EVOLUTIONARY CONSEQUENCES OF DENGUE VIRUS EMERGENCE

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 登革病毒（黄病毒属）是节肢动物传播病毒中对公共卫生最严重的威胁，以两个不同的生命周期传播。 引起人类登革热的流行性登革热病毒在人类和居住区周围的伊蚊之间循环。 森林登革热病毒在非洲和亚洲的森林冠层中在森林伊蚊物种和非人类灵长类之间循环。 地方性病毒和森林病毒显示出高度的序列同源性，但森林病毒不会在人类中引起暴发。我们最初的假设是解释这个明显的悖论， 适应障碍 防止森林登革热病毒的出现，或者更具体地说，防止森林登革热病毒在人类或栖息地附近的伊蚊物种中复制不良。然而，在与INBRE导师Scott Weaver（UTMB）及其实验室成员的合作中，我们已经证明不存在这种适应性屏障，因为DENV血清型2的森林和地方毒株对人类病毒复制模型（Vasilakis et al. 2007，Vasilakis et al. in preparation）和Ae.埃及伊蚊，地方性登革热的主要媒介（汉利等人，准备中）。 森林登革热对森林循环的限制的另一种解释是，与登革病毒地方毒株的竞争阻止了森林毒株的出现。 目前，缺乏有关DENV竞争的数据，无法评估这一假设。 因此，我们目前的研究重点是表征不同血清型登革病毒之间竞争的强度和对称性。我们选择使用不同的血清型而不是同一血清型中的森林型和地方性菌株来启动这项研究，因为易于处理的基于抗体的方法可用于区分和量化不同血清型的复制。 到目前为止，我们已经证明，在培养的细胞和活蚊子，血清型之间的宿主内竞争可能会导致减少病毒后代的生产，共感染的影响是不对称的血清型之间，以及较弱的竞争对手可以获得优势，如果它感染宿主细胞之前，一个更强的竞争对手。我们计划在这项研究的基础上，使用基于PCR的测定来量化每种毒株的相对复制，以测试地方性和森林登革热病毒株之间竞争的强度和对称性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Dengue virus (genus Flavivirus) the most significant threat to public health among the arthropod-borne viruses, circulates in two distinct life cycles. Epidemic dengue viruses, which cause human dengue fever, cycle between humans and peridomestic Aedes mosquitoes. Sylvatic dengue viruses cycle in the forest canopies of Africa and Asia between sylvatic Aedes species and non-human primates. Endemic and sylvatic viruses show high sequence homology, but sylvatic viruses do not cause outbreaks in humans. Our initial hypothesis to explain this apparent paradox was that an adaptive barrier prevents the emergence of sylvatic dengue virus, or more specifically that sylvatic dengue virus replicates poorly in either humans or in peridomestic Aedes species. However, in collaboration with INBRE mentor Scott Weaver (UTMB) and members of his lab, we have demonstrated that no such adaptive barrier exists, because sylvatic and endemic strains of DENV serotype 2 are equally infectious for models of virus replication in humans (Vasilakis et al. 2007, Vasilakis et al. in preparation) and for Ae. aegypti, the primary vector of endemic dengue (Hanley et al. in preparation). An alternative explanation for the restriction of sylvatic dengue to the forest cycle is that competition with endemic strains of DENV prevents emergence of sylvatic strains. At present, the paucity of data on competition in DENV makes it impossible to assess this hypothesis. Thus, our current research focuses on characterizing the strength and symmetry of competition among different serotypes of dengue virus. We chose to initiate this research using different serotypes rather than sylvatic and endemic strains within a serotype because tractable, antibody-based methods are available to distinguish and quantify replication of different serotypes. To date we have demonstrated in both cultured cells and live mosquitoes that intra-host competition between serotypes can cause decreased virus progeny production, that effects of co-infection are asymmetric among serotypes, and that a weaker competitor can gain an advantage if it infects host cells prior to a stronger competitor. We plan to build on this research to test the strength and symmetry of competition between endemic and sylvatic dengue virus strains, using a PCR-based assay to quantify relative replication of each strain.