云杉芽孢子虫的蛋白质，如病毒组织蛋白酶和几丁质酶，时间比天然病毒更早，水平也更高。云杉芽孢子虫调节蛋白的基因也将被纳入其中，这样病毒产生的基因将扰乱昆虫的正常发育，并导致行为变化，如停止取食。这两种策略都应该对环境无害，因为它们只使用自然生态系统固有的遗传物质。将在不同的环境条件下(例如，剂量、杀死时间、减少取食损害)表征修改后的变种的活性和效力，以确定哪些提供了更好的保护。这些数据，以及关于宿主范围、传播、持久性和与本地病毒的竞争力的额外研究，将被用于评估修改后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”，但有望为这种重大害虫提供更好的控制剂。我们的研究可以扩大到森林帐篷毛虫(损失100-2400万公顷)。此外，我们还将评估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.