Vector Population Modification Using Wolbachia Symbionts

描述(由申请人提供)：细胞内的沃尔巴克氏菌感染各种无脊椎动物宿主，包括医学上重要的疾病媒介。许多沃尔巴克氏菌感染导致细胞质不相容，这有效地使携带不同感染类型的宿主之间的交配绝育。我们最近开发了一个模型，该模型定义了沃尔巴克氏菌感染频率和宿主种群大小之间的关系。模型模拟预测了一种抑制昆虫种群的新策略。这一策略是基于人为地延长不稳定的共存，当两个或更多不相容的沃尔巴克氏菌类型感染宿主种群，导致宿主种群抑制时发生的不稳定共存。由于沃尔巴克氏菌自然存在于广泛的无脊椎动物中，这一策略潜在地适用于各种医学和经济上重要的系统。除了种群抑制策略外，种群替换策略还建议使用沃尔巴克氏菌作为媒介，将所需的基因类型(例如，对疾病传播不敏感)传播到媒介种群中。在概述的研究中，我们将在媒介蚊虫种群中开发、测试和评估通过模型模拟预测的种群抑制和替换策略。CX.库蚊被选为最初的目标是因为它作为疾病媒介的重要性，以及在自然发生的库蚊种群中存在多种不相容的沃尔巴克氏菌感染。其他实验将研究延缓、阻止或逆转基于沃尔巴克氏菌的种群替换的策略。后一种战略是一种适当的保障措施，如果人口更替带来意想不到的负面后果，这种保障措施可能被证明是必要的。为了改进策略设计、实施和评估，目标将包括更好地定义库蚊/沃尔巴克氏菌共生的感染动态(例如，母体传播率和沃尔巴克氏菌对宿主健康的影响)，简化库蚊感染类型之间的区分，以及改进现场笼养评估沃尔巴克氏菌控制策略的方法。

DESCRIPTION (provided by the applicant): Intracellular Wolbachia bacteria infect a diverse range of invertebrate hosts, including medically important disease vectors. Many Wolbachia infections cause cytoplasmic incompatibility, which effectively sterilizes mating between host individuals that harbor differing infection types. We have recently developed a model that defines the relationship between the Wolbachia infection frequency and host population size. Model simulations predict a novel strategy for suppressing insect populations. This strategy is based upon artificially prolonging an unstable coexistence that occurs when two or more incompatible Wolbachia types infect a host population, resulting in host population suppression. As Wolbachia occurs naturally within a broad range of invertebrates, this strategy is potentially applicable to a variety of medically and economically important systems. In addition to population suppression strategies, population replacement strategies propose to employ Wolbachia as a vehicle for spreading desired genotypes (e.g., refractoriness to disease transmission) into vector populations. In the outlined research, we will develop, test and evaluate population suppression and replacement strategies predicted by model simulations in populations of the vector mosquito Culex pipiens. Cx. pipiens has been selected as the initial target due to its importance as a disease vector and the availability of multiple, incompatible Wolbachia infections in naturally occurring Culex populations. Additional experiments will examine strategies for retarding, arresting or reversing Wolbachia-based population replacement. The latter strategies represent an appropriate safeguard that may prove necessary if unexpected, negative consequences become associated with population replacement. To improve strategy design, implementation, and evaluation, aims will include better defining the infection dynamics of the Culex/Wolbachia symbiosis (e.g., maternal transmission rates and Wolbachia effects on host fitness), simplifying discrimination between Culex infection types, and improving methods for field cage evaluation of Wolbachia control strategies.