Genotypic and Phenotypic Analysis of West Nile virus, Yucatan Peninsula of Mexico

描述(申请人提供)：西尼罗河病毒(WNV)于1999年在纽约首次在西半球爆发，自那以来该病毒迅速在美国和加拿大蔓延，在那里它导致了严重的人类发病率和死亡率。相比之下，墨西哥尤卡坦半岛没有出现西尼罗河病毒人感染病例，尽管有证据表明西尼罗河病毒的活动，但该地区也没有任何与西尼罗河病毒相关的疾病在该地区广泛传播的报告。事实上，我们和我们在梅里达尤卡坦自治大学(DAY)的墨西哥同事在YP中的马、鸟和其他脊椎动物中检测到了西尼罗河病毒的抗体。然而，与这项建议最相关的是在科祖梅尔岛进行的一项血清调查的结果；在144匹马中有75匹(52%)检测到西尼罗河病毒抗体，但这些马都没有疾病迹象，也没有西尼罗河病毒样疾病的病史。因此，这项建议的基本假设是，YP中的主要西尼罗河病毒变异株在基因和表型上与美国的WNV显性变异株不同。在这项授权中，我们和我们在UAY的同事将获得YP中的WNV分离株，并确定它们的基因类型和细胞培养表型。在具体目标1中，蚊子将被困在青年计划中以前发现血清阳性脊椎动物的地点。将通过RT-PCR和病毒分离对蚊子进行西尼罗河病毒检测。这些研究将确定西尼罗河病毒在青枯期的可能媒介，从而为未来媒介能力和寄主取食行为的研究提供基础。在特定目标2中，将对西尼罗河病毒分离株进行部分核苷酸测序和系统发育分析。西尼罗河病毒的主要变异株将被完全测序。在具体目标3中，将比较来自yp和美国的西尼罗河病毒主要变异株的细胞培养表型(即复制动力学和产量、斑块形态和温度敏感性)。这些研究将为今后脊椎动物宿主体内发病机制的研究奠定基础。相关性：在这项建议中，将描述该地区西尼罗河病毒主要变异株的基因类型和细胞培养表型，并确定该地区西尼罗河病毒的可能载体。这些信息将有助于确定为什么在青年计划中没有西尼罗河病毒的流行，并将确定与西尼罗河病毒病相关的风险因素。

DESCRIPTION (provided by applicant): The initial outbreak of West Nile virus (WNV) in the Western Hemisphere occurred in New York in 1999, and since then the virus has rapidly spread across the United States and Canada, where it has been responsible for significant human morbidity and mortality. In contrast, there have been no human cases of WNV in the Yucatan Peninsula (YP) of Mexico, nor have there been any reports of widespread WNV associated illness in horses or birds in this region, despite evidence of WNV activity. Indeed, we and our Mexican colleagues at the Universidad Autonoma de Yucatan (DAY) in Merida detected antibodies to WNV in horses, birds and other vertebrate animals in the YP. Most pertinent to this proposal, however, are the findings from a serosurvey conducted on Cozumel Island; antibodies to WNV were detected in 75 of 144 (52%) horses, but none of the horses had signs of illness and none had a history of WNV-like illness. Thus, the underlying hypothesis in this proposal is that the dominant WNV variants in the YP are genotypically and phenotypically distinct from the dominant WNV variants in the U.S. In this grant, we and our colleagues at the UAY will obtain WNV isolates in the YP, and define their genotypes and cell culture phenotypes. In specific aim 1, mosquitoes will be trapped at sites in the YP where seropositive vertebrates have previously been identified. Mosquitoes will be assayed for WNV by RT-PCR and virus isolation. These studies will identify likely vectors of WNV in the YP, thereby providing the groundwork for future vector competence and host-feeding behavior studies. In specific aim 2, WNV isolates will be examined by partial nucleotide sequencing and phylogenetic analysis. Dominant WNV variants will be completely sequenced. In specific aim 3, the cell culture phenotypes (i.e. replication kinetics and yields, plaque morphologies and temperature sensitivities) of dominant WNV variants from the YP and U.S. will be compared. These studies will provide the groundwork for future in vivo pathogenesis studies in vertebrate hosts. RELEVANCE: In this proposal, the genotypes and cell culture phenotypes of dominant WNV variants in the YP will be characterized, and likely vectors of WNV in this region will be identified. This information will help determine why there has not been an epidemic of WNV in the YP, and will identify risk factors associated with WNV disease.